Hamstrings Stiffness and Landing Biomechanics Linked to Anterior Cruciate Ligament Loading

Abstract

Context: Greater hamstrings stiffness is associated with less anterior tibial translation during controlled perturbations. However, it is unclear how hamstrings stiffness influences anterior cruciate ligament (ACL) loading mechanisms during dynamic tasks.Objective: To evaluate the influence of hamstrings stiffness on landing biomechanics related to ACL injury.Design: Cross-sectional study. Setting: Research laboratory. Patients or Other Participants: A total of 36 healthy, physically active volunteers (18 men, 18 women; age ¼ 23 6 3 years, height ¼ 1.8 6 0.1 m, mass ¼ 73.1 6 16.6 kg).Intervention(s): Hamstrings stiffness was quantified via the damped oscillatory technique. Three-dimensional lower extremity kinematics and kinetics were captured during a doublelegged jump-landing task via a 3-dimensional motion-capture system interfaced with a force plate. Landing biomechanics were compared between groups displaying high and low hamstrings stiffness via independent-samples t tests.Main Outcome Measure(s): Hamstrings stiffness was normalized to body mass (N/mÁkg À1 ). Peak knee-flexion and -valgus angles, vertical and posterior ground reaction forces, anterior tibial shear force, internal knee-extension and -varus moments, and knee-flexion angles at the instants of each peak kinetic variable were identified during the landing task. Forces were normalized to body weight, whereas moments were normalized to the product of weight and height.Results: Internal knee-varus moment was 3.6 times smaller in the high-stiffness group (t 22 ¼ 2.221, P ¼ .02). A trend in the data also indicated that peak anterior tibial shear force was 1.1 times smaller in the high-stiffness group (t 22 ¼ 1.537, P ¼ .07). The high-stiffness group also demonstrated greater knee flexion at the instants of peak anterior tibial shear force and internal knee-extension and -varus moments (t 22 range ¼ 1.729-2.224, P , .05).Conclusions: Greater hamstrings stiffness was associated with landing biomechanics consistent with less ACL loading and injury risk. Musculotendinous stiffness is a modifiable characteristic; thus exercises that enhance hamstrings stiffness may be important additions to ACL injury-prevention programs.Key Words: viscoelastic, musculotendinous, valgus, anterior tibial shear force Key PointsIndividuals with greater hamstrings stiffness displayed more favorable landing biomechanics for anterior cruciate ligament (ACL) loading and injury risk than individuals with less hamstrings stiffness as evidenced by smaller frontalplane knee moments and a more-flexed knee at the instants of critical biomechanical knee events. Greater hamstrings stiffness was associated with smaller anterior tibial shear forces. A high level of hamstrings stiffness may limit ACL injury risk by limiting frontal-and sagittal-plane ACL-loading mechanisms.

Jump-Landing Biomechanics and Knee-Laxity Change Across the Menstrual Cycle in Women With Anterior Cruciate Ligament Reconstruction

“…48 However, this omission most likely had a negligible effect on the results of our study given the repeated-measures design.…”

“…The biomechanical model used in this study has been shown to provide a valid assessment of peak lower extremity kinetics even with the foot segment omitted. 48 The following bony landmarks defined the segment endpoints and joint centers of the lower extremity segments: medial and lateral femoral condyles, medial and lateral malleoli, and left and right anteriorsuperior iliac spines. The malleoli defined the ankle joint center, and the femoral condyles defined the knee joint center.…”

ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION & THE HAMSTRINGS Implications for injury prevention & rehabilitation

“…Neuromuscular training is a process which involves learning how to move more effectively (Mandelbaum et al, 2005), while neuromuscular control involves the activation of dynamic restraints surrounding a joint in response to sensory stimuli (Griffin et al, 2000;. This control requires proficient communication between the afferent and efferent pathways of the central nervous system (Blackburn et al, 2013;Ford et al, 2005). Many intervention studies have employed neuromuscular training programs in an attempt to reduce ACL injury risk (Heidt, Sweeterman, Carlonas, Traub, & Tekulve, 2000;Mandelbaum et al, 2005;Myklebust et al, 2003).…”

“…As major flexors of the knee, the hamstrings provide the greatest active restraint against anterior tibial translation shear forces (Blackburn, Norcross, Cannon, & Zinder, 2013;Ford, Myer, Toms, & Hewett, 2005;Myer et al, 2009).…”

“…As major flexors of the knee, the hamstrings provide the greatest active restraint against anterior tibial translation shear forces (Blackburn et al, 2013;Ford et al, 2005;Myer et al, 2009). The ACL runs from the posteromedial aspect of the lateral femoral condyle in the intercondylar notch to the anterior intercondylar area of the tibia as a collection of individual fascicles (Alentorn-Geli et al, 2009a;Arnoczky, 1983;Levangie & Norkin, 2011;Tengman et al, 2014).…”