Lumbopelvic hyperlordosis is linked to higher femoral head coverage, lower femoral anteversion and younger age at periacetabular osteotomy.

Purpose: The dynamic alignment of the lumbar spine, pelvis and femur is increasingly studied in hip preservation surgery. However, the interaction between lumbopelvic alignment, acetabular and femoral morphology and its influence on patients' preoperative symptom burden remains poorly understood. The aim of this study was to evaluate whether lumbopelvic malalignment affects osseous hip morphology and exacerbates preoperative patient-reported joint functionality in patients undergoing periacetabular osteotomy (PAO).

Methods: One hundred thirteen patients were prospectively enroled in this single-centre study. Sagittal lumbopelvic radiographs were used to divide the patients in accordance with their lumbopelvic alignment (pelvic incidence [PI]-lumbar lordosis [LL] mismatch) into a balanced (PI-LL: 10° and 10°/n = 60) and unbalanced alignment (PI-LL: <10° and >10°/n = 53) group. Intergroup analyses were performed for acetabular and femoral morphology as well as various patient-reported outcome measures (PROMs) scores (modified Harris-Hip, Hip Osteoarthritis Outcome, International Hip Outcome tool-12 and University of California Los Angeles activity scale).

Results: Patients with concomitant unbalanced lumbopelvic alignment due to hyperlordosis showed higher femoral head coverage and lower femoral anteversion (lateral centre-edge angle 20.2° vs. 15.8°, p = 0.012/anterior wall index 0.47 vs. 0.36, p = 0.001/acetabular inclination 10.2° vs. 13.6°, p = 0.008/Femoral anteversion 21.3° vs. 28.2°, p = 0.041). Furthermore, these patients were significantly younger at the time of PAO (28.7 vs. 32.4 years, p = 0.020), even when there were no intergroup differences in all analyzed PROMs.

Conclusion: Concomitant lumbopelvic deformity affecting the hip joint morphology could aggravate clinical symptoms leading to earlier presentation in patients undergoing PAO. Thus, the lumbopelvic balance needs to be carefully evaluated in clinical decision-making in PAO patients and future research should focus on long-term outcomes of patients with concomitant unbalanced lumbopelvic alignment.

Level of evidence: Level III, prognostic study.