JP4215867B2 - Bipolar-unipolar type femoral head adapter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an adapter for converting a bipolar substitute shell into a unipolar substitute femoral head.
[0002]
[Prior art]
Successful replacement or formation of the hip depends in part on whether a joint prosthesis that is very close to or similar to the geometry and function of the natural healthy hip joint can be selected. When selecting a prosthesis, typically the joint images are analyzed before surgery. When selecting the prosthesis, one or more temporary members are temporarily fixed to the bone or bones before the joint prosthesis is permanently fixed. The temporary member mimics some of the characteristics of a permanent prosthesis so that the surgeon can check various measurements and experiment with several different member sizes and placements. . Therefore, this temporary member is called “trial (femur substitute)”.
[0003]
In known surgical procedures, trials for the buttocks and thighs are used as follows. First, the front end of the femur is cut to pierce the bone marrow. That is, a hole punch (broach) is inserted into the front end of the femur that has been cut, and a void is provided inside the bone shaped to accommodate the femoral stem. Prior to removing the boring device, the trial neck (neck) or the ear and the trial head should be secured to the boring device so that the complete femoral stem can be simulated. Then, in order to determine the appropriate neck length and total length of the femoral stem, several trial necks and heads of different lengths and shapes are usually connected to a boring device. Once these lengths have been determined, the trial neck and head are removed from the boring device, and the boring device is removed from the femur. The person skilled in the art then selects the appropriate length of the femoral stem for insertion into the gap formed by the boring device using known techniques.
[0004]
Typically, two types of femoral prosthetic devices are suitable for hip plasty. One is a bipolar prosthesis. In general, a bipolar buttocks prosthesis includes a shell (shell-shaped portion) having an outer surface that rotates with the acetabulum and an inner surface that rotates with the spherical head of the femoral prosthesis. Another type is a unipolar endoprosthesis, which has a spherical head large enough for the femoral prosthesis to rotate directly with the acetabulum.
[0005]
[Problems to be solved by the invention]
US Pat. No. 5,156,626 describes a procedure for implanting a bipolar hip prosthesis using a reduction system using a four-part trial. The system includes a substitute femoral broach, a neck attached to the broach, a substitute femoral head attached to the neck, and a shell for receiving and securing the substitute femoral head in a patient's acetabulum. It is. Substitution techniques using these four parts can often be cumbersome for physicians. This is because when a doctor tries to fix the substitute femoral head, the substitute is easy to move and easily disengages from the shell. Furthermore, since this trial system performs various combinations, it is necessary to use a large number of components that must be appropriately selected and combined.
[0006]
A unipolar trial system used to implant a unipolar buttock typically includes a broach, a cervical trial, and a head trial. A corresponding unipolar substitute can be used in some cases to perform substitution reduction of a bipolar hip implant. This is one of the main factors in performing substitution reduction in both bipolar and unipolar implantation procedures, as it may determine the parts that fit the acetabulum. Also, in many cases, the range of movement of the bipolar implant is similar to that of a unipolar substitute.
[0007]
[Means for Solving the Problems]
The present invention overcomes the disadvantages of conventional femoral substitutes by providing a bipolar-unipolar trial adapter that can be attached to and detached from the bipolar substitute shell by changing the bipolar substitute shell to a unipolar femoral head. is there.
[0008]
In one aspect of the adapter, there is provided a neck that can be adjusted in length without the need to select a unipolar femoral head having different neck lengths for different sizes of femoral heads. In a preferred example of this embodiment, a spring loaded fit-in adapter and a mechanism that can easily adjust the neck length are provided.
[0009]
The present invention also provides a fixed length femoral head trial adapter system. The fixed length trial adapter includes a cylindrical barrel having a void shaped to receive a cervical trunnion from a substitute femoral stem. The adapter also includes a circumferential flange on the outer surface of the barrel to which an elastic connection member is attached. The connection member that secures the adapter to the substitute shell has a nominal first diameter and a second diameter smaller than that obtained when the first diameter is compressed. When the compressive force is released, the connecting member returns to the first diameter. In a preferred embodiment, the connecting member is shaped to just fit into the annular groove of the substitute shell.
[0010]
In a preferred embodiment, the orbiting flange is provided at a predetermined position on the outer surface of the barrel, and the internal cavity has a predetermined depth for simulating a predetermined length of cervical trunnion. Thus, this trial system uses a plurality of adapters having various neck lengths.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be better understood from the following detailed description.
[0012]
1-3 show an adjustable trial adapter 10 of the present invention. The adjustable trial adapter 10 includes a cylindrical portion (annular portion) 11 having a through-opening 12 and a ball plunger (joining portion to a substitute shell) 14 that is biased by a spring and protrudes from an outer periphery 13 of the cylindrical portion 11. And a claw member 15 protruding through the outer periphery 13 of the cylindrical portion 11.
[0013]
The surrogate adapter further includes a barrel (adapter neck member) 16 that operates as an adjustable neck member of the unipolar surrogate head when the adapter 10 is inserted into the bipolar surrogate shell 30. The barrel 16 has three grooves 17 provided on the outer periphery of the barrel 16. The barrel 16 further includes a slot 18 provided in the longitudinal direction on the outer periphery 24 of the barrel 16 and an opening 19 penetrating the cylindrical wall 20 of the barrel. The barrel 16 has a longitudinal opening 21 that extends from the bottom 26 of the barrel to the top wall 22 of the barrel. A small opening 23 communicating with the opening 21 is provided in the top wall 22.
[0014]
The dowel pin 28 is pressed and fixed to the side portion of the cylindrical portion 11, and the dowel pin 28 extends through the side portion and is fitted into the slot 18 of the barrel 16. The pin 28 detachably fixes the cylindrical portion 11 to the barrel 16, and the slot 18 allows the barrel 16 to be positioned between three neck length positions determined by the groove 17. It can be moved up and down.
[0015]
The claw member 15 has a button portion 40, a groove engaging portion 42, and a compression spring 41 for receiving a blind hole 46. When the claw member 15 is assembled, the claw member 15 is inserted into the opening 25, the dowel pin 47 is pushed into the through hole 51 of the cylindrical portion 11, and the through hole 48 of the claw member 15 is penetrated and fixed. As a result, the claw member 15 is rotatably assembled to the cylindrical portion 11. The compression spring 41 is inserted into the hole 49 of the cylindrical portion 11 and the hole 46 of the claw member and is disposed in the hole 49 of the cylindrical portion 11. The dowel pin 50 extends into the cylindrical portion 11, crosses the hole 49, and the spring 41 is confined in the holes 46 and 49 in a compressed state. The claw member 15 is urged toward the barrel 16 by the spring 41. As a result, when the barrel 16 is in the fixed position, the groove engaging portion 42 is engaged with one of the grooves 17. The button part 40 is exposed on the outer periphery 13 of the cylindrical part 11, and as a result, the user moves the button part 40 to release the engaging part 42 from engaging with the groove 17, thereby 16 can be moved to a desired position.
[0016]
As shown in FIGS. 4 (a) and 4 (b) and attached to the adapter 10 of FIG. 5, the bipolar substitute shell 60 has a spherical shape including a flat lower region 62. The adapter storing opening 64 is surrounded by the lower region 62. An outer surface 66 that contacts the bone of the substitute shell 60 rotates with the acetabulum. The top of the substitute shell 60 is provided with a second opening 67 used for the difference reaching the inside of the substitute shell 60. In general, the bipolar substitute shell 60 is available in various sizes having an outer diameter of about 38 mm to 63 mm and a height of 27.5 mm to 40 mm.
[0017]
The substitute shell 60 also has an inner surface 65 that does not contact bone, extending from the opening 64 into the shell 60 and defining a void. The inner surface 65 includes a hemispherical region 68 that rotates with the trial head 65 in reduction using a bipolar trial without the adapter of the present invention. Thus, a single surrogate shell 60 can be used in a bipolar trial or with the adapter of the present invention to be the trial head.
[0018]
The inner surface 65 of the substitute shell 60 also defines an annular shelf 72 that engages an adapter, such as the trial adapter 10 of the present invention, with the annular groove 70 and adapter resting thereon. The annular groove 70 is located inside the adapter accommodation opening 64 and is shaped to accommodate a connection member attached to the trial adapter 10 such as the ball-shaped plunger 14 loaded with a spring. An annular shelf 72 is located in the opening 64 and serves as a pedestal means for the trial adapter 10 in relation to the substitute shell 60.
[0019]
The substitute shell 60 is made of a material suitable for temporary use during surgery. Such materials include various copolymers, particularly acetal copolymers, and polymeric materials such as polyethylene, polypropylene, polyphenylsulfone and nylon.
[0020]
In use, the cylindrical portion 11 is inserted into the opening 31 of the bipolar substitute shell 60, and the barrel 16 is extended downward from the adapter 10. The top 27 of the cylindrical portion 11 abuts on a shelf 72 in the opening 31 of the shell 30, and the spring-loaded ball plunger 14 is fitted into a groove 70 formed in the bipolar substitute shell 60. As a result, the adapter 10 is fitted into the bipolar substitute shell 60 and is held by a spring biased ball plunger that enters the groove 70.
[0021]
As shown in FIG. 6, the barrel 16 serves as a coupling portion with a femoral neck trunnion (cylinder ear, rotating shaft portion) 56 of the substitute thigh 74. The femoral neck rotation shaft portion 76 can be coupled to the adapter 10 by inserting the femoral neck rotation shaft portion 76 into the opening 21 of the barrel 16.
[0022]
The unipolar adapter 10 can be removed from the bipolar substitute shell 30 by manually pushing it out from the top hole 67 of the substitute shell using a cylindrical instrument having a small diameter.
[0023]
7 to 11D, a fixed-length trial adapter 80 can be used instead of the trial adapter 10 whose length is adjustable. The fixed length adapter 80 generally comprises a cylindrical barrel 82 having an outer surface 84 and an upper end 86 and a lower end 88. The rotating flange portion 90 is integral with the outer surface 84 of the barrel between the upper end 86 and the lower end 88. Flange portion 90 is generally cylindrical, the height is lower than the barrel 82, the outer diameter outwardly from the outer surface 84 of the barrel 82 extends in the radial direction to the position of D _2.
[0024]
Barrel 82 has an inner surface 95 that extends inwardly from opening 94 and demarcates void 96 and an opening 94 there. The gap 96 is shaped to allow the femoral neck trial to be placed. The void 96 is generally cylindrical and extends upwardly from the lower opening 94 toward the upper region 98 where the femoral neck trunnion contacts. The air gap 96 is also tapered to accommodate a conventional cervical trial trunnion that is normally tapered. One skilled in the art will readily recognize that various tapers can be used. Typical tapers are 10/12 and 11/13, which represent the neck diameter at two different points in its length direction.
[0025]
Grooves 100 and 102 for fitting the O-rings 104 and 106, respectively, can be provided in the gap 96. The O-rings 104 and 106 are preferably formed from silicone rubber, but with these O-rings, the trunnion size is a trial or permanent prosthesis, or the taper is dimensioned and measured. The adapter 80 can be mated with a cervical trial trunnion, although it may vary from manufacturer to manufacturer adopting different standards. Further, if there is an O-ring, the neck and the adapter 80 can be combined at two points along the length of the gap. This configuration is preferable in controlling the combination of the gaps 96 in the length direction. This is because the trial adapter 80 is unlikely to come off the neck. As an alternative to the O-ring, at least one circumferentially raised part (not shown) can be used in the air gap.
[0026]
In a preferred embodiment, the flange portion 90 has a groove 108 suitable for receiving the elastic connecting member 110 on the outer periphery thereof. In the embodiment shown in FIGS. 9 and 10, the connecting member 110 has an arc shape having an inner diameter 112 larger than the diameter D 1 of the groove 108. Therefore, when the connecting member 110 is in a position without the first deflection, a gap 114 (shown in FIG. 8) is formed between the groove 108 and the connecting member 110. The nominal outer diameter 116 (when there is no deflection) of the connecting member 110 is preferably larger than the outer diameter D ₂ of the flange portion 90 by about 0.05 to 0.11.
[0027]
The connecting member 110 is made of a flexible material so that the arcuate shape can be pushed from a first undeflected position to a second compressed position. The connecting member 110 maintains a second outer diameter that is smaller than the nominal outer diameter 116 in response to a compressive force, such as when the adapter is pushed against the substitute shell 60. The connecting member 110 can also be shaped into a complete ring shape. However, the portion corresponding to the angle α is removed from the ring shape. The removed portion α has an arcuate shape of about 10 ° to about 60 °, preferably about 30 °.
[0028]
Those skilled in the art will readily appreciate that the connecting member 110 can be manufactured from a variety of elastic materials having shape memory properties. Such materials include polymer materials as well as shape memory alloys. For example, copolymers, polyethylene, polypropylene, polyphenylsulfone and nylon.
[0029]
When the adapter 80 is inserted into the shell 60, the force accompanying the contact transmitted from the gap 65 of the substitute shell 60 causes the elastic connecting member 110 to move from the position of the first nominal outer diameter 116 to the second compressed outer diameter. Compressed into position, adapter 80 slides into substitute shell 60. When the flange 90 rides on the annular shelf 72 in the opening 64 of the substitute shell, the connecting member 110 aligns with the annular groove 70 in response, and the elastic connecting member 110 fits into the groove 70 when expanded. The adapter 80 is fixed to the substitute shell 60. The connection member 110 preferably has a round outer edge corresponding to the shape of the annular groove 70 in order to facilitate fitting into the groove 70.
[0030]
The fixed length trial adapter 80 can be removed from the substitute shell by inserting a suitable tool through the top hole 67 of the substitute shell as described for the variable length adapter 10. Further, the adapter 80 may be provided with an elliptical opening 120 at the upper end 86 thereof. Then, using a tool (not shown) comprising a cylindrical insertion member and a cruciform member aligned with the opening 120 near the insertion end, this tool is opened from the inside through the elliptical opening 120 to open the cruciform member. It can be inserted while being aligned with 120. The tool is then rotated 90 ° so that the cross member is unaligned with the oval hole 120. Thereafter, the adapter 80 is removed from the shell 60 by pulling the tool with sufficient force to compress the resilient connecting member 110 and remove the adapter 80.
[0031]
Trials with various cervical trunnions can be simulated using fixed length trial adapters with different effective lengths. The effective length of the trial adapter 80 can be changed in various ways, for example, by providing the orbiting flange 90 at different positions of the barrel 82. The position of the end region 98 of the void 96 inside the barrel can be varied as well. Fixed-length trial adapters 80 having effective lengths of −3 mm, 0, +5 mm, and +10 mm are shown in FIGS. 11 (a), 11 (b), 1 (c), and 11 (d), respectively.
[0032]
Specific embodiments of the present invention are as follows.
(1) The adapter according to claim 1, further comprising a circumferential groove formed in the flange.
(2) The adapter according to claim 1, wherein the contact member has an arc shape.
(3) The adapter according to the embodiment (2), wherein the arcuate shape defines an angle smaller than 360 °.
(4) The adapter according to the embodiment (1), wherein the contact member is disposed in a circumferential groove of the flange.
(5) The adapter according to the embodiment (4), wherein the nominal first diameter of the contact member is larger than the outer diameter of the flange.
[0033]
(6) The adapter according to the above embodiment (5), wherein the contact member is formed in a shape that fits with a corresponding annular groove in the substitute shell.
(7) The adapter according to claim 1, wherein the flange is provided at a predetermined position between the upper end and the lower end along the outer surface of the barrel for use in simulation of a substitute neck portion having a predetermined length.
(8) The adapter according to the embodiment (1), wherein the contact member is formed of an acetal copolymer.
(9) The system according to claim 2, wherein the contact member can be pushed into a groove of the flange portion.
(10) The system according to claim 2, wherein the contact member is shaped into a shape that can be fitted into a corresponding groove of the substitute shell.
[0034]
(11) The system according to the embodiment (10), wherein the contact member defines an arcuate shape having an angle smaller than 360 °.
(12) The system according to embodiment (11), wherein the contact member defines an arc shape of about 300 ° to 350 °.
(13) The system according to claim 2, wherein the flange is provided at a predetermined position between the upper end and the lower end along the outer surface of the barrel.
(14) The system according to the embodiment (13), wherein the system includes a plurality of barrels provided with flange portions at a plurality of predetermined positions on the outer surface of the barrel.
(15) The system according to claim 3, wherein the system includes an annular groove formed in a gap of the substitute shell.
[0035]
(16) The trial system according to embodiment (15), wherein the contact member has an arc shape.
(17) The trial system according to the above embodiment (16), wherein the arcuate shape defines an angle smaller than 360 °.
(18) The trial system according to the above embodiment (17), wherein the arc-shaped contact member is disposed in a circumferential groove of the flange.
(19) The trial system according to the embodiment (17), wherein the nominal first diameter of the contact member is larger than the outer diameter of the flange.
(20) The trial system according to the embodiment (17), wherein the contact member can be pushed into a groove of the circumferential flange.
[0036]
(21) The trial system according to the above embodiment (17), wherein the contact member is formed into a shape that fits with a corresponding annular groove in the substitute shell.
(22) The trial system according to the above embodiment (17), wherein the flange is provided at a predetermined position between the upper end and the lower end along the barrel outer surface in order to be used for simulation of a substitute neck portion having a predetermined length.
[0037]
【The invention's effect】
The physician can choose to convert the bipolar substitute shell to a unipolar substitute bone head by inserting the variable length unipolar trial adapter 10 or the fixed length unipolar trial adapter 10 into the shell 60 during surgery. With either adapter, the surgeon can adjust the fit of the femoral head or bipolar shell while selecting the appropriate neck length, reducing the femur without relying on the previous cumbersome bipolar trial system be able to.
[0038]
This surrogate system preferably has various dimensions for the bipolar shell and femoral stem so that the surgeon can select suitable dimensions during reduction surgery. When using a fixed length adapter 80, the trial system preferably includes a plurality of adapters 80 having different neck lengths.
[0039]
The present invention has been described above with reference to specific embodiments, configurations, and applications. However, the present invention is not limited to these, and various modifications and changes may be made without departing from the scope of the claims of the present invention. It can be changed.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a substitute adapter of the present invention.
2 is an exploded perspective view of the substitute adapter of FIG. 1 rotated about 90 degrees. FIG.
FIG. 3 is a side view of the substitute adapter of the present invention.
4 (a) is a side view of a bipolar shell trial, and FIG. 4 (b) is a cross-sectional view of the trial bipolar shell trial shown in FIG. 4 (a).
FIG. 5 is a cross-sectional view of the trial adapter shown in FIG. 1 used with a bipolar shell trial.
FIG. 6 is a cross-sectional view of a thigh trial system according to the present invention.
FIG. 7 is a plan view of a fixed length adapter according to the present invention.
8 is a cross-sectional view taken along line 8-8 in FIG.
FIG. 9 is a plan view of a connection member according to the present invention.
10 is a cross-sectional view taken along line 10-10 of FIG.
11A is a cross-sectional view of the fixed length adapter according to the present invention shifted by −3 mm, FIG. 11B is a cross-sectional view of the fixed length adapter according to the present invention without any shift, and FIG. c) is a sectional view of the fixed length adapter according to the present invention shifted by +5 mm, and FIG. 11D is a sectional view of the fixed length adapter according to the present invention shifted by +10 mm.

Claims (3)

A fixed-length surrogate femoral head adapter for changing a bipolar surrogate shell to a unipolar femoral head,
A cylindrical barrel having an outer surface with an upper end and a lower end, an inner surface defining a gap for receiving a cervical trunnion of a substitute femoral stem, and an orbiting flange having an outer diameter;
An elastic connection member disposed on the circumferential flange, the elastic connection member having a nominal first diameter and a second diameter smaller than the first diameter obtained when a compressive force is applied. And the second diameter returns to the first diameter when the compressive force is removed, and the adapter has an elastic connecting member to fix the adapter to the bipolar substitute shell. A surrogate femoral head adapter system for changing a bipolar surrogate shell to a unipolar femoral head,
A barrel having an outer surface having an upper end and a lower end and an inner surface defining a gap for accommodating a neck trunnion of a substitute femoral stem, and further including a circumferential flange having an outer diameter and a circumferential groove on the outer surface of the barrel A cylindrical barrel;
An elastic connection member disposed on the circumferential flange, the elastic connection member having a nominal first diameter and a second diameter smaller than the first diameter obtained when a compressive force is applied. And the second diameter returns to the first diameter upon removal of the compressive force to secure the adapter to the bipolar substitute shell. A substitute thigh system,
A substitute femoral stem including the neck,
A bipolar substitute shell having an outer surface that contacts the bone and an inner surface that defines a void and does not contact the bone;
A fixed length adapter that can be removably attached to the neck to change the bipolar substitute shell to a unipolar substitute femoral head,
A barrel having an outer surface having an upper end and a lower end and an inner surface defining a gap for accommodating a neck trunnion of a substitute femoral stem, and further including a circumferential flange having an outer diameter and a circumferential groove on the outer surface of the barrel A cylindrical barrel;
An elastic connection member disposed on the circumferential flange, the elastic connection member having a nominal first diameter and a second diameter smaller than the first diameter obtained when a compressive force is applied. And the second diameter returns to the first diameter upon removal of the compressive force to secure the adapter to the bipolar substitute shell and includes an adapter having an elastic connection member.

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