人工股関節置換術前後の骨盤傾斜, 脊椎矢状面アライメント変化の検討

抄録

Objective: Recently, it has been determined that spinal alignment may change among patients who have undergone total hip arthroplasty (THA). We report the changes in pelvic inclination and spinal alignment in such patients before and after THA surgery.

Methods: Our cohort comprised of patients who underwent THA for unilateral degenerative hip arthritis at our hospital from May 2010 to August 2012, inclusive. Image evaluation was performed in 63 cases at their one-year of follow-up; 52 of them were re-evaluated two or three years postoperatively. Sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and femoral inclination (FI) were examined.

Results: FI, PT, and SS changed significantly at the 1-year follow-up (FI: 12.4±5.8 to 7.5±4.8 degrees, PT: 15.7±10.7 to 21.7±14 degrees, SS: 35.5±11.2 to 31.9±10.9 degrees). Moreover, taking PT=20 degrees as a criterion, the variables were further examined by dividing the patients into two groups. Postoperatively, FI significantly decreased in both groups. In the pelvic anterior group, PT significantly increased (18.2±12.5 degrees) and SS significantly decreased (32.9±10.9 degrees). The pelvic posterior group did not show significant differences. No significant difference was observed between both groups in the evaluation three years postoperatively.

Conclusion: As in the study by Weng et al., improvement in FI after THA improves SVA, which is thought to be caused by improved bending contracture of the femur. In general, it is reported that the pelvic tilt becomes more posterior caused by the THA, suggesting the possibility that the tendency becomes stronger in patients with an anterior pelvis.