Viability of shear wave elastography to predict mechanical/ultimate failure in the anterolateral and medial collateral ligaments of the knee.

The purpose of this study was (1) to determine the utility of shear wave elastography as a predictor for the mechanical failure of superficial knee ligaments and (2) to determine the viability of shear wave elastography to assess injury risk potential. Our hypothesis was that shear wave elastography measurements of the anterolateral ligament and medial collateral ligament would directly correlate with the material properties and the mechanical failure of the ligament, serving as a prognostic measurement for injury risk. 8 cadaveric specimens were acquired, and tissue stiffness for the anterolateral ligament and medial collateral ligament were evaluated with shear wave elastography. The anterolateral ligament and medial collateral ligament were dissected and isolated for unilateral mechanical failure testing. Ultimate failure testing was performed at 100 % strain per second after 50 cycles of 3 % strain viscoelastic conditioning. Each specimen was assessed for load, displacement, and surface strain throughout failure testing. Rate of force, rate of strain development, and Young's modulus were calculated from these variables. Shear wave elastography stiffness for the anterolateral ligament correlated with mean longitudinal anterolateral ligament strain at failure (R2 = 0.853; P<0.05). Medial collateral ligament shear wave elastography calculated modulus was significantly greater than the anterolateral ligament shear wave elastography calculated modulus. Shear wave elastography currently offers limited reliability in the prediction of mechanical performance of superficial knee ligaments. The utility of shear wave elastography assessment for injury risk potential remains undetermined.

Ligament Strain Response Between Lower Extremity Contralateral Pairs During In Vitro Landing Simulation.

BACKGROUND: Limb asymmetries, as determined through in vivo biomechanical measures, are known risk factors for anterior cruciate ligament (ACL) injury. Previous cadaveric studies have shown a lack of significant differences in ligament strain between contralateral lower extremities when identical kinematics were simulated on specimens. Recent methodological developments have applied in vivo knee kinetics to exert landing forces on cadaveric lower extremities to mimic ACL injury events, but it is unknown whether contralateral limbs fail in a consistent manner during impact simulator testing. HYPOTHESIS: It was hypothesized that contralateral lower extremities would not exhibit side-to-side differences in ligament strains. Furthermore, it was hypothesized that failure loads and failure locations would be independent of limb dominance. STUDY DESIGN: Controlled laboratory study. METHODS: Fourteen pairs of cadaveric lower extremities were obtained from an anatomic donations program (8 female, 6 male; mean ± SD: age, 41.7 ± 8.1 years; mass, 86.8 ± 27.0 kg; body mass index, 29.4 ± 9.0 kg/m2). A mechanical impact simulator was used to re-create the impulse ground-reaction force generated during an in vivo landing task. Ligament strains were recorded by differential variable force transducers implanted on the ACL and medial collateral ligament (MCL). RESULTS: No significant differences were observed in peak ACL or peak MCL strain for 5 loading conditions. Fisher exact tests of independence revealed that limb dominance was independent of both load at failure and failure location. CONCLUSION: There were no significant differences in ACL and MCL strain values between limb sides during in vitro impact simulation testing. This finding indicates that limb dominance does not influence the failure threshold of the ACL, since there was no significant difference in failure strains. The functional mechanics of the ACL are comparable between contralateral pairs from the same healthy specimen. CLINICAL RELEVANCE: Injury mechanisms and intra-articular mechanics cannot be ethically studied in an in vivo setting. The current study provides additional insight into limb asymmetry that is observed among athletes in clinical sports medicine settings.

INTER- AND INTRA-RATER RELIABILITY OF PERFORMANCE MEASURES COLLECTED WITH A SINGLE-CAMERA MOTION ANALYSIS SYSTEM.

BACKGROUND: Previous reliability investigations of single-camera three dimensional (3D) motion analysis systems have reported mixed results. PURPOSE: The purpose of the current study was to determine the intra- and inter-rater reliability of a single-camera 3D motion analysis system for subject standing height, vertical jump height, and broad jump length. STUDY DESIGN: Experimental in vivo reliability study. PARTICIPANTS: Twelve subjects (age 20.6 ± 4.9 years) from a cohort that included high school to adult athletes who participated in sports at a recreational or competitive level entered and completed the study. Performance measurements were collected by a single-camera 3D motion analysis system and two human testers for standard clinical techniques. Inter- and intra-class correlation coefficients (ICC (2,k), ICC (2,1)) were determined. RESULT: Intra-tester and inter-tester reliability were excellent (ICC ≥ 0.935) for single-camera system measured variables. Single-camera system measurements were slightly more reliable than clinical measurements for intra-tester ratings (ICC difference 0.020) for the standing broad jump. Single-camera system measurements were slightly less reliable than clinical measures for both intra- and inter-specimen standing height (mean ICC difference 0.003 and 0.043, respectively) and vertical jump height (mean ICC difference 0.017 and 0.036, respectively). CONCLUSIONS: The excellent reliability and previously demonstrated validity of the single-camera system along the anterior-posterior axis indicates that single-camera motion analysis may be a valid surrogate for clinically accepted manual measurements of performance in the horizontal plane. However, this single-camera 3D motion analysis system is likewise reliable, but inaccurate, for vertically oriented performance measurements. LEVEL OF EVIDENCE: 2b.

VALIDITY OF ATHLETIC TASK PERFORMANCE MEASURES COLLECTED WITH A SINGLE-CAMERA MOTION ANALYSIS SYSTEM AS COMPARED TO STANDARD CLINICAL MEASUREMENTS.

BACKGROUND: Previous investigations of single-camera 3D motion analysis camera systems validity have yielded mixed results for clinical applications. PURPOSE: The purpose of the current study was to determine the validity of a single-camera 3D motion analysis system for subject standing height, vertical jump height, and broad jump length. It was hypothesized that single-camera system values would demonstrate high correlation to the values obtained from accepted standard clinical measurements. STUDY DESIGN: Experimental in vivo validation study. METHODS: Twelve subjects (age 20.6 ± 4.9 years) from a cohort that included high school to adult athletes who participate in sports at a recreational or competitive level entered and completed the study. Performance measurements for standing height, vertical jump height, and broad jump length were measured with standard clinical measurements and a single-camera 3D motion system. RESULT: Single-camera system measurements were significantly different than clinical measures for standing height (p < 0.01) and vertical jump height (p < 0.01). There was no statistically significant difference between single-camera system measures and clinical measures for broad jump distance (p > 0.07). The relative performance of subjects was highly correlated between single-camera and clinical measurements (r2 > 0.80). CONCLUSIONS: Single-camera measurements lacked precision along the vertical axis of motion, but correlated well with clinically accepted measurements for standing height, broad jump length, and vertical jump height. The single-camera system may be capable of making accurate performance assessments in the horizontal plane, but should be limited to relative assessments along the vertical axis of motion. Additional refinement to increase the data reporting accuracy of the motion system along the vertical axis should be considered before relying on this single-camera 3D motion analysis system over clinical techniques to measure vertical jump and standing broad jump performances. LEVEL OF EVIDENCE: 2b.