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Abstract Presented at the 29th Annual Meeting of the Arthroscopy Association of North America| Volume 26, ISSUE 6, SUPPLEMENT , e21-e22, June 01, 2010

Fatigue Mediated Alteration of Knee Proprioception in the Adolescent Athlete: An Implication for Sports Related Injuries (SS-43)

      Introduction

      Knee injuries generally occur late in the course of athletic play, suggesting that fatigue may contribute to altered neuromuscular control. The present study aims to investigate the effect of whole body fatigue on knee joint proprioception.

      Methods

      This was an IRB approved, prospective study, with data gathered on thirty-six healthy volunteers. All participants were male, healthy (high school) students with ages between 15 to 18 years (average 16 years) with no history of any neuromuscular disorders or lower limb injuries. Data regarding proprioception was measured with the Biometrics Electrogoniometer, Model ADU301. The Electrogoniometer was secured to the subject's dominant leg. Each subject was then verbally instructed to squat to a specific angle. Once the desired angle was reached, the subject was instructed to hold the angle for 3-5 seconds and then to return to a standing position. From the standing position, subject was asked to replicate the angle previously positioned. The protocol was carried out for a knee flexion range between 10 degree and 60 degrees at 5 degree intervals, where these target angles were chosen in a randomized order for each subject. Measurements were taken before and after a reproducible fatigue protocol. “Proprioceptive error” was defined as the achieved angle, minus the target angle. Proprioceptive error was evaluated in a two-way repeated-measures ANOVA, examining the effect of fatigue state and target angle. Alpha=0.05 for main effects, alpha=0.1 for interactive effects, and post-hoc Fishers LSD tests were performed at alpha=0.05 for all significant effects.

      Results

      There was a significant effect of target angle on proprioceptive error (p<0.001); subjects consistently overshot the target angle at lower target angles. Proprioceptive error was significantly greater (p<0.001) in the fatigued state. There was a significant target angle/fatigue interaction (p=0.071); post-fatigue errors were significantly greater than pre-fatigue errors at target angles of 10-30, and 45-50 degrees.

      Conclusion

      Study subjects demonstrated statistically significant worsening of proprioception abilities with fatigue when measured in a closed chain, double leg stance, i.e., a functionally relevant position. Our study suggests that a fatigue mediated alteration in proprioception is a cause for an altered ability of body to dynamically stabilize the knee joint suggesting an increased incidence of sports related injuries with fatigue. This is particularly evident at the knee flexion angles that generally correlate with the risk of non-contact ACL injury, namely less than 30 degrees of knee flexion.