title: Symmetry tensiomyographic neuromuscular response after chronic anterior cruciate ligament (ACL) reconstruction.
abstract: OBJECTIVE
  Quadriceps muscle weakness is common following anterior cruciate ligament (ACL) reconstruction. Tensiomyography is a recent method to assess muscle strength, and one that also enables evaluation of individual muscles. The purpose of this study was to evaluate motor unit recruitment and investigate the effects on mechanical and contractile characteristics of the quadriceps and hamstring muscles after chronic ACL reconstruction.
  
  
  METHODS
  This study recruited 20 participants: three males and seven females at 24 months after ACL reconstruction, and three males and seven females with no history of knee injury (control group). All participants underwent tensiomyographic assessment of each thigh muscle, bilaterally, to measure maximal displacement, delay time, contraction time, sustained time, and half-relaxation time. The following muscles were evaluated: vastus medialis, vastus lateralis, rectus femoris, semitendinosus, and biceps femoris. Mean normalized muscle peak torque, mean normalized maximum work done, mean angle to peak torque, and mean time to peak torque based on isokinetic peak torque measurements were calculated in both groups.
  
  
  RESULTS
  Maximal displacement of the vastus medialis on the ACL reconstruction side was significantly higher than for the non-ACL reconstruction side and for the control group (p = 0.026). Half-relaxation time for the vastus medialis and biceps femoris was significantly higher for both the ACLR and non-ACLR sides compared with the control group (p = 0.001). There were also significant differences in symmetry in the vastus medialis and biceps femoris when comparing results between the ACL reconstruction group and the control group (p = 0.034, p = 0.043, respectively).
  
  
  CONCLUSIONS
  The presence of strength and symmetry deficits in the vastus medialis and biceps femoris suggests the need for long-term post-operative training following ACL reconstruction. There are clinical relevant improvements of muscle response and velocity as well as muscle strength in patients with chronic ACLR.
  
  
  METHODS
  II.
authors.affiliation: Division of Sport Rehabilitation, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan. norimmi@hiroshima-u.ac.jp.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Maeda
authors.affiliation: Division of Sport Rehabilitation, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Urabe
authors.affiliation: Division of Sport Rehabilitation, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan.
authors.forename: Syogo
authors.initials: S
authors.lastname: Tsutsumi
authors.affiliation: Division of Sport Rehabilitation, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan.
authors.forename: Hironori
authors.initials: H
authors.lastname: Fujishita
authors.affiliation: Division of Sport Rehabilitation, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Numano
authors.affiliation: Division of Sport Rehabilitation, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Takeuchi
authors.affiliation: Department of Sports Medical Center, Hiroshima University, Hiroshima, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Hirata
authors.affiliation: Department of Rehabilitation, Hiroshima University Hospital, Hiroshima, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Mikami
authors.affiliation: Department of Rehabilitation, Hiroshima University Hospital, Hiroshima, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kimura
mesh_terms: D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries / Q000601:surgery*; D059549:Anterior Cruciate Ligament Reconstruction; D003430:Cross-Sectional Studies; D005260:Female; D000070633:Hamstring Muscles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D018908:Muscle Weakness / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D009213:Myography / Q000379:methods; D011183:Postoperative Complications / Q000175:diagnosis / Q000503:physiopathology; D052097:Quadriceps Muscle / Q000503:physiopathology*; D016896:Treatment Outcome; D055815:Young Adult
keywords: Anterior cruciate ligament; Muscle strength; Tensiomyography; Time to peak torque