Surgery for femoroacetabular impingement using a minimally invasive anterolateral approach: analysis of 118 cases at 2.2-year follow-up

Introduction: Treatment of femoroacetabular impingement (FAI) has progressed over time from using long incisions and dislocation to using arthroscopic surgery. Minimally invasive treatment has rarely been evaluated and a minimally invasive, anterolateral approach has not been used up to now for this indication. A prospective, on-going study was performed to evaluate surgical treatment of FAI with a minimally invasive, anterolateral approach.

Hypothesis: Femoral neck, acetabulum and labrum abnormalities can be corrected without significant morbidity using a minimally invasive, anterolateral approach without dislocation.

Patients and methods: Treatment of 120 FAI cases (108 patients, 16 women, 92 men, 12 bilateral cases during one surgical session), average age: 34 years (18.9-63.5 years), was done prospectively and in an uninterrupted series. Two cases were lost to follow-up; 106 patients (118 FAI cases) were evaluated with a follow-up of at least 1 year. Assessments consisted of the Non-Arthritic Hip Score (NAHS), WOMAC, measurement of internal rotation with 90° flexion and the Nötzli alpha angle on an A/P radiograph in 45° of flexion, 45° abduction and 30° external rotation.

Results: Blood loss averaged 1.2g/dl (range 0.5 to 2.7g/dl) and the average operative time was 44.9 minutes (range 30 to 65). With an average follow-up of 2.2 years (range 12 to 54 months), the NAHS changed by 32.5 points (P<0.0001), internal rotation by 19.0° (P<0.0001) and the alpha angle by -24.9° (P<0.0001). Eight surgical revisions were required (6.8%) (four haematomas, two capsular debridement, two additional procedures on the acetabulum) and these had a good outcome; there were no nerve-related or infection-related complications. Four failures (3.5%) were revised by arthroplasty (two patients experienced residual pain and two patients rapidly progressed to osteoarthritis). Eighteen cases progressed by only one Tönnis stage. Brooker stage II and III ossification were observed in 12 cases (10.2%) but these did not affect the functional score and range of motion improvement.

Discussion: This approach, which can be learned and performed quickly, does not require any specific materials and yields a reliable surgical procedure without major complications. This short-term study, where the central cartilaginous compartment was not explored and the labrum was not sutured, comprised a consecutive, non-selected series of patients (independent of age, weight, osteoarthritis stage) and had encouraging results.

Level of evidence: Level III, prospective study, no control group.