FIELD OF INVENTION
The present disclosure relates to implants and methods for tracking implant performance, and particularly to joint implants and methods for tracking joint implant performance.
BACKGROUND OF THE INVENTION
Monitoring patient recovery after joint replacement surgery is critical for proper patient rehabilitation. A key component of monitoring a patient's recovery is evaluating the performance of the implant to detect implant dislocation, implant wear, implant malfunction, implant breakage, etc. For example, a tibial insert made of polyethylene (“PE”) implanted in a total knee arthroscopy (“TKA”) is susceptible to macroscopic premature failure due to excessive loading and mechanical loosening. Early identification of improper implant functioning and/or infection and inflammation at the implantation site can lead to corrective treatment solutions prior to implant failure. Data relating to postoperative range of motion and load balancing of the new TKA implants can be critical for managing recovery and identification of a proper replacement solution if necessary.
However, diagnostic techniques to evaluate implant performance are generally limited to patient feedback and imaging modalities such as X-ray fluoroscopy or magnetic resonance imaging (“MRI”). Patient feedback can be misleading in some instances. For example, gradual implant wear or dislocation, onset of infection, etc., may be imperceptible to a patient. Further, imaging modalities offer only limited insight into implant performance. For example, X-ray images will not reveal information related to the patient's range of motion or the amount of stress on the knee joint of a patient recovering from a TKA. Furthermore, the imaging modalities may provide only an instantaneous snapshot of the implant performance, and therefore fail to provide continuous real time information related to implant performance.
Patients may sometimes experience patellar tendonitis after a TKA procedures. Patellar tendonitis, often referred to as “Jumper's Knee” results in inflammation of a patient's patellar tendon. If left untreated, patellar tendonitis can lead to tears in the patellar tendon and instability in a patient's knee. After a TKA procedure, a misaligned or improperly rotated patellar implant may cause premature inflammation by applying mechanical forces to the surrounding tendons and tissue.
Therefore, there exists a need for implants and related methods for tracking implant performance and recovery parameters of a patient's joint.
BRIEF SUMMARY OF THE INVENTION
Disclosed herein are joint implants and methods for tracking joint implant performance.
In accordance with an aspect of the present disclosure a joint implant is provided. A joint implant according to this aspect, may include a first implant coupled to a first bone of a joint and a second implant coupled to a second bone of the joint. The first implant may include at least one marker. The second implant may contact the first implant. The second implant may include at least one marker reader to detect a position of the marker to identify positional data of the first implant with respect to the second implant. The second implant may include at least one load sensor to measure load data between the first and second implants. A processor may be operatively coupled to the marker reader and the load sensor. The processor may simultaneously output the positional data and the load data to an external source.
Continuing in accordance with this aspect, the marker may be a magnet and the marker reader may be a magnetic sensor. The magnetic sensor may be a Hall sensor assembly including at least one Hall sensor. The magnet may be a magnetic track disposed along a surface of the first implant. The first implant may include a first magnetic track extending along a medial side of the first implant and a second magnetic track extending along a lateral side of the first implant.
Continuing in accordance with this aspect, the second implant may include a first Hall sensor assembly on a medial side of the second implant and a second Hall sensor assembly on a lateral side of the second implant. The first Hall sensor assembly may be configured to read a magnetic flux density of the first magnetic track and the second Hall sensor assembly configured to read a magnetic flux density of the second magnetic track.
Continuing in accordance with this aspect, a central portion of the first magnetic track may be narrower than an anterior end and a posterior end of the first magnetic track. The first magnetic track may include curved magnetic lines extending across the first magnetic track.
Continuing in accordance with this aspect, the magnetic sensor may be coupled to the load sensor by a connecting element. The connecting element may be a rod configured to transmit loads from the magnetic sensor to the load sensor. The load sensor may be a strain gauge.
Continuing in accordance with this aspect, the joint may be a knee joint. The first implant may be a femoral implant and the second implant may be a tibial implant. The tibial implant may include a tibial insert and a tibial stem. The marker reader and the processor may be disposed within the tibial insert.
Continuing in accordance with this aspect, the positional data may include any of a knee flexion angle, knee varus-valgus rotation, knee internal-external rotation, knee medial-lateral translation, superior-inferior translation, anterior-posterior translation, and time derivatives thereof. The load data may include any of a medial load magnitude, lateral load magnitude, medial load center and lateral load center. The tibial insert may include any of a pH sensor, a temperature sensor and a pressure sensor operatively coupled to the processor. The tibial insert may include a spectroscopy sensor. The tibial insert may be made of polyethylene.
Continuing in accordance with this aspect, the joint implant may include an antenna to transmit the positional data and the load data to an external source. The external source may be any of a tablet, computer, smart phone, and remote workstation.
In accordance with another aspect of the present disclosure, a joint implant is provided. A joint implant according to this aspect, may include a first implant coupled to a first bone of a joint and a second implant coupled to a second bone of the joint. The first implant may include a plurality of medial markers located on a medial side of the first implant, and a plurality of lateral markers located on a lateral side of the first implant. The second implant may contact the first implant. The second implant may include at least one medial marker reader to identify a position of the medial markers and at least one lateral marker reader to identify a position of the lateral markers. The position of the medial markers and the position of the lateral markers may provide positional data of the first implant with respect to the second implant. The second implant may include a medial load sensor to measure medial load data between the first and second implants on a medial side of the joint implant, a lateral load sensor to measure lateral load data between the first and second implants on a lateral side of the joint implant. A processor may be operatively coupled to the medial marker reader, the lateral marker reader, the medial load sensor, and the lateral load sensor. The processor may simultaneously output the positional data, the medial load data, and the lateral load data to an external source.
Continuing in accordance with this aspect, a number of medial markers may be different from a number of lateral markers. The medial markers and the lateral markers may include magnets located at discrete locations on the first implant. The medial marker reader and the lateral marker reader may include a Hall sensor assembly with at least one Hall sensor. The medial load sensor and the lateral load sensor may include piezo stacks.
Continuing in accordance with this aspect, the joint implant may include a battery disposed within the second implant. The joint implant may include a charging circuit disposed within the second implant to charge the battery using power generated by the piezo stacks during loading between the first and second implants.
Continuing in accordance with this aspect, the joint may be a knee joint. The first implant may be a femoral implant and the second implant may be a tibial implant. The tibial implant may include a tibial insert and a tibial stem. The marker reader and the processor may be disposed within the tibial insert. The positional data may include any of a knee flexion angle, knee varus-valgus rotation, knee internal-external rotation, knee medial-lateral translation, anterior-posterior translation, superior-inferior translation, and time derivatives thereof.
Continuing in accordance with this aspect, the medial load data may include a medial load magnitude and a medial load center. The tibial insert may include any of a pH sensor, a temperature sensor, accelerometer, gyroscope, inertial measure unit and a pressure sensor operatively coupled to the processor. The tibial insert may include a spectroscopy sensor.
In accordance with another aspect of the present disclosure, a joint implant system is provided. A joint implant system according to this aspect, may include a first implant coupled to a first bone of a joint, a second implant coupled to a second bone of the joint, and an external sleeve configured to be removably attached to the joint. The first implant may include at least one marker. The second implant may contact the first implant. The second implant may include at least one marker reader to detect a position of the marker to identify positional data of the first implant with respect to the second implant. The second implant may include at least one load sensor to measure load data between the first and second implants. A processor may be operatively coupled to the marker reader and the load sensor. The processor may be configured to simultaneously output the positional data and the load data to an external source.
Continuing in accordance with this aspect, the joint implant system may include a battery to power the marker reader and the processor. The battery may be disposed within the second implant and including a joint implant charging coil. The external sleeve may include an external charging coil to charge the battery. The battery may be configured to be charged by ultrasonic wireless charging or optical charging.
In another aspect of the present disclosure, a method for monitoring a joint implant performance is provided. A method according to this aspect, may include the steps of providing a first implant couplable to a first bone of a joint, providing a second implant couplable to a second bone of the joint, tracking magnetic flux density magnitudes over time using a magnetic sensor, and initiating a warning when a tracked magnetic flux density magnitude is different from a predetermined value. The first implant may include at least one magnetic marker. The second implant may be configured to contact the first implant. The second implant may include at least one magnetic sensor to detect the magnetic flux density of the magnetic marker. The magnetic flux density value may be proportional to a thickness of the second implant.
In accordance with another aspect of the present disclosure, a method for monitoring a joint implant performance is provided. A method according to this aspect, may include the steps of providing a first implant couplable to a first bone of a joint, providing a second implant couplable to a second bone of the joint, tracking a rate of change of a magnetic flux density over time using a magnetic sensor, and initiating a warning when a tracked rate of change of the magnetic flux density exceeds a predetermined value. The first implant may include at least one magnetic marker. The second implant may be configured to contact the first implant. The second implant may include at least one magnetic sensor to detect the magnetic flux density of the magnetic marker. The rate of change of the magnetic flux density may be proportional to a wear rate of the second implant.
In accordance with another aspect of the present disclosure, a method of monitoring implant performance is provided. A method according to this aspect, may include the steps of providing an implant with a first sensor to detect implant temperature, a second sensor to detect a fluid pressure, and a third sensor to detect implant alkalinity, tracking and outputting implant temperature, implant pressure and implant alkalinity over time to an external source using a processor disposed within the implant, and initiating a notification when any of the implant temperature, implant pressure and implant alkalinity, or any combination thereof, exceeds a predetermined value. The implant temperature, implant pressure and implant alkalinity may be related to any of an implant failure and an implant infection. The fluid pressure may be a synovial fluid pressure.
Disclosed herein are joint implants and methods for tracking joint implant performance. The joint implant disclosed herein may include multiple components that are customized to interact with the joint anatomy. A first implant may be coupled to a femur and a second implant may be coupled to a patella. The second implant may include a processor and a plurality of sensors, which may be operatively coupled to the processor. The sensors may be able to measure data from the joint, and collect information such as the movement and alignment between the first and second implants, as well as the condition of the patella. This data may be fed to the processor, with the information indicating the extent and occurrence of conditions such as patellar rotation, patellar tilt, patellar tendonitis, etc. Furthermore, this data may be used to evaluate the overall performance of the implant, and identify any necessary adjustments to ensure optimal functioning.
In accordance with an aspect of the present disclosure, a knee joint implant comprises: a femoral implant coupled to a femur of the patient, the femoral implant including at least one marker; a patellar implant coupled to a patella of a patient, the patellar implant including: at least one marker reader to detect a position of the marker to identify positional data of the patellar implant with respect to the femoral implant, and a processor operatively coupled to the marker reader, wherein the processor outputs the positional data to an external source.
In a different aspect, the marker is a magnet and the marker reader is a magnetic sensor.
In another aspect, the magnetic sensor is a Hall sensor assembly including at least one Hall sensor.
In a different aspect, the magnet is a magnetic track disposed along a surface of the femoral implant.
In another aspect, the femoral implant includes a first magnetic track extending along a medial side of the first implant and a second magnetic track extending along a lateral side of the femoral implant.
In a further aspect, the patellar implant includes a first Hall sensor assembly on a medial side of the patellar implant and a second Hall sensor assembly on a lateral side of the patellar implant, the first Hall sensor assembly configured to read a magnetic flux density of the first magnetic track and the second Hall sensor assembly configured to read a magnetic flux density of the second magnetic track.
In yet another aspect, a central portion of the first magnetic track is narrower than an anterior end and a posterior end of the first magnetic track.
In another aspect, the first magnetic track includes curved magnetic lines extending across the first magnetic track.
In a different aspect, the magnetic sensor is coupled to a load sensor by a connecting element.
In a further aspect, the patellar implant includes any of a pH sensor, a temperature sensor and a pressure sensor operatively coupled to the processor.
In a different aspect, the patellar implant includes a transmitter to transmit the positional data and the load data to an external source.
In another aspect, the external source is any of a tablet, computer, smart phone, and remote workstation.
In a further aspect, an antenna is positioned within the patellar implant.
In a different aspect, the positional data indicates at least one of patellar shift and patellar rotation.
In accordance with another aspect of the present disclosure, a method for monitoring a patellar implant comprises: coupling a femoral implant to a femur of a joint; coupling a patellar implant to a patella; sensing sensor data with a sensor positioned in the patellar implant, the sensor data indicating a relative position of the patellar implant with reference to the femoral implant; and outputting the sensor data from a processor to an external source.
In a further aspect, the sensing step includes sensing the sensor data from at least one Hall sensor positioned in the patellar implant.
In another aspect, the sensing step further includes sensing magnetic flux density caused by at least one magnet positioned within the femoral implant.
In a different aspect, the outputting step includes gathering sensor data from the sensor, analyzing the sensor data with the processor, storing the sensor data, and emitting the sensor data to an external source.
In another aspect, storing step includes storing the sensor data within a memory system, the memory system including one of RAM, ROM, and flash.
In a different aspect, the outputting step includes outputting the sensor data to the external source via near-field communication.
In another aspect, the method further includes analyzing the sensor data with a machine learning algorithm.
In a different aspect, the analyzing step includes analyzing a first sensor data from a first point in time and comparing it to a second sensor data at a second point in time to determine a change in sensor data.
In another aspect, a change in sensor data indicates patellar tendonitis.
In accordance with another aspect of the present disclosure, a method of monitoring implant position over time comprises: coupling a femoral implant to a first bone of a joint; coupling a patellar implant to a second bone of the joint, the patellar implant including a sensor, a microcontroller, and a power source; measuring a reference movement value at a first time; measuring a secondary movement value at a second time; and comparing the reference movement value to the secondary movement value.
In another aspect, the coupling steps include coupling the femoral implant to a femur and coupling the patellar implant to a patella.
In another aspect, the measuring steps include measuring a first magnetic flux from a Hall sensor corresponding to the reference movement and measuring a second magnetic flux from the Hall sensor corresponding to the second movement.
In a further aspect, the measuring steps further include measuring first and second magnetic fluxes caused by magnets imbedded within the femoral implant.
In another aspect, the measuring steps include manipulating the joint in the same orientations at the first time and the second time, the first and second times being different.
In accordance with another aspect of the present disclosure, a method of measuring joint implant movement over time comprises: coupling a femoral implant to a first bone, the femoral implant including a magnet; coupling a patellar implant to a second bone, the patellar implant including a sensor configured to sense a magnetic flux caused by the magnet of the first implant; manipulating the joint at a first time such that the sensor registers a first magnetic flux data; repeating the manipulating step at a second time, the second time being different than the first time such that the sensor registers a second magnetic flux data; and outputting the first and second magnetic flux data from the first time and the second time to an external source.
In another aspect, the method further comprises processing the first and second magnetic flux data with a microcontroller.
In a different aspect, the method further comprises powering the microcontroller with a battery.
In yet another aspect, the method further comprises outputting the first and second magnetic flux data to the external source with Bluetooth communication.
In a different aspect, the method further comprises powering the microcontroller with an inductive coil positioned adjacent the microcontroller.
In another aspect, the powering step includes positioning an external power source adjacent the inductive coil to provide power to the inductive coil and the microcontroller via near-field communication.
In a different aspect, the method further comprises charging a battery when the external power source is positioned adjacent the inductive coil.
In another aspect, the method further comprises outputting the first and second magnetic flux data to the external source via near field communication.
In another aspect, the repeating step includes repeating identical movements of the joint.
In a further aspect, the repeating step includes repeating the manipulating movements at frequent intervals of time.
In another aspect, the sensor is a Hall sensor.
In a different aspect, the first bone is a femur and the second bone is a patella.
In another aspect, the joint is a knee joint.
In a further aspect, a change in the first and second magnetic flux data at the second time indicates patellar shift or patellar rotation.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the subject matter of the present disclosure and the various advantages thereof can be realized by reference to the following detailed description, in which reference is made to the following accompanying drawings:
FIG. 1 is a front view of a knee joint implant according to an embodiment of the present disclosure;
FIG. 2 is a side view of a femoral implant of the knee joint implant of FIG. 1;
FIG. 3A is a bottom view of the femoral implant of FIG. 2;
FIG. 3B is schematic view of encoder tracks of the femoral implant of FIG. 2;
FIG. 4 is a partial view of an encoder read head and a load sensor of a tibial implant of the knee joint implant of FIG. 1;
FIG. 5A is a front view of an antenna of the knee joint implant of FIG. 1;
FIG. 5B is a top view of the antenna of FIG. 5A;
FIG. 6 is a perspective side view of a knee joint implant according to another embodiment of the present disclosure;
FIG. 7 is a perspective front view of a tibial implant of the knee joint implant of FIG. 6;
FIG. 8 is a partial perspective view of an insert of the tibial implant of FIG. 6;
FIG. 9 is a partial top view of the insert of FIG. 8 showing details of various insert components;
FIG. 10 is a perspective side view of the insert of the tibial implant of FIG. 7;
FIG. 11 is a perspective side view of a cover of the insert of FIG. 10;
FIG. 12 are graphs showing magnetic flux density measurements of the implant sensors and knee flexion angles;
FIG. 13 is a graph showing various implant sensor readings of the knee joint implant of FIG. 6;
FIG. 14 is a schematic view of implant sensors of the knee joint implant of FIG. 6 in communication with a processor;
FIG. 15 is a graph showing voltage measurements of the implant sensors;
FIG. 16 is a schematic view of a charging circuit for the knee joint implant of FIG. 6;
FIG. 17A is a graph showing measured voltage of the implant sensors;
FIG. 17B is a graph showing rectified voltage of the implant sensors;
FIG. 18 is a schematic view of a knee joint implant with a charging sleeve according to an embodiment of the present disclosure;
FIG. 19 is a front view of the charging sleeve of the knee joint implant of FIG. 17;
FIG. 20 is a side view of an insert of the knee joint implant of FIG. 17;
FIG. 21 shows top and front views of the insert of FIG. 19;
FIG. 22A is front view of a knee joint implant according to another embodiment of the present disclosure;
FIG. 22B is a side view of the knee joint implant of FIG. 22A;
FIG. 23A is a front view of a tibial implant according to another embodiment of the present disclosure;
FIG. 23B is a top view of an insert of the tibial implant of FIG. 22A;
FIG. 24A is a front view of a tibial implant according to another embodiment of the present disclosure;
FIG. 24B is a top view of an insert of the tibial implant of FIG. 24A;
FIG. 25A is a front view of a tibial implant according to another embodiment of the present disclosure;
FIG. 25B is a top view of an insert of the tibial implant of FIG. 25A;
FIG. 26 is a side view of a knee joint implant according to another embodiment of the present disclosure;
FIG. 27 is a front view of a tibial implant of the knee joint implant of FIG. 26;
FIG. 28 is a schematic side view of a knee joint implant illustrating various measurements according to another embodiment of the present disclosure;
FIG. 29 is a schematic side view of a spinal implant assembly according to another embodiment of the present disclosure;
FIG. 30 is side view of a hip implant according to another embodiment of the present disclosure;
FIG. 31A is a schematic view of a sensor assembly of the hip implant of FIG. 30;
FIG. 31B is a side view of the sensor assembly and an insert of the hip implant of FIG. 31A;
FIG. 31C is a top view of the sensor assembly and the insert of FIG. 31B;
FIG. 32 is a side view of a hip implant according to another embodiment of the present disclosure;
FIG. 33 is a partial top view of the hip implant of FIG. 32;
FIG. 34 is a side view of a hip implant according to another embodiment of the present disclosure;
FIG. 35 is a side view of an electronic assembly of the hip implant of FIG. 34 according to another embodiment of the present disclosure;
FIG. 36 is a side view of an electronic assembly of the hip implant of FIG. 34 according to another embodiment of the present disclosure;
FIG. 37 is a side view of a shoulder implant according to another embodiment of the present disclosure;
FIG. 38 is top view of an insert of the shoulder implant of FIG. 37;
FIG. 39 is a top view of a cup of the shoulder implant of FIG. 37;
FIG. 40 is side view of a shoulder implant according to another embodiment of the present disclosure;
FIG. 41 is a side view of an insert of the shoulder implant of FIG. 40;
FIG. 42 is a flowchart showing steps to determine implant wear according to another embodiment of the present disclosure;
FIG. 43 is a first graph showing implant thickness over time;
FIG. 44 is a second graph showing implant thickness over time;
FIG. 45 is a flowchart showing steps to determine implant wear according to another embodiment of the present disclosure;
FIG. 46 is a flowchart showing for implant data collection according to another embodiment of the present disclosure;
FIGS. 47A and 47B is a flowchart showing steps for patient monitoring according to another embodiment of the present disclosure;
FIG. 48 is a front view of a knee joint implant according to an embodiment of the present disclosure;
FIG. 49 is a perspective view of a femoral implant of the knee joint implant of FIG. 48;
FIG. 50 is a perspective view of a patellar implant;
FIG. 51 is a side view of the patellar implant of FIG. 50;
FIG. 52 is perspective view of another embodiment of a patellar implant;
FIG. 53 is another perspective view of the patellar implant of FIG. 52;
FIG. 54 is a perspective view of the femoral implant of FIG. 49 with the patellar implant of FIGS. 52-53, and
FIG. 55 is a schematic flowchart view of the data stream of the knee joint implant of FIG. 48.
DETAILED DESCRIPTION
Reference will now be made in detail to the various embodiments of the present disclosure illustrated in the accompanying drawings. Wherever possible, the same or like reference numbers will be used throughout the drawings to refer to the same or like features within a different series of numbers (e.g., 100-series, 200-series, etc.). It should be noted that the drawings are in simplified form and are not drawn to precise scale. Additionally, the term “a,” as used in the specification, means “at least one.” The terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import. Although at least two variations are described herein, other variations may include aspects described herein combined in any suitable manner having combinations of all or some of the aspects described.
As used herein, the terms “load” and “force” will be used interchangeably and as such, unless otherwise stated, the explicit use of either term is inclusive of the other term. Similarly, the terms “magnetic markers” and “markers” will be used interchangeably and as such, unless otherwise stated, the explicit use of either term is inclusive of the other term.
As used herein, the terms “power” and “energy” will be used interchangeably and as such, unless otherwise stated, the explicit use of either term is inclusive of the other term. Similarly, the terms “implant” and “prosthesis” will be used interchangeably and as such, unless otherwise stated, the explicit use of either term is inclusive of the other term. The term “joint implant” means a joint implant system comprising two or more implants. Similarly, the terms “energy generator” and “energy harvester” will be used interchangeably and as such, unless otherwise stated, the explicit use of either term is inclusive of the other term.
In describing preferred embodiments of the disclosure, reference will be made to directional nomenclature used in describing the human body. It is noted that this nomenclature is used only for convenience and that it is not intended to be limiting with respect to the scope of the present disclosure. As used herein, when referring to bones or other parts of the body, the term “anterior” means toward the front part of the body or the face, and the term “posterior” means toward the back of the body. The term “medial” means toward the midline of the body, and the term “lateral” means away from the midline of the body. The term “superior” means closer to the head, and the term “inferior” means more distant from the head.
FIG. 1 is a front view of a knee joint implant 100 according to an embodiment of the present disclosure. Knee joint implant 100 includes a femoral implant 102 located on a femur 106 and a tibial implant 104 located on a tibia 108. Tibial implant 104 has a tibial insert 110 configured to contact femoral implant 102, and a tibial baseplate or tibial stem 112 extending distally into tibia 108. Femoral implant 102 includes a medial encoder track 114 located on a medial side and a lateral encoder track 116 on a lateral side of the femoral implant. While the encoder tracks are shown along a surface of femoral implant 102 in FIG. 1, these tracks can be located within or partially within a femoral implant on the medial and lateral sides thereof in other embodiments. The encoder tracks can be made of various structures, including magnetic tape of varying lengths and magnetic markers positioned at discrete locations. The resolution of the encoder track can be adjusted depending on the required precision of the measured parameters such as joint displacement, joint rotation, joint slip, etc. Tibial insert 110 includes a medial read head 118 and lateral read head 120 to read a magnetic flux density from medial encoder track 114 and lateral encoder track 116, respectively. Medial read head 118 and lateral read head 120 can be any suitable magnetometer configured to detect and measure magnetic flux density, such as a Hall effect sensor. As tibia 108 rotates with reference to femur 106 during knee flexion and extension, medial encoder track 114 and lateral encoder track 116 move along medial read head 118 and lateral read head 120, respectively. This movement causes a change in magnetic flux density which is detected by read heads 118, 120, and can be utilized to measure knee joint implant 100 movement, rotation, speed and range of articulation, motion/activity, joint slip, and other motion related information. The magnetic-mechanic coupling of the read heads with the encoder tracks allows for direct, instantaneous, and continuous measurements of these knee joint implant parameters. A data transmitter such as an antenna 122 located on tibial insert 110 transmits the knee joint implant parameters measured by the read heads via Bluetooth or other similar wireless means to an external source such as a smart phone, tablet, monitor, network, etc. to allow for real time review of the knee joint implant performance.
FIGS. 2-3B illustrate additional details of femoral implant 102, medial encoder track 114 and lateral encoder track 116. As shown in FIG. 2, medial encoder track 114 extends from an anterior portion 126 of femoral implant 102 to a posterior portion 128 of the femoral implant along a track axis 130. Medial encoder track 114 includes a central portion 124 which is narrower than anterior and posterior portions 126, 128 as shown in FIG. 3A. As shown in FIG. 3B, medial encoder track 114 includes arched or curved magnetic lines to compensate for joint rotations in order to maintain uniform readings during a full range of motion of the knee joint. Similarly, lateral encoder track 116 extends from an anterior portion to a posterior portion of the femoral implant and includes a narrow central portion relative to the anterior and posterior portions with arched or curved magnetic lines. The conical profile and curved magnetic lines of the encoder tracks are configured to compensate for joint rotational motion and maintain alignment and coupling between the read heads and the tracks. This maximizes measurement collection and measurement accuracy during a full range of motion of the knee joint. The shape, size and location of the encoder tracks can vary depending on the implant.
FIG. 4 shows details of a medial side of tibial insert 110. Tibial insert 110 includes a medial load sensor 132 in connection with medial read head 118 via a medial connector 134. Medial load sensor 132 is a load measuring sensor such as a strain gauge or piezoelectric sensor configured to measure loads or forces transmitted from medial read head 118 via medial connector 134. Medial connector 134 can be a rigid member such as a connecting rod to transmit loads from medial read head 118 to medial load sensor 132. As shown in FIG. 4, a portion of the medial side of femoral implant 102 directly contacts medial read head 118 to transmit loads (medial side loads), which is then measured by medial load sensor 132. Medial read head 118 is spring-loaded by a medial load spring 136 located below medial load sensor 132 to ensure contact between medial read head 118 and femoral implant 102. Similarly, a lateral side of tibial insert 110 includes a lateral load sensor, a lateral connector, and a lateral load spring. The lateral load sensor is configured to measure lateral loads between femoral implant 102 and tibial implant 104. Measured medial and lateral loads are transmitted via antenna 122 to an external source. Thus, knee joint implant 100 can simultaneously provide knee motion information (rotation, speed, flexion angle, etc.) and knee load (medial load, medial load center, lateral load, lateral load center, etc.) in real time to an external source.
Details of antenna 122 are shown in FIGS. 5A and 5B. Antenna 122 includes screw threads configured to be attached to tibial insert 110. Antenna 122 can include a coax interface to shield knee joint and improve transmission between knee joint implant 100 and the external source. A battery is located adjacent antenna 122 (not shown) to power knee joint implant 100. Antenna 122 can serve as a charging port via radio frequency (RF) or inductive coupling if a rechargeable battery is used. The location of battery and antenna 122 in tibial insert 110 allow for convenient access to remove and replace these components if necessary. Various other sensors such as a temperature sensor, pressure sensor, accelerometer, gyroscope, magnetometer, pH sensor, etc., can be included in knee joint implant 100 as more fully described below.
FIG. 6 is a perspective side view of a knee joint implant 200 according to another embodiment of the present disclosure. Knee joint implant 200 is similar to knee joint implant 100, and therefore like elements are referred to with similar numerals within the 200-series of numbers. For example, knee joint implant 200 includes a femoral implant 202, a tibial implant 204 with a tibial insert 210 and a tibial stem 212. However, knee joint implant 200 includes magnetic medial markers 214 and magnetic lateral markers 216 located at discrete locations along the medial and lateral sides of femoral implant 202, respectively.
Details of tibial insert 210 are shown in FIGS. 7-11. Tibial insert 210 includes batteries 242 on both medial and lateral sides. Batteries 242 can be solid state batteries, lithium ion batteries, lithium carbon monofluoride batteries, lithium thionyl chloride batteries, lithium ion polymer batteries, etc. As best shown in FIG. 9, Hall sensor assemblies, with each assembly including at least one Hall sensor, are used as a medial marker reader 252 and a lateral marker reader 248 to read medial markers 214 and lateral markers 216, respectively. Each Hall sensor assembly can include multiple Hall sensors arranged in various configurations and orientations. For example, the Hall sensor assembly can include Hall sensors oriented in Cartesian coordinates. As the tibia rotates with reference to the femur during knee flexion and extension, medial markers 214 and lateral markers 216 move along medial marker reader 252 and lateral marker reader 248, respectively. This movement causes a change in magnetic flux density, which is detected by marker readers 252, 248, to measure knee joint implant 200 movement, rotation, speed and range of articulation, motion/activity, joint slip, and other motion related information. The magnetic-mechanic coupling of the marker readers with the markers allows for direct, instantaneous, and continuous measurements of these knee joint implant parameters without the need to process this information via an algorithm or other means. While eight Hall sensor assemblies (four on each side) are shown in this embodiment, other embodiments can have more than eight or less than eight Hall sensor assemblies positioned at various locations. The arrangement of marker readers and markers provide absolute positions of knee joint implant 200 supporting wake-up-and-read kernels. Thus, no inference of movement by data synchronization techniques is required to obtain absolute position data of knee joint implant 200. The number of medial markers 214 can be different from the number of lateral markers 216 to account for variation in signal fidelity between these sides. For example, seven magnetic markers can be provided on the medial side and only four magnet markers can be provided on the lateral side to improve signal fidelity and motion detection precision on the medial side.
As best shown in FIG. 9, three piezo stacks on the medial side serve as medial load sensors 232, and three piezo stacks on the lateral side serve as lateral load sensors 254. The staggered or non-linear arrangement of the three piezo stacks on the medial and lateral sides allow for net load measurements and identification of resultant load centers at the medial and lateral sides. Thus, knee joint implant 200 can simultaneously provide knee motion information (joint rotation, joint speed, joint flexion angle, joint slippage, etc.) and knee load (medial load, medial load center, lateral load, lateral load center, etc.) in real time to an external source. The piezo stacks are configured to generate power from the patient's motion by converting pressure on the piezo stacks to charge batteries 242 as more fully described below. Thus, knee joint implant 200 does not require external charging devices or replacement batteries for the active life of the implant.
Tibial insert 210 includes an infection or injury detection sensor 244. For example, the infection or injury detection can be a pH sensor configured to measured bacterial infection by measuring the alkalinity of synovial fluid to provide early detection of knee joint implant 200 related infection. A temperature and pressure sensor 246 is provided in tibial insert 210 to monitor knee joint implant 200 performance. For example, any increase in temperature and/or pressure may indicate implant-associated infection. Pressure sensor 246 is used to measure synovial fluid pressure in this embodiment. Temperature and/or pressure sensor 246 readings can provide early detection of knee joint implant 200 related infection. Thus, injury detection sensors 244 and 236 provide extended diagnostics with heuristics for first level assessment of infections or injury related to knee joint implant 200. An onboard processor 250 such as a microcontroller unit (“MCU”) is used to read sensors 244 and 236 and process results for transmission to an external source. This data can be retrieved, processed, and transferred by the MCU via antenna 222 continuously, at predefined intervals, or when certain alkalinity, pressure, and/or temperature thresholds, or any combinations thereof, are detected.
The various sensors and electronic components of tibial insert 210 are contained within an upper cover 256 and a lower cover 258 as shown in FIG. 10. The upper and lower covers can be made from a polymer. Antenna 222 is located on an anterior portion of knee joint implant 200 to provide better line of site for transmitting data with less interference. The antenna is fixed inside the polymer covers to provide predictable inductance and capacitance. A cover 260 encloses the sensors and electronic components of tibial insert 210 as shown in FIG. 11. Cover 260 can be a hermetic cover to hermetically seal tibial insert 210. Cover 260 is preferably made of metal and provides radio frequency (“RF”) shielding to the knee joint.
The modular design of knee joint implant 200 provides for convenient maintenance of its components. For example, an in-office or outpatient procedure will allow a surgeon to access the tibia below the patella (an area of minimal tissue allowing for fast recovery) to access component of knee joint implant 200. The electronic components and sensors of knee joint are modular and connector-less allowing for convenient replacement of tibial insert 210 or upgrades to same without impacting the femoral implant or the tibial stem.
Graphs plotting magnetic flux density measurements 310 and knee flexion angles 312 are shown in FIG. 12. Magnetic flux density measurements 310 are generated from the magnetic-mechanic coupling of marker readers 248, 252 with the markers 214, 216 as more fully described above. Graphs 302 and 304 show magnetic flux density (mT) measurements from two Hall sensor assemblies (medial marker reader 252 or lateral marker reader 248) for a first range of motion of the knee joint. Similarly, graphs 306 and 308 show magnetic flux density (mT) measurements from two Hall sensors (medial marker reader 252 or lateral marker reader 248) for a second range of motion of the knee joint. The placement of magnetic markers 214, 216 on the femoral component create a sinusoidal magnetic flux density around femoral implant 202. As the femoral implant 202 rotates around an axis of rotation 201 shown in FIG. 6, the marker readers read sine and cosine waveforms. The magnitude of the sine and cosine waves are interpolated to a near linear knee flexion angle. Placing the individual magnetic markers of medial markers 214 and lateral markers 216 at different separation angles on each condyle of femoral implant 202 creates a phase shift in the measurements from one condyle to the next as the knee rotates. This phase shift can then be used to correct for any rollovers in the interpolated waveform. Thus, marker readers 248, 252 and markers 214, 216 serve as an absolute rotation sensor measuring knee flexion through a full range of motion of knee joint implant 200. In addition to the two Hall sensor assemblies on the lateral and medial side of tibial insert 210, the remaining Hall sensor assemblies of marker readers 248, 252 allow for 6-degrees of freedom movement measurements of knee joint implant 200 as more fully explained below. While an absolute magnetic encoder is disclosed in this embodiment, other embodiments can include a knee joint implant with an incremental magnetic encoder.
FIG. 13 is a graph showing various implant injury detection sensor readings 404 of knee joint implant 200 for early detection of knee joint implant related infection and/or failure. Pressure 408 and temperature 406 are measured using temperature and pressure sensor 246, and alkalinity 410 is measured using pH sensor 244 over time 402. As more fully explained above, alkalinity 410 measurements of joint synovial fluid can indicate bacterial infection to provide early detection of knee joint implant 200 related infection. Increase in pressure 408 and temperature 406 readings may indicate implant-associated infection. Variation or change in synovial fluid pressure 408 may indicate implant malfunction. In addition to predetermined absolute thresholds of the temperature, pressure and alkalinity readings indicating impending infection or implant failure, collective analysis of these readings can offer early detection warning ahead of the failure/infection thresholds. As shown in FIG. 14, a combination of temperature, pressure and alkalinity may indicate early detection of trauma 414 or infection 412. Thus, injury detection sensor readings provide extended diagnostics with heuristics for first level assessment of infections or injury related to knee joint implant 200.
FIG. 14 is a schematic view of piezo stacks of medial load sensors 232 and lateral load sensor 254 in communication with a processor 266. Analog impulses generated by the piezo stacks when subjected to loading are converted to continuous digital signals via analog-to-digital converters 262 and 264 as shown in FIG. 14. The continuous digital signals (voltage) 508 can be serially loaded into a shift register and measured as shown in a graph 500 of FIG. 15. A sampling window 506 is selected to identify a peak reading 508 to detect knee joint motion. For continuous loading case, such as when a patient is standing, additional sensors such as an inertial measurement unit (“IMU”) located in the tibial insert or other locations on knee joint implant 200 can be used to detect or confirm knee joint position. Load data from piezo stacks and IMU measurements can be used to create load and motion profiles for patient-specific or patient-independent analyses.
FIG. 16 is a schematic view of a charging circuit 600 for charging battery 242 of knee joint implant 200. The charging circuit includes a charge circuit 602 connected to a charging coil 606 and piezo stacks of medial load sensors 232 and lateral load sensors 254 via bridge rectifier 604. Charging circuit is configured to direct charge to battery 242 utilizing inputs from one or more piezo stacks from the medial or lateral load sensors. This allows for singular or combined charging using individual or multiple piezo stacks. A minimum voltage output threshold of the piezo stacks can be predetermined to initiate battery charging. For example, when a patient is asleep, low piezo stack pulses will not be used to charge battery 242. Raw piezo stack pulses (voltage 704) as shown in a graph 700 of FIG. 17 over time 706 are rectified by a voltage rectifier 708 to produce a rectified and smoothed voltage output (voltage 704) shown in a graph 702 of FIG. 17B. The rectified and smoothed voltage output from the piezo stacks is used to charge battery 242. Thus, power harvesting from motion of knee joint implant 200 is achieved by using the pulses generated by the piezo stacks.
FIG. 18 is a schematic view of a knee joint implant 800 according to another embodiment of the present disclosure. Knee joint implant 800 is similar to knee joint implant 200, and therefore like elements are referred to with similar numerals within the 800-series of numbers. For example, knee joint implant 800 includes a femoral implant 802, a tibial implant 804 with a tibial stem 812 and a tibial insert 810. However, knee joint implant 800 includes a chargeable implant coil 872 located in tibial insert 810 which can be charged by an external coil 870 contained in an external sleeve 868 as shown in FIG. 18.
External sleeve 868 shown in FIG. 19 includes an outer body 873 made of stretchable fabric or other material. Outer body 873 is configured to be a ready-to-wear pull-on knee sleeve which a patiently can conveniently put on and remove. A kneecap indicator 875 allows the patient to conveniently align sleeve 868 with knee joint implant 800 for proper placement of external coil 870 with reference to implant coil 872 for charging. As shown in FIG. 18, when a patient aligns external sleeve 868 using kneecap indicator 875 and assumes a flexion position, external coil 870 is adjacent to implant coil 872 for proper charging. External sleeve 868 includes a battery 876 and a microcontroller 874 as shown in FIG. 19. Battery 876, which can be conveniently replaced, provides power to external coil 870. In another embodiment, external coil 870 may be charged by an external source not located on sleeve 868.
FIG. 20 shows a side view of tibial insert 810 of knee joint implant 800. Tibial insert 810 is made of a polymer or other suitable to facilitate charging of implant coil 872. Implant coil 872 is located within tibial insert 810 at an indent or depression at a proximal-anterior corner of the tibial insert as show in FIG. 20 and FIG. 21 (top and front views of tibial implant 810). The proximal-anterior location of implant coil 872 maximizes access to external coil 870 for efficient and convenient charging.
FIGS. 22A and 22B show a knee joint implant 900 according to another embodiment of the present disclosure. Knee joint implant 900 is similar to knee joint implant 800, and therefore like elements are referred to with similar numerals within the 900-series of numbers. For example, knee joint implant 900 includes a femoral implant 902, a tibial implant 904 with a tibial stem 912 and a tibial insert 910. However, knee joint implant 900 includes a chargeable implant coil 972 located at anterior end of tibial insert 910 which can be charged by an external coil 970 (not shown). An external sleeve as described with reference knee joint implant 900, or another charging mechanism can be used to conveniently charge implant coil 972.
FIG. 23A is a front view of a tibial implant 1004 according to an embodiment of the present disclosure. Tibial implant 1004 is similar to tibial implant 204, and therefore like elements are referred to with similar numerals within the 1000-series of numbers. For example, tibial implant 1004 includes a tibial stem 1012 and a tibial insert 1010. However, tibial insert 1010 includes a charging coil 1072 located around a periphery of the tibial insert 1010 as shown in FIG. 23B. A spectroscopy sensor 1074 in tibial insert 1010 serves as an infection detection sensor for tibial implant 1004. Spectroscopy sensor 1074 is configured to identify the onset of biofilm on tibial implant (or a corresponding femoral implant) to provide early detection of implant related infection.
FIG. 24A is a front view of a tibial implant 1104 according to an embodiment of the present disclosure. Tibial implant 1104 is similar to tibial implant 204, and therefore like elements are referred to with similar numerals within the 1100-series of numbers. For example, tibial implant 1104 includes a tibial stem 1112 and a tibial insert 1110. However, tibial insert 1110 includes an IMU 1176 and five Hall sensor assemblies for each of the medial and lateral marker readers. The arrangement of the Hall sensor assemblies differ from tibial insert 210. Sensor data from IMU 1176 provides additional knee implant joint movement data as more fully explained above. For example, IMU 1176 can detect or confirm knee joint position during continuous loading positions of a patient such as standing. IMU data can reveal, or support measurements related to gait characteristics, stride, speed, etc., of a patient. pH sensor 1144 of tibial insert 1110 is located adjacent to a proximal face of the tibial insert at a central location as shown in FIG. 24B. All sensors of tibial implant 1104 are powered by batteries located in tibial insert 1110.
A tibial implant 1204 according to another embodiment of the present disclosure is shown in FIGS. 25A and 25B. Tibial implant 1204 is similar to tibial implant 204, and therefore like elements are referred to with similar numerals within the 1200-series of numbers. For example, tibial implant 1204 includes a tibial stem 1212 and a tibial insert 1210. However, tibial insert 1210 includes an IMU 1276 and a pressure sensor. Tibial insert 1210 is made of polyethylene and tibial stem 1212 is made of titanium in this embodiment.
FIG. 26 is a side view of a knee joint implant 1300 according to another embodiment of the present disclosure. Knee joint implant 1300 is similar to knee joint implant 200, and therefore like elements are referred to with similar numerals within the 1300-series of numbers. For example, knee joint implant 1300 includes a femoral implant 1302, a tibial implant 1304 with a tibial stem 1312 and a tibial insert 1310. However, battery 1342 of knee joint implant 1300 are located in tibial stem 1312 as best shown in FIG. 27. Locating batteries 1342 in tibial stem provides room for additional sensors in tibial insert 1310. The tibial stem and tibial insert 1310 can be made of polyethylene in this embodiment. Various knee joint implant motion data 1301 collected by magnetic markers and marker readers is shown in FIG. 26. Motion data 1301 can include internal-external rotation, medial-lateral rotation, varus-valgus rotation, etc.
A knee joint implant 1400 according to another embodiment of the present disclosure is shown in FIG. 28. Knee joint implant 1400 is similar to knee joint implant 200, and therefore like elements are referred to with similar numerals within the 1400-series of numbers. For example, knee joint implant 1400 includes a femoral implant 1402, a tibial implant 1404 with a tibial stem 1412 and a tibial insert 1410. However, tibial insert 1410 includes an IMU 1476. Sensor data from IMU 1476 provides additional knee implant joint motion data 1401. Motion data 1401 can include internal-external rotation, medial-lateral rotation, varus-valgus rotation, etc. for reviewing knee joint implant 1400 performance. For example, internal-external rotation measurements exceeding a predetermined threshold can indicate knee joint implant lift-off (instability), medial-lateral rotation measurements exceeding predetermined thresholds can indicate knee joint implant stiffness. Combining these measurements with inputs from the various other sensors of tibial insert 1410 will provide a detailed assessment of knee joint implant 400 performance.
Referring now to FIG. 29, a spinal implant assembly 1500 is shown according to an embodiment of the present disclosure. Spinal implant assembly 1500 includes a spinal implant 1510 such as a plate, rod, etc., secured to first and second vertebrae by a first fastener 1502 and a second fastener 1504, respectively. The first and second fasteners can be screws as shown in FIG. 29. First fastener 1502 includes magnetic flux density detectors such as Hall sensor assemblies 1506 located along a body of the fastener 1502. Second fastener 1504 includes magnetic markers 1508 located along a body of the fastener. Any movement of second fastener 1504 with respect to the first fastener is detected and measured by Hall sensor assemblies 1506. Thus, the first and second fasteners function as an absolute or incremental encoder to detect spinal mobility of a patient during daily activity. As described with reference to the knee joint implants disclosed above, various other sensors such as temperature, pressure, pH, load, etc., can be included in fast fastener 1502 to provide additional measurements related to spinal implant assembly 1500 performance during a patient's recovery and rehabilitation. Ideally, there should be little to no movement between the first and second vertebrae for successful for spinal fusion. Therefore, any movement detected between the first and second fastener may indicate a compromised spinal implant assembly.
FIG. 30 is side view of a hip implant 1600 according to an embodiment of the present disclosure. Hip implant 1600 includes a stem 1602, a femoral head 1604, an insert 1606 and an acetabular component 1608. Magnetic flux density sensors such as Hall sensor assemblies 1626 are located on a flex connect 1628 and placed around femoral head 1604 as shown in FIGS. 31A and 31B. A connector 1622 on flex connect 1628 allows for convenient connection of femoral head 1604 with stem 1602. Magnetic markers 1630 are located on insert 1606 as best shown in FIG. 31C. Any motion of insert 1606 is detected by Hall sensor assemblies 1626 by measuring the change in magnetic flux density. Thus, Hall sensor assemblies 1626 and markers 1630 function as an absolute or incremental encoder to detect hip movement of a patient during daily activity.
Hip implant 1600 includes a charging coil 1610 located on stem 1602 as shown in FIG. 30. Charging coil 1610 charges a battery 1612 via a connector 1624 to power the various sensors located in hip implant 1600. A load sensor 1614 such a strain gauge detects forces between stem 1602 and acetabular component 1608 to monitor and transmit hip loads during patient rehabilitation and recovery. Various electronic components 1616, including sensors described with reference to knee joint implants, are located in stem 1602. A pH sensor 1618 located on stem can measure alkalinity and provide early detection notice of implant related infection. Data from these sensors is transmitted to an external source via an antenna 1620 as described with reference to the knee joint implants disclosed above.
FIG. 32 is a side view of a hip implant 1700 according to another embodiment of the present disclosure. Hip implant 1700 is similar to hip implant 1600, and therefore like elements are referred to with similar numerals within the 1700-series of numbers. For example, hip implant 1700 includes a stem 1702, a femoral head 1704 and an acetabular component (not shown). However, battery 1712 of hip implant 1700 is located away from electric components 1716 as best shown in FIG. 32. Battery 1712 can be conveniently inserted into hip implant 1700 via a slot 1734 as shown in FIG. 33. Similarly, electric components 1716 can be inserted into hip implant 1700 via a slot 1732. This allows for convenient replacements and upgrades to the battery and electric components without disturbing hip implant 1700.
FIG. 34 is a side view of a hip implant 1800 according to another embodiment of the present disclosure. Hip implant 1800 is similar to hip implant 1600, and therefore like elements are referred to with similar numerals within the 1800-series of numbers. For example, hip implant 1800 includes a stem 1802, a femoral head 1804 and an acetabular component (not shown). However, slot 1832 of hip implant 1800 is configured to receive all electronic components structured as a modular electronic assembly 1801 or a sensor assembly. A slot cover 1834 ensures that electronic assembly 1801 is secured and sealed in slot 1832. Thus, hip implant 1800 can be easily provided with replacement or upgrades to the electric components without disturbing hip implant 1800.
A first embodiment of a modular electronic assembly 1801 is shown in FIG. 35. Electronic assembly includes a connector 1822 to connect to femoral head 1804, various electronic components 1816, a battery 1812 and an antenna 1820. Another embodiment of a modular electronic assembly 1801′ is shown in FIG. 36. Electronic assembly 1801′ includes various electronic components 1816′, a battery 1812′, a load sensor such as a strain gauge 1814′ and an antenna 1820′. Electronic assembly 1801′ includes a pH sensor 1818′ to provide early detection of implant related infection.
FIG. 37 is a side view of a reverse shoulder implant 1900 according to an embodiment of the present disclosure. Shoulder implant 1900 includes a stem 1902, a cup 1904, an insert 1906 and a glenoid sphere 1908. Magnetic flux density sensors such as Hall sensor assemblies 1922 are located on insert 1906 as shown in FIG. 38. A connector 1920 on cup 1904 as shown in FIG. 39 allows for attachment of the cup to insert 1906. Magnetic markers 1910 are located on glenoid sphere 1908 as best shown in FIG. 37. Any motion of glenoid sphere 1908 is detected by Hall sensor assemblies 1922 by measuring the change in magnetic flux density. Thus, Hall sensor assemblies 1922 and markers 1910 function as an absolute or incremental encoder to detect shoulder movement of a patient during daily activity.
Shoulder implant 1900 includes a battery 1914 and an electronic assembly 1912 located within cup 1904. A pH sensor 1916 is located on cup 1904 to measure alkalinity and provide early detection notice of implant related infection. An antenna 1918 located on insert 1906 is provided to transmit sensor data to an external source to monitor and transmit shoulder implant 1900 performance during patient rehabilitation and recovery. Various electronic components of electronic assembly 1912, including sensors described with reference to knee joint implants, are located in cup 1904.
FIG. 40 is a side view of a reverse shoulder implant 2000 according to another embodiment of the present disclosure. Shoulder implant 2000 is similar to shoulder implant 1900, and therefore like elements are referred to with similar numerals within the 2000-series of numbers. For example, shoulder implant 2000 includes a stem 2002, a cup 2004 and an insert 2006. However, electronic assembly 2012, battery 2014 and pH sensor 2018 are located in insert 2006 as shown in FIG. 41. Thus, only a single component—i.e., the cup, of shoulder implant 2000 can be replaced or upgraded to make changes to sensor collection and transmission of the shoulder implant performance data.
FIG. 42 is a flowchart showing steps of a method 2100 to determine implant wear according to an embodiment of the present disclosure. While method 2100 is described with reference to a knee joint implant below, method 2100 can be applied to any implant with sensors described in the present disclosure, including all of the implants disclosed above. In a first step 2102, the initial thickness of the knee joint implant (such as thickness of the tibial insert) is recorded. This can be obtained by measuring the tibial insert prior to implantation, or measured based on the magnetic flux density generated by the magnetic markers as measured by the Hall sensor assemblies. Once the knee joint implant is implanted, periodic measurements of tibial insert thickness are determined in a step 2104 by evaluating the magnetic flux density. As the polyethylene housing of tibial insert degrades over time, the distance between the markers and Hall sensor assemblies are reduced as measured in a step 2106. This results in increased magnetic flux density values, which are used to estimate tibial insert wear in a step 2108.
The decision to replace the tibial insert can be based on a rate of wear threshold 2206 as shown in graph 2200 of FIG. 43 in a step 2110, or a critical thickness value 2308 as shown in graph 2300 of FIG. 44 in a step 2112. Graph 2200 plots tibial insert thickness 2202 over time 2204. A change in slope 2206 denotes the rate of wear of tibial insert. When slope 2206 exceeds the predetermined rate of wear threshold, notification to replace the tibial insert is triggered in a step 2114. Graph 2300 plots tibial insert thickness 2302 over time 2304. When the tibial insert thickness is less than a predetermined critical thickness value 2308, a notification 2310 is triggered to replace the tibial insert in step 2114.
FIG. 45 is a flowchart showing steps of a method 2400 to determine implant wear according to another embodiment of the present disclosure. While method 2400 is described with reference to a knee joint implant below, method 2400 can be applied to any implant with sensors described in the present disclosure, including all of the implants disclosed above. In a first step 2402, a knee angle of a patient with the knee joint implant is measured. The knee is then placed in full extension in a step 2404. Hall sensor amplitudes are measured in a step 2408. This process is repeated over time to track the Hall sensor amplitude. These values are then compared with initial Hall sensor amplitude values obtained when the knee implant joint template was implanted (obtained by performing steps 2412 to 2418). As the Hall sensor amplitudes are directly related to a distance between the markers and the marker readers—i.e., a tibial insert thickness, a difference between the initial Hall sensor amplitudes and current Hall sensor amplitudes from step 2408 represent wear of the tibial insert in a step 2420. When a predetermined minimum implant thickness is reached in a step 2420, a notification to replace the tibial insert is triggered in a step 2422.
FIG. 46 is a flowchart showing steps of a method 2500 for implant data collection according to an embodiment of the present disclosure. While method 2500 is described with reference to a knee joint implant below, method 2500 can be applied to any implant with sensors described in the present disclosure, including all of the implants disclosed above. In a first step 2502, a patient is implanted with a knee joint implant. The knee joint implant is in a low-power mode (to conserve battery power) until relevant activity is detected (steps 2504 and 2506). Once the relevant activity is identified by the sensor(s) of the knee joint implant (step 2508), the implant shifts to a high-power mode. Relevant activity to trigger the high-power mode can be patient-specific, and may include knee flexion speed, gait, exposure to sudden impact loads, temperature thresholds, alkalinity levels, etc. Upon identifying the relevant activity and switching over to the high-power mode, various sensors in the knee joint implant record and store sensor measurements on the device (step 2512). This data can be transferred from the patient to a home station when the patient is in the vicinity of the home station or a smart device (step 2514). The data is then transferred from the home station or the smart device to the cloud to be reviewed and analyzed by software, virtual machines and/or by experts (steps 2518, 2520). Relevant information for patient rehabilitation and recovery uncovered from the sensor data is sent back to the patient (steps 2523, 2522) via a client portal. Thus, method 2500 preserves and extends battery life of the knee joint implant by shifting the implant from low-power to high-power mode when required, and shifting the implant back to the low-power mode to conserve energy during other periods.
In some examples, the relevant patient information may be that the knee joint and knee joint implant are in a healthy state, or alternatively that the knee joint is in an infected state. If the knee joint is determined to not be in a healthy state, the clinician can then take steps to review the condition more closely and prepare a plan for treatment if necessary. After review, the clinician can input the state of the joint as determined by the clinician so that the confirmed diagnosis is then associated with the data provided by the joint implant. The diagnosis data combined with corresponding sensor data is then stored in the cloud and henceforth considered in the software's future determinations of the state of a joint and joint implant. In some examples, the software is adapted to adjust and further refine its parameters and/or thresholds used in determining the state of an implant upon receipt of the diagnosis data.
FIGS. 47A and 47B shows steps of a method 2600 for patient monitoring according to an embodiment of the present disclosure. While method 2600 is described with reference to a knee joint implant below, method 2600 can be applied to any implant with sensors described in the present disclosure, including all of the implants disclosed above. After installing the knee joint implant, various sensors within the sensor are activated (steps 2624, 2626) to track and monitor patient rehabilitation and recovery (step 2628). When the tracked data indicates that the desired recovery parameters are achieved, some of the sensors in the knee joint implant are deactivated or turned to a “sleep mode” (step 2616). For example, the recovery target can be a desired range of motion of the knee joint. Once a patient exhibits the desired knee flexion-extension range, some of the sensors on the knee joint implant can be turned off. Alternatively, peer data can be used to identify recovery thresholds (step 2612). If the recovery threshold or milestones are not achieved, the knee joint implant continues to charge and use all sensors (step 2608). Some sensors in the knee joint implant will be periodically used even after achieving the recovery milestones to monitor for early identification of improper implant performance (step 2610, 2618, 2620). For example, after turning off the magnetic readers upon achieving the desired flexion-extension range of motion, the pH or temperature sensors can be used to periodically measure alkalinity and temperature to identify infection or implant failure. Upon identification of an anomalous condition, the knee joint implant can be configured to fully recharge and turn on the previously turned off sensors to provide additional implant performance measurements (step 2624). A surgeon can customize the sensor readings and frequency based on the observed condition (steps 2626 and 2628). Additional rehabilitation steps for patient recovery can be provided to the patient at this point. The impact of the new rehabilitation steps can be monitored and compared with peers to observe patient recovery (steps 2636-2642).
FIG. 48 is a front view of a knee joint implant 8600 according to an embodiment of the present disclosure. Knee joint implant 8600 includes a femoral implant 8602 located on a femur 8608 and a tibial implant 8604 located on a tibia 8610. A tibial insert 8609 is located between tibial implant 8604 and femoral implant 8602. A patellar implant 8606 (not shown) is coupled to the posterior side of patella 8612 and contacts femoral implant 8602. Femoral implant 8602 includes at least one magnet 8636. Patellar implant 8606 includes at least one Hall sensor 8646 configured to sense a magnetic field from magnet 8636. Patellar implant 8606 further includes a power source, such as a battery 8648 and a microcontroller 8650 for storing, processing, and transmitting sensor data 8652 from Hall sensor 8646.
FIG. 49 illustrates additional details of femoral implant 8602. Femoral implant 8602 extends in a general arc-shape and defines a central opening 8614. Central opening 8614 defines medial and lateral condyles 8616, 8618 extending in arc-shapes adjacent to central opening 8614. A first axis 8632 extends from an anterior portion 8628 of femoral implant 8602 to a posterior portion 8630 of femoral implant 8602. Similarly, a second axis 8634 extends from an anterior portion 8628 to a posterior portion of femoral implant 8602. Various structures, including magnetic tape of varying lengths and magnetic markers can be positioned at discrete locations along or around first axis 8632 and second axis 8634 as shown in FIG. 49. The shape, size, and location of the magnets can vary depending on the implant.
Magnets 8636 may be any type of magnet capable of producing a magnetic field detectable by a Hall sensor. Examples of such magnet types include neodymium, samarium-cobalt (SmCo), aluminum-nickel-cobalt (AlNiCo), and ferrite. Such magnets may be in the form of magnetic tape or individual structures as shown in FIG. 49.
FIGS. 50 and 51 depict a patellar implant 8606 according to one embodiment of the present disclosure. Patellar implant 8606 includes an outer shell 8638 that surrounds various internal components and circuitry. Outer shell 8638 is generally disc-shaped with a bulbous outer face 8640. Outer face 8640 is configured to contact and articulate against femoral implant 8602 during knee flexion and extension. As such, patellar implant 8606 may have a coating to lubricate the articulating surfaces of outer face 8640 and femoral implant 8602 to minimize wear on the implant. Patellar implant 8606 further includes at least one leg 8642 configured to extend into and engage with patella 8612. As depicted, patellar implant 8606 includes two legs 8642, although other leg configurations are envisioned. Legs 8642 may have attachment structures such as barbs or arcs that facilitate attachment with patella 8612. Bone cement may also be used to secure patellar implant 8606 to patella 8612.
A printed circuit board 8644 is housed within shell 8638. Printed circuit board 8644 may be any board known in the art, such as a single sided, double sided, multilayered, or the like. Various electrical components attach to printed circuit board 8644. Such components include at least one Hall sensor 8646, at least one battery 8648, and at least one microcontroller 8650. Each of these components is described in detail below.
Hall sensor 8646 includes three Hall effect sensors placed on medial, superior, and lateral locations of the printed circuit board 8644. Such Hall sensors 8646 may be oriented in Cartesian coordinates or arranged in other configurations. For example, four Hall effect sensors may be implemented, with the fourth sensor being located at an inferior location on printed circuit board 8644. Hall sensor 8646 is configured to sense a magnetic flux density created by magnets 8636 and output a signal proportional to the strength of the sensed magnetic field. Such an output may be readable via serial communication. The location of Hall sensor 8646 may be optimized to indicate patella shift, patella rotation or any deviation of patellar position, which may ultimately lead to patellar tendonitis.
Microcontroller 8650 includes at least one microcontroller chip. As depicted, microcontroller 8650 includes two microcontroller chips. At least one processor (CPU), memory system 8658, and a communication interface are integrated within microcontroller 8650. The CPU is configured to execute a computer program tailored to the operation of Hall sensor 8646. As such, the CPU may be configured to gather, analyze, and output sensor data 8652. Such a program and its corresponding settings may be adjusted by an operator before, during, or after implantation. The program memory may be any type configured to store sensor data, such as RAM, ROM, flash, or the like. The communication interface, otherwise known as input/output (I/O) peripherals, is configured to receive sensor data from Hall sensor 8646 and communicate the sensor data 8652 to the processor. The data is then transmitted to an external source such as a computer or a smartphone via near-field communication (NFC), Bluetooth or other wireless communication such that an operator can analyze the data. An antenna 8656 may facilitate transmission of sensor data 8652 to the external device. Microcontroller 8650 may further include an inertial measurement unit to measure acceleration changes in and around microcontroller 8650. In alternative embodiments, microcontroller 8650 may include a first microcontroller chip including an advanced RISC machine (ARM) core and a communication system. Such a communication system may be compatible with at least one of Bluetooth and near-field communications. A second microcontroller may further be utilized. Such a second microcontroller may include any combination of cores, communication systems, and memory systems.
Battery 8648 is configured to power printed circuit board 8644 and may be any battery type known in the art. For example, battery 8648 can be solid state batteries, lithium-ion batteries, lithium carbon monofluoride batteries, lithium thionyl chloride batteries, lithium ion polymer batteries, etc.
FIGS. 52-53 illustrate another embodiment of a patellar implant. In this embodiment, patellar implant 8706 is similar to patellar implant 8606, and therefore like elements are referred to with similar numerals within the 8700-series of numbers. Patellar implant 8706 includes an outer shell 8738 surrounding internal circuitry and components. Outer shell 8738 is generally disc-shaped and has a bulbous outer face 8740. Outer shell 8738 may have a coating that decreases friction between outer shell 8738 and femoral implant 8602 to allow outer shell 8738 to articulate against femoral implant 8602 without causing excess wear. Patellar implant 8706 may further include at least one leg 8742 configured to extend within and engage patella 8612. As depicted, patellar implant 8706 includes three legs spaced approximately 120° from each other; however, it is envisioned that other leg configurations may be implemented. Leg 8742 may have arcs, barbs, or other attachment features to secure leg 8742 within patella 8612. Bone cement may additionally be used to secure legs 8742 within patella 8612.
A printed circuit board 8744 is housed within shell 8738. Printed circuit board 8744 may be similar to printed circuit board 8644, and as such may be single sided, double sided, multilayered, or the like. At least one Hall sensor 8746 and at least one microcontroller 8750 are attached to printed circuit board 8744. Unlike printed circuit board 8644, printed circuit board 8744 includes a coil 8748 that provides inductive power to the printed circuit board 8744 and its components. Such a coil 8748 may be advantageous over a battery 8648 as the coil may prolong the utility of patellar implant 8706 as a battery would otherwise deteriorate over time and lose battery-life. In this way, printed circuit board 8744 may be powered solely by an external device or in a combination of an external device and a batter. Coil 8748 may be activated using near-field communication (NFC). Accordingly, to power printed circuit board 8744, a mobile device with NFC capability is moved into range of coil 8748. Once in place, the mobile device can activate to power coil 8748, which in turn powers printed circuit board 8744. NFC technology also allows microcontroller 8750 to communicate with an external mobile device, such that the mobile device can obtain the measured sensor data 8652.
Hall sensor 8746 and microcontroller 8750 operate similarly to Hall sensor 8646 and microcontroller 8650, and thus will not be fully described for sake of brevity. Unlike microcontroller 8650, microcontroller 8750 transmits data via NFC, which requires an external mobile device with NFC capability to be within a close proximity to microcontroller 8750 such that data can be transmitted between the two devices.
Machine learning may be implemented within a mobile device to analyze the sensor data from Hall sensors 8646, 8746. As such, manual comparison of sensor data points may not be required to determine when a patient is developing patellar tendonitis. A database (not shown) of average magnetic flux densities for various leg movements may be created and stored within the mobile device. This database ideally includes information from patients of all ages, body types, and various parameters regarding the surgery that took place. The machine learning algorithm may extract data from the database and compare it to measured data from Hall sensors 8646, 8746. Based on the difference between the two data sets, the machine learning algorithm may indicate to the patient and/or an operator that knee implant 8600 is imparting improper forces on patella 8612, which may lead to patellar tendonitis. The machine learning algorithms may use classifier algorithms such as random forest or support vector algorithms to compare and contrast the data. Alternatively, other algorithm types capable of comparing and contrasting data may be utilized to determine if forces are being imparted on patella 8612.
FIG. 54 illustrates a perspective view of femoral implant 8602 and patellar implant 8706. As illustrated, patellar implant 8606 is positioned at an anterior portion of femoral implant 8602 such that outer face 8740 of patellar implant 8706 contacts and articulates against femoral implant 8602. Magnets 8636 within first and second axis 8632, 8624 may pass by Hall sensors (not shown) as articulation of the knee joint takes place. Accordingly, different magnetic flux densities are created based on the position of the femoral implant 8602 relative to patellar implant 8706. Based on these different magnetic fluxes, one may determine whether improper forces are being imparted to patella 8612 to cause the patellar component to deviate from the expected path such that patellar tendonitis is more likely to occur. Although FIG. 54 illustrates patellar implant 8706, patellar implant 8606 operates in a similar manner.
FIG. 55 illustrates a data flow block diagram implemented by the systems described herein. Such a method begins with sensor data 8652 collection from Hall sensors 8646. Sensor data 8652 then flows into microcontroller 8650, where it is processed and analyzed. From microcontroller 8650, processed data 8654 flows into a memory system 8658 configured to store processed data. To transmit data to an external source, such as a mobile device, two separate methods are possible using the methods described herein. The first method involves the use of patellar implant 8606. After processed data 8654 flows from memory 8658 and microcontroller 8650 to a data transmitter, such as antenna 8656, wireless communication such as Bluetooth low energy (BLE) can be used to transmit data to an external source. Alternatively, the second method involve the use of patellar implant 8706 and NFC technology. After processed data 8654 flows from memory 8658 to a data transmitter, such as antenna 8656 within microcontroller chip 8650, wireless NFC communication types can be implemented to communicate with an external mobile device.
In addition to detecting patellar tendonitis by detecting movement of patella 8612 relative to femoral component 8602, the system described herein may also be used to detect other knee abnormalities. Anterior knee pain is a common symptom after a TKA. The system described herein can be utilized to determine if the patella 8612 is tracking medially, centrally, or anteriorly within the femoral groove. If such a determination is made, a physiotherapist may direct the patient to strengthen certain muscle groups of the patient's quadriceps to balance the loads acting on the knee. This same method may ultimately determine whether a patient's quadriceps are properly activated in relation to certain knee movements. Further, the system described herein may communicate with other sensor systems or smart implants to determine various other abnormalities throughout a patient's body.
A method of using patellar implant 8606 of FIGS. 48-51 is provided herein. First, a patient undergoes a total knee arthroscopy and a knee implant including a femoral implant 8602, a patellar implant 8606, and a tibial implant 8604 is implanted in the patient's knee. An operator may select a unique patellar implant 8606 containing a specific microcontroller 8650 desirable for a specific patient. Once the implant is secured in place, magnets 8636 of first axis 8632 correspond to a medial portion of femoral implant 8602 and magnets 8636 of second axis 8634 correspond to a lateral portion of femoral implant 8602. Outer face 8640 of patellar implant 8606 can then articulate relative to femoral implant 8602, thus causing Hall sensors 8646 to pass through various magnetic fields depending on the specific movement the patient's leg is undergoing.
Once the knee implant is implanted, sensor data 8652 can be collected to determine baseline position data. An operator may manipulate a patient's leg through various movements to ensure a variety of data points are captured and that Hall sensors 8646 sense magnetic flux from a plurality of magnets 8636. Over time, a patient may repeat the same movements under similar conditions. For example, a patient may repeat the same movements annually. At each iteration, sensor data 8652 is taken, compared to previous sensor data, and stored in memory system 8658. If microcontroller 8650 detects a change in sensor data 8652 over a period time, it may transmit sensor data 8652 to an external source via Bluetooth or other wireless communication methods to create an alert that forces may be acting on patella 8612 that could indicate patellar tendonitis is developing. Sensor data 8652 may also be used to detect a change in kinematic pathways. Rather than measuring direct forces applied to the patella 8612, sensors 8646 may be used to measure and track the kinematic position of the patella 8612 relative to the femoral implant 8602. A change in the kinematic pathways may indicate patellar tendonitis or other worsening knee conditions. Alternatively, microcontroller 8650 may transmit sensor data 8652 to an external source each time sensor data 8652 is measured, and the external source may analyze sensor data 8652 using machine learning or other algorithms to determine if the magnetic fields have shifted between femoral implant 8602 and patellar implant 8606, which could indicate patellar tendonitis.
A method of using patellar implant 8706 of FIGS. 52-53 is provided herein. First, a patient undergoes a total knee arthroscopy and a knee implant including a femoral implant 8602, a patellar implant 8706, and a tibial implant 8604 is implanted in the patient's knee. An operator may select a unique patellar implant 8706 containing a specific microcontroller 8750 desirable for a specific patient. Once the implant is secured in place, magnets 8636 of first patellar track 8620 correspond to a medial portion of femoral implant 8602 and magnets 8636 of second patellar track 8622 correspond to a lateral portion of femoral implant 8602. Outer face 8740 of patellar implant 8706 can then articulate relative to femoral implant 8602, thus causing Hall sensors 8746 to pass through various magnetic fields depending on the specific movement the patient's leg is undergoing.
Once the knee implant is implanted, sensor data 8652 can be collected to determine baseline position data. An operator may manipulate a patient's leg through various movements to ensure a variety of data points are captured and that Hall sensors 8746 sense magnetic flux from a plurality of magnets 8636. Over time, a patient may repeat the same movements under similar conditions. For example, a patient may repeat the same leg movements annually. At each iteration, sensor data 8652 is taken, compared to previous sensor data, and stored in memory system 8658. If microcontroller 8750 detects a change in sensor data 8652 over a period of time, it may transmit sensor data 8652 to an external source via NFC communication methods to create an alert that forces may be acting on patella 8612 that could indicate patellar tendonitis is developing. Alternatively, microcontroller 8750 may transmit sensor data 8652 to an external source each time sensor data 8652 is measured, and the external source may analyze sensor data 8652 using machine learning or other algorithms to determine if the magnetic fields have shifted between femoral implant 8602 and patellar implant 8606, which could indicate patellar tendonitis.
Each component described herein may be provided in a kit. Such a kit (not shown) may include different size implant components that correspond to different patients and different TKA scenarios. For instance, an operator may select implant components from a kit that correspond to the patient's unique knee geometry. Further, additional software programs may be programmed into microcontroller 8650 such that other knee parameters, such as implant loosening or subsidence, may also be measured from various Hall sensors through the implant. Accordingly, providing a kit allows an operator flexibility to determine the best treatment option for individual patients.
While a knee joint implant, hip implant, shoulder implant and a spinal implant are disclosed above, all or any of the aspects of the present disclosure can be used with any other implant such as an intramedullary nail, a bone plate, a bone screw, an external fixation device, an interference screw, etc. Although, the present disclosure generally refers to implants, the systems and method disclosed above can be used with trials to provide real time information related to trial performance. While sensors disclosed above are generally located in the tibial implant (tibial insert) of the knee joint implant, the sensors can be located within the femoral implant in other embodiments. Sensor shape, size and configuration can be customized based on the type of implant and patient-specific needs.
Furthermore, although the invention disclosed herein has been described with reference to particular features, it is to be understood that these features are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications, including changes in the sizes of the various features described herein, may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention. In this regard, the present invention encompasses numerous additional features in addition to those specific features set forth in the paragraphs below. Moreover, the foregoing disclosure should be taken by way of illustration rather than by way of limitation as the present invention is defined in the examples of the numbered paragraphs, which describe features in accordance with various embodiments of the invention, set forth in the paragraphs below.
Patent Application
20230320871
