Are extra-labral MR findings useful in the diagnosis of a labral tear?

Objective: To determine diagnostic performance statistics of extra-labral magnetic resonance (MR) findings for detection of labral tears in a population of patients with clinical suspicion of this diagnosis. Materials and Methods: Seventy-nine patients clinically suspected of having a labral tear (who underwent arthroscopy) had their MR studies retrospectively reviewed to determine the presence of lateral acetabular oedema-like marrow signal, ganglia, dysplastic femoral bumps, synovial herniation pits and geodes. These findings were then correlated with the arthroscopic presence (or absence) of a labral tear. Results: All findings (lateral acetabular oedema-like marrow signal, ganglia, dysplastic femoral bumps, synovial herniation pits and geodes) had a specificity and positive predictive value (PPV) of 100%. Lateral acetabular oedemalike marrow signal had a sensitivity of 35% and 20% negative predictive value (NPV). This was the only statistically significant finding (P < 0.05). The sensitivity and NPV of ganglia were 12% and 16%, dysplastic femoral bumps (12%, 16%), synovial herniation pits (4%, 14%) and geodes (6%, 15%) respectively, (P > 0.05). Conclusion: Lateral acetabular oedema-like marrow signal is a useful sign (100% PPV) in the MR diagnosis of a labral tear, if one is clinically suspected. The other findings (ganglia, dysplastic femoral bumps, synovial herniation pits and geodes) were not statistically significant. Further studies are required to evaluate these.