MODIFICATION OF THE SAGITTAL LOMBOPELVIC BALANCE AFTER TOTAL HIP REPLACEMENT

Abstract

Introduction: The goal of the study was to analyse the modification of the sagittal lombo-pelvic equilibrium after total hip replacement for osteoarthritis.

Materials and Methods: The sagittal lombo-pelvic equilibrium was analysed among 89 patients who underwent total hip replacement for osteoarthritis, using lateral X-rays of the whole spine including the hips performed pre-operatively and at one year post-operatively. Reference values were calculated by carrying out the same analysis among 100 asymptomatic healthy volunteers. The studied parameters were: the sacral tilt (ST), the pelvic version (PV) and the sacral incidence (SI).

Results: The mean pre-operative value of STangle was significantly lower in the osteoarthritis group (20.6° +/−6) compared to the reference group (39.4 +/6, p< 0,00001). The mean pre-operative value of VP angle was significanlty higher in the osteoarthritis group (31°+/−8) compared to the reference group (13.5 +/−6 p < 0,00001). There was no significant difference between the two groups for the sacral incidence (p=0,3). At one year post-operatively, the sacral tilt has significantly increased by 5.5° (p< 0.00001).

Discussion: Compared to asymptomatic healthy volunteers, patients affected by osteoarthritis had a pelvic retroversion that has decreased post-operatively but still remained lower than the norm.

Conclusion: The lombo-pelvic equilibrium is different in case of osteoarthritis. After total hip replacement the pelvis remained retroverted. This phenomenon should be taken into account for the planning of total hip arthroplasty.