The effects of patient characteristics and stem alignment on distal femoral cortical hypertrophy after cemented polished tapered stem implantation

Background The objective of this study was to evaluate the results of over 10 years of total hip arthroplasty (THA) practice with Exeter TM stems and the clinical relevance of distal femoral cortical hypertrophy (DFCH). Methods We retrospectively reviewed 127 hips (120 patients) that had undergone THA with Exeter TM stems between 2004 and 2007. Kaplan–Meier survival analyses for the stem of all 127 hips were performed using different endpoints. Of 127 hips, 100 (94 patients) had complete 10-year follow-up data, including the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ) as the patient-reported outcomes, and the clinical relevance of DFCH was analyzed using multivariable logistic regression analysis. Results The survival of the stem with the endpoint of re-operation for loosening, > 5-mm subsidence, and re-operation for any reason were 100%, 99.1% (95% CI 97.5–100%), and 98.3% (95% CI 96.0–100%), respectively. Of 100 hips followed completely for 10 years, DFCH occurred in 20 hips (20%). The satisfaction and pain visual analog scale of JHEQ revealed high satisfaction and less pain in patients with DFCH. By multivariate logistic regression analysis, body weight > 55 kg (odds ratio: 2.88, p = 0.035) and varus stem alignment (odds ratio: 6.56, p = 0.003) were found to be predictors for DFCH. Conclusions The incidence of DFCH with the Exeter TM stem was 20%. A body weight > 55 kg and varus stem alignment are predictors for future DFCH. DFCH with the Exeter TM stem indicates a good outcome with less hip pain.