Anatomy of the proximal femur at the time of total hip arthroplasty is a matter of morphotype and etiology but not gender.

This study aimed to determine (1) whether: gender, morphotype, or etiology are correlated with the shape of the proximal femur in patients with advanced hip osteoarthritis and (2) is there any clinical predictive factors of potential abnormal anatomy of the hip at the time of total hip arthroplasty (THA)? We reviewed 689 European hips of patients who underwent THA for primary osteoarthritis (OA) or avascular necrosis (AVN), between 2000 and 2005. The patients were stratified according to their (1) Morphotype, (2) Gender, and (3) Etiology for undergoing THA. Two independent observers measured the following four anatomical parameters on preoperative CT-scans: neck shaft angle (NSA) and femoral neck version, femoral offset and lower-limb torsion. Our results showed that both morphotype and etiology, but not gender or body mass index, were correlated with femoral anatomical parameters. Two types of patients were identified as "at risk" for abnormal hip anatomy: (1) AVN-Endomorphic patients (2) OA-Ectomorphic patients. Etiology of the advanced hip osteoarthritis and patients' morphotype may predict the proximal femur anatomy at the time of THA.