Over the last decades, the arthroscopic treatment of hip pathology has highly grown thanks to the evolution of surgical techniques and instrumentation development. An alternative approach consisting in making a first outside-in longitudinal capsulotomy was described by Laude at the end of the 2000s and is experiencing significant development in France. The clinical results of this technique have rarely been reported and in particular the influence of the repair of the capsule is unknown. Therefore we performed a retrospective case control study aiming to asses: (1) the clinical outcomes and complication rates of the outside-in extracapsular approach for the treatment of FemoroAcetabular Impingement (FAI) and (2) the effect of capsular closure on the functional outcome.

We hypothesize that the outside-in extracapsular approach is a safe and efficient technique and the capsular closure at the end of the procedure positively affects the functional outcome.

A retrospective study was conducted on prospectively collected data of a consecutive series of hip arthroscopies performed for surgical treatment of FAI using the outside-in extracapsular approach. Any complications during follow-up were identified and recorded. Linear regression models were used to estimate the influence of capsular closure on the functional outcome. Functional outcome was assessed using modified Harris Hip Score (mHHS) and Non-arthritic Hip Score (NAHS).

Sixty-four hips in 57 patients operated by a single surgeon between October 2013 and December 2016 were analyzed at the time of final follow-up of 34.17 months (range 24 to 53). As the surgical technique evolved over time, a side-to-side capsular closure was performed at the end of the procedure for 25 hips and the capsule was left open for the remaining 39 patients. Functional outcome measurements showed an improvement from the preoperative to the last follow-up: 63.5±11.0 to 88.1±11.2 for mHHS, 63.1±13.8 to 86.4±13.4 for NAHS. Capsular closure leads to a significantly improved clinical outcome: gain in mHHS: 25.8±2.3 vs. 20.6±1.9 (p≤0.044), gain in NAHS: 26.1±2.5 vs. 19.6±2.1, (p=0.023). No major complications occurred. One case of postoperative tensor fascia latae atrophy was documented in the group “capsule left open”.

Hip arthroscopy in the management of FAI with an extraarticular starting point (outside-in) is a safe technique with functional results and postoperative morbidity comparable to previously reported techniques. Side-to-side capsular closure at the end of the procedure might positively affect the final functional outcome.

III, case control retrospective study.