Summary

Current cadaveric and MRI study showed the variability of size and stiffness of meniscotibial ligament depending on laterality or individuals that can be considered as risk factor or meniscal extrusion following meniscal allograft transplantation.

Abstract

Introduction

Meniscotibial ligament defines capsular structure which connect the inferior edges of the menisci to the periphery of the tibial plateaus. Compared with meniscal root and meniscofemoral ligament of which attachment anatomy and biomechanics are well documented, little is known about meniscotibial ligament. The aim of this cadaveric and magnetic resonance imaging study was to evaluate anatomical characteristics and mechanical properties of meniscotibial ligament and understand the mechanism of meniscal extrusion following meniscal allograft transplantation based on the properties of meniscotibial ligaments.

Material & Method: Cadaveric study was performed on 15 knees of which medial and lateral menisci were intact. To evaluate anatomical chracteristics, insertional depth(distance from articular surface to meniscotibial ligament insertion) and lengh of meniscotibial ligament(distance from inferior border of menisci to meniscotibial ligament insertion) were measured at the mid point of each menisci. After detachment of anterior and posterior root insertion, displacement of menisci under upward and peripheral traction force were recorded. Also, 1cm-sized meniscotibial ligament was detatched and stiffness was measured using tensile machine. On 50 knee MRI, insertional depth and length of meniscotibial ligament of medial and lateral meniscus were measured. All parameters of medial and lateral meniscus were statistically compared.

Results

In cadaveric study, the mean insertional depth and length of meniscotibial ligament were 6.3±2.7mm and 9.1±2.3mm in lateral meniscus and 4.1±1.8mm and 5.0±1.6mm in medial meniscus. Lateral meniscus showed significantly lager insertional depth, length, and length/insertional depth ratio of meniscotibial ligament compared with medial meniscus(p<.05). The mean displacement under peripheral and upward traction were 7.3±1.3mm and 7.6±1.6mm in lateral meniscus and 3.8±1.1mm and 3.6±0.9mm in medial meniscus. In the absence of root attachment, lateral meniscus was significantly more mobile compared with medial meniscus(p<.05). The mean stiffness of meniscotibial ligment were higher in medial meniscus(9.5±2.2N/mm) compared with lateral meniscus (6.4±1.8N/mm)
(p<.05). The mean insertional depth, length, and length/insertional depth ratio of meniscotibial ligament on knee MRI were 7.1±2.4mm, 9.8±2.7mm, and 1.41 in lateral meniscus and 4.8±1.7mm, 5.4±1.8mm, and 1.12 in medial meniscus.

Conclusion

Meniscotibial ligament of lateral meniscus showed significantly lager insertional depth, length, and length/insertinal depth ratio compared with that of medial meniscus. On the other hand, stiffness of meniscotibial ligament was significantly higher in medial menisus. These anatomical and mechanical properties of meniscotibial ligament can be a factor that contribute to mobility of lateral meniscus. Also, insertional depth and length of lateral meniscotibial ligament can be considered as a risk factor of meniscal extrusion following meniscus allograft transplantation, especially when bone plug is malpositioned or meniscal allograft size is mismatched largely.