Radiographic Methods Are as Accurate as Magnetic Resonance Imaging for Graft Sizing Before Lateral Meniscal Transplantation: Letter to the Editor

Dear Editor:

With great interest we read the study of Ambra et al ¹ stating that radiographic methods are as accurate as magnetic resonance imaging (MRI) for graft sizing in lateral meniscal transplantation. However, studying the article more closely some questions arose, which we believe should be clarified by the authors.

The MRI measurements performed in the study are described to be similar as described by Kaleka et al. ⁸ However, Figure 2 in the manuscript does not match the technique of Kaleka et al, ⁸ as the medial-lateral length should be measured perpendicular to the anterior-posterior length. Beside this, it seems that the modification performed does not match the technique used for measurement in the “anatomic measurements.” We believe that for a better comparison, the same approach would have been favorable. This is one of the major advantages of MRI compared with fluoroscopic measurements. We would like to ask the authors why the present approach has been chosen. This might be the reason why previous studies comparing fluoroscopic anatomic cadaveric measurements and MRI concluded a superiority of MRI matching.^5,7,10

Moreover, it has been shown that further parameters of the meniscus anatomy; for example, height ⁹ and variant cross-sectional measurements,^5,7 have a weak correlation with length and width. Zhang et al ¹¹ found that the lateral meniscus has at least 6 principal morphological variations. When choosing a graft only with radiological methods, variations are neglected that could have been detected with MRI.

Several studies have shown that the closer the graft meets the anatomy of the former meniscus, important biomechanical parameters, such as contact pressure, can be decreased.^4,6,7 Focus in research should therefore shift to approaches that contain these aspects. Three-dimensional modelling of the menisci and the tibia can even improve graft selection as shown in the study of Beeler et al.^2,3 Although this is not adopted to the clinical work today, it can serve as a valid tool in the future. We believe that simple enhanced MRI measurements, also from the ipsilateral side, can already improve current sizing techniques and is cost-effective. One of the major and relevant advantages of MRI measurements compared with fluoroscopic imaging might further be that in a clinical set-up, it is very hard to achieve true anterior-posterior and lateral views. It would be interesting if the authors documented the mean number of radiograph images performed in each cadaveric meniscus.

We would like the authors to consider our concerns and enlighten us on their methodological thoughts.