Preoperative Delayed Gadolinium-Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC) for Patients Undergoing Hip Arthroscopy: Indices Are Predictive of Magnitude of Improvement in Two-Year Patient-Reported Outcomes.

BACKGROUND: Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) has been used in the detection of chondropathy. Our study aimed to determine whether dGEMRIC indices are predictive of two-year patient-reported outcomes and pain scores following hip arthroscopy.
METHODS: Between August 2008 and April 2012, sixty-five patients (seventy-four hips) underwent primary hip arthroscopy with preoperative dGEMRIC and a minimum of two years of follow-up. Exclusion criteria were previous hip surgery, slipped capital femoral epiphysis, inflammatory arthropathy, Legg-Calvé-Perthes disease, and arthritis of >1 Tönnis grade. Patients were classified in two groups on the basis of a dGEMRIC cutoff of 323 msec, which was one standard deviation (SD) below the study cohort mean dGEMRIC index of 426 msec. Patient-reported outcome tools used included the modified Harris hip score (mHHS), the Nonarthritic Hip Score (NAHS), the Hip Outcome Score Activities of Daily Living (HOS-ADL), and the Hip Outcome Score Sport-Specific Subscale (HOS-SSS) as well as a visual analog scale (VAS) for pain and a patient satisfaction score.
RESULTS: There were sixty-four hips that met the inclusion criteria; fifty-two (81.3%) had a minimum of two years of follow-up. Twelve of the sixty-four hips had a dGEMRIC index of <323 msec (Group 1), and fifty-two hips had a dGEMRIC index of ≥323 msec (Group 2). There was no significant difference between the groups with respect to age, sex, and body mass index. There was no significant difference between the groups in mean preoperative patient-reported outcome scores and the VAS for pain. At the two-year follow-up, Group 1 had significant improvement in the mHHS, whereas Group 2 demonstrated significant improvement in all patient-reported outcome scores and the VAS. The improvement in all patient-reported outcome scores was significantly larger for Group 2 compared with Group 1. There was no significant difference in patient satisfaction between groups and no significant correlation between dGEMRIC indices and the patient-reported outcome measures.
CONCLUSIONS: Patients with a dGEMRIC index of ≥323 msec (less than one SD below the cohort mean) demonstrated significantly greater improvement in patient-reported outcome scores and the VAS for pain after hip arthroscopy.