Robert J. Butler

Functional movement test scores improve following a standardized off-season intervention program in professional football players

The purpose of this study was to determine if an off‐season intervention program was effective in improving Functional Movement Screen™ (FMS) scores in professional American football players. Pre‐ and post‐intervention FMS scores were obtained on 62 subjects who completed a 7‐week off‐season intervention program. A repeated measures ANOVA was conducted to determine the effectiveness of the training program on FMS scores. A chi‐square was performed to determine if there were a greater number of players who met the injury threshold and if asymmetries were reduced following intervention. Logistic regression was used to predict what factors were associated with failure (post‐test score of <14). There was a positive main effect for time (P<0.01) and a greater number of individuals with a score >14 following the intervention. At post‐test, 41 players were free of asymmetry as compared with 31 at the pre‐test. The strongest predictor of program failure was a low squat score at pre‐test. This study demonstrated that fundamental movement characteristics do change with a standardized intervention. Further research is required to determine if injury risk is reduced when a players score improves beyond the established cut‐off of 14 and/or asymmetry is resolved.

Gait mechanics after ACL reconstruction: implications for the early onset of knee osteoarthritis

Background: Individuals who sustain a rupture of the anterior cruciate ligament (ACL) are at an increased risk for developing early-onset knee osteoarthritis (OA). The mechanism behind the early onset of the disease is still unknown. Knee OA progression has been previously examined by calculating the internal knee-abduction moment during gait. However, knee-joint moments have not been examined in individuals after ACL reconstruction as a potential mechanism for disease progression in early knee OA. Objective: To determine if individuals who have undergone ACL reconstruction exhibit altered gait mechanics that may be associated with knee OA progression. Methods: In total, 17 people who had previously undergone ACL reconstruction were enrolled in the study. A matched control group was recruited for comparison. All participants underwent gait analysis at an intentional walking speed to examine variables previously associated with knee OA progression, primarily the internal peak knee-abduction moment, during gait. One way ANOVAs were performed to examine differences in gait mechanics between the two groups. All joint moments were calculated as internal moments. Results: The peak knee-abduction moment was increased by 21% in the ACL compared with the control group (p = 0.04). No other differences were seen in frontal plane knee or hip mechanics. Conclusion: It seems that individuals who have undergone ACL reconstruction exhibit an increased peak knee-abduction moment that may establish a potential mechanism of the earlier onset of knee OA in this population.

Interaction of Arch Type and Footwear on Running Mechanics

Background Running shoes are designed to accommodate various arch types to reduce the risk of lower extremity injuries sustained during running. Yet little is known about the biomechanical changes of running in the recommended footwear that may allow for a reduction in injuries. Purpose To evaluate the effects of motion control and cushion trainer shoes on running mechanics in low-and high-arched runners. Study Design Controlled laboratory study. Methods Twenty high-arched and 20 low-arched recreational runners (>10 miles per week) were recruited for the study. Three-dimensional kinematic and kinetics were collected as subjects ran at 3.5 ms-1 ± 5% along a 25-m runway. The motion control shoe evaluated was the New Balance 1122, and the cushioning shoe evaluated was the New Balance 1022. Repeated-measures analyses of variance were used to determine if low- and high-arched runners responded differently to motion control and cushion trainer shoes. Results A significant interaction was observed in the instantaneous loading rate such that the low-arched runners had a lower instantaneous loading rate in the motion control condition, and the high-arched runners had a lower instantaneous loading rate in the cushion trainer condition. Significant main effects for shoe were observed for peak positive tibial acceleration, peak-to-peak tibial acceleration, mean loading rate, peak eversion, and eversion excursion. Conclusion These results suggest that motion control shoes control rearfoot motion better than do cushion trainer shoes. In addition, cushion trainer shoes attenuate shock better than motion control shoes do. However, with the exception of instantaneous loading rate, these benefits do not differ between arch type. Clinical Relevance Running footwear recommendations should be based on an individuals running mechanics. If a mechanical analysis is not available, footwear recommendations can be based empirically on the individuals arch type.

Arch height index measurement system: establishment of reliability and normative values.

BACKGROUND The purposes of this study were 1) to determine the intrarater and interrater reliability of the arch height index measurement system device, 2) to establish population normative values for the arch height index in recreational runners, and 3) to compare arch height index values between the right and left feet and between genders. METHODS Eleven subjects were used to establish intrarater and interrater reliability of the arch height index measurement system. This system was then used to measure the arch height index of 100 recreational runners. RESULTS Measurements taken with the arch height index measurement system device exhibited high intrarater and interrater reliability. The mean +/- SD arch height index of the recreational runners was 0.340 +/- 0.030. Men had larger feet than women, but the arch height index between genders was similar. CONCLUSIONS The arch height index measurement system device is reliable to use between testers while simplifying the measurement procedure for recording the arch height index. The arch height index may be helpful in identifying potential structural factors that predispose individuals to lower-extremity injuries.

Modifiable risk factors predict injuries in firefighters during training academies

OBJECTIVE To examine whether measures of physiologic function and fundamental movement are predictive of injury in firefighters during a training academy. PARTICIPANTS 108 firefighter trainees enrolled in the training academy. METHODS Baseline measures of physical performance and fundamental movement patterns were obtained in firefighters entering a training academy to determine predictors of injury. The physical performance measures were standardized tests of individual maximum performance on a set of four different total body tests and one firefighter specific performance test, the tower test. Measurements of fundamental movement patterns consisted of the seven tests of the Functional Movement Screen (FMS) along with the composite score.Performance on each of the individual tests was examined to determine if any of the variables were predictive of injury. RESULTS ROC curve analysis established that a FMS cut score of ≤ 14 was able to discriminate between those at a greater risk for injury. In addition, the deep squat and push up component of the FMS were statistically significant predictors of injury status along with the sit and reach test. CONCLUSIONS Injury in firefighters during academy can be predicted by baseline measures of musculoskeletal movement and physiology.

Biomechanical analysis of the different classifications of the Functional Movement Screen deep squat test

The purpose of this study is to examine the peak sagittal plane joint angles and joint moments of the lower extremity during the deep squat (DS) movement of the Functional Movement Screen (FMS) to assess differences between the classifications (1,2,3). Twenty-eight participants volunteered for the study and were screened to assess their FMS score on the DS task. All participants underwent a quantitative movement analysis performing the FMS DS movement at a self-selected speed. The participants in Group 3 exhibited greater dorsiflexion excursion compared to those in Group 1. Participants in Group 3 had greater peak knee flexion and knee flexion excursion than those in Group 2 who exhibited more than the participants in Group 1. Group 3 also exhibited a greater peak knee extension moment compared to Group 1. At the hip, Groups 3 and 2 exhibited greater peak hip flexion, hip flexion excursion and peak hip extension moment compared to Group 1. Thus, it appears that individuals who score differently on the deep squat as determined by the FMS exhibit differences in mechanics that may be beneficial in assessing strategies for interventions. Future research should assess how fundamental changes in mobility and stability independently affect DS performance.

Effect of laterally wedged foot orthoses on rearfoot and hip mechanics in patients with medial knee osteoarthritis

The purpose of this study was to examine the effects of laterally wedged foot orthotic devices, used to treat knee osteoarthritis, on frontal plane mechanics at the rearfoot and hip during walking. Thirty individuals with diagnosed medial knee osteoarthritis were recruited for this study. Three dimensional kinematics and kinetics were recorded as the subjects walked in the laboratory at an intentional walking speed. Peak eversion, eversion excursion and peak eversion moment were increased while the peak knee adduction moment was reduced in the laterally wedged orthotic condition compared to the no wedge condition. In contrast, no changes were observed in the variables of interest at the hip. There was no significant relationship between the change in the peak frontal plane moment at the rearfoot and change in the peak frontal plane moment at the knee or hip as a result of the lateral wedge. Laterally wedged foot orthotic devices, used to treat knee osteoarthritis, do not influence hip mechanics. However, they do result in increased rearfoot eversion and inversion moment. Therefore, a full medical screen of the foot should occur before laterally wedged foot orthotic devices are prescribed as a treatment for knee osteoarthritis.

Dynamic balance performance and noncontact lower extremity injury in college football players: an initial study.

Background: Field expedient screening tools that can identify individuals at an elevated risk for injury are needed to minimize time loss in American football players. Previous research has suggested that poor dynamic balance may be associated with an elevated risk for injury in athletes; however, this has yet to be examined in college football players. Hypothesis: To determine if dynamic balance deficits are associated with an elevated risk of injury in collegiate football players. It was hypothesized that football players with lower performance and increased asymmetry in dynamic balance would be at an elevated risk for sustaining a noncontact lower extremity injury. Study Design: Prospective cohort study. Methods: Fifty-nine collegiate American football players volunteered for this study. Demographic information, injury history, and dynamic balance testing performance were collected, and noncontact lower extremity injuries were recorded over the course of the season. Receiver operator characteristic curves were calculated based on performance on the Star Excursion Balance Test (SEBT), including composite score and asymmetry, to determine the population-specific risk cut-off point. Relative risk was then calculated based on these variables, as well as previous injury. Results: A cut-off point of 89.6% composite score on the SEBT optimized the sensitivity (100%) and specificity (71.7%). A college football player who scored below 89.6% was 3.5 times more likely to get injured. Conclusion: Poor performance on the SEBT may be related to an increased risk for sustaining a noncontact lower extremity injury over the course of a competitive American football season. Clinical Relevance: College football players should be screened preseason using the SEBT to identify those at an elevated risk for injury based upon dynamic balance performance to implement injury mitigation strategies to this specific subgroup of athletes.

Male and female gluteal muscle activity and lower extremity kinematics during running

BACKGROUND Patellofemoral pain is one of the most common lower extremity overuse injuries in runners and is significantly more common in females. This study evaluated differences in the timing and magnitude of gluteal muscle activity as well as hip and knee joint frontal and transverse plane kinematics between male and female runners in the context of this gender bias. METHODS Twenty healthy male and 20 healthy female runners were participants. Three-dimensional lower extremity kinematics, and gluteus medius and gluteus maximus muscle activation were recorded using motion analysis and electromyography as subjects ran at 3.7 m/s (+/-5%). Comparisons of hip and knee joint kinematic and gluteus muscle activation data were made using independent t-tests (α=0.05). FINDINGS Females ran with 40% greater peak gluteus maximus activation level (P=0.028, effect size=0.79) and 53% greater average activation level (P=0.013, effect size=0.93) than males. Female runners also displayed greater hip adduction (P=.001, effect size=1.20) and knee abduction (P=0.011, effect size=0.87) angles at initial contact, greater hip adduction at peak vertical ground reaction force (P<0.001, effect size=1.31), and less knee internal rotation excursion than males (P=0.035, effect size=0.71). INTERPRETATION Greater gluteus maximus activation levels during running may predispose females to earlier gluteus maximus fatigue, promoting altered lower extremity running kinematics thought to be associated with the etiology of patellofemoral pain. Gender differences in transverse and frontal plane hip and knee kinematics observed in this study may also contribute to the gender bias for patellofemoral pain among females.

The Effect of Total Hip Arthroplasty Surgical Approach on Postoperative Gait Mechanics

Surgical approach for total hip arthroplasty (THA) is determined by clinician preference from limited prospective data. This study aimed to examine the effect of surgical approach (direct lateral, posterior, and anterolateral) on 6-week postoperative gait mechanics. Thirty-five patients (direct lateral, 8; posterior, 12; anterolateral, 15) were tested preoperatively and 6 weeks after THA. Patients underwent a gait analysis at a self-selected walking speed. A 2-way analysis of variance was used for analysis. Stride length, step length, peak hip extension, and walking speed increased after THA. The 3 surgical approach variables were not significantly different for any of the study variables after THA. All patients showed some increase in selected variables after THA regardless of surgical approach. In this study, surgical approach did not appear to significantly influence the early postoperative gait mechanics that were quantified.