Patient-specific Accetabular Guide

Abstract

A patient-specific acetabular guide comprises a cup body, a plurality of alignment arms extending from the cup body and engaging periacetabular areas of a pelvis, and a supporting leg protruding from the cup body and abutting against a portion of an acetabular fossa. Each alignment arm has a fixing hole extending inclinedly therethrough to allow a Kirschner pin to pass through and enter the periacetabluar area of the pelvis for positing and orienting the acetabular guide on a predetermined location of an acetabulum.

Claims

1. A patient-specific acetabular guide comprising: a cup body configured with a hemispherical shape; a plurality of spaced alignment arms extending from the cup body: a supporting leg protruding outwardly from the cup body; and a guiding element extending upwardly from a bottom of the cup body and defining an elongated bore extending therethough, the elongated bore having an axis predetermined by a preoperative surgical plan.

2. The patient-specific acetabular guide of claim 1, wherein the supporting leg has an abutted surface at an end thereof, and wherein the alignment arms each configured to extend from the cup body include a first alignment arm and a second alignment arm arranged separating from each other.

3. The patient-specific acetabular guide of claim 2, wherein the first alignment arm has a first arm portion defining a contacting portion at an end thereof, and wherein the second alignment arm has a second arm portion defining a touching portion at a tip thereof, and wherein the contacting portion has an engaging surface at a bottom thereof, and wherein the touching portion has a contacting surface at a bottom thereof.

4. The patient-specific acetabular guide of claim 3, wherein the contacting portion extends downwardly from the first arm portion and has a locating hole with an axis extending inclinedly therethrough.

5. The patient-specific acetabular guide of claim 4, wherein the touching portion extending downwardly from the second arm portion has a positioning hole with an axis extending inclinedly from a top thereof to a bottom thereof.

6. The patient-specific acetabular guide of claim 5, wherein the axis of the positioning hole is inclined to the axis of the locating hole, and wherein the axis of the positioning hole is inclined to the axis of the elongated bore, and wherein the axis of the locating hole is inclined to the axis of the elongated bore.

7. The patient-specific acetabular guide of claim 2, wherein the first arm has a marker aperture with an axis extending through the first arm portion, and wherein the axis of the marker aperture is parallel to the axis of the elongate bore.

8. The patient-specific acetabular guide of claim 3, wherein the first arm portion defines a reinforcing rib protruding downwardly from a bottom thereof, and wherein the second arm includes a stiffener disposed at a bottom of the second arm portion.

9. The patient-specific acetabular guide of claim 1, wherein the guide element has a plurality of reinforcement portion protruding around thereof.

10. The patient-specific acetabular guide of claim 1, wherein the patient-specific guide includes an identification position protruding upwardly from a top portion of the cup body and located at a portion adjacent to the second arm.

11. A patient-specific acetabular guide positioned and oriented on a predetermined location of an acetabulum of a pelvis to provide an accurate alignment axis relative to the planned orientation of an acetabular cup, comprising: a cup body covering an acetabular fossa of the acetabulum at a central of the acetabulum; a plurality of alignment arms extending outwardly from the cup body and engaging the periacetabular surface of the pelvis; a supporting leg protruding from the cup body and abutting against the acetabular fossa; and a guiding element defining an elongated bore extending therethrough, wherein the elongated bore having a patient-specific alignment axis configured to be central to the acetabluar cup and perpendicular to the acetabular cup's surface when the acetabular guide is positioned on the acetabulum.

12. The patient-specific acetabular guide of claim 11, wherein the alignment arms each configured to extend over a corresponding portion of an acetabular rim and/or an acetabular ligament for fixing the acetabular guide to the predetermined location include a first arm and a second arm arranged separating from each other.

13. The patient-specific acetabular guide of claim 12, wherein the first arm extending from a top portion of the cup body has a contacting portion at an end thereof, and wherein the second arm extending from another top portion of the cup body defines a touching portion at an end thereof.

14. The patient-specific acetabular guide of claim 13, wherein the first arm has an engaging surface located at a bottom of the contacting portion to fit a periacetabular surface of the pelvis, and wherein the second arm has a contacting portion located at a bottom of the touching portion to fit another periacetabular surface of the pelvis, and wherein the supporting leg defines an abutted surface at en end thereof for engaging with a corresponding surface of the acetabular fossa.

15. The patient-specific acetabular guide of claim 14, wherein the engaging surface of the first arm and the contacting surface of the second arm both are custom-made to conform to and mirror complementary surface of the corresponding periacetabluar surface of the pelvis, and wherein the abutted surface of the supporting leg is mirror complementary surface of the acetabular fossa.

16. The patient-specific acetabular guide of claim 14, wherein the first arm has a locating hole extending inclinedly from a top of the contacting portion to a bottom of the contacting portion, and wherein the second arm has a positioning hole extending inclinedly from a top of the touching portion to a bottom of the touching portion, and wherein the locating hole has an axis inclined to the axis of the elongated bore, and wherein the positioning hole has an axis inclined to the axis of the elongated bore, and wherein the axis of the locating hole is inclined to the axis of the positioning hole.

17. The patient-specific acetabular guide of claim 16, wherein the first arm defines a marker aperture extending inclinedly therethrough and wherein the marker aperture is arranged separating from the locating hole, and wherein the marker aperture defines an axis parallel to the axis of the elongated bore.

18. The patient-specific acetabular guide of claim 12, wherein the first arm includes a reinforcing rib located at a bottom thereof, and wherein the second arm has a stiffener protruding downwardly from a bottom thereof.

19. The patient-specific acetabular guide of claim 12, wherein an identification portion protrudes from a top portion of the cup body and is configured with an arrow shape to point to an acetabular notch of the acetabulum when the patient-specific acetabular guide is fixed on the acetabulum.

20. The patient-specific acetabular guide of claim 19, wherein the identification portion is located at a portion of the cup body which is adjacent to the second arm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is an assembled, perspective view of a patient-specific guide and an acetabulum of a specific patient in accordance with the preferred embodiment of the present invention;

[0012] FIG. 2 is an exploded, perspective view of the patient-specific guide and an acetabulum of the specific patient shown in FIG. 1;

[0013] FIG. 3 is a perspective view of the patient-specific guide shown in FIG. 1;

[0014] FIG. 4 is another perspective view of the patient-specific guide shown in FIG. 3;

[0015] FIG. 5 is another perspective view of the patient-specific guide shown in FIG. 3.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0016] Reference is now made to the drawings to describe the invention in detail.

[0017] Referring to FIGS. 1-5, a patient-specific acetabular guide 100 in accordance with a preferred embodiment of this invention is disclosed. The patient-specific acetabular guide 100 is used in connection with other instruments described in prior art for facilitate guided reaming of an acetabulum 202 of a pelvis 200 and guided insertion and implantation of an acetabular cup (not shown) in the acetabulum 202 during a hip-joint replacement surgery. The patient-specific acetabular guide 100 comprises a cup body 1 having a rim portion 10 at the top thereof, a plurality of spaced alignment arms 2 extending from the rim portion 10 of the cup body 1, and a supporting leg 3 protruding from the cup body 1. The patient-specific acetabular guide 100 is positioned and orientated on a predetermined location of the acetabulum 202 to provide an accurate alignment axis relative to the planned orientation of the acetabular cup (not shown) through the alignment arms 2 engaging the periacetabular surface of the pelvis 200 and the supporting leg 3 abutting against an acetabular fossa 203 of the acetabulum 202. The predetermined location of the acetabulum 202 is determined during a preoperative surgical plan and based on a three-dimensional reconstruction of the pelvis 200 and an implanting position of the acetabular cup (not shown). The three-dimensional reconstruction can be based on two-dimensional medical images, including MRI, CT or X-ray scans and prepared using commercially available imaging software.

[0018] The cup body 1 covers an acetabular fossa 203 at the center of the acetabulum 202 which provides a landmark for rotational stability and unique positioning on the acetabulum 202. The cup body 1 configured to be a hemispherical shape defines an inner surface 11 and an outer surface 12 opposite to each other. The inner and outer surfaces 11, 12 of the cup body 1 both are configured to be a hemispherical shape and connect with each other through the rim portion 10. The cup body 1 defines a guiding element 4 with a hollow shape extending upwardly from the bottom thereof. The guiding element 4 has an elongated bore 40 with a patient-specific alignment axis A configured to be central to the acetabular cup (not shown) and perpendicular to the acetabular cup's surface when the acetabular guide 100 is positioned on the acetabulum 202. The elongated bore 40 is configured as a threaded hole and can cooperate with a handle (not shown) to place the guide 100 on the acetabulum 202.

[0019] The alignment arms 2 each configured to extend over a corresponding portion of the acetabular rim 204 and/or the acetabular ligament 205 for fixing the guide 100 to a desired position predetermined by a preoperative surgery plan include a first alignment arm 21 and a second alignment arm 22 arranged separating from each other. The first alignment arm 21 includes a first arm portion 210 bending upwardly from the corresponding rim portion 10 of the cup body 1 and a contacting portion 211 disposed at the end of the first arm portion 21. The first arm portion 210 extends beyond the corresponding portion of the acetabular rim 204 along a horizontal direction. The contacting portion 211 extends downwardly from the end of the first arm portion 210 and has an engaging surface 212 at the end thereof. The engaging surface 212 can engage with a periacetabular surface 206 of the pelvis 200. The engaging surface 212 is custom-made to conform to and minor complementary surface of the periacetabular surface 206 of the pelvis 200.

[0020] The first alignment arm 21 also includes a reinforcing rib 213 protruding downwardly from a bottom of the first arm portion 210. The first arm portion 210 is configured to be a plate board and has an increasing width. The reinforcing rib 213 is defined at a central section of the bottom of the first arm portion 210 for improving the strength of the first arm 21 to prevent the first arm 21 from breaking during using. The first arm portion 210 defines a marker aperture 214 extending from a top to a bottom thereof. The marker aperture 214 has an axis B parallel to the alignment axis A of the elongated bore 40 of the guide element 4. The contacting portion 211 has a locating hole 215 extending therethough. The locating hole 215 extends from a top of the contacting portion 211 to a bottom of the contacting portion 211 along an inclined direction and has an axis C inclined to the axis B of the marker aperture 214.

[0021] The second arm 22 has a structure which is similar to the first arm 21 and defines a second arm portion 220 with a touching portion 221 at a tip thereof. The second arm portion 220 bends upwardly from the rim portion 10 of the cup body 1 and extends over the corresponding portion of the acetabular rim 204 and the acetabular ligament 205 along a horizontal direction. The touching portion 221 extends downwardly from an end of the second arm portion 220 and has a contacting surface 222 matching a periacetabular surface 207 of the pelvis 200. The contacting surface 222 is configured as a mirror complementary surface of the periacetabular surface 207 of the pelvis 200. The second arm 22 has a stiffener 223 disposed at a bottom of the second arm portion 220. The stiffener 223 is structured as a rib and protrudes downwardly from the bottom of the second arm portion 220 to improve the strength of the second arm portion 220 for avoiding the second arm portion 220 breaking during using.

[0022] The second arm 22 has a positioning hole 224 with an axis D inclined to the axis C of the locating hole 215 of the first arm 21. The positioning hole 224 extends inclinedly from a top of the touching portion 221 to a bottom of the touching portion 221. The axis D of the positioning hole 224 is also inclined to the axis A of the elongated bore 4 of the guide element 4. The acetabular guide 100 is fixed on the acetabulum 202 through Kirschner pins 300 respectively cooperating with the locating hole 215 of the first arm 21 and the positioning hole 224 of the second arm 22 to enter the corresponding portions of the periacetabular area of the pelvis 200. The marker aperture 214 of the first arm 21 can guide a marker pin 301 to enter the periacetabular area of the pelvis 200. The marker pin 301 is configured as a reference during the surgery drills the acetabulum 202.

[0023] The supporting leg 3 defines an abutted surface 30 at the end thereof for engaging with a corresponding surface of the acetabular fossa 203. The abutted surface 30 is patient-specific to conform to and mirror complementary surface of the acetabular fossa 203 of the acetabulum 202. The supporting leg 3 protrudes from the outer surface 12 of the cup body 1 and is spaced from the alignment arms 2. The guiding element 4 is structured to be a conical shape and extends upwardly from the inner surface 11 of the cup body 1 along the patient-specific alignment axis A. The guiding element 4 has a plurality of reinforcement portion 41 distributed circumferentially thereon. The reinforcement portion 41 are spaced from each other and each projects outwardly from the guiding element 4. An identification portion 5 protrudes upwardly from the rim portion 10 of the cup body 1 and configured with an arrow shape to point to an acetabluar notch 208 of the acetabulum 202 when the guide 100 is fixed on the acetabulum 202. The identification portion 5 used for a reference during placing the guide 100 on the acetabulum 202 is located at a portion of the cup body 1 which is adjacent to the second arm 22.

[0024] In assembling, the patient-specific acetabular guide 100 is placed on the acetabulum 202 of the pelvis 200 by a jig (not shown). The acetabular guide 100 is firmly positioned and oriented on the acetabulum 202 through the Kirschner pins 300 entering the corresponding portions of the periacetabular areas of the pelvis 200 along the locating hole 215 and the positioning hole 224 of the alignment arm 2. The engaging surface 212 of the first arm 21 completely fits the periacetabular surface 206 of the pelvis 200 and the contacting surface 222 of the second arm 22 completely fits the periacetabular surface 207 of the pelvis 200. The abutted surface 30 of the supporting leg 3 completely abuts against the surface of the acetabular fossa 203.

[0025] Furthermore, although the present invention has been described with reference to particular embodiments, it is not to be construed as being limited thereto. Various alterations and modifications can be made to the embodiments without in any way departing from the scope or spirit of the present invention as defined in the appended claims.