Abnormal coupling of knee and hip moments during maximal exertions in persons with cerebral palsy

Abstract

The motions of lower-limb extension, adduction, and internal rotation are frequently coupled in persons with cerebral palsy (CP) and are commonly referred to as an extension synergy. However, the underlying joint moments that give rise to these coupled motions are not well understood. We hypothesized that maximal voluntary exertions in a direction of one component of a synergy (e.g., hip extension) would result in the concurrent presence of other components of the synergy in subjects with CP but not in control subjects. To test this hypothesis, we measured three-dimensional moments about the hip and knee as nine subjects with spastic CP and six control subjects performed maximal isometric exertions of the hip and knee flexors and extensors. During maximal hip extension exertions, control subjects simultaneously generated a knee flexion moment, whereas CP subjects generated a knee extension moment (P < 0.05) and a larger hip internal rotation moment than did controls (P < 0.05). During maximal knee extension exertions, control subjects generated a hip flexion moment, whereas CP subjects generated a hip extension moment (P < 0.05). The patterns of joint moments generated by CP subjects are consistent with an extension synergy and may underlie the coupled motion patterns of the lower extremity in such persons.

Backward walking treadmill therapy can improve walking ability in children with spastic cerebral palsy

“…Individuals with CP show an extension pattern because the supraspinal inputs may fail to properly integrate with spinal control systems (Thelen et al, 2003). It is possible that activation of existing spinal and supraspinal pattern generators through the BW training can occur (Schindl et al, 2000).…”

Evidence of Abnormal Lower-Limb Torque Coupling After Stroke

“…20 In light of the abnormal gait patterns involving the hip frontal plane and knee sagittal plane kinematics after stroke, our data suggest that it is likely that poststroke gait impairments can be attributed to the individual hip, knee, and ankle weakness, as well as the observed abnormal within-and across-joint torque patterns. Whereas similar experimental set-ups have been used in lower 21 extremity studies, it can be argued that the observed torque couplings may be attributed to the intrinsic design of our experimental set-up. In this case, one would expect the "set-up" effect to be independent of group (control versus stroke).…”

“…This crossover behavior by a minority of the control participants has been observed in data derived from a number of earlier investigations of across-joint coupling in the neurologically impaired populations. 9,21 Others have suggested that abnormal torque coupling in stroke population may be caused by the exploitation of lower-level neural circuits, such as the bulbospinal tracts, circuitry that also present in healthy controls. 22 Given that the task is volitional, it is conceivable that some control subjects can activate these pathways and hence present stroke-like behaviors.…”

“…Indeed, torque-coupling studies on stroke subjects and other neurologically diseased states have found that extension coupling is more prevalent than flexion coupling. 21,23 Although selective weakness may have contributed to the decrease in achievable torque space at the hip after stroke, it does not explain the observed hip/knee-coupling. Although some researchers presume that torque coupling is predominantly due to abnormal neural coupling between motorneuron pools, 24 Lum et al propose that torque couplings are a manifestation of strength imbalances.…”

The impact of strength training on skeletal muscle morphology and architecture in children and adolescents with spastic cerebral palsy: A systematic review

“…Microscopically, sarcomeres are longer and extracellular matrix composition is different to TD muscle (Smith, Lee, Ward, Chambers, & Lieber, 2011). These specific musculotendinous adaptations in individuals with CP begin to occur within the first five years of life (Barber et al, 2011;Gough & Shortland, 2012;Willerslev-Olsen, Lorentzen, Sinkjaer, & Nielsen, 2013) and are likely to contribute to reduced muscle strength and power compared to TD individuals (Dallmeijer et al, 2015;Nooijen et al, 2014;Thelen, Riewald, Asakawa, Sanger, & Delp, 2003;Wiley & Damiano, 1998;Yanci et al, 2016) and gradual decline in functional ability throughout adulthood (Bottos, Feliciangeli, Sciuto, Gericke, & Vianello, 2001).…”