Inhibition of knee joint sensory afferents alters covariation across strides between quadriceps muscles during locomotion

Abstract

Sport-related injuries to articular structures often alter the sensory information conveyed by joint structures to the nervous system. However, the role of joint sensory afferents in motor control is still unclear. Here we evaluate the role of knee joint sensory afferents in the control of quadriceps muscles, hypothesizing that such sensory information modulates control strategies that limit patellofemoreal joint loading. We compared locomotor kinematics and muscle activity before and after inhibition of knee sensory afferents by injection of lidocaine into the knee capsule of rats. We evaluated whether this inhibition reduced the strength of correlation between the activity of vastus medialis (VM) and vastus lateralis (VL) both across strides and within each stride, coordination patterns that limit net mediolateral patellofemoral forces. We also evaluated whether this inhibition altered correlations amongst the other quadriceps muscles activity, the time-profiles of individual EMG envelopes, or movement kinematics. Neither the EMG envelopes nor limb kinematics were affected by the inhibition of knee sensory afferents. This perturbation also did not affect the correlations between VM and VL, suggesting that the regulation of patellofemoral joint loading is mediated by different mechanisms. However, inhibition of knee sensory afferents caused a significant reduction in the correlation between vastus intermedius (VI) and both VM and VL across, but not within, strides. Knee joint sensory afferents may therefore modulate the coordination between the vasti muscles but only at coarse time scales. Injuries compromising joint afferents might result in altered muscle coordination, potentially leading to persistent internal joint stresses and strains.

Kinematics but not kinetics alterations to single-leg drop jump movements following a subject-tailored fatiguing protocol suggest an increased risk of ACL injury

“…Considering the observed increase in knee and hip extension at foot contact, interpreting the reduction in vertical GRF upon landing is not trivial. The reduction of vertical GRF impact peak may indicate that the CNS developed protective strategies to reduce joint loading ( 62 – 64 ), potentially mediated by joint ( 65 ) and muscle afferents ( 66 ). These mechanisms may result in a redistribution of force absorption across joints ( 37 ) or in a reduction of joint stiffness ( 40 ), which would cause longer force dissipation with reduced force peak.…”