Summary

We present durable results at long term (>9 years) follow-up of patients who underwent hip arthroscopy for FAI with underlying borderline dysplasia.

Abstract

Background

Outcomes following isolated hip arthroscopy for patients with dysplasia have been unfavorable, results have included iatrogenic instability and conversion to total hip arthroplasty (THA) at a young age. However, patients with borderline dysplasia have portended more favorable results at short and medium term follow-up. The purpose of this study was to assess long term outcomes after hip arthroscopy for femoroacetabular impingement (FAI) in borderline dysplasia (BD) patients (LCEA, 18°-25°) compared to a control cohort of nondysplastic patients (LCEA, 25°-40°).

Methods

Between March 2009 and July 2012, a BD group of 33 patients (38 hips) was identified. An age- and sex-matched control group of 83 patients (96 hips) was also identified. Patient-reported outcome scores, including the modified Harris Hip Score (mHHS), the Hip Outcome Score–Activities of Daily Living (HOS-ADL) and Sport-Specific Subscale (HOS-SSS), and the International Hip Outcome Tool (iHOT-33), were collected preoperatively and subsequently at an average of 9.6 years post-operatively.

Results

The mean LCEA and Tönnis angle was 22.4° +/- 2.02° and 6.2° +/- 3.23° in the BD group and 31.7° +/- 3.52° and 2.42° +/- 3.02° in the control group, respectively (P <0.001). A labral repair was performed in 78.9% and 76% of the BD and control groups, respectively, all patients underwent capsular closure as part of routine hip arthroscopy. A cam decompression was performed in 97.4% of the BD patients and 99.0% of the control patients. At mean follow-up of 9.6 years (range, 8.2-11.6 years) on average there was significant improvement in all patient-reported outcomes scores in both groups (P<0.001). There were no significant differences between pre and post-operative scores or rates of achieving MCID between BD and control groups. Two hips (5.2%) underwent revision surgery in the BD group and 10 hips (10.4%) in the control group, of these one patient in the BD group underwent THA and one patient who underwent bilateral hip arthroscopies in the control group underwent bilateral hip resurfacing.

Conclusion

Durable outcomes (>9 years) with low revision rates can be expected after isolated hip arthroscopy that includes cam resection, labral refixation and capsular closure in BD patients with equivalent outcomes to a FAI cohort with normal coverage parameters.