Increasing pre-activation of the quadriceps muscle protects the anterior cruciate ligament during the landing phase of a jump: An in vitro simulation

Javad Hashemi, Ryan Breighner, Taek Hyun Jang, Naveen Chandrashekar, Stephen Ekwaro-Osire, James R. Slauterbeck

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

We hypothesize that application of an unopposed quadriceps force coupled with an impulsive ground reaction force may induce anterior cruciate ligament (ACL) injury. This situation is similar to landing from a jump if only the quadriceps muscle is active; an unlikely but presumably dangerous circumstance. The purpose of this study was to test our hypothesis using in vitro simulation of jump landing. A jump-landing simulator was utilized. Nine cadaveric knees were tested at an initial flexion angle of 20°. Each ACL was instrumented with a differential variable reluctance transducer (DVRT). Quadriceps pre-activation forces (QPFs) ranging from 25. N to 700. N were applied to each knee, followed by an impulsive ground reaction force produced by a carriage-mounted drop weight (7. kg) that impulsively drove the ankle upward. ACL strain was monitored before landing due to application of QPF (pre-activation strain) and at landing due to application of the ground reaction force (landing strain). No ACLs were injured. Pre-activation strains exhibited a positive correlation with QPF (r=0.674, p<0.001) while landing strains showed a negative correlation (r=- 0.235, p=0.032). Total ACL strain (pre-activation. +. landing strain) showed no correlation with QPF (r=0.023, p=0.428). Our findings indicate that elevated QPF increases pre-activation strain but reduces the landing strain and is therefore protective post-landing. Overall, there is a complete lack of correlation between "total" ACL strain and QPF suggesting that the total strain in the ACL is independent of the QPF under the simulated conditions.

Original languageEnglish
Pages (from-to)235-241
Number of pages7
JournalKnee
Volume17
Issue number3
DOIs
StatePublished - Jun 2010

Keywords

  • ACL
  • ACL injury mechanism
  • ACL strain
  • Anterior cruciate ligament
  • In vitro simulation
  • Quadriceps

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