PROSTHETIC FEMORAL STEM FOR USE IN HIGH OFFSET HIP REPLACEMENT
A total hip femoral prosthesis provides high lateral offset with a construct including a conventional length neck. The neck is shifted medially to position the head center in a high offset location. The proximal medial portion of the stem is augmented to provide adequate support to the medialized neck. Modular components are disclosed. Methods of using the prosthesis in total hip arthroplasty are described.
1 . A femoral prosthesis for total hip replacement, comprising:
a stem, wherein the stem comprises a center longitudinal stem axis;
a neck coupled to the stem, wherein the neck comprises a center longitudinal neck axis, a distal center of rotation on the neck axis in a distal portion of the neck, and a proximal center of rotation on the neck axis in a proximal portion of the neck, wherein the distance between the distal and proximal centers of rotation along the neck axis is between 26.5 mm and 38.5 mm, wherein the distal portion of the neck is coupled to a proximal medial portion of the stem; and
a spherical head coupled to the proximal portion of the neck, wherein the head component comprises a head center of rotation;
wherein the stem, neck, and head are coupled together so that the head center of rotation is at least 30 mm from the stem axis.
2 . The femoral prosthesis of claim 1 , wherein the head center of rotation is at least 50 mm from the stem axis.
3 . The femoral prosthesis of claim 1 , wherein the distance between the distal and proximal centers of rotation perpendicular to the stem axis is between 20 mm and 50 mm.
4 . The femoral prosthesis of claim 1 , wherein a proximal lateral profile of the stem is convex.
5 . The femoral prosthesis of claim 4 , wherein the stem has a continuously curved proximal profile on both the lateral profile and a medial and a medial profile.
6 . The femoral prosthesis of claim 1 , wherein the stem and neck are coupled together by integral formation.
7 . The femoral prosthesis of claim 1 , wherein the stem and neck are separate components.
8 . A femoral prosthesis for total hip replacement, comprising:
a stem, wherein the stem comprises a center longitudinal stem axis;
a neck coupled to the stem, wherein the neck comprises a center longitudinal neck axis, a distal center of rotation on the neck axis in a distal portion of the neck, and a proximal center of rotation on the neck axis in a proximal portion of the neck, wherein the distance between the distal and proximal centers of rotation perpendicular to the stem axis is between 20 mm and 50 mm, wherein the distal portion of the neck extends from a proximal medial portion of the stem; and
a spherical head coupled to the proximal portion of the neck, wherein the head component comprises a head center of rotation;
wherein the stem, neck, and head are coupled together so that the head center of rotation is at least 30 mm from the stem axis.
9 . The femoral prosthesis of claim 8 , wherein the head center of rotation is at least 50 mm from the stem axis.
10 . The femoral prosthesis of claim 8 , wherein the distance between the distal and proximal centers of rotation along the neck axis is between 26.5 mm and 38.5 mm.
11 . The femoral prosthesis of claim 8 , wherein a proximal lateral profile of the stem is convex.
12 . The femoral prosthesis of claim 11 , wherein the stem has a continuously curved proximal profile on both the lateral profile and a medial and a medial profile.
13 . The femoral prosthesis of claim 8 , wherein the stem and neck are coupled together by integral formation.
14 . The femoral prosthesis of claim 8 , wherein the stem and neck are separate components.
15 . A femoral prosthesis for total hip replacement, comprising:
a stem, wherein the stem comprises a center longitudinal stem axis and a pocket, wherein the pocket is recessed into a proximal medial portion of the stem;
a neck coupled to the stem, wherein the neck comprises a center longitudinal neck axis, a distal center of rotation on the neck axis in a distal portion of the neck, and a proximal center of rotation on the neck axis in a proximal portion of the neck, wherein the distance between the distal and proximal centers of rotation along the neck axis is between 26.5 mm and 38.5 mm, wherein the distal portion of the neck is received in the pocket; and
a spherical head coupled to the proximal portion of the neck, wherein the head component comprises a head center of rotation;
wherein the stem, neck, and head are coupled together so that the head center of rotation is at least 30 mm from the stem axis.
16 . The femoral prosthesis of claim 15 , wherein the head center of rotation is at least 50 mm from the stem axis.
17 . The femoral prosthesis of claim 15 , wherein the distance between the distal and proximal centers of rotation perpendicular to the stem axis is between 20 mm and 50 mm.
18 . The femoral prosthesis of claim 15 , wherein a proximal lateral profile of the stem is convex.
19 . The femoral prosthesis of claim 18 , wherein the stem has a continuously curved proximal profile on both the lateral profile and a medial and a medial profile.
20 . The femoral prosthesis of claim 15 , wherein the stem and neck are separate components.
21 . A prosthetic hip joint system comprising:
a stem having a distal end adapted for insertion a prepared canal within the proximal end of the femur, the stem including a proximal end defining a profile that extends beyond the proximal end of the femur and that includes a mounting socket that receives a distal end of a modular neck, so as to locate a ball joint on a proximal end of the modular neck at a location defining a high-offset geometry; and
wherein the modular neck defines a length and an angular orientation of a non-high-offset neck.
22 . The prosthetic hip joint system as set forth in claim 21 wherein the modular neck defines a medial axis having a length of between centers of rotation on each of opposing ends of approximately 26.5 to 38.5 millimeters.
23 . The prosthetic hip joint system as set forth in claim 21 wherein the modular neck defines a medial axis having an angle with respect to an axis of the femur of between approximately 127 and 143 degrees.
24 . The prosthetic hip joint system as set forth in claim 21 wherein the proximal end of the stem includes a mounting socket that enables attachment of the modular neck subsequent to implantation of the stem into the femur.
25 . A medical treatment procedure for total hip replacement comprising the steps of:
performing an osteotomy to a femur and defining a canal for receiving a prosthetic stem;
implanting a stem in the canal, the stem defining a distal end adapted for insertion a prepared canal within the proximal end of the femur, the stem including a proximal end defining a profile that extends beyond the proximal end of the femur and that includes a mounting socket that receives a distal end of a modular neck, so as to locate a ball joint on a proximal end of the modular neck at a location defining a high-offset geometry;
selecting a modular neck, wherein the modular neck defines a length and an angular orientation of a non-high-offset neck, and securing the modular neck into the mounting socket; and
attaching a ball joint to a proximal end of the modular neck to as to properly mate with a prepared pelvic socket in a high-offset geometry.