Preoperative Morphology of the Proximal Femoral Canal Did Not Affect the Postoperative Bone Mineral Density Change Around the Zweymüller-Type Stem.

The bone mineral density (BMD) around a femoral component changes after total hip arthroplasty (THA). The aim of this study was to investigate the influence of the morphology of the preoperative proximal femoral canal on the postoperative BMD change of the femur around a Zweymüller-type stem. The authors performed a retrospective review of their institutional arthroplasty database. Patients were classified into following 3 groups according to canal flare index (CFI): CFI<3.0, stovepipe group; 3.0<CFI<4.7, normal group; and CFI>4.7, champagne-flute group. This study included 120 hips of 112 patients (26 hips with stovepipe femurs, 72 hips with normal femurs, and 22 hips with champagne-flute femurs) in patients who had undergone THA using the Zweymüller-type stem. The BMD of the proximal femur (Gruen's zones 1-7) was measured at 3 weeks and 6, 12, and 24 months postoperatively. At each follow-up period, the differences in the relative change in the BMD were not statistically significant in any regions of interest among the 3 groups. This study showed the lack of significant differences in the relative change in the BMD among the different morphologies of the proximal femoral canal. The preoperative morphology of the femoral canal did not affect the postoperative BMD change around the Zweymüller-type stem at 2 years postoperatively. [Orthopedics. 2019; 42(5):e449-e453.]. Copyright 2019, SLACK Incorporated.