Background: Although many designs of cementless femoral stems are available for revision hip arthroplasty, there is no consensus about which design features are required to achieve an optimal clinical outcome and maximum preservation of bone. The purpose of this study was to report the clinical and radiographic results for a specific design.
Methods: A selected series of 107 revision total hip arthroplasties with use of the Mallory-Head calcar-replacement prosthesis was reviewed with clinical and radiographic evaluation. The study group consisted of sixty-six hips (sixty patients), with an average follow-up of 11.5 years (range, 8.8 to 14.5 years). All revisions in this series were performed because of failure of a cemented or cementless femoral component of standard length. All revision stems were 220 mm long.
Results: Three of the 107 original stems demonstrated subsidence of 3, 7, and 9 mm. Two stems had definite loosening, resulting in a 1.9% rate of mechanical failure. The rate of survival was 94% with revision for any reason as the end point and 97.1% with revision because of mechanical failure (aseptic loosening) as the end point. The Harris clinical score was 49 points preoperatively and 80 points postoperatively. Radiographic analysis demonstrated that the average percentage of the diaphysis filled by the prosthesis was 86%. Fifty-four (88.5%) of the sixty-one hips with complete radiographic follow-up showed no stress-shielding on final radiographs, whereas seven hips (11.4%) showed some stress-shielding.
Conclusions: This proximal load-bearing calcar-replacement design achieves reliable fixation and stability at intermediate-term follow-up. There is no deterioration in the clinical outcome or radiographic findings at an average of eleven years of follow-up. The prevalence of disuse osteopenia from stress-shielding is very low. Proper surgical technique includes maximum fill of the diaphysis of the femur, with contact of the collar on part of the proximal aspect of the femoral shaft.
Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.