Background <p>The capsular healing status and capsular thickness changes in patients with femoroacetabular impingement syndrome (FAIS) following revision hip arthroscopy are poorly documented, and their relationship with subjective clinical outcomes remains unclear. The purpose of this work is to evaluate the incidence of capsular defects and changes in capsular thickness using magnetic resonance imaging (MRI) following hip arthroscopy in patients with FAIS, and to compare the subjective clinical outcomes between patients with and without capsular healing after revision hip arthroscopy.</p> Patients and methods <p>Consecutive patients with FAIS who underwent revision hip arthroscopy between 2013 and 2023 were included. Patients were categorized into two groups on the basis of capsular healing status after revision hip arthroscopy. Patient-reported outcomes (PROs) were collected preoperatively and at minimum 2-year follow-up, including the modified Harris Hip Score (mHHS), International Hip Outcome Tool-12 (iHOT-12), Hip Outcome Score-Activity of Daily Living Scale (HOS-ADL), Hip Outcome Score-Sport Specific Subscale (HOS-SSS), and visual analog scale (VAS). Achievements in minimal clinically important difference (MCID) and patient acceptable symptom state (PASS), patient satisfaction, and re-revision rates were evaluated and compared between groups. Capsular thickness was assessed by MRI pre-index, pre-revision, and at a minimum of 12-month post-revision time points in cases with healed capsule. Spearman rank correlation analysis was performed to assess the association between PROs and capsular thickness postoperatively.</p> Results <p>A total of 19 patients (20 hips) were included. Capsular defects were observed in six hips (30%) at minimum 1&#xa0;year follow-up following revision hip arthroscopy. No significant differences were identified between the healed and unhealed groups in patient demographics, intraoperative findings, arthroscopic procedures, or preoperative PROs (<i>P</i> &gt; 0.05). Postoperative PROs, MCID and PASS achievement rates, patient satisfaction, and re-revision rates were also comparable between groups (<i>P</i> &gt; 0.05). The proximal (<i>P</i> = 0.015) and middle (<i>P</i> = 0.009) capsular thickness significantly increased at the final follow-up after revision hip arthroscopy compared to pre-revision surgery time point. No significant correlations were found between capsular thickness and PROs following revision hip arthroscopy (<i>P</i> &gt; 0.05).</p> Conclusions <p>Although the rate of capsular defects following revision hip arthroscopy was 30% at minimum 1&#xa0;year follow-up, comparable improvements in subjective clinical outcomes were observed at minimum 2-year follow-up regardless of capsular healing status. Patients with healed capsules exhibited increased proximal and middle capsular thickness after revision hip arthroscopy, with no correlation observed between capsular thickness and PROs.</p> <p><b>Level of Evidence:</b> IV.</p>