Patent Grant
10478197
The present invention relates to the art of orthopedic cutting devices, more particularly, to an orthopedic cutting device designed to remove bone and tissue from the acetabulum.
Reamers are devices intended to remove tissue and bone from the human body. Similarly to that of a traditional reamer device, the orthopedic cutting device of the present invention is designed to remove bone and tissue from the cotyloid cavity or acetabulum in preparation for the insertion of a prosthetic cup during hip arthroplasty.
The cotyloid cavity is a cup shaped cavity at the base of the hipbone into which the ball-shaped head of the femur is received (
Traditional prior art acetabular reamers, such as the one disclosed in U.S. Pat. No. 5,709,688 to Salyer, are generally constructed having a rigid hemispherical shell structure with a continuous hemispherical surface. A plurality of spaced apart teeth, arranged in the same direction, outwardly extend from the shell exterior. The hemispherical structure is suited to create a cavity within the acetabulum which receives a prosthetic cup. Prosthetic cups generally have a curved exterior surface that is inserted into the cotyloid cavity.
During a traditional total hip arthroplasty procedure, a series of prior art reamers are used to form a hemispherically shaped cavity within the acetabulum. The series of prior art reamers of increasing diameter are typically used to gradually form a hemispherical cavity, reaming from the acetabular floor and fossa outwards to the acetabular labrum until a desired diameter is reached. Prior art orthopedic reamers are typically fabricated as modular units that are sold in a set of an array of diameters. These reamer tool sets are generally manufactured with reamer cutting heads providing bore sizes ranging from about 36 mm to about 80 mm in 1 mm increments sometimes totaling over 45 sizes. Since it is desirable to achieve a close prosthetic fit, a wide array of reaming tools of varying sizes are required to be on hand to provide the most precise cut and optimum bore diameter.
The rigid hemispherical shape of prior art reamers causes the hemispherical cavity to gradually be formed of increasing diameter from the acetabular fossa at the center of the acetabular floor outwards to the acetabular roof. Each time a different reamer is inserted, the reamer apex contacts and abrades the acetabular floor and fossa. Such a procedure is believed to remove excessive bone from the acetabular fossa, thus resulting in a reamed acetabulum having reduced strength and rigidity. In addition, the insertion and removal of multiple prior art reamers may potentially lead to infection. Furthermore, the procedure of inserting and removing multiple prior art reamers is potentially traumatic to the body.
The present invention addresses these potential problems by providing a bone cutter that is configured to ream the cotyloid cavity with one device. In contrast to prior art reamers, the bone cutter of the present invention is designed to ream the acetabular roof and acetabular labrum prior to significantly reaming the acetabular floor and acetabular fossa. Therefore, abrasion to the acetabular floor and fossa is reduced, thus resulting in the preservation of more of the acetabular floor and fossa bone structure. As a result, the bone structure of the reamed acetabulum has greater strength and rigidity in comparison to an acetabulum that is reamed by the prior art procedure with the prior art reamers. Furthermore, since the bone cutter of the present invention eliminates the need to introduce and remove multiple prior art reamers, the risk of infection and trauma is minimized.
Many minimally invasive prior art reamers have been designed in an attempt to minimize surgical trauma to the patient. Among these prior art reamer designs is the device disclosed in U.S. Pat. No. 7,850,692 to White et al., which is assigned to the assignee of the present invention and incorporated herein by reference. White discloses an acetabular reamer having a reduced “lemon wedge shaped” profile so that it can pass through an incision of a reduced opening size. However, in contrast to the bone cutter of the present invention, the acetabular reamer of White comprises a fixed rigid reamer shell that necessitates the use of multiple reamer devices to create a hemispherical cavity of a desired diameter. Furthermore, the rigid partial hemispherical design may cause additional abrasion of the acetabular fossa and floor as the apex of the multitude of increasingly large reamers come into contact with the acetabular floor surface.
Another prior art acetabular reamer is disclosed in U.S. Pat. No. 7,608,076 to Ezzedine, which is assigned to the assignee of the present invention and incorporated herein by reference. Ezzedine discloses a collapsible surgical reamer having a hinge along its rotating axis. While the collapsed configuration allows for the device to pass through a minimally invasive incision, the Ezzedine device must be in an unfolded configuration to ream bone and tissue. Thus, the Ezzedine reamer comprises a rigid hemispherical shape having teeth that extend from the hemispherical structure when used within the body. In addition, similar to the other prior art reamer devices, multiple reamers of increasing diameters are required to be inserted and removed from the body to create a cavity of a desired diameter. Thus, the rigid hemispherical structure of the Ezzedine reamer may cause additional abrasion to the acetabular floor and fossa during a procedure which may potentially cause the acetabulum to become less rigid.
Yet another embodiment of an acetabular reamer is disclosed by Sherry et al. in U.S. Pat. No. 8,052,689, which is assigned to the assignee of the present invention and incorporated herein by reference. Sherry discloses an acetabular reamer having a truncated cutting shell that is constructed without an apex. The omission of the apex from the reamer shell allows for the reaming of the acetabular roof and acetabular labrum without contacting the acetabular fossa. However, in order to form a full hemispherical cavity within the acetabulum, the Sherry device must be rocked in a back and forth manner for the cutting teeth to contact the acetabular floor region. Such a rocking motion is not preferred as this may not produce a true hemispherical cavity. Furthermore, the rocking motion of the reamer within the body may aggravate and traumatize surrounding tissue.
The '689 to Sherry et al. patent discloses an alternate embodiment comprising a cap or plate that is positioned over the apex opening. As disclosed by Sherry, the cap or plate is stationary, but separately attached to the shell. Thus, in order to attach the cap or plate, the shell must either be removed from the body or manipulated by the surgeon within the body. In either case, the removal and insertion or the manipulation of the shell within the body to attach the apex cap may cause additional trauma or result in infection to the patient.
In contrast to the prior art reamer device, the bone cutter of the present invention comprises a bone cutting insert that extends and retracts from within an opening that extends through the reamer shell. In addition, the bone cutter of the present invention is configured such that the insert is capable of rotational and axial movement independent of the reamer shell. Thus, when the insert is retracted within the reamer shell, the bone cutter is configured to ream the acetabular labrum and roof. The acetabular fossa or floor may then be reamed by outwardly extending the insert from within the reamer shell without removing the bone cutter from the body. Furthermore, the retracted configuration of the bone cutter of the present invention provides for insertion within a minimally invasive incision.
Thus, the present invention provides a reamer that incorporates design features which address various limitations of the prior art. The features of the bone cutter of the present invention enable the reaming of the acetabular roof and the acetabular floor in separate steps without removal of the device from the body, thus more of the bone structure of the acetabulum preserved while minimizing patient trauma and infection.
The present invention is an orthopedic cutting device designed to cut and remove tissue and bone material. The device is designed to efficiently remove tissue and bone from the cotyloid cavity for the insertion of an orthopedic implant.
In an embodiment, the bone cutter comprises a reamer shell and a reamer insert that resides within an opening that extends through the apex of the reamer shell. The insert is capable of independent axial and rotational movement within the shell opening. The reamer shell is preferably of a partially hemispherical structure comprising a plurality of spaced apart shell teeth, each having a tissue cutting surface that extends outwardly from the reamer shell exterior surface. The insert preferably comprises an annular sidewall that meets an insert end wall that comprises a plurality of spaced apart insert cutting teeth having a tissue cutting surface.
In an embodiment, the insert rides within a pin and slot mechanism that is positioned within the shell interior. This pin and slot mechanism provides axial and rotational movement of the insert with respect to the shell. In an embodiment, the insert is positioned within a collar that is secured within the reamer interior. The collar comprises an annular sidewall having a slot extending to a groove formed at least partially within the collar sidewall interior surface. A pin extending from the insert sidewall is received within the collar slot and rides therewithin. In an alternate embodiment, the insert is positioned within a collar that is secured within the reamer interior. The collar comprising an annular sidewall having at least one pin that extends outwardly from the collar sidewall interior surface. The insert comprising an insert sidewall having a slot extending to a groove is formed at least partially within the insert sidewall exterior surface. The pin extending from the collar sidewall interior surface is received within the insert slot and rides therewithin.
When the insert is in a retracted position the bone cutter is configured to ream the acetabular roof. In addition, the retracted configuration provides a low profile orientation that helps allow for the insertion of the reamer through a minimally invasive incision. When the insert is in an extended position, the bone cutter is configured to ream the acetabular floor. Thus, the bone cutter of the present invention provides for the separate reaming of the acetabular roof and floor without the need to remove the device from the body.
Now turning to the figures,
The insert 22 is designed to rotate either in a clockwise or counter-clockwise direction independent of the reamer shell 20 within the opening 24. In addition, the insert 22 is configured to move in an axial direction along the rotational axis A-A within the shell opening 24. The shell 20 is configured to ream the acetabular roof and labrum while the movable bone cutting insert 22 enables independent reaming of the acetabular floor and fossa. The bone cutter 10 of the present invention thus eliminates the need to remove and insert multiple reamers of increasing diameter during a procedure. Therefore, the possibility that surgical trauma or infection may result is minimized. Furthermore, the insert 22 may be positioned below the shell opening 24 within the shell interior thus providing the bone cutter 10 of the present invention with a low profile that is minimally invasive to insert and remove from the body.
In the case of reaming the acetabulum 26 during a hip replacement procedure as shown in
The shell 20 preferably comprises a plurality of spaced apart reamer teeth 46. Each tooth 46 is formed from the reamer sidewall 34 that outwardly extends from the reamer shell exterior surface. In addition, each of the plurality of reamer shell teeth 46 comprises a tooth opening 48 that extends through the thickness of the shell sidewall 34. The tooth opening 48 allows for the removal of tissue debris during a reaming surgical procedure. A tissue cutting surface 50 is formed at a distal end 52 of each of the plurality of teeth 46 extending outwardly from the reamer shell exterior surface and positioned over the respective tooth opening 48. In an embodiment, the plurality of reamer shell tissue cutting surfaces 50 is arranged in either a clockwise or counter-clockwise orientation about the rotational axis A-A.
As illustrated in
In an embodiment, illustrated in
In a preferred embodiment, the anchor tissue cutting surface 76 is oriented in an opposite direction as the tissue cutting surface 50 of the reamer shell cutting teeth 46, about the rotational axis A-A. This preferred anchor orientation allows for the shell 20 to ream bone and tissue without causing the anchor 70 to become embedded within tissue or bone. For example, an exemplary bone cutter is configured with the reamer shell teeth 46 oriented in a clockwise direction and the anchor tissue cutting surface 76 oriented in the opposite, counterclockwise direction about the rotational axis A-A. Thus, rotation of the shell 20 in the clockwise direction enables the shell 20 to ream bone and tissue without causing the anchor 70 to become embedded within surrounding bone or tissue. Rotation in the opposite, counter-clockwise direction about the rotational axis A-A, however, causes the anchor 70 to become embedded within surrounding tissue or bone, thereby immobilizing the reamer shell. Subsequent rotation of the shell 20 in an opposite direction, i.e., clockwise direction about rotational axis A-A, causes the anchor 70 to become dislodged from the surrounding tissue and bone. In an embodiment, immobilizing the reamer shell 20 allows for independent reaming of tissue and bone by rotation of the insert 22.
In an embodiment, the insert end wall 86 comprises a plurality of spaced apart insert teeth 94, each tooth having a tissue cutting surface 96. In an embodiment, each of the plurality of reamer insert teeth 94 is formed from the insert end wall 86 that outwardly extends from the insert end wall distal surface and provides for cutting a hemispherically shaped cavity within the acetabulum. In addition, each of the plurality of insert teeth 94 comprises a tooth opening 98 that extends through the thickness of the insert end wall 86. The opening 98 allows for the removal of tissue debris during a reaming surgical procedure. In an embodiment, the tissue cutting surface 96 is formed at the distal end of each of the teeth 94 extending outwardly from the insert end wall distal surface 88 and is positioned over a respective tooth opening 98. In an embodiment, the plurality of tissue cutting surfaces 96 of the reamer insert teeth 94 are oriented about the rotational axis A-A in an opposite direction to that of the tissue cutting surfaces 50 of the reamer shell teeth 46. For example, if the tissue cutting surfaces 50 of the reamer shell teeth 46 are oriented in a clockwise direction about the rotational axis A-A, the tissue cutting surfaces 96 of the insert teeth 94 are preferably oriented in the opposite, counter-clockwise direction about the rotational axis A-A. Furthermore, the tissue cutting surface 76 of the at least one anchor 70 is oriented in the same direction as the tissue cutting surfaces 96 of the insert teeth 94.
In an embodiment, the insert end wall 86 may have a curved construction. As illustrated in
In an embodiment, as shown in
In an embodiment, the collar 100 comprises at least two slots 116 (
In an embodiment, as illustrated in
In an embodiment, the collar distal end 104 is secured to the reamer shell flange 54 such that rotational movement of the insert 22 within the reamer shell opening 24 is not impeded. In a preferred embodiment, the collar 100 is secured to the flange 54 such that there is a gap 122 (
Similar to the embodiment of the insert 22 of the bone cutter 10, the insert end wall 150 comprises a plurality of spaced apart insert teeth 156, each tooth having a tissue cutting surface 158. In an embodiment, each of the teeth 156 is formed from an outwardly extending portion of the insert end wall 150. In addition, each tooth 156 resides adjacent to an opening 160 that extends through the thickness of the insert end wall 150. The opening 160 allows for the removal of tissue debris during a reaming surgical procedure. The tissue cutting surface 158 formed at the distal end of each of the teeth 156 extends outwardly from the insert end wall 150 and is positioned over a respective tooth opening 160. In an embodiment, the plurality of tissue cutting surfaces 158 of the reamer insert teeth 156 are oriented about the rotational axis A-A in an opposite direction as that of the tissue cutting surfaces 50 of the reamer shell teeth 46. For example, if the tissue cutting surfaces 50 of the reamer shell teeth 46 are oriented in a clockwise direction about the rotational axis A-A, the tissue cutting surfaces 158 of the insert teeth 156 are preferably oriented in the opposite, counter-clockwise direction about the rotational axis A-A. The insert end wall 150 preferably comprises a convex structure that outwardly extends in a distal direction. The curvature of the insert end wall 150 thus allows for the insert 126 to ream a cavity having a curved surface. In an embodiment, the insert end wall 150 may comprise a convex structure having a radius of curvature R2 that ranges from about 1 cm to about 5 cm.
In an embodiment, the insert annular sidewall 148 comprises at least two slots 162 that extend part-way through the sidewall 148 thickness from exterior surface 164 thereof. Each of the at least two slots 162 is preferably oriented at an angle with respect to the rotational axis A-A. In a preferred embodiment, each of the at least two slots 162 is positioned in a spiral orientation with respect to the longitudinal axis A-A extending from the insert proximal end 144 to the insert distal end 146. In an embodiment, the at least two slots 162 are configured to each receive a collar pin 142 that extends inwardly from the collar interior sidewall surface 138. A groove 166 is formed part-way through the sidewall 148 thickness from the exterior surface 164 thereof resides at the insert proximal end 144. The groove 166 forms a track on which the collar pins 142 ride. In an embodiment, the groove 166 is oriented perpendicular to the rotational axis A-A.
In an embodiment, the insert 126 is positioned within the interior of the collar 128 with each of the at least two collar pins 142 received within an insert slot 162, respectively. In an embodiment, the at least two pins 142 ride within a respective insert slot 162 that is positioned in opposition to each other. In a preferred embodiment, the pins 142 are capable of riding within the insert slot 162 in a back and forth manner from the distal insert end 146 to the groove 166 at the insert proximal end 144. As the collar pins 142 ride within the slot 162, the insert 126 rotates within the reamer shell opening 24 traveling in either a distal or proximal direction. For example, as the insert 126 is rotated in a clockwise direction, the insert may travel in a distal direction until the pins 142 exit their respective slot 162 and ride along the track formed by the groove 166 at the insert proximal end 144. In a preferred embodiment, the collar pins 142 ride along the track formed by the groove 166 so that the insert 126 is capable of 360° rotation. In an embodiment, the insert 126 may be retracted within the reamer shell 20 by rotating the insert in an opposite direction, i.e., counter-clockwise, such that the pins 142 leave the groove 166 to enter and ride within a respective slot 162 in a proximal direction so that the insert 126 retracts within the reamer shell 20.
In an embodiment, the collar 128 is secured to the reamer shell flange 54 that extends within the reamer shell 20. In an embodiment, the collar distal end 132 is secured to the reamer shell flange proximal end 58 such that rotational movement of the insert 126 within the reamer shell opening 24 is not impeded. In a preferred embodiment, the collar 128 may be secured to the reamer shell flange 54 with an adhesive or by welding the collar 100 to the flange 54. The collar 100 may be secured to the reamer shell flange 54 by a fastener (not shown). In an embodiment, the fastener (not shown) may at least partially extend through the thickness of the sidewalls of the collar 100 and reamer shell flange 54.
A band 170 (
The bone cutters 10, 124 of the present invention are designed to be connectable to a driver shaft (not shown).
Once the acetabular roof and labrum have been sufficiently reamed, the reamer shell 20 is rotated in the opposite direction to thereby anchor the reamer shell within surrounding tissue and/or bone. After the shell 20 is anchored, the insert 22, 126 is continued to be rotated in the same direction to extend the insert tissue cutting teeth 94, 156 from within the shell interior. In a preferred embodiment, the insert is rotated in the opposite direction of the orientation of the shell cutting teeth 46 to extend the insert cutting teeth 94, 156 past the reamer shell opening 24. Once extended, the insert 22, 126 is continued to be rotated so that acetabular floor and fossa are adequately reamed to the appropriate diameter. The reamer insert is then rotated in the opposite direction to retract the insert cutting teeth 94, 156 into the reamer shell interior. The bone cutter anchors 70 are dislodged from the surrounding bone and tissue and the bone cutter 10, 124 is removed from the body.
In a preferred embodiment, the reamer shell 20, inserts 22, 126, collars 100, 128 and band 170 are composed of a biocompatible material. More specifically, at least one of the reamer shell 20, inserts 22, 126, collars 100, 128 and band 170 may be composed of a biocompatible polymer, metal or ceramic material. Examples of such polymeric materials include, but are not limited to, acrylonitrile butadiene styrene (ABS), polyacrylamides (PARA), polyetherimide (PEI), and polyetheretherketone (PEEK). In addition, examples of metallic materials include, but are not limited to, stainless steel, titanium, MP35N, and a biocompatible metal.
While the preferred embodiments of the cutting device and methods have been described in reference to the environment in which they were developed, they are merely illustrative of the principles of the inventions. Other embodiments and configurations may be devised without departing from the spirit of the inventions and the scope of the appended claims.
This application claims priority from U.S. Provisional Patent Application Ser. No. 62/266,342, filed Dec. 11, 2015.
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| Number | Date | Country | |
|---|---|---|---|
| 20170164955 A1 | Jun 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| 62266342 | Dec 2015 | US |
