Anteromedial structures, including the joint capsule sleeve and the deep collateral ligament, serve as a stabilizer and contribute to midflexion stability in cruciate ligament-deficient knees: A cadaveric study.

INTRODUCTION/OBJECTIVES: The specific contributions of the soft tissue attachments along the tibial rim remain poorly understood, while the importance of medial stability in the knee joint has been widely emphasized. This study aimed to evaluate the effect of releasing individual anteromedial stabilizers by replicating the soft tissue release typically performed in total knee arthroplasty.

METHODS

Eight cadaveric knees were evaluated. Passive stress in each direction with six degrees of freedom was applied to the knees under image-free navigation monitoring. Measurements were taken following the sequential release of soft tissue structures: normal; anterior and posterior cruciate ligament resection; removal of the medial meniscus with 1 ​cm of anteromedial meniscotibial ligament release; 3 ​cm of anteromedial joint capsule release; and tibial attachment release of the deep collateral ligament. The entire section was performed sequentially on the identical cadaver knee.

RESULTS

Anterior translation exhibited a statistically significant increase following dissection of the medial meniscus and 1 ​cm of the meniscotibial ligament at an intermediate flexion angle compared with the previous section. External laxity statistically significantly increased following dissection of the medial meniscus and 1 ​cm of the meniscotibial ligament overall flexion angle. Moreover, further external rotational laxity was observed following 3-cm anteromedial joint capsule release and subsequent deep collateral ligament release throughout an extensive flexion angle. Due to the dissection of each medial structure, gradual increases in external rotation laxity were observed in all sections, with statistically significant differences. Following deep collateral ligament dissection, laxity in each of the six degrees of freedom increased by approximately 20-30 ​% compared with the values observed after anterior and posterior cruciate ligament dissection.

CONCLUSION

Structures attaching to the anteromedial rim of the tibia serve as critical secondary stabilizers during midflexion in cruciate-deficient knees, with the anteromedial joint capsule sleeve and deep medial collateral ligament contributing to rotational stability despite the presence of an intact superficial medial collateral ligament.

LEVEL OF EVIDENCE

V.