Abstract
Introduction
Architectural changes occurring in the proximal femur after THA continues to be a problem. Stress shielding occurs regardless of fixation method. The resultant bone loss can lead to implant loosening and breakage of the implant. A new novel tissue sparing neck-stabilised stem has been designed to address these concerns.
Methods
Over 1,200 stems have been implanted since April 2010 and 2012. Patient profile showed two-thirds being female with an age range between 17 to early 90s. 90% were treated for OA. This stem has been used in all Dorr bone classification (A, B, & C). Two surgical approaches were utilised (single anterior incision and standard posterior incision). All were used with a variety of cementless acetabular components and a variety of bearing surfaces (CoC, CoP, MoM, MoP). Complications were track by surgeon Members of the Tissue Sparing Study Group of the Joint Implant Surgery and Research Foundation. Complications include first year of limited clinical release. No surgeon was permitted usage without specific cadaver / surgical training. No head diameters below 32 mm were used.
Observations
There is a short but definitive learning curve (2–3 cases) and an easy transition for the O.R. team due to the limited inventory of stem sizes. The three main surgical technique features are: Level of neck resection, angle of resection and rasping the proximal medial curvature of the femur.
Stem usage: size 0, 1 and 2 were used for more females and 3, 4, and 5 stems for males. The neutral modular neck was the single most selected (35%), however, all angled necks totaled 65% usage.
Slightly more complications in the anterior approach compared to posterior approach.
We are encouraged with our initial clinical / surgical / radiographic observations and believe our results warrant not only further evaluation but expanded evaluation of this tissue conserving approach to THA.
