Patent Application
20170258480
1. Field of the Invention
The present invention relates to a patient-specific acetabular guide, and more particularly to a patient-specific acetabuluar guide used in a hip joint replacement surgery and method of manufacturing the same. The patient-specific acetabular guide can be used in connection with various other instruments to facilitate guided reaming of an acetabulum of a pelvis of a specific patient and guided insertion and implantation of an acetabulum implant or acetabular cup in the acetabulum.
2. Description of the Prior Art
A conventional patient-specific acetabular guide disclosed in U.S. Pat. No. 8,608,749 issued to Meridew et al. on Dec. 17, 2013 comprises a patient-specific body covering the acetabular fossa at the center of the acetabulum and a guiding element having an elongated bore with a patient-specific alignment axis configured to be central to the acetabular cup and perpendicular to the acetabular cup's surface when the acetabular guide is positioned to the acetabulum. The elongated bore of the guiding element is used for leading a tool to drill the acetabulum along the patient-specific alignment axis.
The acetabular guide also includes two marker elements each having an elongated bore for guiding marker pin. The marker pins are used for supporting a secondary guide which is used to adjust the orientation and position of the acetabular cup when the acetabular cup is placed onto the acetabulum. The marker elements both extend upwardly from the patient-specific body. The patient-specific body designed by using a three-dimensional model of the acetabulum and surrounding pelvic area of the patient includes an inner portion from which the guiding element extends, and an outer portion extending from the inner portion and configured to extend over a portion of the acetabular rim. The inner portion is designed to engage the acetabulum. The outer portion extends sufficiently beyond the rim to the periacetabular area of the pelvis to accommodate the marker elements.
The patient-specific body also has an underside three-dimensional engagement surface that is custom-made or patient-specific to conform to and mirror complementary surface of the acetabulum, rim or other periacetabular surface of the pelvis of the specific patient. The engagement surface of the patient-specific body enables the acetabular guide to nest or closely mate relative to the complementarily acetabular surface of the patient. However, the process of placing the acetabular guide is not described and malposition of the acetabular guide is easily produced due to the hemispherical shape of the acetabular during manually placing the acetabular guide to the acetabulum of the patient.
Hence, it is desirable to provide an improved patient-specific acetabular guide and method of manufacturing the same to overcome the aforementioned disadvantages.
Accordingly, an object of the present invention is to provide a patient-specific acetabular guide.
According to one aspect of the present invention, a patient-specific acetabuluar guide comprises 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, and wherein the elongated bore has an axis predetermined by a preoperative surgical plan.
Other objects, advantages and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:
Reference is now made to the drawings to describe the invention in detail.
Referring to
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.
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.
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.
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.
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.
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.
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.
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.
