Bucket-handle meniscal lesions: magnetic resonance imaging criteria for reparability.

PURPOSE: The purpose of this study was to determine the accuracy of magnetic resonance imaging (MRI) in predicting knee bucket-handle meniscal tear (BHMT) reparability.
METHODS: Twenty-eight patients who underwent knee arthroscopy by a single surgeon for BHMT with prior MRI examination were included. BHMTs were diagnosed by MRI based on the association of a displaced meniscal fragment on coronal images and one of the following three signs on sagittal slices: flipped meniscus sign, double posterior cruciate ligament, and meniscal fragment within the intercondylar notch. BHMT patients' MRIs were retrospectively reviewed independently to search for criteria of reparability by 2 observers with different degrees of experience in musculoskeletal radiology, and disagreements were arbitrated to consensus. The criteria for BHMT reparability were as follows: (1) rim width of less than 4 mm; (2) tear length of 1 cm or greater, regardless of total lesion length; and (3) generation of isosignals by the inner meniscal fragment and peripheral rim compared with the normal contralateral meniscus of the same knee. The first 2 criteria indicate an adequate meniscal lesion length in the vascularized zone (only the peripheral third), enabling meniscal healing after repair; the third criterion guarantees that the meniscus is nondegenerative.
RESULTS: Of the BHMTs, 5 (17.9%) were arthroscopically reparable and 23 (82.1%) were not. Interpretation of magnetic resonance images correctly predicted reparability in 4 of 5 reparable BHMTs and irreparability in 22 of 23 irreparable BHMTs (26/28 lesions). Interobserver agreement was good for the prediction of reparability (kappa = 0.7).
CONCLUSIONS: These results suggest that knee BHMTs that are predicted to be reparable by MRI would have a high likelihood of actually being reparable. LEVEL OF EVIDENCE: Level II, development of diagnostic criteria on basis of consecutive patients and gold standard.