In vivo strain patterns in the four major canine knee ligaments

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Veterinary Medicine

Background:

• The knee joint's stability is maintained by a complex interplay of ligaments.
• Understanding ligamentous strain under various loading conditions is crucial for diagnosing injuries and developing treatments.

Purpose of the Study:

• To quantify in vivo ligament strains in the canine knee under valgus and varus loading with free axial rotation.
• To determine the contribution of collateral and cruciate ligaments to knee stability at different flexion angles.

Main Methods:

• In vivo measurement of ligament strains using mercury gauges in canine knees.
• Application of valgus and varus loads to the tibia at fixed flexion angles (0, 45, 90 degrees).
• Allowing free axial rotation of the tibia relative to the femur.

Main Results:

• Valgus loading caused significant strain in the medial collateral ligament at extension, and in multiple ligaments including cruciates at increased flexion.
• Varus loading resulted in strain of the lateral collateral and anterior cruciate ligaments, with increasing involvement of the posterior cruciate at higher flexion.
• Tibial rotation occurred with both loading types, increasing with flexion during valgus and remaining constant during varus.

Conclusions:

• Both collateral and cruciate ligaments contribute to knee stability under valgus and varus loads when axial rotation is permitted.
• The role of cruciate ligaments in maintaining stability increases with knee flexion and tibial axial rotation.
• Findings provide insights into knee joint biomechanics and injury mechanisms.