Association of Radiographic Markers of Hip Instability and Worse Outcomes 2 to 4 Years After Hip Arthroscopy for Femoroacetabular Impingement in Female Patients

Background: Reported outcomes of patients undergoing hip arthroscopy for femoroacetabular impingement (FAI) with underlying borderline acetabular dysplasia are mixed. This may in part be the result of mixed-sex reporting. Purpose: To determine the effect of radiographic measures of acetabular dysplasia and hip instability on outcomes of female patients undergoing hip arthroscopy for FAI. Study Design: Case-control study; Level of evidence, 3. Methods: This was a retrospective study of female patients undergoing arthroscopic surgery for FAI. All patients had preoperative radiographs including a standing anteroposterior pelvic view on which lateral center-edge angle (LCEA), anterior wall index (AWI), posterior wall index (PWI), and femoroepiphyseal acetabular roof (FEAR) index were measured. Patient outcomes were quantified by preoperative and postoperative 12-Item International Hip Outcome Tool (iHOT-12) scores. All patients had follow-up at 2 to 4 years postoperatively. Published values for minimal clinically important difference (MCID), substantial clinical benefit (SCB), Patient Acceptable Symptom State (PASS), and a normal (iHOT-12 > 86 points) or abnormal (iHOT-12 < 56 points) hip were used to determine outcome, as well as the final iHOT-12 score and iHOT-12 preoperative to postoperative difference. Results: The cohort consisted of 249 female patients (83% follow-up) with iHOT-12 scores at 2 to 4 years after surgery (mean, 34.6 months). Female patients with combined LCEA <= 25 degrees and AWI <0.35 had lower final iHOT-12 score and iHOT-12 difference and were less likely to meet MCID, SCB, and PASS and have a normal hip and were more likely to have an abnormal hip as determined by iHOT-12 cutoffs when compared with those patients who had an LCEA >25 degrees and an AWI >= 0.35 (all P < .05). There was no effect of PWI on outcomes. Similarly, female patients with combined LCEA <= 25 degrees and a laterally oriented (positive) FEAR index were less likely to meet MCID, SCB, and PASS and have a normal hip and were more likely to have an abnormal hip compared with those patients who had an LCEA >25 degrees and a negative (medial) FEAR index (all P < .05). In multivariate regression, an LCEA between 18 degrees and 25 degrees was an independent predictor of worse outcomes. Conclusion: An LCEA of 18 degrees to 25 degrees, in combination with an AWI of <0.35 or a laterally opening FEAR index, was predictive of worse outcomes in female patients undergoing hip arthroscopy for FAI.

Automated summary

This study aimed to explore the impact of acetabular dysplasia and hip instability on outcomes of female patients undergoing hip arthroscopy for FAI. The findings suggest that female patients with combined LCEA ≤ 25 degrees and AWI <0.35 had worse postoperative outcomes, and an LCEA between 18 degrees and 25 degrees was predictive of poorer results.