Evaluation of hamstring muscle strength and morphology after anterior cruciate ligament reconstruction

Yumi Nomura*, R. Kuramochi, T. Fukubayashi

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    56 Citations (Scopus)


    This study aimed to clarify the relationship between knee flexor strength and hamstring muscle morphology after anterior cruciate ligament (ACL) reconstruction using the semitendinosus (ST) tendon and to determine the causative factors of decreased knee flexor muscle strength. Fourteen male and ten female patients who resumed sports activities after surgery participated in the experiment. Isometric knee flexion torque was measured at 30°, 45°, 60°, 90°, and 105° of knee flexion. Magnetic resonance imaging (MRI) was used to calculate ST muscle length and hamstring muscle volume, and to confirm the status of ST tendon regeneration. The correlation between the MRI findings and flexor strength was analyzed. Regenerated ST tendon was confirmed in 21 of the 24 patients, but muscle volume (87.6%) and muscle length (74.5%) of the ST in the operated limb were significantly smaller than those in the normal limb. The percentage of the knee flexion torque of the operated limb compared with that of the normal was apparently lower at 105° (69.1%) and 90° (68.6%) than at 60° (84.4%). Tendon regeneration, ST muscle shortening, and ST muscle atrophy correlated with decreased knee flexion torque. These results indicated that preserving the morphology of the ST muscle-tendon complex is important.

    Original languageEnglish
    Pages (from-to)301-307
    Number of pages7
    JournalScandinavian Journal of Medicine and Science in Sports
    Issue number3
    Publication statusPublished - 2015 Jun 1


    • Anterior cruciate ligament
    • Flexion torque
    • MRI
    • Muscle volume
    • Semitendinosus

    ASJC Scopus subject areas

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


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