PURPOSE: To compare the changes in labral size following primary hip arthroscopy between patients requiring revision surgery and those did not. METHODS: Data collected between August 2016 and September 2021 was retrospectively reviewed. Patients diagnosed with FAIS and undergoing primary and revision hip arthroscopy at our institute were included in the revision group. Exclusion criteria were Tönnis grade >
1, concomitant hip conditions, and incomplete MRI data. Patients who did not undergo revision surgery or conversion to total hip arthroplasty (THA) at minimum 2-year follow-up were matched in a 1:2 ratio and included in the control group. The labral size (width and height at 11:30, 1:30, and 3:00) on MRI (non-contrast, 3.0 T) before and after 12 months of primary surgery were compared. RESULTS: Twenty-one patients were included in the revision group, and 42 patients were matched in the control group. In the revision group, significant reduction in labral width and height at 11:30 and 1:30, and labral width at 3:00 was observed at 12 months after primary hip arthroscopy (all with P <
.05), while the control group did not demonstrate significant difference of changes in labral size (all with P >
.05). Smaller postoperative labral width at 1:30 and 3:00 was observed in the revision group compared to the control group (all with P <
.05). The revision group presented with greater reduction of labral width at all three positions and labral height at 1:30 compared to the control group (all with P <
.05). CONCLUSION: Patients requiring revision surgery following primary hip arthroscopy for FAIS presented with smaller postoperative labral size (less than 1mm difference) and greater reduction of labral size (at or less than 1mm difference) on MRI 12 months after primary surgery compared to those patients that did not require later revision surgery. LEVEL OF EVIDENCE: Level III. Retrospective case control.