Quadriceps neural alterations in anterior cruciate ligament reconstructed patients: A 6-month longitudinal investigation

A. S. Lepley, P. A. Gribble, A. C. Thomas, M. A. Tevald, D. H. Sohn, B. G. Pietrosimone

Research output: Contribution to journalArticlepeer-review

137 Scopus citations


The purpose of this investigation was to evaluate differences in quadriceps corticospinal excitability, spinal-reflexive excitability, strength, and voluntary activation before, 2 weeks post and 6 months post-anterior cruciate ligament reconstruction (ACLr). This longitudinal, case-control investigation examined 20 patients scheduled for ACLr (11 females, 9 males; age: 20.9±4.4years; height:172.4±7.5cm; weight:76.2±11.8kg) and 20 healthy controls (11 females, 9 males; age:21.7±3.7 years; height: 173.7±9.9cm; weight: 76.1±19.7kg). Maximal voluntary isometric contractions (MVIC), central activation ratio (CAR), normalized Hoffmann spinal reflexes, active motor threshold (AMT), and normalized motor-evoked potential (MEP) amplitudes at 120% of AMT were measured in the quadriceps muscle at the specific time points. ACLr patients demonstrated bilateral reductions in spinal-reflexive excitability compared with controls before surgery (P=0.02) and 2 weeks post-surgery (P≤0.001). ACLr patients demonstrated higher AMT at 6 months post-surgery (P≤0.001) in both limbs. No MEP differences were detected. Quadriceps MVIC and CAR were lower in both limbs of the ACLr group before surgery and 6 months post-surgery (P≤0.05) compared with controls. Diminished excitability of spinal-reflexive and corticospinal pathways are present at different times following ACLr and occur in combination with clinical deficits in quadriceps strength and activation. Early rehabilitation strategies targeting spinal-reflexive excitability may help improve postoperative outcomes, while later-stage rehabilitation may benefit from therapeutic techniques aimed at improving corticospinal excitability.

Original languageEnglish
Pages (from-to)828-839
Number of pages12
JournalScandinavian Journal of Medicine and Science in Sports
Issue number6
StatePublished - Dec 2015

Bibliographical note

Publisher Copyright:
© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.


  • Knee injury
  • Muscle inhibition
  • Neuromuscular function
  • Transcranial magnetic stimulation

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation


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