Effect of varying hamstring tension on anterior cruciate ligament strain during in vitro impulsive knee flexion and compression loading

Department of Mechanical Engineering, Vanderbilt University, VU Station B 351592, Nashville, TN 37235, USA.
The Journal of Bone and Joint Surgery (Impact Factor: 4.31). 05/2008; 90(4):815-23. DOI: 10.2106/JBJS.F.01352
Source: PubMed

ABSTRACT The hamstring muscles are well positioned to limit both anterior tibial translation and anterior cruciate ligament strain during the knee flexion phase of a jump landing. We hypothesized that systematically increasing or decreasing hamstring tension during the knee flexion phase of a simulated jump landing would significantly affect peak relative strain in the anterior cruciate ligament.
Ten cadaveric knees from four male and six female donors (mean age [and standard deviation] at the time of death, 60.3 +/- 23.6 years) were mounted in a custom fixture to initially position the specimen in 25 degrees of knee flexion and simulate axial impulsive loading averaging 1700 N to cause an increase in knee flexion. Quadriceps, hamstring, and gastrocnemius muscle forces were simulated with use of pretensioned linear springs, with the tension in the hamstrings arranged to be increased, held constant, decreased, at "baseline," or absent during knee flexion. Impulsive loading applied along the tibia and femur was monitored with use of triaxial load transducers, while uniaxial load cells monitored quadriceps and medial and lateral hamstring forces. Relative strain in the anterior cruciate ligament was measured with use of a differential variable reluctance transducer, and tibiofemoral kinematics were measured optoelectronically. For each specimen, anterior cruciate ligament strains were recorded over eighty impact trials: ten preconditioning trials, ten "baseline" trials involving decreasing hamstring tension performed before and after three sets of ten trials conducted with increasing hamstring tension, constant hamstring tension, or no hamstring tension. Peak relative strains in the anterior cruciate ligament were normalized for comparison across specimens.
Increasing hamstring force during the knee flexion landing phase decreased the peak relative strain in the anterior cruciate ligament by >70% compared with the baseline condition (p = 0.005). Neither a constant hamstring muscle force nor the absence of a hamstring force significantly changed the peak strain in the anterior cruciate ligament relative to the baseline condition.
Increasing hamstring muscle force during the knee flexion phase of a simulated jump landing significantly reduces the peak relative strain in the anterior cruciate ligament in vitro.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Anterior cruciate ligament injury is a common and potentially catastrophic knee joint injury, afflicting a large number of males and particularly females annually. Apart from the obvious acute injury events, it also presents with significant long-term morbidities, where osteoarthritis is a frequent and debilitative outcome. With these facts in mind, a vast amount of research has been undertaken over the past fifty years geared towards characterizing the structural and mechanical behaviors of the native ACL tissue under various external load applications. While these efforts have afforded important insights, both in terms of understanding and treating ACL injuries; injury rates, their well-established sex-based disparity and long-term sequelae have endured. In reviewing the vast amount of literature conducted to date in this area, the current paper identifies important knowledge gaps that appear to contribute directly to this long-standing clinical dilemma. In particular, the following limitations remain. First, minimal data exist that accurately describe native ACL mechanics under the extreme loading rates synonymous with actual injury. Second, current ACL mechanical data are typically derived from isolated and oversimplified strain estimates that fail to adequately capture the true 3-D mechanical response of this anatomically complex structure. Third, graft tissues commonly chosen to reconstruct the ruptured ACL are mechanically flawed, being over-designed for stiffness compared to the native tissue. The net result is an increased risk of re-rupture and a modified and potentially hazardous joint contact profile. These major limitations appear to warrant explicit research attention moving forward in order to successfully maintain/restore optimal knee joint function and long-term life quality in a large number otherwise healthy individuals.
    Journal of Biomechanical Engineering 12/2014; 137(2). DOI:10.1115/1.4029278 · 1.75 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study aimed to investigate whether treadmill versus overground soccer match simulations have similar effects on knee joint mechanics during side cutting. Nineteen male recreational soccer players completed a 45 min treadmill and overground match simulation. Heart rate (HR) and rating of perceived exertion (RPE) were recorded every 5 min. Prior to exercise (time 0 min), at 'half-time' (time 45 min) and 15 min post exercise (time 60 min) participants performed five trials of 45° side cutting manoeuvres. Knee abduction moments and knee extension angles were analysed using two-way repeated measures ANOVA (α = 0.05). Physiological responses were significantly greater during the overground (HR 160 ± 7 beats • min -1 ; RPE 15 ± 2) than treadmill simulation (HR 142 ± 5 beats • min -1 ; RPE 12 ± 2). Knee extension angles significantly increased over time and were more extended at time 60 min compared with time 0 min and time 45 min. No significant differences in knee abduction moments were observed. Although knee abduction moments were not altered over time during both simulations, passive rest during half-time induced changes in knee angles that may have implications for ACL injury risk.
    Journal of Sports Sciences 01/2015; DOI:10.1080/02640414.2014.990491 · 2.10 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Investigators use in vitro joint simulations to invasively study the biomechanical behaviors of the anterior cruciate ligament. The aims of these simulations are to replicate physiologic conditions, but multiple mechanisms can be used to drive in vitro motions, which may influence biomechanical outcomes. The objective of this review was to examine, summarize, and compare biomechanical evidence related to anterior cruciate ligament function from in vitro simulations of knee motion. A systematic review was conducted (2004 to 2013) in Scopus, PubMed/Medline, and SPORTDiscus to identify peer-reviewed studies that reported kinematic and kinetic outcomes from in vitro simulations of physiologic or clinical tasks at the knee. Inclusion criteria for relevant studies were articles published in English that reported on whole-ligament anterior cruciate ligament mechanics during the in vitro simulation of physiologic or clinical motions on cadaveric knees that were unaltered outside of the anterior-cruciate-ligament-intact, -deficient, and -reconstructed conditions. A meta-analysis was performed to synthesize biomechanical differences between the anterior-cruciate-ligament-intact and reconstructed conditions. 77 studies met our inclusion/exclusion criteria and were reviewed. Combined joint rotations have the greatest impact on anterior cruciate ligament loads, but the magnitude by which individual kinematic degrees of freedom contribute to ligament loading during in vitro simulations is technique-dependent. Biomechanical data collected in prospective, longitudinal studies corresponds better with robotic-manipulator simulations than mechanical-impact simulations. Robotic simulation indicated that the ability to restore intact anterior cruciate ligament mechanics with anterior cruciate ligament reconstructions was dependent on loading condition and degree of freedom examined. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Clinical biomechanics (Bristol, Avon) 01/2015; 30(1):1-13. DOI:10.1016/j.clinbiomech.2014.12.006 · 1.88 Impact Factor

Full-text (2 Sources)

Available from
May 31, 2014