Progressive adaptation of whole-limb kinematics after peripheral nerve injury

• Published in: Biology open Vol. 7; no. 8
• Main Authors: Chang, Young-Hui, Housley, Stephen N, Hart, Kerry S, Nardelli, Paul, Nichols, Richard T, Maas, Huub, Cope, Timothy C
• Format: Journal Article
• Language: English
• Published: England The Company of Biologists Ltd 15-08-2018; The Company of Biologists
• Subjects: Adaptation; Ankle; Functional recovery; Hypotheses; Injuries; Joints (anatomy); Kinematics; Locomotor compensation; Muscle paralysis; Muscles; Peripheral nerves; Recovery; Recovery of function; Locomotor compensation; Muscle paralysis; Functional recovery
• ISSN: 2046-6390; 2046-6390
• DOI: 10.1242/bio.028852

The ability to recover purposeful movement soon after debilitating neuromuscular injury is essential to animal survival. Various neural and mechanical mechanisms exist to preserve whole-limb kinematics despite exhibiting long-term deficits of individual joints following peripheral nerve injury. However, it is unclear whether functionally relevant whole-limb movement is acutely conserved following injury. Therefore, the objective of this longitudinal study of the injury response from four individual cats was to test the hypothesis that whole-limb length is conserved following localized nerve injury of ankle extensors in cats with intact nervous systems. The primary finding of our study was that whole-limb kinematics during walking was not immediately preserved following peripheral nerve injuries that paralyzed subsets of ankle extensor muscles. Instead, whole-limb kinematics recovered gradually over multiple weeks, despite having the mechanical capacity of injury-spared muscles across all joints to achieve immediate functional recovery. The time taken to achieve complete recovery of whole-limb kinematics is consistent with an underlying process that relies on neuromuscular adaptation. Importantly, the gradual recovery of ankle joint kinematics remained incomplete, discontinuing once whole-limb kinematics had fully recovered. These findings support the hypothesis that a whole-limb representation of healthy limb function guides a locomotor compensation strategy after neuromuscular injury that arrests progressive changes in the joint kinematics once whole-limb kinematics is regained.