The early peak knee abduction moment waveform is a novel risk factor predicting anterior cruciate ligament injury in young athletes: A prospective study.

PURPOSE: In this study, prospective data were used to evaluate whether the early peak knee abduction moment waveform is associated with the risk of anterior cruciate ligament (ACL) injury. METHODS: Biomechanical data from 84 athletes who participated in the study as adolescents were analysed after cross-referencing national health registry data to confirm ACL reconstruction in the subsequent years. The knee abduction moment waveform shape was obtained with cluster analysis for the first 100 ms of a cutting manoeuvre (1776 trials in total) and classified as either containing an early peak knee abduction moment or not, and the odds ratio for later ACL injury was then calculated. Additionally, discrete kinematic and kinetic variables were extracted, and tested against the risk of ACL injury using mixed model logistic regression. RESULTS: Of 84 athletes, 8 (all female) sustained a total of 13 ACL injuries in the years after motion analysis data collection. Six clusters of knee abduction moment waveform shapes were identified. Two clusters containing 446 trials were classified as an early peak knee abduction waveform. This waveform was associated with a 7.2-fold increase in the risk of ACL injury (95% confidence interval: 2.4-24.6; p < 0.001). Of the kinematic and kinetic variables tested, only the knee abduction angle at initial contact was associated with an increased risk of ACL injury (p < 0.001). CONCLUSION: This is the first study to confirm the association between the early peak knee abduction moment waveform and the risk of ACL injury. Using waveforms, instead of discrete peak values of the knee abduction moment, may better represent risky movement patterns. Replicating these findings in a larger cohort will support the use of this method to screen athletes for risk and guide targeted preventive interventions and their efficacy. LEVEL OF EVIDENCE: Level II.

Re-defining wearable robots: a multidisciplinary approach towards a unified terminology.

Effective communication is especially important in the wearable robots (WRs) community, which encloses a great variety of devices across different application domains, e.g., healthcare, occupational, and consumer. In this paper we present a vocabulary of terms with the aim to create a common understanding of terms and concepts among the different fields of expertise relevant in the WRs community. Our goal is to develop shared documentation that could serve as a reference to facilitate the use of accepted definitions in the field. The presented vocabulary is the result of different focus group discussions among experts in the field. The resulting document was then validated by presenting it to the WR community through an online survey. The results of the survey highlight a strong agreement in terms of acceptance of the vocabulary, its usefulness, and applicability of the proposed definitions as well as an overall appreciation for its purpose and target. This work represents a pilot study providing unique material for the WR community, encouraging the use of shared agreed definitions. The reported version of the vocabulary has been made available as a live document in a github repository, for public commenting and further improvements.

Boys demonstrate greater knee frontal moments than girls during the impact phase of cutting maneuvers, despite age-related increases in girls.

PURPOSE: Anterior cruciate ligament (ACL) injury rate is low among children, but increases during adolescence, especially in girls. Increases in the knee valgus moment within 70 ms of contact with the ground (KFM0-70) may explain the sex-specific increase in the risk of ACL injury. The purpose of the study was to investigate sex-dependent changes in the KFM0-70 from pre-adolescence to adolescence during a cutting maneuver (CM). METHODS: Kinematic and kinetic data during the CM task, performed before and after physical exertion, were recorded using a motion capture system and a force plate. A total of 293 team handball and soccer players, aged 9-12 years, were recruited. A number of those who continued sports participation (n = 103) returned five years later to repeat the test procedure. Three mixed-model analysis of variance (ANOVA) for repeated measures tests were used to determine the effects of sex and age period on the KFM0-70 (1: with no adjustment, 2: adjusted for repeated measurements, and 3: additionally adjusted with hip and knee joint frontal plane kinematics). RESULTS: Boys had significantly higher KFM0-70 than girls at both age periods (p < 0.01 for all models). Girls, not boys, demonstrated significantly increased KFM0-70 from pre-adolescence to adolescence. Importantly, this was fully explained by kinematic variables. CONCLUSION: Although the marked increase in KFM0-70 seen in girls may play a role in their risk of ACL rupture, the higher values demonstrated by boys during CM reflect the complexity of multifactorial biomechanical risk factor analysis. The role of kinematics in mediating the KFM0-70 provides means for modification of this risk factor, but as boys had higher joint moments, continued investigation into sex-dependent biomechanical risk factors is warranted. LEVEL OF EVIDENCE: II.

Younger age increases the risk of sustaining multiple concomitant injuries with an ACL rupture.

PURPOSE: Anterior cruciate ligament (ACL) tears have a major impact on the individual and society. Long term effects may be mediated by injuries that occur concurrently to the ACL tear. The purpose of this study was to describe in a nationwide cohort the traumatic meniscal injuries and bone marrow lesions concomitant to ACL tears, their age and sex distribution and the rate any association with ACL reconstruction. METHODS: All ACL tears in Iceland from 2006 to 2011 and their concomitant bone marrow lesions and meniscal injuries were identified from MRI reports. These injuries were further classified by location, sex and age. The cohort was divided into under 17, 17-29, 30-49 and above 50 to reflect likely differences in the mechanisms of injury and risk factors that may vary with age. Data from the Icelandic Social Insurance Administration were used identify all those who were operated. Descriptive analysis was performed to show the proportion of ACL injured knees sustaining concomitant injuries and how these injuries varied with age, sex, and subsequent treatment RESULTS: 1365 knees with ACL ruptures were included. Only 13% of knees had no concomitant injury identified. Overall, 57% of knees had a bone marrow lesion in at least one location and 70% of knees had at least one traumatic meniscal injury. A greater number of combined lateral tibial and femoral bone marrow lesion was seen in younger age groups (χ2 (3) = 113.32, p < 0.0001). Bruises in the medial compartment were the least common concomitant injuries. More injuries were related to higher chances of ACL reconstruction (OR 1.6, 95% CI 1.4-1.7). Age was associated with risk of all injury types and locations with older age generally being associated with fewer injuries. CONCLUSION: In an ACL ruptured cohort, the overall incidence of BMLs may be lower and meniscus injuries higher than previously reported. However, these injuries are more prevalent in the younger cohort potentially resulting in a poorer long-term prognosis. Knowledge of the association between age and concomitant injuries will help guide rehabilitation. LEVEL OF EVIDENCE: II.

Assessing the Involvement of Users During Development of Lower Limb Wearable Robotic Exoskeletons: A Survey Study.

OBJECTIVE: To explore user-centered design methods currently implemented during development of lower limb wearable robots and how they are utilized during different stages of product development. BACKGROUND: Currently, there appears to be a lack of standardized frameworks for evaluation methods and design requirements to implement effective user-centered design for safe and effective clinical or ergonomic system application. METHOD: Responses from a total of 191 experts working in the field of lower limb exoskeletons were analyzed in this exploratory survey. Descriptive statistics were used to present responses and measures of frequency, and chi-square tests were used to contrast the answers of respondents who identified as clinicians versus engineers. RESULTS: A vast majority of respondents involve users in their development, in particular at the initial and iterative stages, although some differences were found between disciplines. A variety of methods and metrics are used to capture feedback from users and test devices, and although valuable, some methods used may not be based on validated measures. Guidelines regarding tests on safety of exoskeletons also lack standardization. CONCLUSION: There seems to be a consensus among experts regarding the importance of a user-centered approach in exoskeleton development; however, standardized frameworks with regard to appropriate testing methods and design approaches are lacking. Such frameworks should consider an interdisciplinary focus on the needs and safety of the intended user during each iteration of the process. APPLICATION: This exploratory study provides an overview of current practice among engineers and clinicians regarding the user-centered design of exoskeletons. Limitations and recommendations for future directions are identified.

Timing, not magnitude, of force may explain sex-dependent risk of ACL injury.

PURPOSE: The anterior cruciate ligament is loaded through valgus moment, vertical ground reaction force, and internal rotation moment. The aim of this study was to compare the timing of force peaks during early stance between youth girls and boys. METHODS: One-hundred and twenty-nine team sport athletes aged 9-12 completed a total of 2540 cutting maneuvers captured with an 8-camera motion capture system. Timing of early force peaks was analyzed within 100 ms after ground contact. RESULTS: Genders showed different mean (95% CI) time to peak valgus-(32 ms (30-33 ms) vs 37 ms (36-38 ms), P < 0.001) and time to peak internal rotation moments (36 ms (35-37 ms) vs 38 ms (37-39 ms), P = 0.029) but not time to peak vertical ground reaction force [38 ms (37-40 ms) vs 37 ms (36-38 ms, n.s.)]. Girls showed a smaller time between vertical ground reaction force and valgus moment peaks (mean (95% CI) of 1 ms (1-2 ms) vs 7 ms (5-9 ms), P < 0.001), and valgus- and internal rotation moment peaks (0 ms (- 2 to 1.0 ms) vs - 5 ms (- 6 to - 3 ms), P = 0.0003) but not between internal rotation moment and vertical ground reaction force. CONCLUSIONS: Concurrent force peaks are more common for girls compared with boys, leading to more frequent multi-planar loading of the knee. Timing may explain sex-dependent risk of ACL injuries. Exposure to repeated cutting movements may result in greater ACL injury risk due to timing of knee forces as well as magnitude. Such exposure should be minimized for at-risk athletes. LEVEL OF EVIDENCE: III.

Nationwide study highlights a second peak in ACL tears for women in their early forties.

PURPOSE: Anterior cruciate ligament (ACL) rupture continues to be a focus of research on knee injuries. Despite this, data on the total number of ruptures on a national basis including both reconstructed (ACLR) and non-reconstructed injuries are limited. The purpose of this study was to describe the national incidence of MRI diagnosed ACL ruptures in Iceland and its subsequent rate of operation with regard to sex and age. METHODS: All MRI knee reports taken in Iceland between 2006 and 2011 were gathered to identify ACL ruptures. Software was written to search for phrases relating to ACL rupture. Duplicate records were removed and yearly incidence for sex and age groups was determined. Data from the Icelandic Social Insurance Administration were used identify all those who were operated and to determine the yearly incidence of ACLR. General additive models were used assuming either a Poisson or binomial distribution to model ACL rupture incidence and ACLR rate, respectively. RESULTS: The average age was 33.9 (95% CI 33.1-34.6; Table 1). The average incidence of ACL tears per year was 75.1 (95% CI 71.3-79.1) per 100,000 person-years. For males the peak incidence was in their early twenties. Females showed two peaks, one in their teens and another in their forties resulting in an older average age at rupture compared to males (35 ± 16 vs 33 ± 13, p = 0.06). The main effects of age and sex and their interaction were significant (p < 0.001). The average incidence of ACLR was 39.4 (95% CI 36.7-42.4) per 100,000 person-years. Those operated were significantly younger than those who were not (27 ± 10 vs 42 ± 15 years, p < 0.001). The main effects of age and the interaction between sex and age were significant (p < 0.001). CONCLUSION: This nationwide study indicates that ACL rupture incidence may be higher than previously thought, implying an underestimated impact of the burden of this serious knee injury. The incidence of injury peaked twice in the female population, a result not previously reported. Older persons are less likely to undergo ACLR and, therefore, sex-dependent differences in overall mean age at injury are contrary to previous reports. These data suggest that prevention programs focused solely on young girls should be extended to older women who are returning to sports. LEVEL OF EVIDENCE: II.

Effects of an Education and Prevention Course for University Music Students on Their Body Awareness and Attitude Toward Health and Prevention.

BACKGROUND: Studies show a high cumulative prevalence of musculoskeletal disorders among musicians. Increased emphasis is needed on studying the effectiveness of education and prevention courses in music schools. OBJECTIVES: To investigate the effects on music students of an education and prevention course on body awareness and their attitude toward health and prevention. METHODS: 23 music students participated in this prospective descriptive comparative study, with 13 students taking the course and serving as a prevention education group (PG) and 10 students serving as a comparison group (CG). The course met once weekly for 2 semesters and included lectures and practical sessions. Before and after the course, participants answered a questionnaire about their level of physical activity, warm-up exercises prior to musical performance, health-promoting activities, and subjective body awareness during musical performance and during activities of daily living (ADL). RESULTS: Over the 9-month study period, the PG group increased, and the CG lessened, the amount of warm-up prior to music performance, showing a significant group difference after the course (p=0.036). Significant interactions were seen for subjective body awareness scores (between groups over time) during practice (p=0.026) and during ADLs (p=0.004), as the PG group had greater positive change over time. No group differences were found in students' subjective rating of body awareness during live performance. CONCLUSIONS: Participation in a prevention and education course may be beneficial for music students due to improved subjective body awareness and attitude toward prevention strategies.

Muscular strength and physical function in elderly adults 6-18 months after a 12-week resistance exercise program.

AIMS: Benefits of resistance exercise in elderly people are well documented; however, sustaining these benefits can be difficult and adherence is often poor. Muscular strength and physical function usually decline after a supervised resistance exercise program (REP). We investigated these changes in older adults during an observational follow-up and whether leisure time physical activity (LTPA) or unsupervised resistance exercise (RE) limit these changes. METHODS: Subjects (N = 236, 73.7 ± 5.7 years, 58.2% female) had participated in a supervised 12-week REP. Quadriceps strength and timed-up-and-go performance (TUG) at follow-up were compared to values before and after REP. Multivariate statistics were used to predict changes in strength or function. RESULTS: Two hundred and eleven (90.3%) participants completed REP and 149 (63.1%) completed follow-up (11.4 ± 2.9 months). Quadriceps strength at follow-up decreased significantly compared to after REP (-27N), but was higher than before REP (+ 30N). TUG did not decrease during follow-up and was better than before REP (-0.9 seconds). LTPA (+ 38.0N, p < 0.001) and RE (+31.6N, p = 0.006) predicted strength at follow-up, although they did not completely prevent loss of strength during follow-up. CONCLUSIONS: quadriceps strength declines after a 12-week resistance exercise program in older adults. Neither LTPA nor RE completely prevents loss of quadriceps strength during follow-up, although they limited the loss. TUG did not change during follow-up and was better at follow-up than before the start of the resistance exercise program.

Medial hamstring muscle activation patterns are affected 1-6 years after ACL reconstruction using hamstring autograft.

PURPOSE: Although changes in hamstring muscle morphology after anterior cruciate ligament reconstruction (ACLR) using a semitendinosus autograft hamstrings-gracilis (HG) of the ipsilateral limb are recognized, alterations in muscle activation patterns have not been extensively studied. The purpose of this controlled laboratory trial was therefore to monitor muscle activation levels of the medial (MH) and lateral (LH) hamstring muscles in athletes who had undergone ACLR using a HG autograft and to contrast these to activation levels demonstrated by healthy controls. METHODS: Surface electromyography (EMG) was sampled from bilateral hamstring muscles of 18 athletes 1-6 years after ACLR and 18 matched controls (CTRL) during the performance of two dissimilar exercises, both involving eccentric knee flexor activity. Peak normalized muscle activation levels were identified for MH and LH of both limbs during the performance of the Nordic Hamstring (NH) exercise and TRX) hamstring curl (TRX) exercise. RESULTS: A statistically significant limb by exercise interaction was found for peak activation levels of LH, due to significant interlimb differences in activation during the performance of the TRX exercise compared to more symmetrical activation during the NH (p < 0.001). A three-way interaction was found for peak activation levels of MH, due to group differences in peak muscle activation between limbs and exercise type (p = 0.025). Whereas CTRL group participants consistently favoured one limb over the other during the performance of both exercises, ACLR participants demonstrated dissimilar peak MH activation patterns between limbs during the performance of the NH exercise compared to the TRX. CONCLUSIONS: In light of these results and considering the surgical procedure, patients who undergo ACLR using a HG autograft from the ipsilateral limb may benefit from post-operative rehabilitation that involves muscle activation and strengthening specifically targeting the MH component.

Playing-related musculoskeletal disorders among icelandic music students: differences between students playing classical vs rhythmic music.

Most research studies investigating the prevalence of musculoskeletal disorders affecting musicians and music students have focused on classical music, while less is known about their prevalence in other music genres. The purpose of this study was to document cumulative and point prevalence of playing-related musculoskeletal disorders (PRMD) among music students in Iceland and, specifically, to identify differences between those studying classical vs rhythmic music. We hypothesized that students of classical music would report more frequent and more severe musculoskeletal disorders than students involved in rhythmic music, as classical instruments and composition typically require more demanding, sustained postures during practice and performance. A total of 74 students from two classical music schools (schools A and B) and 1 rhythmic school (school C) participated in the study by answering a questionnaire assessing PRMDs. The results showed that 62% of participants had, at some point in their musical career, suffered a PRMD. The cumulative prevalence was highest in music school A (71.4%) and lowest in music school C (38.9%). A statistically significant difference was identified between the cumulative prevalence of PRMD from schools A and B combined compared to music school C (p=0.019). Over 40% of participants reported a "current PRMD," and a significant difference was identified between the three schools (p=0.011), with the highest point prevalence being registered in music school A (66.6%) and the lowest in music school C (22.2%). The prevalence of PRMDs among Icelandic music students was high. The difference found between students who play classical vs rhythmic music may be explained by different demands of the instruments and composition on playing posture.

Perceptions and biomechanical effects of varying prosthetic ankle stiffness during uphill walking: A case series.

BACKGROUND: Prosthetic foot stiffness, which is typically invariable for commercially available prosthetic feet, needs to be considered when prescribing a prosthetic foot. While a biological foot adapts its function according to the movement task, an individual with lower limb amputation may be limited during more functionally demanding gait tasks by their conventional energy storing and return prosthetic foot. RESEARCH QUESTION: How do changes in prosthetic foot stiffness during incline walking affect biomechanical measures as well as perception of participants. METHODS: Kinetic and kinematic data were collected during incline walking, for five participants with trans-tibial amputation. A mixed model analysis of variance was used to analyse the effects of changing the stiffness during incline walking, using a novel variable-stiffness unit built on a commercially available prosthetic foot. Biomechanical results were also analysed on an individual level alongside the participant feedback, for a better understanding of the various strategies and perceptions exhibited during incline walking. RESULTS: Statistically significant effects were only observed on the biomechanical parameters directly related to prosthetic ankle kinematics and kinetics (i.e., peak prosthetic ankle dorsiflexion, peak prosthetic ankle power, dynamic joint stiffness during controlled dorsiflexion). Participant perception during walking was affected by changes in stiffness. Individual analyses revealed varied perceptions and varied biomechanical responses among participants. SIGNIFICANCE: While changes in prosthesis mechanical properties influenced the amputee's experience, minimal immediate effects were found with the overall gait pattern. The reported inter-participant variability may be due to the person's physical characteristics or habitual gait pattern, which may influence prosthesis function. The ability to vary prosthetic foot stiffness during the assessment phase of setting up a prosthesis could provide useful information to guide selection of the appropriate prosthetic device for acceptable performance across a range of activities.

Quadriceps and Hamstrings Activation Peaks Earlier as Athletes Repeatedly Hop, but There are Differences Depending on ACL Reconstruction Technique.

Background: After Anterior Cruciate Ligament Reconstruction (ACLR) athletes face the challenge of regaining their previous competitive level while avoiding re-injury and early knee joint cartilage degeneration. Quadriceps and hamstrings strength reductions and neuromuscular alterations potentially related to risk of re-injury are present after ACLR and relate to deficits in muscle activation. Design: Cross-sectional laboratory study. Purpose: To examine quadriceps and hamstrings muscle activation during repeated hops in healthy pivoting-sport athletes and those who had undergone ACLR (bone-tendon-bone and semitendinosus graft) who had met functional criteria allowing return to training. Methods: Surface electromyography (SEMG) was recorded from vastus medialis and lateralis and medial and lateral hamstrings bilaterally during 30 seconds' repeated hopping in male athletes on average eight months after ACLR surgery (5-12 months). All patients underwent hamstring (HS) (n=24) or bone-tendon-bone (BTB) reconstruction (n=20) and were compared to healthy controls (n=31). The SEMG signals were normalized to those obtained during maximal voluntary isometric contraction. Results: A significant time shift in peak muscle activation (earlier) was seen for: vastus medialis and vastus lateralis activation in the control group, in the BTB group's healthy (but not injured) leg and both legs of the HS group. A significant time shift in peak muscle activation was seen for lateral hamstrings (earlier) in all but the BTB group's injured leg and the medial hamstrings in the control group only. Lower peak activation levels of the vastus lateralis (p\<0.001) and vastus medialis (p\<0.001) were observed in the injured compared to healthy legs and lower peak lateral hamstrings activity (p\<0.009) in the injured leg compared to control leg. Decline in medial hamstring peak activation (p\<0.022) was observed between 1st and 3rd phase of the hop cycle in all groups. Conclusion: Repeated hop testing revealed quadriceps and hamstring activation differences within ACLR athletes, and compared to healthy controls, that would be missed with single hop tests. Level of evidence: 3.

Effects of a Novel Web-Based Sensorimotor Exercise Program for Patients With Subacute Whiplash-Associated Disorders: Protocol for a Randomized Clinical Trial.

INTRODUCTION: Whiplash-associated disorder (WAD) often becomes a persistent problem and is one of the leading causes of disability in the world. It is a costly condition for individuals, for insurance companies, and for society. Guidelines for the management of WAD have not been updated since 2014, and the use of computer-based sensorimotor exercise programs in treatment for this patient group has not been well documented. The purpose of this randomized clinical trial is to explore the degree of association between self-reported and clinical outcome measures in WAD. METHODS: Individuals (n = 180) with subacute WAD grades I and II will be randomized into 3 groups using block randomization. The 2 primary intervention groups (A and B) will receive physical therapy involving manual therapy and either a remote, novel, computer-based cervical kinesthetic exercise (CKE) program starting at visit 2 (Group A) or neck exercises provided by the corresponding physical therapist (Group B). These groups will be compared to a "treatment as usual" Group C. Movement control, proprioception, and cervical range of motion will be measured. Neck disability and pain intensity, general health, self-perceived handicap, and physical, emotional, and functional difficulties due to dizziness will be measured using questionnaires. The short-term effects will be measured 10 to 12 weeks after the baseline measurements, and the long-term effects will be measured 6 to 12 months after the baseline measurements. IMPACT: The successful completion of this trial will help guide clinicians in the selection of outcome measures for patients with subacute WAD in the assessment of the short- and long-term effectiveness of treatment combining manual therapy with computer-based CKE compared with manual therapy and non-computer-based exercises. This trial will also demonstrate the potential of using a computer-based intervention to increase the exercise dose for this patient group and how this influences outcomes such as levels of pain and disability in the short and long term.

Smoking and secondary ACL rupture are detrimental to knee health post ACL injury-a Bayesian analysis.

PURPOSE: To identify potential prognostic factors for patient-reported outcomes in an Icelandic cohort of ACL injured subjects. METHODS: All knee MRI reports written in Iceland between the years 2001 to 2011 were read to identify individuals with a possible ACL injury. These individuals were contacted and asked to complete an online questionnaire regarding their injury and current knee related health. The questionnaire collected information on years since surgery, injury circumstance, brace use, physiotherapy, ACL surgery, second ACL injury and current smoking status. In addition, the baseline status of their meniscii were assessed from the original MRI report and medical records were used to identify any subsequent, non-ACL surgery. The patient-reported Knee Osteoarthritis and Injury Outcome Score (KOOS) was used assess current knee related health. A Bayesian proportional odds model was used to assess the effect of all potential prognostic factors above as well as age and sex on KOOS outcomes. RESULTS: A total of 408 subjects completed the questionnaire indicating that they did rupture their ACL. The following variables were associated with worse outcomes across all KOOS subscales: having a subsequent arthroscopy, reinjury to your ACL, and smoking. Having physiotherapy for 9 months was associated with worse KOOS pain scores than having 6 months of physiotherapy. Conversely KOOS pain score tended to be higher if you injured your knee during sports. CONCLUSION: Reinjuring your ACL, smoking and having subsequent (non-ACLR) surgery predict your knee related health following an ACL injury. Strategies should be implemented to reduce the risk of secondary ACL injury, and patients should be strongly advised not to smoke.

Musculoskeletal ultrasound imaging of proximal and distal hamstrings cross sectional area in individuals with history of anterior cruciate ligament reconstruction.

BACKGROUND: Ultrasound (US) imaging is used by physical therapists for diagnosis and assessment of musculoskeletal injury and follow-up. PURPOSE: The aim was to identify long-term effects of graft harvesting on hamstrings muscle mass among athletes who had undergone anterior cruciate ligament reconstruction (ACLR). METHODS: Twenty-eight participants (ages 18-55) were recruited: 18 with history of ACLR using semitendinosus (ST) autograft and 10 healthy controls. Images of the cross-sectional area (CSA) of ST and biceps femoris (BF) were captured at 30% and 70% of the distance from the ischial tuberosity to the popliteal crease. A mixed model ANOVA was used to identify inter-limb differences in the CSA of ST and BF at each location, for each group. RESULTS: Inter-limb differences were found for the CSA of ST but not BF across both locations for the ACLR group, not controls (p < .001). Within the ACLR group, ST atrophy of the injured limb was relatively greater at the distal vs. proximal location (p < .001). CONCLUSION: US imaging identified selective atrophy of ST on the injured side with no compensatory hypertrophy of BF. Specific rehabilitation may influence muscle mass of medial vs. lateral hamstrings muscle groups after ACLR using a ST graft, and monitored with US imaging.

Don't Peak Too Early: Evidence for an ACL Injury Prevention Mechanism of the 11+ Program.

Background: The 11+ program prevents anterior cruciate ligament (ACL) injuries in athletes through unknown mechanisms. Purpose: The aim of the current study was to evaluate the effects of The 11+ intervention program, performed by female soccer players during a single season, on the frequency of Early Peaks during athletic tasks. Methods: Three teams (69 players) of collegiate female soccer athletes (Divisions I and II) were recruited. Two teams (49 players) volunteered to perform The 11+ three times per week for one season (~22 weeks plus three weeks pre-season), and one team (20 players) served as controls. The athletes performed three repetitions of a cutting maneuver, side shuffle direction change, and forwards to backwards running direction change before and after the competitive season and were recorded using marker-based 3D motion capture. Knee valgus moment time series were calculated for each repetition with inverse kinematics and classified as either "Very Early Peak", "Early Peak" or "other" using cluster analysis. The classification was based timing of the peak relative to the timing of ACL injuries. The effect of the intervention on the frequency of Very Early Peaks and Early Peaks was evaluated with a mixed Poisson regression controlling for the movement task and pre-season frequency. Results: The 11+ intervention reduced the frequency of Early Peak knee valgus moment in one intervention team (coefficient = -1.16, p = 0.004), but not the other (coefficient = -0.01, p = 0.977). No effect was observed on the frequency of Very Early Peak knee valgus moment. Conclusions: Reduced frequency of knee valgus moment Early Peak during athletic tasks may explain the mechanism by which The 11+ program decreases risk of ACL injury. Prospective studies with a much larger sample size are required to establish a link between Early Peak knee valgus moments and risk of ACL injury. Level of evidence: 2b.

Effects of kinesio tape compared with nonelastic sports tape and the untaped ankle during a sudden inversion perturbation in male athletes.

STUDY DESIGN: Controlled laboratory study. OBJECTIVES: To examine the effect of 2 adhesive tape conditions compared to a no-tape condition on muscle activity of the fibularis longus during a sudden inversion perturbation in male athletes (soccer, team handball, basketball). BACKGROUND: Ankle sprains are common in sports, and the fibularis muscles play a role in providing functional stability of the ankle. Prophylactic ankle taping with nonelastic sports tape has been used to restrict ankle inversion. Kinesio Tape, an elastic sports tape, has not been studied for that purpose. METHODS: Fifty-one male premier-league athletes were tested for functional stability of both ankles with the Star Excursion Balance Test. Based on the results, those with the 15 highest and those with the 15 lowest stability scores were selected for further testing. Muscle activity of the fibularis longus was recorded with surface electromyography during a sudden inversion perturbation. Each participant was tested under 3 conditions: ankle taped with nonelastic white sports tape, ankle taped with Kinesio Tape, and no ankle taping. Differences in mean muscle activity were evaluated with a 3-way mixed-model analysis of variance (ANOVA) for the 3 conditions, across four 500-millisecond time frames, and between the 2 groups of stable versus unstable participants. Differences in peak muscle activity and in the time to peak muscle activity were evaluated with a 2-way mixed-model ANOVA. RESULTS: Significantly greater mean muscle activity was found when ankles were taped with nonelastic tape compared to no tape, while Kinesio Tape had no significant effect on mean or maximum muscle activity compared to the no-tape condition. Neither stability level nor taping condition had a significant effect on the amount of time from perturbation to maximum activity of the fibularis longus muscle. CONCLUSION: Nonelastic sports tape may enhance dynamic muscle support of the ankle. The efficacy of Kinesio Tape in preventing ankle sprains via the same mechanism is unlikely, as it had no effect on muscle activation of the fibularis longus.

Task dependent changes in mechanical and biomechanical measures result from manipulating stiffness settings in a prosthetic foot.

BACKGROUND: Adaptation of lower limb function to different gait tasks is inherently not as effective among individuals with lower limb amputation as compared to able-bodied individuals. Varying stiffness of a prosthetic foot may be a way of facilitating gait tasks that require larger ankle joint range of motion. METHODS: Three stiffness settings of a novel prosthetic foot design were tested for level walking at three speeds as well as for 7,5° incline and decline walking. Outcome measures, describing ankle range of motion and ankle dynamic joint stiffness were contrasted across the three stiffness settings. Standardized mechanical tests were done for the hindfoot and forefoot. FINDINGS: Dorsiflexion angle was incrementally increased with a softer foot and a faster walking speed / higher degree of slope. The concurrent dynamic joint stiffness exhibited a less systematic change, especially during INCLINE and DECLINE walking. The small difference seen between the stiffness settings for hindfoot loading limits analysis for the effects of stiffness during weight acceptance, however, a stiffer foot significantly restricted plantarflexion during DECLINE. INTERPRETATIONS: Varying stiffness settings within a prosthetic foot does have an effect on prosthetic foot dynamics, and differences are task dependent, specifically in parameters involving kinetic attributes. When considering the need for increased ankle range of motion while performing more demanding gait tasks, a foot that allows the users themselves to adjust stiffness according to the task at hand may be of benefit for active individuals, possibly enhancing the user's satisfaction and comfort during various daily activities.