Excellent midterm clinical outcomes and restoration of native hip anatomy with a calcar guided short femoral stem in cementless THA

Abstract

Restoration of the femoroacetabular offset and leg- length is critical in optimizing hip function following total hip arthroplasty (THA). The short femoral stems allow bone sparing and implantation through a minimally invasive approach ; however, they might not anatomically reconstruct the native hip anatomy. Therefore, the purpose of the present study was to investigate whether a calcar guided short femoral stem could restore hip anatomy and provide satisfactory clinical outcomes at a 5-years follow-up. A total of 114 consecutive patients treated with THA and a calcar guided short femoral stem with an average age of 67 years, and a median follow-up of 5 years were evaluated clinically and radiographically. All patients were operated either through a minimally invasive anterior or anterolateral approach. The contralateral native hip was used as reference to examine whether a calcar guided short femoral stem could restore the native hip anatomy. The Harris hip score improved significantly at an average of 45 points following the short-stem THA. The rest and loading pain decreased significantly from an average VAS of 4 and 7 points preoperative to VAS 0 and 0 points postoperative, respectively. Compared to the contralateral native hip the total offset was not significantly different, and the leg length increased by an average of 2 mm compared to the contralateral native hip. Although the minimally invasive anterolateral approach had similar functional outcomes and patient satisfaction with the anterior approach, it showed more discrepancies from the contralateral native hip in the total offset and leg length than the anterior approach. A calcar guided short femoral stem, implanted through a minimally invasive approach could restore native hip anatomy regarding total offset and leg length, and provide excellent functional outcomes and patient satisfaction 5-years following THA. Surgeons performing THA with minimally invasive anterolateral approach should be aware of the discrepancies in total offset and leg length to prevent a malalignment of the femoral component.