Femoral Neck Preservation and Diaphyseal Invasion Comparing a Calcar-Metaphyseal Short Stem with its Homonymous Standard Femoral Stem. A Radiographic Study.

BACKGROUND: We aim to compare the preoperative planning radiographs of 50 patients in whom both a short stem and its homonymous standard version were programmed, focusing on the preservation of the neck and the invasion of the femoral shaft. The secondary objective was to evaluate the 50 preoperative radiographs with the 50 postoperative radiographs in which the short stem was implanted, measuring the real invasion of the diaphysis and the real preservation of the femoral neck. MATERIAL AND METHODS: We measured cut level at the femoral neck and diaphyseal invasion in 50 preoperative x-rays where an Alteon Neck Preserving Stem (ANPS) was templated and we compared it with 50 preoperative x-rays where an Alteon Taper Wedge Stem (ATWS) was templated. After surgery, we compared both parameters previously measured in the preoperative x-rays with the 50 postoperative radiographs where the short stem was implanted obtaining the real bone preservation at the femoral neck and the real diaphyseal invasion length. RESULTS: For templating comparison, mean bone preservation at the femoral neck was 14.87mm (SD 3.64) for the ANPS group and 9.94mm (SD 8.39) for the ATWS group (p <0.001). The mean diaphyseal bone invasion was 47.21mm (SD 5.89) and 76.77mm (SD 8.39) for ANPS and ATWS respectively (p <0.001). After surgery, the mean postoperative bone preservation at the femoral neck was 15.08mm (SD 3.1) with a mean of 0.17mm (SD 0.51) more preservation in the preoperative group. CONCLUSION: 1. ANPS allow bone preservation with limited diaphyseal invasion when compared with his homonymous ATWS in the preoperative templates. 2. ANPS showed a good correlation between preoperative radiographs and real bone preservation of the femoral neck and invasion of the femoral shaft.

Evaluation of the learning curve and initial outcomes with a short cervicometaphyseal fixation stem: A case series. / Evaluación de la curva de aprendizaje y resultados iniciales con un vástago corto de fijación cervicometafisaria: Una serie de casos.

INTRODUCTION: Total hip arthroplasty in young patients has evolved in recent decades, and the use of short stems in young adult patients has been gaining popularity. The restitution of the biomechanics of the hip is a primary requirement to determine the future success of total hip replacement, and even more so in young adults who present the particularity of having a high functional demand and a long life expectancy. OBJECTIVE: The aim of this prospective study was to evaluate the learning curve and initial clinical-radiological outcomes of the Alteon Neck Preserving Stem™ (ANPS) (Exactech, Gainesville, FL, USA) with a minimum of 2 years follow up. MATERIAL AND METHODS: We conducted a multicenter prospective study that analyzed 90 consecutive total hip replacements during 2014. We performed a clinical-radiological analysis measuring Harris Hip Score (HHS), subjective Rodes and Maudsley satisfaction evaluation, radiolucencies, components position, limb length discrepancy, heterotopic ossification, medical and surgical complications and learning curve. RESULTS: During the first 30 cases, the intraoperative complication rate was 16%, while in the next 60 cases no intraoperative complications were reported. Thigh pain was reported in 3 cases (3.3%), being 2 moderates, and 1 severe. In 2 cases subsidences of 3 mm were detected in the first scheduled X-ray, both related to intraoperative fractures with no progression after 3 months. Mean HHS improved from 42.9 points (range 37-54 points) preoperatively to 93.2 on average (range, 87-96) at the end of the follow up (p < 0.01). Subjective evaluation was excellent in 75 (83.3%) cases and good in 15 patients (16.6%). CONCLUSIONS: This short stem has good clinical radiological results in a short and medium term follow-up and in the hands of surgeons specializing in arthroplasty the learning curve is estimated to be less than 30 surgeries.