A short to midterm follow-up of periprosthetic BMD after total hip arthroplasty with the anatomic cementless femoral stem

Abstract:

Objective：To explore the periprosthetic bone mineral density（BMD） changes in patients undergoing total hip arthroplasty（THA） with the anatomic cementless femoral stem during the short to midterm follow-up period，and to provide a theoretical frame－work for prosthesis design in the future. Methods：A total of 28 patients undergone primary unilateral cementless THA（T.O.P. hip ac－etabular cup/Ribbed stem，Link） more than one years were chosen and followed in the study. Periprosthetic and contralateral bone mineral density（BMD） in seven Gruen zones was measured with dual energy X-ray absorptiometry（DEXA）. These data were ana－lyzed subsequently using SPSS software. Results：Twenty-eight patients who underwent THA during April 2010 and January 2015 with an average follow-up of 35.5 months were included in this study，of which 13 were males and 15 were females，at a mean age of （61.36±9.40） years（range，41-75 years）. Their body mass index was （24.78±2.80） kg/m2. The disease spectrum leading to primary THA consist of vascular necrosis of the femoral head（10 cases），developmental dysplasia of the hip（8 cases），femoral neck fractures （6 cases），and hip osteoarthritis（4 cases）. Periprosthetic BMD changes were most pronounced only in the distal Gruen zone 4[surgi－cal side BMD（1.58±0.28） g/cm2，non-operated control side BMD（1.66±0.20） g/cm2；t=-2.216，P=0.035]，and no significant differ－ences were detected when compared with the non-operated control side in other Gruen zones. Conclusion：The Ribbed anatomic cementless femoral stem contributes to periprosthetic bone ingrowth in patients undergoing THA，proximal load transfer comparatively approximates normal bio-stress，the features of which are well worth learning from in the future.