Pre-Operative MRA Accurately Predicts Capsulolabral Adhesions at Revision Hip Arthroscopy.

Background: To determine the accuracy of preoperative magnetic resonance arthrogram (MRA) in detecting capsulolabral adhesions in patients undergoing revision hip arthroscopy.

Methods: We retrospectively reviewed revision hip arthroscopies performed by a single surgeon between 2019 and 2022. Patients without preoperative MRA were excluded. Musculoskeletal radiologists blinded to surgical variables assessed pre-operative axial T1 FS MRA for adhesions and graded adhesions as mild (length <5 mm), moderate (5-10 mm), or severe (> 10mm). Paralabral sulcus effacement increased the grade one level beyond adhesion length. Intraoperative arthroscopy images were evaluated for the incidence and severity of adhesions. Adhesions were graded intraoperatively as mild (rare, small adhesions), moderate (multiple or large adhesions), or severe (many adhesions disrupting labral function). A grade of 0 was assigned if no adhesions were present. Graders were blinded to each other, and Wilcoxon signed-rank test compared diagnosis methods. Sensitivity, specificity, and predictive values (PPV, NPV) were also calculated.

Results: We identified 42 patients, 45 hips with pre-operative MRA undergoing revision hip arthroscopy. On MRA grading, there were 41 patients with adhesions (93%), of which 14 were considered severe (33%), 22 moderate (52%), and 6 mild (14%). On intraoperative grading (ICC 0.73, Kappa 0.35), there were 32 cases (71%) with 14 considered severe (31%), 10 moderate (22%), and 8 mild (18%). There was no difference in severity assessment between pre-operative MRA and intraoperative findings (P<0.001). Pre-operative MRA was moderately able to predict intra-operative adhesions (sensitivity 90.6%, PPV 69%). Specificity could not be calculated.

Conclusion: Axial T1 FS MRA is a sensitive tool to assess for capsulolabral adhesions in the revision arthroscopy setting. MRA best predicts severe adhesions and is moderately predictive of mild and moderate adhesions. .