Abstract
Background
Postural change after total hip arthroplasty (THA) is still a matter of discussion. Previous studies have mainly concentrated on the pelvic motions. We report the postoperative changes of the global sagittal posture using pelvic, spinal and lower extremities parameters.
Methods
139 patients (primary THA, without previous spinal or lower extremity surgery) were included. We measured pelvic parameters [SS: Sacral Slope, PI: Pelvic Incidence, PT: Pelvic Tilt, APP angle: Anterior Pelvic Plane angle] and the global posture parameters (SVA: Sagittal Vertical Angle, GSA: Global Sagittal Angle, TPA: T1 pelvic angle). Patients were categorized into low PI group <45°, 45°< medium PI <65° and high PI >65°.
Results
Mean GSA and SVA decreased postoperatively (p=0.005 and p=0.004 respectively). The TPA change was not significant (p=0.078). In low PI group, GSA (5.4 ± 5.0 to 4.3 ± 4.0, p=0.005) and SVA (5.4 ± 4.9 to 4.2 ± 4.1, p=0.038) decreased with more posterior pelvic tilt. Postoperative TPA was significantly higher (8.4 ± 10.6 to 9.8 ± 10.7; p=0.048). In medium PI group, SVA decreased (4.2 ± 4.6 to 3.6 ± 4.5, p=0.020) with more posterior pelvic tilt. In high PI group, pelvic and global posture parameters did not evolve significantly.
Conclusion
PI is the key determining factor in pelvic tilt modification after THA. Patients with low PI demonstrate significant modification in spine, pelvic and lower extremities. Pelvic tilt is the main adaptation mechanism for medium incidence patients whereas pelvic tilt does not change in high PI patients after surgery.
