Background and purpose
Besides current strategies to treat potentially disabling anterior cruciate ligament (ACL) injury, a new and innovative approach
was designed based on electrical stimulation of the muscle to prevent unwanted displacement of the tibia relative to the femur.
Our aim was to measure muscular strain and anterior tibial translation (ATT) in a controlled study using an animal model of
ACL-deficient knee undergoing muscular electric stimulation.
Methods
Seventeen cat knees under tibial anterior traction of 24.5 N were studied before and after ACL transection. Muscular fiber
length variation was obtained by ultrasonomicrometry and ATT by video recordings at the beginning, during, and at the end
of the movement. Square pulses of 0.2 ms with 5 V were applied in trains of 500, 100, and 20 ms simultaneously to both the
quadriceps and hamstrings before and immediately after traction.
Results
Electric stimulation of ACL-deficient knees normalized muscular strain to values of control knees. An increased resistance
to muscular lengthening was observed in stimulated knees. Stimulation before traction maintained similar ATT than control
knees during the subsequent traction.
Discussion
Electric muscular stimulation in the ACL-deficient knee provoked periarticular muscle contraction, controlling ATT when time-adjusted
stimulus (before traction) was used. This suggested that artificially inducing the muscular response could help to control
anterior knee laxity after ACL injury.
Keywords Anterior cruciate ligament - Muscular stimulation - Stabilization