Radiographic sizing for meniscal transplantation using 3-D CT reconstruction

In meniscus transplantation, allograft size mismatch causes increased contact pressures and early degeneration of the knee. The purpose of this study is to compare the accuracy and reliability of sizing the tibial plateau using three-dimensional (3-D) computed tomography (CT) scans versus plain radiographs (XR). Anteroposterior (AP) and lateral XR as well as CT with 3-D reconstructions were performed on 16 cadaveric knees. Sagittal and coronal dimensions of the hemiplateaus were measured on each imaging modality and then on the disarticulated specimens. CT estimates of plateau size were closer to anatomic measurements compared with radiographic estimates in all dimensions and these differences were statistically significant (p < 0.0001). CT scan fell within 5 mm of anatomic measurements 100% of the time versus 76.5% for XR and within 2 mm 71.9% of the time versus 34.4%. The proportion of CT measurements within 2 mm of actual values was significantly higher for CT for the lateral meniscus on AP (p = 0.0011) and lateral (p = 0.0039) views. 3-D CT has less error in measurement of the tibial plateau than XR and estimates were more likely to be within 2 and 5 mm of actual size. This may decrease the likelihood of allograft size mismatch.