Function and osteoarthritis progression after arthroscopic treatment of femoro-acetabular impingement: a prospective study after a mean follow-up of 4.6 (4.2-5.5) years

Background: Outcomes after arthroscopic femoro-acetabular impingement (FAI) surgery are promising in the short-term but have rarely been evaluated in the mid-term (e.g., about 5 years). Here, our objectives were to obtain mid-term data on functional and radiographic outcomes, to identify prognostic factors, and to determine the mid-term rate of arthroplasty revision with the associated risk factors.

Hypothesis: We hypothesized that the results of arthroscopic FAI surgery were sustained over time.

Materials and methods: We conducted a prospective multi-surgeon study of 53 Tönnis grade 0 or 1 hips treated arthroscopically for symptomatic FAI (23 cam, 10 pincer, and 20 mixed deformities). We obtained short-term (10 months) and mid-term (4.6 years) data on the functional outcome (WOMAC and satisfaction scores), proportion of patients without revision arthroplasty, and development of osteoarthritis (graded using the Tönnis classification).

Results: In the patients without revision arthroplasty, the WOMAC score improved significantly (P<0.01) from baseline (61.4 ± 15.6) to 10 months (84.2 ± 15.6) and last follow-up (85.2 ± 15.5) but remained unchanged between the two postoperative time points, confirming the stability of the results. The proportion of satisfied patients was 79% after 10 months and 68% (36/53) at last follow-up (NS). Osteoarthritis developed in 13/35 (37%) hips for which radiographs were obtained at last follow-up. At last follow-up, 46/53 hips (87%; 95%CI, 78-96) did not required revision surgery; arthroplasty was required in the 7 remaining hips. The main prognostic factor was the preoperative osteoarthritis Tönnis grade: at last follow-up, compared to Tönnis grade 0 hips, Tönnis grade 1 hips had lower WOMAC scores (77 vs. 88), lower satisfaction rates (50% versus 77%), a higher rate of osteoarthritis progression (57% versus 24%), and a higher rate of arthroplasty (33.3% versus 2.9%).

Discussion: Our results are consistent with published data. The outcomes of arthroscopic FAI surgery are sustained over time and the preoperative osteoarthritis status is the main predictor of mid-term outcomes.

Level of evidence: IV, prospective cohort study.