title: Muscular reflexes elicited by electrical stimulation of the anterior cruciate ligament in humans.
abstract: Anterior cruciate ligament (ACL)-deficient knees have impaired proprioception, and, although mechanoreceptors have been found in the ACL, the existence of a reflex elicited from these receptors has not been directly demonstrated in humans. In eight patients that underwent knee arthroscopy and had no sign of ACL disease, thin wire electrodes were inserted into the proximal and mid parts of the ACL. Postoperatively, the sensory nerve fibers inside the ACL were stimulated electrically while motor activity in the knee muscles was recorded using electromyography. In seven of the eight patients, a muscular contraction of the semitendinosus muscle could be elicited with stimulus trains consisting of at least two stimuli. The latency was 95 +/- 35 ms. Stimulation during isometric contraction of either extensor or flexor muscles elicited a short, complete inhibition of the muscle activity in the contracting muscles. The latency of the inhibitory responses was 65 +/- 20 ms in the semitendinosus muscle and 70 +/- 15 ms in the rectus femoris muscle.
authors.affiliation: Institute of Medical Physiology, Panum Institute, University of Copenhagen, DK-2200 Copenhagen, Denmark. dyhre@mfi.ku.dk
authors.forename: P
authors.initials: P
authors.lastname: Dyhre-Poulsen
authors.forename: M R
authors.initials: MR
authors.lastname: Krogsgaard
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000294:innervation / Q000502:physiology*; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D009412:Nerve Fibers / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012018:Reflex / Q000502:physiology*