Hip Arthroscopy for Atypical Posterior Hip Pain: A Comparative Matched-Pair Analysis.

BACKGROUND: Femoroacetabular impingement (FAI) most commonly manifests as anterior groin pain. Patients occasionally have posterior pain but otherwise have clinical and radiographic evidence of FAI.

PURPOSE: To compare outcomes of hip arthroscopy for FAI in patients with atypical posterior pain versus a matched group with the typical anterior pain presentation.

STUDY DESIGN: Cohort study; Level of evidence, 3.

METHODS: Patients undergoing primary hip arthroscopy for FAI were identified from a clinical repository between January 2012 and 2014. Of 503 patients during the study period, 31 (6.2%) had posterior hip or buttock pain reproduced with flexion, adduction, and internal rotation (FADDIR) and were classified as "atypical," while those with anterior hip or groin pain were classified as "typical." Atypical patients were matched in a 1:2 cohort to the typical group based on sex, age, and body mass index (BMI). Postoperative patient-reported outcomes included visual analog scale (VAS) for pain, modified Harris Hip Score (mHHS), and Hip Outcome Scores with Activities of Daily Living (HOS-ADL) and Sports-Specific (HOS-SS) subscales.

RESULTS: Of the 31 atypical patients, 28 (90.3%) were available for a minimum 2-year follow-up (mean ± SD, 2.6 ± 0.6 years). These patients were matched with 56 typical patients. No differences were noted between typical and atypical cohorts in preoperative demographic or radiographic parameters. Postoperatively, both groups demonstrated significant improvements in mHHS (atypical 60.1 ± 12.4 to 78.8 ± 12.9; typical 60.0 ± 12.3 to 76.9 ± 13.6; P < .001), HOS-ADL (atypical 68.5 ± 17.0 to 88.6 ± 11.0; typical 69.2 ± 17.1 to 86.8 ± 14.7; P < .001), and HOS-SS (atypical 42.0 ± 25.5 to 71.0 ± 26.2; typical 44.4 ± 24.9 to 71.3 ± 27.3; P < .001). No differences were found in 2-year score improvements between the atypical and typical cohorts (mHHS 18.7 ± 13.4 vs 16.9 ± 13.1, P = .48; HOS-ADL 20.1 ± 16.8 vs 17.6 ± 14.6, P = .19; HOS-SS 29.0 ± 30.2 vs 26.9 ± 27.3, P = .93). Also, no significant differences were found in VAS pain improvement (5.0 ± 3.2 vs 5.6 ± 2.8, P = .56) or postoperative satisfaction (79.5 ± 5.5 vs 77.5 ± 4.1, P = .78).

CONCLUSION: Atypical posterior hip pain is an uncommon presentation of FAI. Patients demonstrate similar significant improvements after hip arthroscopy in outcome scores, postoperative pain, and satisfaction compared with patients who have classic anterior groin pain.