Commonly used clinical criteria following ACL reconstruction including time from surgery and isokinetic limb symmetry thresholds are not associated with between-limb loading deficits during running

Phys Ther Sport. 2021 May:49:236-242. doi: 10.1016/j.ptsp.2021.03.010. Epub 2021 Mar 23.


Objectives: We included objective measures of gait and functional assessments to examine their associations in athletes who had recently commenced running after ACL reconstruction.

Design: Cross-sectional.

Setting: Sports medicine.

Participants: 65 male athletes with a history of ACL reconstruction.

Main outcome measures: Time from surgery, isokinetic knee extension/flexion strength (60°/s), and peak vertical ground reaction force (pVGRF) measured during running using an instrumented treadmill. We also investigated if a range of recommended isokinetic thresholds (e.g. > 70% quadriceps limb symmetry index) affected the magnitude of pVGRF asymmetry during running.

Results: There were significant relationships between quadriceps (r = 0.50) and hamstrings (r = 0.46) peak torque and pVGRF. Quadriceps peak torque explained a quarter of the variance in pVGRF (R2 = 0.24; p < 0.001). There was no association was between running pVGRF and time from surgery. Between-group differences in running pVGRF LSI% were trivial (d < 0.20) for all quadriceps and hamstring peak torque LSI thresholds.

Conclusions: Current clinical criteria including time from surgery and isokinetic strength limb symmetry thresholds were not associated with lower pVGRF asymmetry measured during running. Quadriceps strength is important, but 'minimum symmetry thresholds' should be used with caution.

Keywords: ACL; Asymmetry; Running.

MeSH terms

  • Adult
  • Anterior Cruciate Ligament / surgery*
  • Anterior Cruciate Ligament Injuries / surgery
  • Anterior Cruciate Ligament Reconstruction / methods*
  • Athletes
  • Cross-Sectional Studies
  • Exercise Test / methods
  • Exercise Therapy
  • Gait Analysis
  • Hamstring Muscles / physiopathology
  • Humans
  • Knee / physiopathology
  • Knee Joint / physiopathology*
  • Male
  • Muscle Strength*
  • Quadriceps Muscle / physiopathology
  • Range of Motion, Articular*
  • Running*
  • Time Factors
  • Torque