Periacetabular osteotomy for hip dysplasia treatment through a mini-invasive technique. Our results at mid-term in 131 cases.

Abstract Background and objective Periacetabular osteotomy (PAO) is an accepted and worldwide technique recognised for residual dysplasia treatment and even in unstable hips with limited acetabular coverage. The aim of this study is to analyse the functional, radiological and complication results in patients treated with mini-invasive PAO. Material and methods We performed a retrospective study in which we analysed 131 cases undergoing mini-invasive PAO at our centre. The degree of joint degeneration was evaluated with Tonnis scale, Wiberg angle, acetabular index (AI), anterior coverage angle (AC), joint space, complications and functional outcome with the Non-Arthritic Hip Score (NAHS) were analysed preoperatively and at the end of follow-up. Results The average age was 32.3 ± 9.5 (SD) years, 102 (77.9%) were female and 29 (22.1%) were male. 7.7 ± 2.8 (SD) years follow up. The radiological parameters improved between the pre-surgical phase and the end of follow-up, Wiberg angle +18.5° (18.3° versus 36.8°, 95% CI 17.3–19.7), AC angle +13.5° (26.2° versus 39.7°, 95% CI 11.6–15.4) and the AI −11.1° (19.5° versus 8.4°; 95% CI −12.1 to −10.1). In addition, the functional results, with the NAHS scale, improved +31.3 points (60.7 pre-surgical versus 92 at the end of follow-up, 95% CI 28.7–33.8). The most common complication was transient lateral femoral cutaneous nerve hypoaesthesia in 10 cases (7%). Conclusion The mini-invasive PAO approach is a reproducible technique, it allows restoration of acetabular coverage and provides an improvement in functional scales as confirmed by our series.