Sagittal alignment in patients with flexion contracture of the hip before and after total hip arthroplasty.

ABSTRACT

INTRODUCTION: In hip osteoarthritis, hip flexion contracture can severely alter the patient's alignment, and, therefore, affect the patient's quality of life (QOL). Hip contracture is not well-studied, partly because of the difficulties of its diagnosis. The aim of this study was to propose a quantitative definition of hip flexion contracture, and to analyse sagittal alignment in these patients compared to non-contracture ones, before and 12 months after total hip arthroplasty (THA). MATERIALS AND METHODS: Consecutive patients with hip arthrosis and an indication for THA were included (N = 123). Sagittal full-body radiographs were acquired in free standing position and in extension. QOL questionnaires were administered before and after surgery. Spinopelvic parameters were measured, including the pelvic-femur angle (PFA). Patients with low pelvic incidence (< 45°) were included in the hip contracture group if PFA > 5°, or PFA > -5° when pelvic incidence ≥ 45°. RESULTS: 29% of patients were in the hip flexion contracture group, and they showed lower pelvic tilt than the no-contracture group (p < 0.001), larger lumbar lordosis (LL) and smaller PI-LL (p < 0.001), as well as a forward position of the head. 16% of patients still had hip contracture 12-months postop. Contracture patients showed higher QOL scores after surgery. CONCLUSIONS: The proposed method to diagnose hip contracture group allowed to define a group of patients who showed a specific pattern of sagittal spinopelvic alignment. These patients improved their alignment and quality of life postoperatively, but their hip mobility was not always restored. Diagnosing these patients is a first step toward the development of more specific surgical approaches, aiming to improve their surgical outcome.