A A De Smet

Classification and localization of acetabular labral tears

ObjectiveThe purpose of this study was to compare the findings on hip MR arthrography (MRA) with the published MRA and arthroscopic classifications of hip labral tears and to evaluate a clock-face method for localizing hip labral tears.Design/patientsWe retrospectively reviewed 65 hip MRA studies with correlative hip arthroscopies. Each labrum was evaluated on MRA using the classification system of Czerny and an MRA modification of the Lage arthroscopic classification. In addition, each tear was localized on MRA by using a clock-face description where 6 o’clock was the transverse ligament and 3 o’clock was anterior. These MRA findings were then correlated with the arthroscopic findings using the clock-face method of localization and the Lage arthroscopic classification of labral tears.ResultsAt MRA, there were 42 Czerny grade 2 and 23 grade 3 labral tears and 22 MRA Lage type 1, 11 type 2, 22 type 3 and 10 type 4 tears. At arthroscopy, there were 10 Lage type 1 flap tears, 20 Lage type 2 fibrillated tears, 18 Lage type 3 longitudinal peripheral tears and 17 Lage type 4 unstable tears. The Czerny MRA classification and the modified MRA Lage classification had borderline correlation with the arthroscopic Lage classification. Localization of the tears using a clock-face description was within 1 o’clock of the arthroscopic localization of the tears in 85% of the patients.ConclusionsThe Lage classification, which is the only published arthroscopic classification system for hip labral tears, does not correlate well with the Czerny MRA or an MRA modification of the Lage classification. Using a clock-face description to localize tears provides a way to accurately localize a labral tear and define its extent.

Open quiz solution: Case report 789

Dorsal defect of the patella is an uncommon but well known abnormality. It is believed to be an incidental finding that should not merit further intervention. However, the association of patellofemoral symptoms and a dorsal defect of the patella suggests abnormality of the cartilage overlying the defect. Resection of this area of abnormal cartilage has resulted in relief of symptoms in some patients. A patient who had a dorsal defect of the patella and persistent symptoms had MR imaging. The MR scans showed signal inhomogeneity with streaks of high signal in the cartilage overlying the lesion on both T1-weighted and T2-weighted images. Drilling of the defect relieved his pain.