Nathaniel A. Bates

Kinetic and kinematic differences between first and second landings of a drop vertical jump task: Implications for injury risk assessments

BACKGROUNDnThough the first landing of drop vertical jump task is commonly used to assess biomechanical performance measures that are associated with anterior cruciate ligament injury risk in athletes, the implications of the second landing in this task have largely been ignored. We examined the first and second landings of a drop vertical jump for differences in kinetic and kinematic behaviors at the hip and knee.nnnMETHODSnA cohort of 239 adolescent female basketball athletes (age=13.6 (1.6) years) completed drop vertical jump tasks from an initial height of 31 cm. A three dimensional motion capture system recorded positional data while dual force platforms recorded ground reaction forces for each trial.nnnFINDINGSnThe first landing demonstrated greater hip adduction angle, knee abduction angle, and knee abduction moment than the second landing (P-values<0.028). The second landing demonstrated smaller flexion angles and moments at the hip and knee than the first landing (P-values<0.035). The second landing also demonstrated greater side-to-side asymmetry in hip and knee kinematics and kinetics for both the frontal and sagittal planes (P-values<0.044).nnnINTERPRETATIONnThe results have important implications for the future use of the drop vertical jump as an assessment tool for anterior cruciate ligament injury risk behaviors in adolescent female athletes. The second landing may be a more rigorous task and provides a superior tool to evaluate sagittal plane risk factors than the first landing, which may be better suited to evaluate frontal plane risk factors.

Relative Strain in the Anterior Cruciate Ligament and Medial Collateral Ligament During Simulated Jump Landing and Sidestep Cutting Tasks Implications for Injury Risk

Background: The medial collateral (MCL) and anterior cruciate ligaments (ACL) are, respectively, the primary and secondary ligamentous restraints against knee abduction, which is a component of the valgus collapse often associated with ACL rupture during athletic tasks. Despite this correlation in function, MCL ruptures occur concomitantly in only 20% to 40% of ACL injuries. Hypothesis/Purpose: The purpose of this investigation was to determine how athletic tasks load the knee joint in a manner that could lead to ACL failure without concomitant MCL failure. It was hypothesized that (1) the ACL would provide greater overall contribution to intact knee forces than the MCL during simulated motion tasks and (2) the ACL would show greater relative peak strain compared with the MCL during simulated motion tasks. Study Design: Controlled laboratory study. Methods: A 6-degrees-of-freedom robotic manipulator articulated 18 cadaveric knees through simulations of kinematics recorded from in vivo drop vertical jump and sidestep cutting tasks. Specimens were articulated in the intact-knee and isolated-ligament conditions. After simulation, each ACL and MCL was failed in uniaxial tension along its fiber orientations. Results: During a drop vertical jump simulation, the ACL experienced greater peak strain than the MCL (6.1% vs 0.4%; P < .01). The isolated ACL expressed greater peak anterior force (4.8% vs 0.3% body weight; P < .01), medial force (1.6% vs 0.4% body weight; P < .01), flexion torque (8.4 vs 0.4 N·m; P < .01), abduction torque (2.6 vs 0.3 N·m; P < .01), and adduction torque (0.5 vs 0.0 N·m; P = .03) than the isolated MCL. During failure testing, ACL specimens preferentially loaded in the anteromedial bundle failed at 637 N, while MCL failure occurred at 776 N. Conclusion: During controlled physiologic athletic tasks, the ACL provides greater contributions to knee restraint than the MCL, which is generally unstrained and minimally loaded. Clinical Relevance: Current findings support that multiplanar loading during athletic tasks preferentially loads the ACL over the MCL, leaving the ACL more susceptible to injury. An enhanced understanding of joint loading during in vivo tasks may provide insight that enhances the efficacy of injury prevention protocols.

Timing differences in the generation of ground reaction forces between the initial and secondary landing phases of the drop vertical jump

BACKGROUNDnRapid impulse loads imparted on the lower extremity from ground contact when landing from a jump may contribute to ACL injury prevalence in female athletes. The drop jump and drop landing tasks enacted in the first and second landings of drop vertical jumps, respectively, have been shown to elicit separate neuromechanical responses. We examined the first and second landings of a drop vertical jump for differences in landing phase duration, time to peak force, and rate of force development.nnnMETHODSn239 adolescent female basketball players completed drop vertical jumps from an initial height of 31cm. In-ground force platforms and a three dimensional motion capture system recorded force and positional data for each trial.nnnFINDINGSnBetween the first and second landing, rate of force development experienced no change (P>0.62), landing phase duration decreased (P=0.01), and time to peak ground reaction force increased (P<0.01). Side-by-side asymmetry in rate of force development was not present in either landing (P>0.12).nnnINTERPRETATIONnThe current results have important implications for the future assessment of ACL injury risk behaviors. Rate of force development remained unchanged between first and second landings from equivalent fall height, while time to peak reaction force increased during the second landing. Neither factor was dependent on the total time duration of landing phase, which decreased during the second landing. Shorter time to peak force may increase ligament strain and better represent the abrupt joint loading that is associated with ACL injury risk.

Arthrometric curve-shape variables to assess anterior cruciate ligament deficiency

BACKGROUNDnInstrumented measurement of asymmetry in anterior-posterior knee laxity is commonly used to assess anterior cruciate ligament integrity. Significant advances in arthrometric technology and data visualization have occurred since first generation arthrometers. However, little has changed with regard to diagnostic criteria employed. To our knowledge, no investigations have assessed the shape of laxity curves to diagnose anterior cruciate ligament (ACL) deficiency. We hypothesized that linear stiffness and compliance after positive curve inflection would be more sensitive and specific to anterior cruciate ligament injury than current measures and would require data from the involved limb only.nnnMETHODSnLaxity curves were obtained from 130 knees on 65 subjects (Anterior Cruciate Injured n=15, Controls n=50) using a CompuKT Knee Ligament Arthrometer. Traditional diagnostic variables and novel descriptive curve-shape variables [(1) inflection point, (2) pre- and post-inflection linear stiffness and (3) a modified compliance index based on the post-inflection linear stiffness] were assessed for sensitivity to anterior cruciate ligament deficiency. Statistical interactions were evaluated using 2-by-2 ANOVA.nnnFINDINGSnSignificant interactions (P<0.001) were identified for laxity symmetry, stiffness, compliance index and modified compliance index. Modified compliance index predicted anterior cruciate ligament deficiency with the highest sensitivity (93%) and specificity (100%). For a test performed on a single limb, modified compliance index demonstrated 98% sensitivity and 80% specificity.nnnINTERPRETATIONnThe modified compliance index is a highly sensitive and specific measure to diagnose anterior cruciate ligament deficiency, and may serve as a simple and accurate diagnostic tool for individuals without a healthy contralateral limb.

Letter to the editor: Effect of Sagittal Plane Mechanics on ACL Strain during Jump Landing

We read with great interest the article entitled, “Effect of Sagittal Plane Mechanics on ACL Strain During Jump Landing” by Bakker et al.1 We congratulate the authors for their complex study design that utilized the in sim approach2 that is designed to cross-correlate the complex results of in vivo, in vitro, and in silico research approaches. The published study adds information in regards to potential models of the mechanisms of ACL injury to the body of literature. This article is protected by copyright. All rights reserved

Effect of sagittal plane mechanics on ACL strain during jump landing: EFFECT OF SAGITTAL PLANE

We read with great interest the article entitled, “Effect of Sagittal Plane Mechanics on ACL Strain During Jump Landing” by Bakker et al.1 We congratulate the authors for their complex study design that utilized the in sim approach2 that is designed to cross-correlate the complex results of in vivo, in vitro, and in silico research approaches. The published study adds information in regards to potential models of the mechanisms of ACL injury to the body of literature. This article is protected by copyright. All rights reserved

Correlating knee characteristics and dynamic load to customize gait simulation in vitro

Anterior cruciate ligament (ACL) tears are one of the most common knee injuries, with estimates reaching approximately 250,000 cases in the US per year [1]. In addition, patients treated with surgical reconstruction, or conservatively through rehabilitation and activity modification, have still been shown to be at increased risk of developing osteoarthritis (OA) earlier in life [2]. Researchers suspect that the failure of current ACL repair techniques is their inability to restore native functionality to the knee after injury.© 2013 ASME