Restoration of the anatomic position during a meniscal allograft transplantation using pre-existing landmarks

Accurate sizing and positioning of a meniscal allograft is an important factor for successful outcomes of meniscal allograft transplantation. The objectives of this study were (1) to search a proper rotational landmark, (2) to determine the sagittal slope of meniscus, and, thus (3) to determine the meniscal positioning.

A total of 121 consecutive patients who underwent magnetic resonance imaging in the 3 months prior to the beginning of the study were selected. To assess the meniscal rotation, rotation 0° line of the meniscus was defined as a line connecting the center of the anterior and the posterior horn of the medial and lateral meniscus, respectively. At this level, four possible reference lines were compared: Akagi line, line perpendicular to the largest mediolateral dimension (LMLD), line between the medial border of the patellar tendon and the apex of the medial tibial spine (PTMS), and line between the lateral border of the patellar tendon and the apex of the lateral tibial spine. To assess the meniscal slope, the slope of the insertional area, meniscal and bony slopes at the mid-plateau area were compared.

Akagi line was significantly different with a true meniscal rotation (line connecting between centers of the anterior and posterior horns) in both medial and lateral meniscus (p < 0.01 and p < 0.01). LMLD was significantly different in the lateral meniscus (p < 0.01), however, no statistical difference was observed in the medial meniscus (n.s.). PTMS was not different in the medial meniscus (n.s.), however, it was different in the lateral meniscus (p < 0.01). On the medial side, significant statistical difference was observed between insertional and bony slope (p < 0.01) and between meniscal and bony slope (p < 0.01). On the lateral side, comparison of three slopes showed significant statistical differences (p < 0.01-p = 0.03).

Line between patellar tendon and tibial spine was a good reference line for a meniscal rotation in the medial meniscus. Among previously introduced reference lines, LMLD showed approximity with a true meniscal rotation. The slope between tibial insertion and mid-portion was significantly different in the lateral meniscus.