Which Are the Most Reliable Methods of Predicting the Meniscal Size for Transplantation?

Background: Although the size of the meniscal allograft is crucial during meniscal transplantation, the accuracy of meniscal measurement methods is still under debate. A number of methods based on radiographic and magnetic resonance imaging (MRI) data as well as on anthropometric data have been proposed, but their reproducibility and reliability are still unclear. Purpose: To compare meniscal length and width as measured by different techniques (anthropometric and plain radiographic) to establish which of these 2 methods is more reliable and cost-effective for determining the meniscal size in comparison to MRI. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: The MRI scans and plain radiographic films of 22 patients (44 knees) from a single institution were studied. The width and length of the medial and lateral menisci were measured using specific techniques. Data on sex, age, body weight, and height were used to develop a regression formula for meniscal measurements (comparing both imaging methods) to establish meniscal dimensions. Data validation was achieved using the Pearson correlation, the intraclass correlation coefficient, and the Wilcoxon nonparametric test for all variables, with a significance level established at 95%. Accuracy was established as a 10% measure discrepancy from the gold standard (MRI) and was considered an average between the right and left knees. Results: No statistically significant difference was observed between the right and left knees on radiographic and MRI measurements. The Pollard technique of radiographic measurement overestimated the width of the lateral meniscus when compared with anthropometric measurements (P<. 001), considering MRI as the gold standard. The same was observed for MRI measurements of the length of the lateral meniscus in which not only anthropometric but also plain radiographic measurements using the Yoon technique were significantly smaller than those values found with the Pollard technique (P<. 001). The anthropometric method underestimated the width and length of the medial meniscus with an accuracy of 68.2% and 63.6%, respectively. The radiographic method was comparable with MRI in establishing all medial meniscal measurements with an accuracy of 93.2% for length and 77.3% for width. Conclusion: Some viable alternatives to MRI have been suggested. For the lateral meniscus, anthropometric data are an alternative for width, and the Yoon method can be used to assess length. For the medial meniscus, the Pollard method is considered a satisfactory alternative. This study emphasized the importance of measuring the width and length of the meniscus independently during preoperative sizing for a meniscal allograft transplantation procedure. Using MRI as a gold standard, the study also proposed other less costly and satisfactory methods of obtaining such measurements.