BIOMECHANICAL RISK FACTORS ASSOCIATED WITH NON-CONTACT ANTERIOR CRUCIATE LIGAMENT INJURIES DURING LANDING PERFORMANCE

Anterior cruciate ligament (ACL) injuries have received much attention in the biomechanics literature. The kinematics and kinetics of landing appear to be important risk factors for non contact ACL injuries especially for females. This paper reviews many of the some of the biomechanical factors that appear to be important to ACL injury risk and how recent modeling approaches have been utilized. Modeling studies depict a rather complex interaction of kinematic, kinetic and anatomical factors that result in ACL loading early in landing. More complex, subject and gender specific models may be important to gain further insight and thus influence injury prevention efforts

MOMENT AND POWER OF SHOULDER AND ELBOW IN SHOT-PUTTING

The purpose of this study was to quantify the moments and power of the elbow and shoulder joints. Three-dimensional methods and inverse dynamics were used to analyze the throwing arm of shot putter performing standing throws. The proximal to distal sequence was found on moments and power of the elbow and shoulder. The mechanical outputs from elbow and shoulder muscles were mainly energy generation

Effects of Medially Wedged Foot Orthoses on Knee and Hip Joint Running Mechanics in Females With and Without Patellofemoral Pain Syndrome.

We examined the effects of medially wedged foot orthoses on knee and hip joint mechanics during running in females with and without patellofemoral pain syndrome (PFPS). We also tested if these effects depend on standing calcaneal eversion angle. Twenty female runners with and without PFPS participated. Knee and hip joint transverse and frontal plane peak angle, excursion, and peak internal knee and hip abduction moment were calculated while running with and without a 6° full-length medially wedged foot orthoses. Separate 3-factor mixed ANOVAs (group [PFPS, control] x condition [medial wedge, no medial wedge] x standing calcaneal angle [everted, neutral, inverted]) were used to test the effect of medially wedged orthoses on each dependent variable. Knee abduction moment increased 3% (P = .03) and hip adduction excursion decreased 0.6° (P < .01) using medially wedged foot orthoses. No significant group x condition or calcaneal angle x condition effects were observed. The addition of medially wedged foot orthoses to standardized running shoes had minimal effect on knee and hip joint mechanics during running thought to be associated with the etiology or exacerbation of PFPS symptoms. These effects did not appear to depend on injury status or standing calcaneal posture. ABSTRACT FROM AUTHO

Concurrent Force Feedback on Load Symmetry in Total Knee Arthroplasty Patients

# Background and Purpose Load asymmetry can be present before and after total knee arthroplasty (TKA), which may affect progress during knee rehabilitation in an outpatient sports medicine setting. Current rehabilitation primarily focuses on strength, pain, and range of motion deficits; however, recent evidence suggests the use of movement retraining strategies such as load feedback to address load asymmetry. Therefore, the purpose of this study was to examine how a single session of concurrent force feedback influences load symmetry during the leg-press and body-weight squat exercises in individuals following TKA. Additionally, a secondary purpose was to examine the retention of any changes over the course of a week. # Study design Case-series study # Methods This observational, repeated-measures study design examined the effect of concurrent force feedback training on the mean and standard deviation of load symmetry index during the leg press and squat exercises in 26 patients with TKA in an outpatient sports medicine clinic.The load asymmetry was measured with loadpad sensors placed underneath the each extremity during leg press and squat (baseline), after one training session consisting of concurrent force feedback during these exercises within a single physical therapy session (post feedback), and after seven to ten days of a washout period (post retention). Separate 2 x 3 repeated measures analysis of variance was used to compare the mean and standard deviation of load symmetry across exercise (leg press and squat) and across time (baseline, post feedback and post retention). # Results There was a time effect for the mean load symmetry index (p=0.027) but not for the standard deviation (p=0.441) during these exercises. The leg press showed a greater mean symmetry index compared to the squat regardless of time (p=0.001). # Conclusions A reduction in the mean load symmetry index following concurrent feedback training suggests improved use of the surgical limb during both leg press and squat exercises during the same therapy session but the more symmetric loading pattern was not retained one week later. Overall, the leg press showed greater mean asymmetry than the squat. Standard deviation in the load symmetry index did not change across time or by exercise. # Level of Evidence 3 ©The Author(s

Post-Trial Feedback Alters Landing Performance in Adolescent Female Athletes Using a Portable Feedback System

# Background Post-performance verbal and visual feedback based on data collected via lab-based instruments have been shown to improve landing patterns related to non-contact ACL injury. Biomechanical methods are often complex, difficult to transport and utilize in field settings, and costly, which limits their use for injury prevention. Developing systems that can readily provide feedback outside of the lab setting may support large scale use of feedback training for ACL injury prevention. # Purpose/Hypothesis The purpose of this study was to investigate the effectiveness of a single training session using a custom portable feedback training system that provides performance cues to promote changes in impact kinetics and lower extremity position during landing in female athletes. # Study Design Repeated measures # Methods One hundred fifty female athletes (ages 13-18 years old) landed from a 50 cm platform with and without feedback related to vertical ground reaction force (vGRF), vGRF symmetry and lower extremity position. Feedback was provided via a portable, low-cost system that included two custom-built force plates interfaced with a digital camera. Each athlete performed six pre-test trials followed by two blocks of six trials where they received visual feedback from the training system and individualized verbal cues from an investigator. Following training blocks, athletes completed six post-test trials without feedback and then six dual-task trials where a ball was randomly thrown to the performer during the landing (transfer task). vGRF and knee to ankle (K:A) separation ratio were measured and the average responses were reported for each trial block. # Results Differences in vGRF between baseline, post-test and transfer task trial blocks were observed (F(2,298)=181.68, p < .0001). Mean (SD) peak vGRF (body weight) were 4.43 (0.90), 3.28 (0.61), and 3.80 (0.92), respectively. Differences in K:A ratio between baseline, post-test and transfer task trial blocks were shown (F(2,298)=68.47, p < .0001). Mean (SD) K:A ratio were 0.87 (0.21), 0.98 (0.19), and 0.92 (0.19), respectively. # Conclusion A portable feedback system may be effective in reducing peak vGRFs and promoting a more desirable K:A ratio during landing and transfer task landing in adolescent female athletes. # Level of Evidence 3

A Multicenter Study Of The Test-Retest Reliability Of The Lower Extremity Functional Test

Context: Many clinicians use functional-performance tests to determine an athlete\u27s readiness to resume activity; however, research demonstrating reliability of these tests is limited. Objective: To introduce the Lower Extremity Functional Test (LEFT) and establish it as a reliable assessment tool. Design: Week 1: Subjects participated in a training session. Week 2: Initial maximal-effort time measurements were recorded. Week 3: Retest time measurements were recorded. Setting: The University of Wisconsin-La Crosse (UW-L) and the University of Central Florida (UCF). Subjects: 27 subjects from UW-L and 30 from UCF. Main Outcome Measures: Time measurements were analyzed using intraclass correlation coefficients (ICCs). Results: ICC values of .95 and .97 were established at UW-L and UCF, respectively. Conclusions: The LEFT is a reliable assessment tool