Mini- Open Direct-anterior Approach vs Hip Arthroscopy for Treatment of Femoroacetabular Impingement. A Prospective Randomized Controlled Trial With 2 Years Follow up

Hip arthroscopy versus mini-open direct anterior approach Surgical approach can have an important effect on post-operative recovery, complications and overall morbidity. Two frequently used approaches will be compared in the proposed study: the HA and the mini-open direct anterior approach. Outcome of HA vs mini-open direct anterior can thus be divided into clinical and morphological outcome parameters.

The clinical outcome parameters should be divided in early and long term outcome.

The early outcome is especially related to the surgery itself and postoperative rehabilitation. Outcome parameters are complication rate, hospital stay, blood loss, transfusion rate and functional recovery. The easiest way to describe functional outcome is by using internationally recognized and validated outcome scores. They are developed as an instrument to assess the patient's opinion about their hip and associated problems. These validated scores aim to assess the functionality and disability of the hip. The functional short and long term results of surgical procedures can be monitored with these outcome scores. In this study we use the Harris Hip Score, Hip disability and Osteoartritis Outcome Score (HOOS) and The Western Ontario and MacMaster (WOMAC) score. The Harris Hip Score (HHS) is probably one of the most frequently used scores to assess the outcome of procedures related to the hip joint16. Finally, the Hip disability and Osteoarthritis Outcome Score (HOOS) is a validated scoring system that consists of 39 items, divided into 5 sub-scales (i.e. pain, other symptoms, activity limitations in daily living (ADL), activity limitations in recreation and sport, and hip-related quality of life (QoL))17. The Western Ontario and MacMaster (WOMAC) is also a frequently used outcome tool and can be subtracted from the HOOS score18.

The late (>1 year) outcome parameters are the late complication rate and conversion to arthroplasty.

The morphological outcome is determined on anteroposterior pelvic x-rays and cross-table lateral views acquired preoperatively and 6 weeks after surgery. Several specific signs will be recorded. The presence of a cross-over sign 19 (COS), a posterior wall sign 19 (PWS), a prominence of the ischial spine 23 (PRISS) and a herniation pit 24 will be noted. Supplementary the CE-Angle 25, AC-Index 26, and quantitative COS 27 and the OA grade according to Tönnis 20 will be assessed. Additionally, the resection width angle 28 and the resection depth ratio 28 will be determined as schematically presented in Table 1.