[Mid-Term Results of Proxima Ultra-Short Anatomical Stem: Analysis of 130 Cases].

PURPOSE OF THE STUDY The aim of this study is to assess the mid-term results of this specific ultra-short, cementless stem in patients younger than 60 years with regard to clinical and radiographic outcomes, survivorship, complication rate and revisions. MATERIAL AND METHODS A consecutive series of one hundred and twenty-one patients (130 hips) younger than 60 years at the time of surgery was enrolled in the study. Primary arthritis (33.8%) and dysplastic hips (30%) were the most common diagnoses. The patients used crutches for 6 weeks to protect femoral components against subsidence and rotational stress. The mean follow-up was 118 months (range 96-156 months). RESULTS At the final evaluation, the mean Harris Hip Score was 98.8. A perioperative periprosthetic fracture occurred in two hips and a perioperative ceramic insert breakage was observed in one hip. One hip had ceramic insert fracture 3.5 years postoperatively. In one hip a dislocation occurred. These two hips (1.5%) were revised due to reasons not associated with the stem. One hip has aseptic asymptomatic polyethylene inlay wear. In two hips squeezing was reported. There were two cases of loosening and migration of stems (1.5%) with osteolysis all around the stems. These patients have moderate thigh pain. The radiological survival is 98.5% and the clinical survival is 100% after 10 years on average. DISCUSSION Although improved clinical results were reported in younger patients with standard cementless stems, some problems still prevail: thigh pain, proximal stress shielding, difficult removal of the stem. In an effort to reduce these problems, Proxima ultra-short anatomical cementless stem was developed. Several studies show that this stem design provides good short- and mid- term results, but only in a limited number of patients and relatively short follow-up. Furthermore, the initial fears of early aseptic loosening due to the absence of diaphyseal fixation were not confirmed. CONCLUSIONS Proxima ultra-short anatomical cementless stem provided excellent mid-term clinical and radiographic results in patients younger than 60 years. Key words: total hip arthroplasty, ultra-short cementless anatomical stem.