Meniscal extrusion is positively correlated with the anatomical position changes of the meniscal anterior and posterior horns, following medial meniscal allograft transplantation.

The purpose was to analyse the correlation between meniscal extrusion and position changes of the anterior horn and posterior horn after medial meniscal allograft transplantation. Patients (n = 68) who underwent medial MAT were included. Anatomical positions of the anterior horn and posterior horn were measured, before and after surgery, using magnetic resonance images in the coronal and sagittal planes. The absolute and relative delta values of the anatomical positions were obtained, and the absolute and relative meniscal extrusion measurements were taken. In the coronal plane, the absolute position change of anterior horn showed moderate positive correlation with the absolute and relative meniscal extrusion. The relative position change of anterior horn showed moderate positive correlation with the absolute and relative meniscal extrusion. The absolute position change of posterior horn showed moderate positive correlation with the absolute and relative meniscal extrusion. The relative position change of posterior horn showed moderate positive correlation with the absolute and relative meniscal extrusion. In the sagittal plane, both absolute and relative position change of anterior horn showed no correlation with the absolute and relative meniscal extrusion, respectively. Both absolute and relative position changes of posterior horn showed nonsignificant weak correlation with the absolute and relative meniscal extrusion, respectively. Transplanting the meniscus close to its native position may reduce subluxation in medial meniscal allograft transplantation. As position changes in the coronal plane can affect the meniscal subluxation more than changes in the sagittal plane, the tibial bone tunnel should be carefully created in the correct anatomical position to avoid a large amount of coronal deviation. Retrospective case series, IV.