Cruciate ligament forces in the human knee during rehabilitation exercises

ACL Strain and Tensile Forces for Weight Bearing and Non—Weight-Bearing Exercises After ACL Reconstruction: A Guide to Exercise Selection

“…57 Toutoungi et al, 57 using a biomechanical model, estimated peak forces applied to the ACL while subjects performed seated isokinetic knee flexion at 60°/s, 180°/s, and 300°/s, and isometric knee flexion exercises at 15°, 30°, 45°, 60°, and 75° of knee flexion. The authors reported that the line of action of the hamstring muscles lay parallel to the tibial plateau at about 90° of knee flexion, so the hamstrings likely unload the ACL during seated resisted knee flexion exer- cises by producing a posteriorly directed force on the proximal end of the tibia.…”

Protocolo de reabilitação para as reconstruções isoladas do ligamento cruzado posterior

“…Rehabilitation protocols prioritize protection of the reconstructed ligament, so as to avoid excessive stress on the graft during the rehabilitation until the graft has become integrated (2) . However, it is not known with any certainty what the safe tensions would be and how much provocation can be allowed during rehabilitation exercises (3) .…”

“…Ranges of 0 to 60º have been used (9,13,14) , while other authors have recommended that this strengthening should be done from 0 to 70º (27) . Dürselen et al (23) demonstrated on cadavers, and other authors (2,33,35) through mathematical models, that in OKC exercises, the quadriceps muscle might diminish the stress on the PCL, especially at the end of the knee extension. Thus, these were the preferred exercises at the start of the rehabilitation process.…”

“…Corroborating this concept, Toutoungi et al (2) found that the effect of axial compression tended to diminish the femorotibial shearing and consequently the stresses generated on the central ligaments.…”

“…When the hamstring muscles are contracted in isolation, i.e. in OKC exercises, the tension on the PCL is increased because of the traction force of these muscles on the tibia (2,26,34,35) . Shelburne and Pandy (26) demonstrated that the hamstrings are responsible for constant posterior tension and that as the knee flexion increases, the forces favoring anteriorization of the tibia diminish.…”