Results of an Ultra Short Metaphyseal Filling Cementless Stem in Primary Total Hip Arthroplasty: Mean 12.1-Year Follow-up

Introduction Cementless ultra-short stems (USS), defined as implants that do not engage the diaphyseal cortex (stemless), have been designed to leave diaphyseal bone undisturbed. This study reports midterm clinical results using an USS in relatively younger patients undergoing primary total hip arthroplasty (THA). Methods The study included 32 THA in 26 patients (8 females, 18 males) with end-stage coxarthrosis of various etiologies, with patients ≤ ≤ 70 years of age using the USS Proxima hip stem. All cups were of cementless design with several bearing configurations and head diameters. Results The mean age at surgery was 47.9 years (28–67 years). The mean follow-up was 12.1 years (range 10.8–13.8 years). Seven patients were classified as Dorr A femoral bone type, 18 were Dorr B, and 7 were Dorr C. Mean Harris Hip Score (HHS) improvement was 39.3 points from preoperative ( p = 0.0001), with 10-year HHS averaging 88. There were two stem failures. One was due to a periprosthetic joint infection, which was removed at 3 years. The other stem was aseptically loose and revised at 8 years. Stem survivorship was 93.7% at final follow-up. Conclusion The ultra-short Proxima cementless stem showed a survival of 93.7% at a mean 12.1 years, proving the USS concept to be durable and effective. The USS is best suited for primary THA in Dorr A and B bones where diaphyseal bone preservation for future surgery is a priority. Level of Evidence: IV Retrospective review consecutive case series.