Results of hip arthroscopy in patients with MRI diagnosis of subchondral cysts—a case series

The aim of this article is to examine the results of arthroscopic management of patients with labral pathology who have preoperative magnetic resonance images (MRIs) demonstrating subchondral cysts. This institution’s database was searched for patients who underwent hip arthroscopy and had subchondral cysts on MRI and >2-year follow-up. Exclusion criteria included previous hip surgery, Tönnis grade >1, inflammatory arthritis, Perthes, slipped capital femoral epiphysis or abductor repair. Patient-reported outcome (PRO) scores including visual analog scale, modified Harris hip score (mHHS), non-arthritic hip score and hip outcome score sports-specific subscale (HOS-SSS) were gathered preoperatively, at 3 months, and annually thereafter. The change in PRO scores was compared with the minimally clinical important difference (MCID) to quantify improvement. Sixty-nine patients were eligible for this study, of which 65 (94%) had >2-year follow-up. All PROs were significantly improved at latest follow-up (P < 0.001). Mean patient satisfaction was 7.2. There was no correlation between Outerbridge grade III or IV cartilage damage noted during arthroscopy and subchondral femoral and acetabular cysts noted on MRI. Seventeen patients required reoperation [13 total hip arthroplasty (THAs) and 4 revision arthroscopies]. Patients with femoral subchondral cysts converted to THA 36% of the time. MCIDs for mHHS and HOS-SSS were surpassed by 63% and 68% of patients, respectively. Hip arthroscopies performed on patients with subchondral cysts present on preoperative MRI should be approached with caution. The rate of conversion to hip arthroplasty appears to be higher than that reported in the literature for patients who undergo arthroscopy without preoperative subchondral cysts. For patients who did not require hip arthroplasty or revision arthroscopy, patients demonstrated significant improvement in symptoms compared with the preoperative state.