Longitudinal Assessment of Clinical Outcomes After Arthroscopic Treatment for Hip Synovial Chondromatosis and the Effect of Residual Loose Bodies: Minimum 4-Year and 8-Year Follow-up

Abstract

Background: Arthroscopic treatment is recommended for hip synovial chondromatosis. However, evidence regarding long-term clinical outcomes is limited. Purpose: To evaluate long-term patient-reported outcomes (PROs) and survival, and to determine the potential effect of residual loose bodies, as evaluated by immediate postoperative computed tomography (CT), on clinical outcomes. Study Design: Case series; Level of evidence, 4. Methods: A consecutive cohort of patients undergoing arthroscopic treatment and diagnosed with synovial chondromatosis between March 2010 and May 2015 were included in the study. Preoperative radiography, CT, and magnetic resonance imaging were performed. Preoperative, midterm (minimum of 4 years), and long-term (minimum of 8 years) PROs were collected for visual analog scale for pain, modified Harris Hip Score (mHHS), Non-Arthritic Hip Score (NAHS), and 12-item international Hip Outcome Tool (iHOT-12). The percentages achieving minimal clinically important difference (MCID) were calculated. PROs and survival were compared between patients with and without residual loose bodies evident on immediate postoperative CT scan. Results: A total of 28 patients (20% of patients were lost to follow-up) were included in the study with a mean follow-up period of 104.9 months (range, 96-139 months). PROs including visual analog scale for pain (preoperative, 3.8 ± 1.2; midterm, 0.9 ± 1.7; long-term, 0.8 ± 1.4), mHHS (preoperative, 66.4 ± 14.4; midterm, 92.8 ± 12.3; long-term, 93.5 ± 10.5), NAHS (preoperative, 45.2 ± 16.2; midterm, 81.8 ± 15.3; long-term, 83.1 ± 12.9), and iHOT-12 (preoperative, 48.4 ± 15.6; midterm, 69.3 ± 11.7; long-term, 72.7 ± 11.4) were improved at both midterm and long-term follow-up (all with P < .001). In total, 27 (96.4%), 28 (100%), and 26 (92.9%) patients achieved MCID for mHHS, NAHS and iHOT-12, respectively, at the long-term follow-up. No significant difference was found in any of the PROs and the rate of achieving MCID between midterm and long-term follow-up (all with P > .05). One patient (3.6%) underwent revision surgery. Among the 23 patients who had loose bodies on preoperative CT or radiographs, 14 patients (60.9%) with residual loose bodies evident on immediate postoperative CT demonstrated lower NAHS ( P = .045) and iHOT-12 ( P = .037) scores but a comparable survival ( P > .05) at long-term follow-up compared with those who did not have loose bodies. Conclusion: Arthroscopic treatment for hip synovial chondromatosis achieved satisfactory long-term clinical outcomes with strong survival. Most patients maintained or improved their overall functional status between midterm and long-term follow-up. Furthermore, patients with residual loose bodies had less favorable clinical outcomes, although the survival rate was comparable.