Hip joint prosthesis with a shaft to be fitted into the medullary canal of the femur

Abstract

A hip joint prosthetic device having a support shank to be fitted into the medullary canal of the femur and which, in its proximal region, has a curvature in the AP plane with a center of curvature at its anterior that makes the shank more compatible to naturally existing conditions of the femur, permits a substantial increase in the shank thickness, reduces shank tendency to turn within the medullary canal, simplifies the prosthesis operating procedures and improves the association of the shank with the trochanter region of the femur.

I claim: 
     
       1. In a hip joint prosthetic device comprising a rigid shank to be fitted into the medullary canal of the femur, a head, a end flange at the proximal end of the shank, a head and a neck section extending from the end flange to the head, the head being anteverted relative to the shank in the LM (lateral-medial) plane, the improvement wherein the shank has, in the proximal region thereof, a section extending a distance between approximately 4-8 cm from the end flange which is curved in the AP (anterior-posterior) plane with a center of curvature in the AP plane anterior of the proximal region of the shank, wherein the axis of the shank at its proximal end extends, in the AP plane, approximately in the direction of the longitudinal axis of the neck section and wherein the shank has, in the distal region thereof, a section curved in the AP plane in the opposite direction to said proximal section. 
     
     
       2. A hip joint prosthetic device according to claim 1 wherein the axis of said curved section of shank has an angular change in direction in the AP plane of approximately 5°-10°. .Iadd. 
     
     
       3.  In a hip joint prosthetic device comprising a rigid shank to be fitted into the medullary canal of the femur, a head, and a neck section extending between the proximal end of the shank and the head, the head being anteverted relative to the shank in the LM (lateral-medial) plane, the improvement wherein the shank has, in the proximal region thereof, a section extending a distance between approximately 4-8 cm from the proximal end of the shank which is curved in the AP (anterior-posterior) plane with a center of curvature in the AP plane anterior of the proximal region of the shank, wherein the axis of the shank at its proximal end extends, in the AP plane, approximately in the direction of the longitudinal axis of the neck section and wherein the shank has, in the distal region thereof, a section curved in the AP plane in the opposite direction to said proximal section. .Iaddend. .Iadd.4. A hip joint prosthetic device according to claim 3 wherein the axis of said curved section of shank has an angular change in direction in the AP plane of approximately 5°-10°. .Iaddend.