Abstract
Background
It is known that excessive varus alignment of the femoral stem in total hip replacement (THR) creates a sub-optimal biomechanical environment which is associated with increased rates of revision surgery and component wear. Little is known regarding the effect of femoral stem alignment on patient functional outcome.
Methods
A retrospective study of patients undergoing primary THR at the RNOH. Alignment of the femoral stem component in-situ was measured subjectively by a consultant musculoskeletal radiologist in both coronal and sagittal planes using post-operative anterior-posterior and lateral pelvic radiographs. Each THR was grouped into valgus, minor-valgus, neutral, minor-varus or varus coronal plane alignment and posterior, minor-posterior, neutral, minor-anterior or anterior sagittal plane alignment. Patient reported functional outcome was assessed by Oxford Hip Score (OHS) and WOMAC questionnaires after a minimum follow-up of 11 months. Maximum range of passive hip flexion, abduction, adduction, external and internal rotation were measured in clinic. A factorial linear regression model was used to analyse data.
Results
90 THRs were studied in 87 patients (55 Female). Mean age at THR=62 (22–86). Mean follow-up 17 months (11–39 months). Median OHS = 16, WOMAC = 8. Coronal plane alignment of the femoral stem was not associated with any significant change in OHS, WOMAC score or hip range of motion in any direction (all p>0.05). Sagittal plane alignment of the femoral stem was not associated with any significant change in OHS, WOMAC score or hip range of motion in any direction (all p >0.05).
Conclusion
Although it is known that alignment of the femoral stem in sagittal and coronal planes has a direct effect on survivorship of the prosthesis, our study does not demonstrate any relationship between femoral stem alignment and functional outcome in patients undergoing primary THR.
