The role of muscle forces on rotational and cranio‐caudal stability in the intact and
CCL
‐deficient stifle: An ex vivo biomechanical study
Pavlos Natsios, Rahel Capaul, Antonio Pozzi, Brian Park Abstract
Objective
To investigate the effects of muscle activation on internal tibial rotation and cranio‐caudal translation (CCT) in intact and cranial cruciate ligament (CCL) deficient stifles.
Study design
Ex vivo biomechanical study.
Animals
Eight cadaveric, nonpaired canine stifles.
Methods
Stifles were tested intact and after arthroscopic CCL transection. Quadriceps, biceps femoris, and gastrocnemius forces were simulated with pneumatic actuators in single or cocontraction muscle activation (0%–100% bodyweight [BW]). The tibia was mounted to a linear–torsional tester; the femur to a six‐degrees‐of freedom fixture. Internal tibial rotation (5 Nm torque) and CCT (30% BW cranial and caudal translation) were recorded via motion tracking system.
Results
Without muscle activation, CCL transection increased internal tibial rotation (34.8 ± 11.8° CCL‐deficient vs. 27.9 ± 10.8° intact; p = .041). Across 0%–100% BW activation, internal rotation decreased in both conditions, to 4.3 ± 2.3° (intact; p < .0001 vs. 0% BW) and 2.8 ± 1.3° (CCL‐deficient; p = .001 vs. 0% BW) at 100% BW. At 100% BW, biceps femoris reduced internal rotation more than quadriceps and gastrocnemius in both CCL conditions. Muscle activation reduced CCT in CCL‐deficient stifles; however, at 100% BW, CCT was 19.1 mm in CCL‐deficient versus 2.8 mm in intact (+582%; p < .0001).
Conclusion
Periarticular muscle activation mitigates axial plane rotational laxity but does not prevent CCT.
Clinical significance
Targeted muscle strengthening may help manage rotational laxity; however, surgical stabilization remains necessary to address CCT after CCL rupture. Internal tibial rotation may require additional surgical stabilization in selected cases.