Patent Application
20210259871
The subject matter disclosed herein relates generally to orthotic devices. More particularly, the subject matter disclosed herein relates to orthotic devices, systems, and methods configured to support an ankle joint and/or lower leg.
Three bones come together to form the ankle: the talus, tibia, and fibula. The talus connects the ankle to the foot while the tibia and fibula combine to form the lower leg. These three bones form the ankle mortise, a U-like shaped structure that allows for plantar and dorsiflexion, the movement of the foot in the sagittal plane. The ankle mortise comprises a medial and lateral malleolus, bony structures formed by the distal portions of the tibia and fibula respectively, generally indicating the end points of the rotational axis of the ankle. The rotational axis passing through the medial and lateral malleolus is not perpendicular to the sagittal plane. The hind foot is connected to the ankle and comprises 4 bones: the talus, calcaneus, cuboid, and navicular. These four bones combine to form the subtalar joint, calcaneocuboid joint, and talonavicular joint. The subtalar joint allows for inversion and eversion of the foot.
Common injuries of the ankle include fractures and sprains, particularly for those affected by degenerative pathologies such as arthritis (both rheumatoid and osteo) or diabetes. Both of these patient groups commonly use bracing as a non-operative treatment technique. Furthermore, bracing can likewise be helpful in the treatment of other lower leg injuries (e.g., tibial stress fractures).
Depending on the type and severity of the pathology, multiple different kinds of braces can be used as treatment options. Three kinds of braces currently used are stabilizing braces, energy storing braces, and patellar tendon bearing braces. Stabilizing braces reduce ankle and foot motion in one or more planes of motion. The reduction of this motion is said to decrease inflammation and might provide some pain relief. In some configurations, stabilizing rigid braces allow no articulation at the ankle joint, thus restricting motion in both the sagittal and coronal planes. Examples of these include rigid ankle foot orthosis (AFO) such that would be made by an orthotist via a mold made of the patient's lower leg. Another common example of a stabilizing rigid brace is the standard walking boot. These orthotics are primarily used when the patient has a degenerative ankle-hind foot disease (Kitaoka).
Stabilizing mobility braces restrict coronal motion, similar to the stabilizing rigid braces, but allow for motion in the sagittal plane (i.e., permitting plantar- and dorsi-flexion). People with arthritic ankles tend to be sensitive to motion in the coronal plane, so restricting such motion but allowing sagittal movement generates a more normal walking motion than achievable from a rigid brace. However, since the axis of rotation of the stabilizing mobility braces is perpendicular to the sagittal plane true physiological ankle movement is not permissible. These braces can be customized by an orthotist using polyethylene similar to the rigid brace or can be made with a design created by a separate company. Examples of such stabilizing mobility braces include a Richie Brace, a DonJoy Velocity ankle brace, and a leather and metal double upright AFO created by an orthotist.
Energy storing braces are used for patients with severe lower-extremity weakness. These braces take some of the load applied to the injured leg during activity and store it via deformation of a material, usually carbon fiber, which then provides a propulsion force when unloading the leg. This force acts to compensate for a lack of musculature and/or structure in the injured lower leg. Examples of such energy storage braces include an Intrepid dynamic exoskeletal orthosis, a PHAT brace, and a BlueROCKER brace.
Patella Tendon Bearing (PTB) ankle foot orthoses function as load sharing orthotics. Examples of patella tendon bearing braces include a full orthotic with shoe insert and a patella wrapping portion attached to a shoe, such as by a double-upright coupling structure. The logic behind the design is that the top/proximal portion of the brace which wraps around the calf and patella provides an alternate structure for the load to flow down. In this way, PTB orthoses provide passive load sharing by having the joint effectively undergo a physical height reduction. These braces must be highly nustomized with good fit to function properly. For example, where the axes of coupling to the shoe or shoe insert are not aligned with the anatomical flexion and/or extension of the foot, such bracing configurations can restrict ankle motion. Also, it is difficult to control exactly how much load sharing the PTB brace contributes.
In accordance with this disclosure, orthotic devices, systems, and methods configured to support an ankle joint are provided. In one aspect, a dynamic ankle orthosis system is provided in which a calf sleeve is configured to be secured about a leg of a user, a foot plate is configured to be secured about a foot of the user, and a distractive force mechanism is connected between the calf sleeve and the foot plate. In this configuration, the distractive force mechanism is configured to generate a force between the foot plate and the calf sleeve acting bidirectionally across the ankle to substantially offload bodyweight of the user passing through the ankle and lower limb.
In another aspect, a method for offloading at least a portion of a user's bodyweight at an ankle or lower leg of the user is provided. The method comprises securing a calf sleeve about a leg of the user, securing a foot plate about a foot of the user, connecting a distractive force mechanism between the calf sleeve and the foot plate, and generating a force by the distractive force mechanism between the foot plate and the calf sleeve acting bidirectionally across the ankle to substantially offload bodyweight of the user passing through the ankle and lower limb.
Although some of the aspects of the subject matter disclosed herein have been stated hereinabove, and which are achieved in whole or in part by the presently disclosed subject matter, other aspects will become evident as the description proceeds when taken in connection with the accompanying drawings as best described hereinbelow.
The features and advantages of the present subject matter will be more readily understood from the following detailed description which should be read in conjunction with the accompanying drawings that are given merely by way of explanatory and non-limiting example.
The features and advantages of the present subject matter will be more readily understood from the following detailed description which should be read in conjunction with the accompanying drawings that are given merely by way of explanatory and non-limiting example, and in which:
The present subject matter provides dynamic ankle orthosis devices, systems, and methods. A primary goal of dynamic ankle orthosis is to offload at least a portion of the force encountered by the lower leg, ankle joint, and parts of the foot in stance/gait without introducing excessive off-axis forces at the ankle's rotational axis and resistance to ankle motion. In some embodiments, such offloading is provided by a distractive force (i.e., a force acting in the opposite direction of the body's weight) applied between the foot and the lower leg. The primary advantage of using a distractive force is the ability to control how much offloading occurs. Introducing a new force to the system creates a new design problem: if the forces are not passed onto the brace approximately at the same location as the ankle's rotational axis, new off-axis forces will be generated by the brace which will affect the user's ability to walk normally.
Accordingly, in one aspect, the present subject matter provides a dynamic ankle orthosis system. In one embodiment illustrated in
In some embodiments, calf sleeve 110 of dynamic ankle orthosis system 100 has a structure that is analogous in some ways to the design of the upper portion of conventional rigid ankle foot orthoses. Those having skill in the art should recognize, however, that any of a variety of further configurations for calf sleeve are provided by the presently-disclosed subject matter, including configurations using multiple different materials and techniques. For example, dynamic ankle orthosis system 100 can incorporate any of a variety of different calf sleeve configurations and/or methods, including but not limited to air bladders, suspension material (e.g., hook-and-loop fasteners, belt-like attachment, shoe laces), leather/shoe laces (i.e., a boot-style cuff), or a hard shell with padding (e.g., custom made with casting).
In any configuration, calf sleeve 110 provides a secure fit on the user's leg to ensure that minimal distractive force is lost as a result of the calf sleeve slipping. In this regard, in some embodiments, such as those illustrated in
In some embodiments, such as is shown in
Alternatively, as illustrated in
The selection of the particular configuration for posterior sleeve portion 111 of calf sleeve 110 can be made based on any of a variety of design considerations, including comfort of the wearer and experience with past designs. In addition, certain embodiments of posterior sleeve portion 111 may be better suited for a given wearer's anatomy to securely engage the wearer's leg without limiting or unnecessarily constraining the wearer's calf muscle belly.
In any configuration, calf sleeve 110 further includes an anterior sleeve portion 118 that is configured to engage the shin of the user, such as by running along the flat portion of the tibial shaft. In one embodiment illustrated in
Alternatively, in another embodiment of the calf sleeve is illustrated in
Again, the selection of the particular configuration for anterior sleeve portion 118 of calf sleeve 110 can be made based on any of a variety of design considerations, including personal preference and comfort of the wearer. In addition, certain embodiments of anterior sleeve portion 118 may better provide a geometric fit with a given wearer's anatomy to securely engage the bone surface of the wearer's tibia.
Regardless of the particular configuration of each of the elements of calf sleeve 110, in some embodiments, posterior sleeve portion 111 (e.g., posterior engagement material 112 or posterior engagement padding 114) and anterior sleeve portion 118 (e.g., anterior engagement blades 119 or unitary anterior engagement blade 122) are held together by one or more coupling elements to maintain a secure fit about the user's lower leg. In the embodiments illustrated in
In any configuration of calf sleeve 110, a calf ring 123 can be fixed to or embedded within the material of the caudal portion of anterior sleeve portion 118 (e.g., to or within anterior engagement blade 119 or unitary anterior engagement blade 122). Calf ring 123 serves as a rigid point of fixation for distractive force mechanism 130. In addition, in some embodiments, calf ring 123 further helps to provide structural stability of calf sleeve 110 and provides an anchor point for arrangements of laces 115 and/or cables 124 that are used to maintain tension of the elements of calf sleeve 110 about the user's leg as discussed above. In some embodiments, calf ring 123 is made of metal, carbon fiber, or dense polymer. Those having ordinary skill in the art will recognize, however, that calf ring 123 as shown and described is optional and not an essential component of the device, since it only serves to provide additional structure for cases when the brace needs reinforcement. Alternatively, the reinforcement can come from an embedded bracket within the material of calf sleeve 110 or a thickening of material of calf sleeve 110 at a desired location.
As discussed above, distractive force mechanism 130 is connected to calf sleeve 110, such as at calf ring 123, and is configured to introduce a distractive force to dynamic ankle orthosis system 100. Similarly to the way in which a variety of configurations and combinations of elements can be used to provide secure fixation for calf sleeve 110, multiple different configurations and combinations of elements for distractive force mechanism 130 can be used to provide this force. In some embodiments, for example, dynamic ankle orthosis system 100 uses one or more pneumatic cylinders to create the distractive force. In some embodiments, these cylinders are attached on the lateral and medial sides of dynamic ankle orthosis system 100 and act in series via pneumatic components that are connected via tubing. That being said, those having ordinary skill in the art will recognize that various different pneumatic cylinders can be used to allow for more or less stroke length or greater force generation at lower pressures (requires larger bore).
In some embodiments, a pressure control assembly PC in communication with pneumatic cylinders 131 can be housed within a pouch 134, which in some embodiments is located on the posterior surface of calf sleeve 110. Pouch 134 attaches to the calf sleeve 110 using one or more fasteners, such as one or more straps 135 (e.g., hook-and-loop straps). In some embodiments, pressure control assembly PC includes pressure control features that are operable to maintain a selected pressure within pneumatic cylinders 131. In the illustrated embodiment, for example, a check valve 136 is configured to insert air into the system. This check valve 136 allows air flow in only one direction so any air introduced into the system will not escape via its entrance route. This arrangement allows pneumatic cylinders 131 to maintain pressures and consistently produce an outward force. In-line with check valve 136, a slow release valve 137 allows the user to slowly release pressure from the pneumatic system if desired. In some embodiments, for example, slow release valve 137 is configured such that each time it is used, the valve will release an incremental amount of pressure (e.g., 10 PSI) from the system. Distractive force mechanism 130 in this embodiment can further include an air pressure gauge 138 that allows the user to see the amount of air pressure (e.g., measured in PSI or Bar) currently in the pneumatic system. This feedback can help the user control the amount of distractive force dynamic ankle orthosis system 100 is currently providing.
Distractive force mechanism 130 can further include a split valve 139 in communication between pressure control assembly PC and pneumatic cylinders 131 that splits the primary tubing (e.g., ¼ inch) into multiple tubes (e.g., ⅛-inch) that then travel to the corresponding one of pneumatic cylinders 131 and provide them with air. In the illustrated embodiment, split valve 139 is attached to one of pneumatic cylinders 131 by a first tube 140a (e.g., a lateral tube) and to the other of pneumatic cylinders 131 by a second tube 140b (e.g., a medial tube).
In this illustrated embodiment, pneumatic cylinders 131 contain a four-inch stroke length and provide a force of 25 lbs. for every 100 PSI of air pressure inserted. In this configuration, since pneumatic cylinders 131 are in series, if one inserts 100 PSI of air pressure, pneumatic cylinders 131 will provide a total of 50 lbs. of force. Pressure control assembly PC serves to control the action of pneumatic cylinders 131.
Regardless of the particular elements of distractive force mechanism 130, pneumatic cylinders 131 can be configured to achieve any of a variety of different load responses. Pneumatic cylinders 131 can also be configured to allow different ankle mobility conditions during these active loading states. For instance, in some embodiments, the bottom ends of both of pneumatic cylinders 131 are connected in a substantially closed system as shown in
Alternatively,
In any form, these springs 141 can be attached on the sides of dynamic ankle orthosis system 100—medially and laterally—or on one of the anterior or posterior portion. In some configurations, springs 141, as illustrated in
In any arrangement, a spring-based configuration for distractive force mechanism 130 can comprise one or more constant force springs 141 and a tension control unit 142, which can vary in design. In some embodiments, constant force springs 141 function to generate a distractive force by way of a cable tension system that acts between calf sleeve 110 and foot plate 150. In the embodiments illustrated in
Tension within tension cable 143 can be controlled using a standard tension control unit 142 as shown in
Furthermore, although some particular structures of dynamic ankle orthosis system 100 are described with respect to various embodiments that uses either one or more pneumatic cylinders 131 or one or more constant force springs 141 in distractive force mechanism 130, any of a variety of alternative configurations for distractive force mechanism 130 are also contemplated by the presently disclosed subject matter. In some embodiments, for example, air baffles or air bladders can be used as the distractive force mechanism. Similarly to pneumatic cylinders, as the pressure increases inside of such elements, the amount of force exerted can increase. In contrast to pneumatics, however, the attachment point for such air bladders can be designed such that they are attached at calf sleeve 110 and the bladders can contribute to both lower leg attachment and distractive force. The mechanism by which the bladders are inflated can be an external device similar to what is currently used (e.g., a bladder-like nipple similar to those used in some shoe wear (e.g. Reebok™ Pumps)) or a device that is placed in the sole area of the shoe and with each step it activates the system and sends air to the system (i.e., an accumulator). In some embodiments, the system can include features that ensure the bladders are not over inflated (e.g., controlled via a bleeder valve), so once a certain pressure is achieved, air will just flow out into the environment.
In yet a further alternative, a physical displacement device (e.g., a ratcheting device) is provided as the distractive force mechanism, wherein two rods that overlap and can be ratcheted to increase rod length. If there is good attachment between calf sleeve and leg, the increase in rod length will engage soft tissue and provide a distractive force.
As discussed above, the foot plate 150 of dynamic ankle orthosis system 100 is coupled to distractive force mechanism 130 and thereby allows for the transfer of the distractive force to bypass the ankle joint and parts of the foot. In some embodiments, the design and build of foot plate 150 can be similar to existing fabrication techniques of ankle and heel cups used by orthotists.
In contrast to conventional configurations, foot plate 150 according to the present subject matter allows for improved mobility. In this regard, in some embodiments, foot plate 150 includes a foot connector 155 that is configured to allow for full sagittal mobility with some mobility laterally and medially. In some embodiments, for example, foot connector 155 is mounted to each of the medial and lateral sides of foot plate 150, such as lateral tab 154a and medial tab 154b , such as is shown in
In some embodiments, foot plate 150 further includes an ankle adapter plate 156 that is either placed by the orthotist at the rotational axis 160 of the ankle or is modular and can be adjusted to be placed at or near bony landmarks (e.g., the malleoli) of the user as illustrated in
Alternatively, in some embodiments, the location of ball joints 157 can be intentionally offset caudal-cranially or anterior-posteriorly as illustrated in
Regardless of the particular combination of element configurations, however, dynamic ankle orthosis system 100 is operable to offload at least a portion of the force encountered by the lower leg, ankle joint, and parts of the foot in stance/gait without introducing excessive off-axis forces at the ankle's rotational axis and resistance to ankle motion. As discussed above, such offloading is achieved by the introduction of a distractive force between foot plate 150 and calf sleeve 110 acting bidirectionally across the ankle to substantially offload bodyweight of the user passing through the ankle and lower limb.
To test the effectiveness of the present dynamic ankle orthosis devices, systems, and methods to meet the design goals, three experiments were performed: a first experiment was conducted to verify the distractive force capabilities of the distractive force mechanisms, a second experiment was conducted to validate how much offloading the dynamic ankle orthosis provides at the ankle joint, and a third experiment was conducted to test the changes in mobility when the dynamic ankle orthosis is added to the leg. Summaries of these experiments are provided below.
To validate the distractive force capacity and efficacy of dynamic ankle orthosis system 100, a first test of an embodiment of dynamic ankle orthosis system 100 using pneumatic cylinders 131 was performed to acquire force values to correspond with the pressures applied to the cylinders.
A plate was created with two clearance holes to place the 7/16-20 threaded ends of the cylinders through. A corresponding nut was then used to secure pneumatic cylinders 131 to the plate. They were each attached to a vertical fixture for positioning, which was securely attached to the platform of the robot, and placed beneath the upper load cell. The cylinders were connected in series in the same manner as when attached to dynamic ankle orthosis system 100. By connecting pneumatic cylinders 131 in series, equivalent pressures were delivered to the two cylinders, corresponding to the pressure value shown on the pressure gauge. (I.E., when the pressure gauge showed 40 PSI both cylinders were inflated to a pressure of 40 PSI.) Both cylinders acted on the load cell, so the reported values show the total amount of force delivered by both of the cylinders.
The compressive force on the load cell was acquired at various cylinder pressure values: 40, 50, 60, 70, and 80 PSI. Each pressure was tested four times and forces were exported and processed in Microsoft Excel. The pneumatic cylinders were emptied of their pressures between all runs and inflated to the targeted pressure to begin the new test. Table 1 shows the mean force values along with standard deviation for the force the pneumatic cylinders exerted when filled to certain pressures.
A second experiment was designed to quantify the offloading capabilities of dynamic ankle orthosis system 100 as a function of pneumatic pressure relative to body weight.
A testing fixture was created to measure the amount of load relief that the dynamic ankle orthosis provided. First and second load cells and were bolted to a bottom plate and wooden planks were then attached to the top of each of the first and second load cells and to give the user somewhere to stand. The user stood with their feet approximately shoulder width apart with one foot on the first load cell and the other foot on the second load cell. Vertical uprights were then attached to the bottom plate on the medial and lateral sides of the first load cell. The subject dons calf sleeve 110 of dynamic ankle orthosis system 100 with pneumatic cylinders 131 attached to both of calf sleeve 110 and the uprights. Sliding members in the uprights allowed for height adjustment of the attachment point for the bottom portion of pneumatic cylinders 131. In this configuration, brace force introduced by pneumatic cylinders 131 bypasses the first load cell and dissipates through the bottom plate.
Testing was performed in stance with each foot positioned on top of a single load cell. Calf sleeve 110 of dynamic ankle orthosis system 100 was placed on the right leg and the bottom portions of pneumatic cylinders 131 were secured into place approximately at the malleoli. A program recorded force and moment values over a specified time. For each test, the program was initiated and the user would stand for approximately five seconds without brace activation. Pneumatic cylinders 131 would then be activated to a specific pressure to create a brace force, and the test would continue to run until the twenty seconds ended. Pneumatic cylinders 131 were inflated to five different pressures: 40, 50, 60, 70, and 80 PSI. Each pressure setting was tested ten times. Force and moment values were recorded for all runs.
Brace force Fb for each run was found by taking the user's bodyweight (490 N), which can be found by readings of a left load cell force FLLC and of a right load cell force FRLC before brace activation, and subtracting out the sum of the two load cell readings after brace activation:
F
b
=BW−F
LLC
−F
RLC
How well dynamic ankle orthosis system 100 transferred offloading forces to the limb, or Efficiency, was calculated using the brace force Fb of dynamic ankle orthosis system 100 and total cylinder force provided by pneumatic cylinders 131.
As a percentage of bodyweight BW, the amount of force dynamic ankle orthosis system 100 relieved ranged from 11.3% at 40 PSI to 30.5% at 80 PSI. It is currently unknown what amount of force relief at the ankle is significant, but through conversation with two orthotists, two general goals were set for dynamic ankle orthosis system 100. First, dynamic ankle orthosis system 100 should provide axial unloading without compromising circulation or soft tissue integrity. The medical literature shows that during noninvasive ankle distraction no nerve damage was seen when tested up to 225 N for 1 hour. (See, Dowdy et al.) This is not directly applicable as this experiment was performed on an unloaded ankle and the ankle would be under load with the dynamic brace design, but it still gave a reference of what was safe without causing nerve damage in an unloaded ankle. Second, a goal of approximately 25% of bodyweight of force relief at the braced ankle was set as a mark of potential clinical efficacy.
This test shows the ability of dynamic ankle orthosis system 100 to provide offloading of the ankle. Dynamic ankle orthosis system 100 provided up to 148 N of brace force Fb to the user which amounted to 30.5% of body weight. Dynamic ankle orthosis system 100 was also able to transfer cylinder force output to brace force Fb at an 83-95% effectiveness rate. Dynamic ankle orthosis system 100 therefore accomplished both goals set by the orthotists.
The second variable of interest is the effect of the DAO on the ankle's resistance to motion. This experiment was separated into two treatment groups: without a brace and with a brace inflated to various levels of cylinder pressure. For all tests, a Biodex unit was set to passively drive the ankle in plantar- and dorsi-flexion. The user sat in a chair and a limb support pad was placed under the thigh so that the lower leg approached the machine parallel to the floor. The right foot was placed on a foot plate, and securely attached thereto to limit motion in the foot. The foot plate was then adjusted so that the dynamometer of the Biodex unit was aligned with the lateral malleolus of the right ankle. This was done so that the Biodex unit rotated about the rotational axis (RA) of the user's ankle.
The Biodex unit was set to rotate passively, which means that the machine would drive motion between two set points at a set speed. The two points were set prior to each run by the user. The foot was initially positioned at a neutral angle, perpendicular to the leg, and then the user set maximum plantarflexion and dorsiflexion angles. The machine rotated back and forth between these maximum angles for a set number of cycles and measured the moments experienced by the machine while moving the foot to these points. The data sets attained from the tests were the angular positions and the corresponding moment values. All tests were run at an angular velocity of 30 degrees/sec. For all tests the ankle was rotated to at least 10 degrees of dorsiflexion and 20 degrees of plantarflexion. The polarity of the measured moment values depends on the direction of the resistive moment. Dorsiflexor moments (directed towards the top of the foot) are measured as negative resistive moments, and plantarflexor moments (directed towards the bottom of the foot) are measured as positive resistive moments). So as the foot is passively moved into dorsiflexion, a resistive plantarflexor moment is generated by the soft tissue of the calf and ankle. First, the foot was placed in the Biodex machine without dynamic ankle orthosis system 100 donned. The straps were securely tightened at the foot to ensure that rotation occurred at the ankle joint. Three tests were run, each for thirty seconds with the system angular velocity set to 30 deg/sec. The mean moments and standard deviations were then calculated at 5 degree increments from −10 degrees to 20 degrees. Moment values for the plate by itself were subtracted out so the reported moment values accurately represent what is added to the Biodex system. These values provided a baseline to compare the results of the different bracing conditions to that of the foot alone.
Five different bracing conditions were tested at the neutral position. The user sat in the chair as above, with dynamic ankle orthosis system 100 donned and the foot secured to the foot plate. Each test was run for 30 seconds and contained between 7 and 10 full revolutions of the foot, moving from maximum dorsiflexion to maximum plantarflexion and back. Tests were run with the pneumatic cylinders filled to 0, 40, 50, 60, 70, and 80 PSI values. Each pressure setting was run three times and the recorded output values were the moments and the corresponding angular position values. Moment values at −10, −5, 0, 5, 10, and 15 degrees were used for analysis. 0 degrees represents when the foot is positioned at a 90 degree angle to the lower leg. Negative angle values indicate dorsiflexion and positive values plantarflexion.
Following in Table 3 are the mean moment values for the non-braced and braced conditions. At each five degree increment in both directions mean moment was compared amongst all different bracing conditions.
The measured moment values for the native ankle are supported by literature (Kay 2009). Across the range of motion (10 degrees dorsiflexion to 20 degrees plantarflexion), the native ankle experienced between 1.5 and 6.0 Nm (4.5 Nm difference) of resistive moment. With dynamic ankle orthosis system 100 donned and cylinders depressurized, between 4.2 and 0.1 ft-lbs (4.1 Nm moment difference) of resistive moment was measured during the motion. With dynamic ankle orthosis system 100 donned and inflated to 50 PSI, between 2 and −1.8 Nm (4.4 ft-lbs moment difference) of resistive moment was measured during the motion. With dynamic ankle orthosis system 100 donned and inflated to 80 PSI, between 1.8 and −4.2 ft-lbs (6 Nm moment difference) of resistive moment was measured during the motion. The increased moment at 20 degrees plantarflexion was likely due to the ball joints of dynamic ankle orthosis system 100 hitting their limit (i.e., the ball joints were constructed to permit up to 20 degrees of motion). In all pressurized bracing conditions, the absolute resistive moment was reduced compared to the native ankle. This shift in values towards the negative was likely due to the brace force vector creating off-axis loads relative to the point of rotation of the Biodex foot plate. In other words, dynamic ankle orthosis system 100 may have been applying an external dorsiflexor moment, which manifested as a shift in the measured moment values towards the negative. However, the resistive moment difference taken at the two extreme ends of motion for each condition was not significantly affected by the brace wear.
The greatest moment differences were found in the 70 PSI and 80 PSI bracing conditions, where the moment difference was 5.2 Nm and 6 Nm, respectively. Compared to the native ankle at 4.5 Nm moment difference, the increase in resistive ankle moment is negligible, and it can be concluded that the presence of dynamic ankle orthosis system 100 does not introduce additional resistance to natural ankle motion.
The present subject matter can be embodied in other forms without departure from the spirit and essential characteristics thereof. The embodiments described therefore are to be considered in all respects as illustrative and not restrictive. Although the present subject matter has been described in terms of certain preferred embodiments, other embodiments that are apparent to those of ordinary skill in the art are also within the scope of the present subject matter.
The presently disclosed subject matter claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 62/481,741, filed Apr. 5, 2017; the disclosure of which is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US18/26254 | 4/5/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62481741 | Apr 2017 | US |
