The validity and accuracy of MRI arthrogram in the assessment of painful articular disorders of the hip

The assessment of a patient with chronic hip pain can be challenging. The differential diagnosis of intra-articular pathology causing hip pain can be diverse. These includes conditions such as osteoarthritis, fracture, and avascular necrosis, synovitis, loose bodies, labral tears, articular pathology and, femoro-acetabular impingement. Magnetic resonance imaging (MRI) arthrography of the hip has been widely used now for diagnosis of articular pathology of the hip. A retrospective analysis of 113 patients who had MRI arthrogram and who underwent hip arthroscopy was included in the study. The MRI arthrogram was performed using gadolinium injection and reported by a single radiologist. The findings were then compared to that found on arthroscopy. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy and 95% confidence interval were calculated for each pathology. Labral tear—sensitivity 84% (74.3–90.5), specificity 64% (40.7–82.8), PPV 91% (82.1–95.8), NPV 48% (29.5–67.5), accuracy 80%. Delamination —sensitivity 7% (0.8–22.1), specificity 98% (91.6–99.7), PPV 50% (6.8–93.2), NPV 74% (65.1–82.2) and accuracy 39%. Chondral changes—sensitivity 25% (13.3–38.9), specificity 83% (71.3–91.1), PPV 52% (30.6–73.2), NPV 59% (48.0–69.2) and accuracy 58%. Femoro-acetabular impingement (CAM deformity)—sensitivity 34% (19.6–51.4), specificity 83% (72.2–90.4), PPV 50% (29.9–70.1), NPV 71% (60.6–80.5) and accuracy 66%. Synovitis—sensitivity 11% (2.3–28.2), specificity 99% (93.6–100), PPV 75% (19.4–99.4), NPV 77% (68.1–84.6) and accuracy 77%. Our study conclusions are MRI arthrogram is a useful investigation tool in detecting labral tears, it is also helpful in the diagnosis of femoro-acetabular impingement. However, when it comes to the diagnosis of chondral changes, defects and cartilage delamination, the sensitivity and accuracy are low.