Does Surgical Technique Matter? A Retrospective Analysis of Five-Year Outcomes After Arthroscopic vs. Open Femoroacetabular Impingement Syndrome Correction

Background: Femoroacetabular impingement syndrome (FAIS) is a major cause of chronic hip pain and early osteoarthritis. Surgical correction, traditionally via open surgical dislocation and increasingly via hip arthroscopy, aims to restore hip function by correcting bony morphology. While both techniques address cam and pincer lesions, the long-term implications of the surgical approach and specific impingement morphology on five-year structural outcomes, including hip instability, osteoarthritis (OA) progression, and conversion to total hip arthroplasty (THA), remain poorly defined. Methods: We conducted a retrospective cohort study using the TriNetX US Collaborative Network, analyzing de-identified electronic medical records from 2,725 patients (2,321 arthroscopic, 404 open) who underwent FAIS correction between 2003 and 2023 with a minimum five-year follow-up. Patients were grouped by surgical approach (Arthroscopic vs. Open) and morphology (Cam-only vs. Pincer-only vs. Mixed). Primary outcomes were five-year cumulative incidence and time-to-event incidence (Hazard Ratio, HR) of hip instability/dislocation, hip OA, and THA conversion. Results: In patients with mixed FAIS morphology, the arthroscopic approach was associated with a significantly lower risk of instability/dislocation (3.7% vs. 11.6%; HR 0.393, p<0.001) compared to the open approach. Conversely, the open approach demonstrated a lower incidence of hip OA (4.6% vs. 7.8%; HR 2.320, p=0.001 favoring open). Although the overall five-year THA incidence was equal (2.4%), arthroscopy had a significantly higher hazard of conversion (HR 6.112, p=0.004). Subgroup analysis found no statistically significant difference in instability, OA, or THA rates between cam and pincer morphologies within either the arthroscopic or open cohort. Conclusion: Surgical approach significantly impacts five-year structural outcomes in FAIS correction. Arthroscopy offers superior early joint stability, but the open approach may be associated with a more protective effect against long-term OA progression. Impingement morphology (cam vs. pincer) did not independently influence these five-year outcomes. These findings support a trade-off between approaches and highlight the need for tailored surgical selection to optimize joint preservation.