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. 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.Background
Methods
The position of the hip-joint centre of rotation (HJC) within the pelvis is known to influence functional outcome of total hip replacement (THR). Superior, lateral and posterior relocations of the HJC from anatomical position have been shown to be associated with greater joint reaction forces and a higher incidence of aseptic loosening. In biomechanical models, the maximum force, moment-generating capacity and the range of motion of the major hip muscle groups have been shown to be sensitive to HJC displacement. This clinical study investigated the effect of HJC displacement and acetabular cup inclination angle on functional performance in patients undergoing primary THR. Retrospective study of primary THR patients at the RNOH. HJC displacement from anatomical position in horizontal and vertical planes was measured relative to radiological landmarks using post-operative, calibrated, anterior-posterior pelvic radiographs. Acetabular cup inclination angle was measured relative to the inter-teardrop line. Maximum range of passive hip flexion, abduction, adduction, external and internal rotation were measured in clinic. Patient reported functional outcome was assessed by Oxford Hip Score (OHS) and WOMAC questionnaires. Data analysed using a linear regression model.Background
Methods
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. Retrospective study of primary THR patients 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. Data analysed using a linear regression model. 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 change in OHS (p>0.05) or WOMAC score (p>0.05). Sagittal plane alignment of the femoral stem was not associated with any change in OHS (p>0.05) or WOMAC score (p>0.05).Methods
Results
Fracture of a ceramic component in total hip
replacement is a rare but potentially catastrophic complication.
The incidence is likely to increase as the use of ceramics becomes
more widespread. We describe such a case, which illustrates how
inadequate initial management will lead to further morbidity and
require additional surgery. We present the case as a warning that
fracture of a ceramic component should be revised to another ceramic-on-ceramic
articulation in order to minimise the risk of further catastrophic
wear.
