Width is a more important predictor in graft extrusion than length using plain radiographic sizing in lateral meniscal transplantation.

PURPOSE: Plain radiographs are frequently used to select appropriately sized meniscal allografts, of which the width and length cannot be always perfectly matched. The objective of this study was to decide which of these dimensions should be matched with a more priority considering proper position of the lateral meniscal transplants.
METHODS: The positions of 34 lateral, fresh-frozen meniscal allografts, transplanted using the central bone bridge method, were evaluated by magnetic resonance imaging (MRI) 2 days after surgery. A size mismatch was defined as a difference between preoperative radiographic size and a real dimension of the transplants. The lateral subluxation of the mid-body on the coronal plane and the anterior and posterior horn positions on the sagittal plane were estimated on the MRIs. It was evaluated whether size mismatches were associated with the meniscal subluxation beyond articular cartilage margin on each plane.
RESULTS: The mean lateral subluxation of the mid-body on the center of coronal sections was 1.7 ± 1.8 mm. The anterior and posterior horns were located 2.0 ± 2.1 mm and -3.8 ± 2.7 mm from the articular edge, respectively, in the center of sagittal images. Lateral subluxation was significantly associated with width mismatch (r = 0.415-0.486, P < 0.05), but length mismatch was not significantly correlated with the anterior or posterior horn position on sagittal images (n.s.).
CONCLUSION: The results of this study suggest that width matching using plain radiographs would be more reliable than length matching when it is sought to assure adequate positioning of meniscal transplants, if both dimensions cannot be simultaneously matched. LEVEL OF EVIDENCE: II.