Gamma loop dysfunction in the quadriceps femoris of patients who underwent anterior cruciate ligament reconstruction remains bilaterally

Y. Konishi, Y. Aihara, M. Sakai, G. Ogawa, T. Fukubayashi

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    Purpose of this study was to investigate the effects of anterior cruciate ligament (ACL) repair on the γ loop of the bilateral quadriceps femoris (QF). Maximal voluntary contraction (MVC) of knee extension and integrated electromyogram (I-EMG) of vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF) were examined in uninjured and injured limbs of 18 patients and 10 normal subjects, before and after 20-min vibration applied to the QF. Mean percentage changes were calculated as: (pre-vibration value-post-vibration value)/pre-vibration value × 100. Patients were divided into two groups: short-term-group (tested ≤12 months after ACL repair, n=8), long-term-group (tested ≥18 months after ACL repair, n=10). Mean percentage changes of the four groups were compared with those of controls. Results indicated that changes of MVC and I-EMG on the uninjured and injured sides in short-term-group in response to vibration were significantly different from those of controls. There were no significant differences between uninjured sides in long-term and control groups. MVC and I-EMG of VM and RF of injured side in patients in the long-term-group in response to vibration were not different from those of controls. From these results, we concluded that this abnormality of the γ loop in both injured and uninjured sides did not recover despite ACL reconstruction. However, the abnormality in uninjured side might recover ≥18 months after repair.

    Original languageEnglish
    Pages (from-to)393-399
    Number of pages7
    JournalScandinavian Journal of Medicine and Science in Sports
    Issue number4
    Publication statusPublished - 2007 Aug



    • γ loop
    • ACL injury
    • Electromyogram
    • EMG
    • Reflex inhibition
    • Vibration stimulation

    ASJC Scopus subject areas

    • Public Health, Environmental and Occupational Health
    • Physical Therapy, Sports Therapy and Rehabilitation
    • Orthopedics and Sports Medicine

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