Is it time to develop specific return to running criteria for ACL rehabilitation? An international survey of physiotherapists criteria for return to running following ACL injury.

OBJECTIVE: To determine return to running criteria currently used by physiotherapists following anterior cruciate ligament (ACL) injury. DESIGN: Self-reported online international survey. METHODS: An online survey of physiotherapists across Australia, the Netherlands and France. RESULTS: A total of 476 respondants participated in the survey across Australia (n = 153), the Netherlands (n = 162), and France (n = 161). For return to running criteria following a non-operative approach, the majority of respondents chose swelling (40.55%, n = 193/476), pain (38.24%, n = 182/476), knee extensor strength (34.34%, n = 163/476), single leg squat (31.93%, n = 152/476) and knee flexor strength (29.83%, n = 142/476). After ACL reconstruction, the highest responses were also swelling (41.18%, n = 196/476), pain (37.18%, n = 177/476), knee extensor strength (37.18%, n = 177/476) and single leg squat (33.19%, n = 158/476). From the identified themes the most common cutoff variables were pain between 0 and 3/10, swelling < grade 1+ and limb symmetry on strength and hop tests >70 %. CONCLUSION: Physiotherapists in Australia, France, and the Netherlands use many different return to running criteria and most of them use more than one criterion. Despite this, there was little consensus on the cut-off physiotherapists use to apply these criteria.

Anterior Cruciate Ligament Rehabilitation for the 10- to 18-Year-Old Adolescent Athlete: Practice Guidelines Based on International Delphi Consensus.

Background: There are 2 treatment options for adolescent athletes with anterior cruciate ligament (ACL) injuries-rehabilitation alone (nonsurgical treatment) or ACL reconstruction plus rehabilitation. However, there is no clear consensus on how to include strength and neuromuscular training during each phase of rehabilitation. Purpose: To develop a practical consensus for adolescent ACL rehabilitation to help provide care to this age group using an international Delphi panel. Study Design: Consensus statement. Methods: A 3-round online international Delphi consensus study was conducted. A mix of open and closed literature-based statements were formulated and sent out to an international panel of 20 ACL rehabilitation experts. Statements were divided into 3 domains as follows: (1) nonsurgical rehabilitation; (2) prehabilitation; and (3) postoperative rehabilitation. Consensus was defined as 70% agreement between panel members. Results: Panel members agreed that rehabilitation should consist of 3 criterion-based phases, with continued injury prevention serving as a fourth phase. They also reached a consensus on rehabilitation being different for 10- to 16-year-olds compared with 17- and 18-year-olds, with a need to distinguish between prepubertal (Tanner stage 1) and mid- to postpubertal (Tanner stages 2-5) athletes. The panel members reached a consensus on the following topics: educational topics during rehabilitation; psychological interventions during rehabilitation; additional consultation of the orthopaedic surgeon; duration of postoperative rehabilitation; exercises during phase 1 of nonsurgical and postoperative rehabilitation; criteria for progression from phase 1 to phase 2; resistance training during phase 2; jumping exercises during phase 2; criteria for progression from phase 2 to phase 3; and criteria for return to sports (RTS). The most notable differences in recommendations for prepubertal compared with mid- to postpubertal athletes were described for resistance training and RTS criteria. Conclusion: Together with available evidence, this international Delphi statement provides a framework based on expert consensus and describes a practice guideline for adolescent ACL rehabilitation, which can be used in day-to-day practice. This is an important step toward reducing practice inconsistencies, improving the quality of rehabilitation after adolescent ACL injuries, and closing the evidence-practice gap while waiting for further studies to provide clarity.

Effects of Pubertal Maturation on ACL Forces During a Landing Task in Females.

BACKGROUND: Rates of anterior cruciate ligament (ACL) rupture in young people have increased by >70% over the past two decades. Adolescent and young adult females are at higher risk of ACL injury as compared with their prepubertal counterparts. PURPOSE: To determine ACL loading during a standardized drop-land-lateral jump in females at different stages of pubertal maturation. STUDY DESIGN: Controlled laboratory study. METHODS: On the basis of the Tanner classification system, 19 pre-, 19 early-/mid-, and 24 late-/postpubertal females performed a standardized drop-land-lateral jump while 3-dimensional body motion, ground-reaction forces, and surface electromyography data were acquired. These data were used to model external biomechanics, lower limb muscle forces, and knee contact forces, which were subsequently used in a validated computational model to estimate ACL loading. Statistical parametric mapping analysis of variance was used to compare ACL force and its causal contributors among the 3 pubertal maturation groups during stance phase of the task. RESULTS: When compared with pre- and early-/midpubertal females, late-/postpubertal females had significantly higher ACL force with mean differences of 471 and 356 N during the first 30% and 48% to 85% of stance, and 343 and 274 N during the first 24% and 59% to 81% of stance, respectively, which overlapped peaks in ACL force. At the point of peak ACL force, contributions from sagittal and transverse plane loading mechanisms to ACL force were higher in late-/postpubertal compared with pre- and early-/midpubertal groups (medium effect sizes from 0.44 to 0.77). No differences were found between pre- and early-/midpubertal groups in ACL force or its contributors. CONCLUSION: The highest ACL forces were observed in late-/postpubertal females, consistent with recently reported rises of ACL injury rates in females aged 15 to 19 years. It is important to quantify ACL force and its contributors during dynamic tasks to advance our understanding of the loading mechanism and thereby provide guidance to injury prevention. CLINICAL RELEVANCE: Growth of ACL volume plateaus around 10 years of age, before pubertal maturation, meaning that a late-/postpubertal female could have an ACL of similar size to their less mature counterparts. However, late-/postpubertal females have higher body mass requiring higher muscle forces to accelerate the body during dynamic tasks, which may increase ACL loading. Thus, if greater forces develop in these females, in part because of their increased body mass, these higher forces will be applied to an ACL that is not proportionally larger. This may partially explain the higher rates of ACL injury in late-/postpubertal females.

Mechanism of Anterior Cruciate Ligament Loading during Dynamic Motor Tasks.

INTRODUCTION: This study determined anterior cruciate ligament (ACL) force and its contributors during a standardized drop-land-lateral jump task using a validated computational model. METHODS: Three-dimensional whole-body kinematics, ground reaction forces, and muscle activation patterns from eight knee-spanning muscles were collected during dynamic tasks performed by healthy recreationally active females (n = 24). These data were used in a combined neuromusculoskeletal and ACL force model to determine lower limb muscle and ACL forces. RESULTS: Peak ACL force (2.3 ± 0.5 bodyweight) was observed at ~14% of stance during the drop-land-lateral jump. The ACL force was primarily generated through the sagittal plane, and muscle was the dominant source of ACL loading. The main ACL antagonists (i.e., loaders) were the gastrocnemii and quadriceps, whereas the hamstrings were the main ACL agonists (i.e., supporters). CONCLUSION: Combining neuromusculoskeletal and ACL force models, the roles of muscle in ACL loading and support were determined during a challenging motor task. Results highlighted the importance of the gastrocnemius in ACL loading, which could be considered more prominently in ACL injury prevention and rehabilitation programs.

Running-related muscle activation patterns and tibial acceleration across puberty.

This study examined whether differences exist in tibial acceleration transients and electromyography (EMG) variables during running across female pubertal development. Sixty-four girls classified as pre- (n = 19), early/mid- (n = 22) and late/post-pubertal development (n = 23) ran in a laboratory whilst EMG data were recorded from quadriceps, hamstring and calf muscle groups, and acceleration transients from a triaxial accelerometer. The late/post-pubertal girls exhibited delayed vastus lateralis onset (mean difference (MD) = 0.02, 95% CI = 0.008, 0.34 ms)) compared to pre-pubertal girls, lower vastus lateralis pre-activation (MD = 7.02, 95% CI = 12.63, 1.42%) compared to early/mid-pubertal girls, and longer time to peak (TTP) anterior/posterior (A/P) tibial acceleration compared to pre-pubertal girls (MD = 0.02, 95% CI = 0.006, 0.03 s). By contrast, late/post-pubertal girls demonstrated earlier semitendinosus onset compared to both early/mid- (MD = 0.02, 95% CI = 0.03, 0.005 ms) and pre-pubertal girls (MD = 0.02, 95% CI = 0.04, 0.007 ms). No other between-group differences were found for peak A/P, vertical and TTP vertical tibial acceleration (p > 0.05). Subsequently, regression analysis revealed that EMG variables accounted for approximately 34% (R2 = 0.34) of the variance in TTP A/P tibial acceleration. These findings highlight that neuromuscular recruitment patterns and kinetics differ across female pubertal development while running and should be further explored in the context of adolescent female musculoskeletal injuries.

Differences and mechanisms underpinning a change in the knee flexion moment while running in stability and neutral footwear among young females.

BACKGROUND: Higher peak external knee flexion moments (KFM) during running has been observed in healthy people wearing athletic footwear compared to barefoot, which may increase risk of knee pathologies such as patellofemoral pain. Currently, no studies have examined whether stability and neutral style athletic shoes influence the peak KFM differently, or explored the underlying biomechanical mechanisms by which footwear alters peak KFM in young females. METHODS: Lower limb biomechanics of sixty girls aged between 10 and 25 years old were collected while running in footwear (both stability and neutral) and barefoot. The external peak KFM, sagittal plane kinematics, sagittal plane knee ground reaction force (GRF) lever arm and sagittal plane resultant GRF magnitude were analysed by repeated measures Analysis of Variance. Linear mixed models were fit to identify predictors of a change in peak KFM, and to determine if the effects of these predictors differed between footwear conditions. RESULTS: The peak KFM was higher wearing both shoe styles compared to barefoot (p < 0.001), while no between-shoe differences were found (p > 0.05). Both shoes also increased kinematic variables at the hip, knee, and ankle (p < 0.05). When all these variables were entered into the mixed model, only a change in the knee-GRF lever arm was predictive of a change in peak KFM wearing shoes compared to barefoot (p < 0.001). CONCLUSION: These findings provide evidence that stability and neutral shoes increase peak KFM compared to barefoot, which is associated with a change in the knee-GRF lever arm rather than a change in lower limb kinematics. Future studies may consider manipulating footwear characteristics to reduce the knee-GRF lever arm in an effort to reduce peak KFM and the potential risk of patellofemoral pain.

Differences in Hip and Knee Landing Moments across Female Pubertal Development.

PURPOSE: The higher prevalence of knee injuries among adolescent females may be related to female pubertal development. The aim of this study was to determine whether girls exhibit higher triplanar knee and hip moments with more advanced pubertal development during a single-limb landing. METHODS: Lower-limb biomechanics of 93 females grouped according to prepubertal (n = 31), early/midpubertal (n = 31) and late/postpubertal (n = 31) development performed a single-limb drop lateral jump. Peak triplanar knee moments and hip moments at the time of peak knee moments were derived from a Vicon motion analysis system and concealed force plate. Joint moments were normalized to body mass (N·m·kg), height (N·m·kg·m) and body mass by height (N·m·kg·m). Between-group differences were analyzed using a one-way ANOVA with Pearson correlations used to explore relationships between joint moments and anthropometrics. RESULTS: Girls at latter stages of puberty landed with higher triplanar knee moments and hip flexion moment at time of peak knee flexion moment when normalized separately to body mass and to height (P < 0.05). In contrast, hip internal rotation moments at time of peak knee internal rotation moment normalized to body mass and to body mass by height were lower in late/postpubertal girls compared to their early/midpubescent (P = 0.01) and prepubescent (P = 0.01) counterparts. Positive correlations were identified between triplanar knee moments and body mass (r = 0.73-0.91, P < 0.001) and height (r = 0.61-0.89, P < 0.001) for all participants. CONCLUSIONS: Higher triplanar knee and sagittal plane hip moments with more advanced pubertal stage is attributed to growth-related increases in body mass and height. Given that growth is a crucial element of puberty, further research is required to quantify the impact of pubertal growth-related changes on risk of adolescent female anterior cruciate ligament injury.

Effect of high and low-supportive footwear on female tri-planar knee moments during single limb landing.

BACKGROUND: Higher landing-related external knee joint moments at later stages of female pubertal development likely contribute to a higher incidence of non-contact anterior cruciate ligament (ACL) injury. Athletic footwear may provide a potential strategy to alter higher knee moments. METHODS: Thirty-one late/post-pubertal girls (Tanner stage IV-V, menarche and growth spurt attained) performed a single limb drop lateral jump in three footwear conditions (barefoot, low support shoes and high support shoes), in which peak knee abduction moment (KAbM), flexion moment (KFM) and internal rotation moments (KIRM) were measured. Repeated measures ANOVA and ANCOVA were used to test for a main effect of footwear with and without foot posture index (FPI) as a covariate (p < 0.05) with post-hoc test carried out via Fisher's Least Significant Difference (LSD). RESULTS: A main effect of footwear condition was observed for peak KFM (p < 0.05), but not KAbM or KIRM, in both unadjusted and adjusted models. Post-hoc analysis demonstrated that both high- and low-support shoes increased peak KFM compared with barefoot (p < 0.001). CONCLUSION: Our findings indicate commercially available high- and low-supportive footwear increase peak KFM, but do not effect KAbM or KIRM while landing among late/post-pubertal girls. This suggests that these styles of footwear are inadequate at reducing higher knee moments in an at-risk cohort.

Differences in Hip and Knee Running Moments across Female Pubertal Development.

PURPOSE: This study aimed to investigate whether knee and hip running moments differ across stages of female pubertal development. METHODS: This was a cross-sectional study comparing the barefoot running moments of 91 prepubertal (n = 31, Tanner stage I), early/midpubertal (n = 30, Tanner stages II and III), and late/postpubertal (n = 30, Tanner stages IV and V) girls. External peak moments for knee abduction (KAbM), knee adduction (KAM), knee flexion (KFM), and knee internal rotation (KIRM) were analyzed. Secondary measures of hip adduction moment at the time of peak KAbM and hip flexion moment at the time of peak KFM were also derived. Between-group differences were analyzed using a series of one-way ANOVAs and ANCOVAs. RESULTS: At the knee, the late/postpubertal girls displayed a higher peak KFM and KAM compared with the prepubertal group (P < 0.05), and the early/midpubertal group exhibited a higher peak KFM than the prepubertal group (P = 0.034). No between-group differences were found for peak KAbM or KIRM (P > 0.05). At the hip, both the late/postpubertal (P = 0.03) and early/midpubertal girls (P = 0.039) ran with a lower hip adduction moment at the time of peak KAbM than the prepubertal girls. The hip flexion moment at the time of peak KFM in late/postpubertal girls was also significantly lower than both the early/mid- and prepubertal girls (P < 0.001). CONCLUSION: Girls at the latter stages of puberty exhibit higher peak external knee flexion and adduction moments, but not abduction or internal rotation moments. This may be partly attributed to a lower hip flexion but higher hip abduction moment at the time of peak knee moments. Future research should examine whether these differences in knee kinetics between pubertal stages have implications for knee injuries such as patellofemoral pain syndrome.

Hsp72 preserves muscle function and slows progression of severe muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a severe and progressive muscle wasting disorder caused by mutations in the dystrophin gene that result in the absence of the membrane-stabilizing protein dystrophin. Dystrophin-deficient muscle fibres are fragile and susceptible to an influx of Ca(2+), which activates inflammatory and muscle degenerative pathways. At present there is no cure for DMD, and existing therapies are ineffective. Here we show that increasing the expression of intramuscular heat shock protein 72 (Hsp72) preserves muscle strength and ameliorates the dystrophic pathology in two mouse models of muscular dystrophy. Treatment with BGP-15 (a pharmacological inducer of Hsp72 currently in clinical trials for diabetes) improved muscle architecture, strength and contractile function in severely affected diaphragm muscles in mdx dystrophic mice. In dko mice, a phenocopy of DMD that results in severe spinal curvature (kyphosis), muscle weakness and premature death, BGP-15 decreased kyphosis, improved the dystrophic pathophysiology in limb and diaphragm muscles and extended lifespan. We found that the sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA, the main protein responsible for the removal of intracellular Ca(2+)) is dysfunctional in severely affected muscles of mdx and dko mice, and that Hsp72 interacts with SERCA to preserve its function under conditions of stress, ultimately contributing to the decreased muscle degeneration seen with Hsp72 upregulation. Treatment with BGP-15 similarly increased SERCA activity in dystrophic skeletal muscles. Our results provide evidence that increasing the expression of Hsp72 in muscle (through the administration of BGP-15) has significant therapeutic potential for DMD and related conditions, either as a self-contained therapy or as an adjuvant with other potential treatments, including gene, cell and pharmacological therapies.