Two-Year Outcome of Arthroscopic Capsular Repair of the Hip: A Prospective Matched-Pair Controlled Study
Authors: Domb Benjamin G. , Stake Christine E. , Finley Zachary John , Baise Ryan A. , Botser Itamar 
Published: September 2013

Objectives:

Capsulotomy and capsulectomy are common procedures to gain better joint access in hip arthroscopy. Based on biomechanical evidence and the principle of restoration of anatomy, it has been suggested that closure of the capsule following hip arthroscopy may be beneficial. However, outcomes have scarcely been reported regarding the routine use of this procedure. The purpose of this study was to compare the clinical results of two matched-pair groups - one undergoing capsular closure following hip arthroscopy and one in which the capsulotomy was left open – with a minimum follow-up of two years.

Methods:

Data was prospectively collected for all patients undergoing hip arthroscopy between February 2008 and June 2010. Revision surgeries and previous hip conditions such as avascular necrosis and Legg-Calves-Perthes Disease were excluded. In the early part of the study period, the capsule was left open at the end of the surgery; in the later part, routine capsular closure was performed. Patients were matched according to gender and age within 3 years. The study group included patients who underwent closure of the capsule, whereas the control group included patients in which the capsule was left open. Surgical outcome was measured according to resolution of hip snapping, and improvement in four hip specific patient-reported outcome (PRO) tools: the modified Harris Hip Score (mHHS), Non-Arthritic Hip Score (NAHS), Hip Outcome Score Activity of Daily Living (HOS-ADL) and Sport-Specific Subscales (HOS-SSS). Pain was estimated on the visual analog scale (VAS) and satisfaction was measured on a scale from 0-10.

Results:

Each group consisted of 46 patients. The mean age of the study group was 28.9 years (range, 14 to 62 years), whereas the average of the control group was 33.8 years (range, 14 to 52) (p=0.03). There were no reported complications with the procedure. The average follow-up was 27.8 months (range, 16 to 41) with no significant difference between the two groups. The patients who received closure of the capsule showed score improvement from preoperative to two-year follow-up of 62 to 88 for mHHS, 60 to 84 for NAHS, 67 to 88 for HOS-ADL, and 43 to 71 for HOS-SSS. The control group showed score improvement of 61 to 87 for mHHS, 54 to 85 for NAHS, 61 to 86 for HOS-ADL, and 35 to 76 for HOS-SSS. All score improvements in both groups were statistically significant (p<0.05). Pain scores decreased from 6.4 to 2.4 in the closed capsule group and 6.3 to 2.2 in the control group. Patient satisfaction was 8.3 for the closed capsule group compared to 8.5 for the control group. In comparing the two groups, there were no differences in magnitudes of score improvement for PRO measures, VAS, or satisfaction. Range of motion at last follow-up was comparable.

Conclusion:

Both repairing the capsule of leaving it open at the end of hip arthroscopy yielded excellent results at minimum two year follow-up, with similar score improvements between the groups. Additionally, repair of the capsule resulted in no related complications and no limitation in range of motion. Cadaveric studies have shown capsulotomy changes the biomechanics of the hip joint, suggesting that routine capsular repair may be advantageous. While this pilot study did not show any difference in clinical outcome between groups, it establishes the feasibility and safety of capsular closure in hip arthroscopy, and may open the door for further refinement of its indications.