The effect of tibiofemoral joint kinematics on patellofemoral contact pressures under simulated muscle loads

Abstract

Altered patellofemoral joint contact pressures are thought to contribute to patellofemoral joint symptoms. However, little is known about the relationship between tibiofemoral joint kinematics and patellofemoral joint contact pressures. The objective of this paper was to investigate the effect of tibiofemordl joint kinematics on patellofemoral joint pressures using an established in vitro robotic testing experimental setup. Eight cadaveric knee specimens were tested at 0", 30", 60°, 90", and 120" of flexion under an isolated quadriceps load of 400 N and a combined quadricepslhamstrings load of 400 N/200 N. Tibiofemoral joint kinematics were measured by the robot and contact pressures by a TekScan pressure sensor. The isolated quadriceps loading caused anterior translation and internal rotation of the tibia up to 60" of flexion and posterior translation and external rotation of the tibia beyond 60". The co-contraction of the hamstring muscles caused a posterior translation and external rotation of the tibia relative to the motion of the tibia under the quadriceps load. Correspondingly, the contact pressures were elevated significantly at all flexion angles. For example, at 60" of flexion, the hamstrings co-contraction increased the posterior tibial translation by approximately 2.8 mm and external tibial rotation by approximately 3.6". The peak contact pressure increased from 1.4 kO.8 to 1.7? 1.0 MPa, a 15% increase. The elevated contact pressures after hamstrings co-contraction indicates an intrinsic relation between the tibiofemoral joint kinematics and the patellofemoral joint biomechanics. An increase in posterior tibial translation and external rotation is accompanied by an increase in contact pressure in the patellofemoral joint. These results imply that excessive strength conditioning with the hamstring muscles might not be beneficial to the patellofemoral joint. Knee pathology that causes an increase in tibial posterior translation and external rotation might contribute to degeneration of the patellofemoral joint. These results suggest that conservative treatment of posterior cruciate ligament injury should be reconsidered.

Patellofemoral Joint Force and Stress Between a Short- and Long-Step Forward Lunge

“…Firstly, MRI knee kinematic data have shown that during the weight-bearing squat the femur moves and rotates underneath a relatively stationary patella, and that excessive femoral rotation may increase patellofemoral joint stress on the contralateral patellar facets. 10,18,24 Unfortunately, there are no MRI knee kinematic data for performing the lunge. Therefore, it is unknown how much femoral rotation occurs during the lunge and how this rotation varies among healthy individuals and those with pathologies.…”

“…Cadaveric data have demonstrated that increased hamstring activity results in posterior translation of the leg relative to the thigh; for any given knee angle, this effect may result in a decrease in the angle formed between the quadriceps force vector and the patellar tendon force vector, increasing patellofemoral joint force and stress. 18 Unfortunately, the effect of hamstrings force on posterior leg translation is currently unknown.…”

The outcome of hip exercise in patellofemoral pain: A systematic review

“…There is increasing evidence that proximal factors may be associated with the pathogenesis of PFP.Biomechanical studies have shown that excessive femoral internal rotation in weight bearing leads to increased lateral patellar tracking, reduction in patellofemoral contact area (Besier et al, 2008;Huberti and Hayes, 1984;Lee et al, 2003;Li et al, 2004;Salsich and Perman, 2007) and increased lateral patellofemoral joint stress (Souza et al, 2010). This is proposed to lead to change in the patellofemoral joint articular cartilage, overloading the subchondral bone, causing pain .…”

Computational modeling of a dynamic knee simulator

“…The use of a robot arm overcomes these issues [11,12]. In this case, the hip is fixed and the distal tibia is rigidly attached to a robot arm, controlling all six DOF.…”