Prior Hip Arthroscopy Is Associated With Inferior Outcomes After Total Hip Arthroplasty: A Propensity-Matched Study.

PURPOSE: To investigate outcomes among patients undergoing total hip arthroplasty after hip arthroscopy (HA-THA) compared with a matched cohort undergoing primary THA without prior arthroscopy (Only-THA).

METHODS

Patients who underwent THA after primary hip arthroscopic labral repair from 2009 to 2022 at a single institution were identified. Cases were propensity-matched 1:4 to primary THA controls by age at THA, sex, body mass index (BMI), surgical approach, and year of surgery. At minimum 2-year follow-up, patient-reported outcomes (PROs)-Forgotten Joint Score (FJS), modified Harris Hip Score (mHHS), and Hip Disability and Osteoarthritis Outcome Score Pain (HOOS-Pain)-were analyzed.

RESULTS

Sixty-two hips (age: 47.5 ± 9.3 years, BMI: 29.7 ± 6.2 kg/m2) were matched to 248 Only-THA hips (age: 47.9 ± 10 years, BMI: 29.5 ± 5.8 kg/m2). Although both HA-THA and Only-THA patients showed significant (P < .001) postoperative improvements in PROs, HA-THA patients reported significantly lower postoperative FJS, mHHS, HOOS-Pain, and inferior Visual Analog Scale pain scores (P < .001) compared with Only-THA controls. A cohort-specific minimal clinical important difference for mHHS was calculated as 9.6 points, with 75.7% of HA-THA and 87.5% Only-THA patients achieving this threshold (P = . 077). At mean 6.6 ± 3.3 years follow-up, HA-THA patients with preoperative Tönnis grades 1 reported significantly decreased FJS, mHHS, and HOOS-Pain compared with HA-THA patients with preoperative Tönnis grade 2-3 (P ≤ .05). HA-THA patients with Tönnis grade 1 also exhibited worse PROs (P < .001) compared with Only-THA controls. Although there were no differences in complication rates between HA-THA and Only-THA patients (8% vs. 5%, P = .49), all-cause reoperation was greater amongst HA-THA (10% vs. 2%, P = .01).

CONCLUSIONS

Patients undergoing THA after prior hip arthroscopy showed modestly inferior subjective outcomes at mid-term follow up compared with an age-matched cohort without prior arthroscopy. Although both groups showed meaningful improvement, a smaller proportion of HA-THA patients achieved the cohort-specific MCID for mHHS compared with Only-THA controls.

LEVEL OF EVIDENCE: Level III, retrospective cohort study.