Mechanoreceptors in the ACL

Abstract

Proprioception is defined by Sherrington as cumulative neural inputs originating from joints, tendons, muscles, and associated deep tissue proprioceptors, which project to the central nervous system for processing stimuli and ultimately results in regulation of reflexes and motor control. Several anatomical and electrophysiological studies have clarified the significance of mechanoreceptors in the anterior cruciate ligament (ACL). Mechanical stimuli applied to mechanoreceptors in the ACL are converted to action potential and transferred to the cerebrum, processing all the peripheral inputs to sense joint position, detect movement and acceleration, and control voluntary movements. In ACL deficiency, impairment of proprioception is indicated by knee proprioception tests, such as reproduction of passive positioning and threshold to detect passive motion. However, it is controversial whether and when impaired proprioception associated with ACL deficiency can be recovered to normal levels following ACL reconstruction. Moreover, there is no consensus on the choice of optimal surgical method or rehabilitation program for improvement of impaired proprioception. To enable full recovery of proprioceptive function in ACL deficiency, further research on mechanoreceptors and proprioception is necessary to clarify these issues.