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Hamstring strain injuries (HSIs) are prevalent in sports involving high-speed running and most of the HSIs are biceps femoris long head (BFlh) injuries. The primary cause for HSIs during high-speed running remains controversial due to the lack of in vivo measurement of the BFlh muscle behavior during running. Therefore, the purpose of this study was to quantify the muscle-tendon unit (MTU) and fascicle behavior of BFlh during running. Seven college male sprinters (22.14 ± 1.8 years; 177.7 ± 2.5 cm; 70.57 ± 5.1 kg; personal bests in 100m: 11.1 ± 0.2 s) were tested on a motorized treadmill instrumented with two force plate for running at 4, 5, 6m/s. The ground reaction force (GRF), 3D lower limb kinematics, EMG, and ultrasound images of biceps femoris long head (BFlh) in the middle region were recorded simultaneously. BFlh fascicles undergo little length change (about 1 cm) in the late swing phase during running at three submaximal speeds. BFlh fascicle lengthening accounted for about 30% of MTU length change during the late swing phase. BFlh was most active during the late swing and early stance phases, ranging from 83%MVC at a running speed of 4 m/s to 116%MVC at 6 m/s. Muscle fascicles in the middle region of BFlh undergo relatively little lengthening relative to the MTU in the late swing phase during running in comparison to results from simulation studies. These results suggest that there is a decoupling between the fascicle in the middle region and MTU length changes during the late swing phase of running., (© Journal of Sports Science and Medicine.)

This study aimed to characterize muscle activity in male soccer players with a history of hamstring strain injuries (HSI) during accelerated sprinting. Thirteen patients each in the HSI group (history of HSI) and in the healthy group (with no history of HSI) were included. 26 male soccer players of which 13 with and 13 without HSI history were included in this study. Ten muscles were evaluated on electromyography activity during overground sprinting. The testing protocol consisted of a maximal sprint over a distance of 30 meters. One running stride was divided into the early stance phase, late stance phase, early swing phase, mid-swing phase, and late swing phase, and the average muscle activity per phase and the timing of the peak root-mean-square value appearance during each stride were calculated. Statistical analysis was performed using repeated-measures two-way ANOVA (group × phase), and multiple comparison tests were performed using the Bonferroni method when the interaction or main effect was significant. The statistical significance level was set at p < 0.05. Gluteus maximus (Gmax), gluteus medius (Gmed), and external oblique (EO) showed activity differences based on HSI history. Gmax was 30% lower, EO was 20% lower, and Gmed was 40% higher in HSI group. This study suggests that, despite previous findings that HSI is most likely during the late swing phase, the HSI group shows a higher injury risk in the early stance phase. This is due to differences in trunk and gluteal muscle activity between the late swing and early stance phases compared to the healthy group. In summary, HSI group had lower activity in the muscles contributing to trunk instability, especially EO and Gmax, before and after ground impact during accelerated sprinting, compared to Healthy., (© Journal of Sports Science and Medicine.)

Introduction: Ankle braces can effectively decrease the incidence of recurrent ankle sprain; however, whether the brace can decrease the severity of sprain and its related mechanism during sprain remain unknown., Methods: Twenty-two patients with functional ankle instability (FAI) (12 males and 10 females) and 16 healthy subjects (8 males and 8 females) were enrolled in this study. All of the subjects walked on a custom-built tilting platform that offered a 30° inversion (IV) to mimic the IV of ankle sprain. We collected the kinematic and surface electromyography data of patients with FAI with or without ankle brace and normal controls 6 times., Results: The FAI without brace group showed significantly higher maximum IV angles and average IV velocities than the control group (P < .001). The FAI with brace group revealed significantly lower maximum IV angles and average IV velocities than the FAI without brace group (P < .001); this group also showed significantly higher maximum external rotation (ER) angle and average ER velocities than the FAI with brace (P < .001) and control (P < .001) groups. The FAI with brace group indicated significantly lower average EMGPrep (P = .047), EMGTilt (P = .037), and EMGafterTilt (P = .004) of the peroneus longus than the FAI without brace group., Conclusions: The ankle brace could effectively decrease IV angles and their velocities and increase ER angles and their corresponding velocities during ankle sprain in patients with FAI. It could also decrease the activity of the peroneus longus muscle during ankle sprain., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

Introduction: Ankle sprains are the second most common sports injury after knee injuries, with about 85% of them affecting the lateral ankle ligaments. These injuries are particularly prevalent in sports like basketball and volleyball., Purpose: To investigate the effect of Aquatic therapy as an early rehabilitation protocol for elite athletes with acute lateral ankle sprain grade III on back-to-sport time, dynamic balance, pain, Athletic performance, and muscle power compared to land-based exercise training., Methods: Thirty elite athletes have ankle sprain grade III with sprain onset from 1 to 7 days, their age ranges from 18-30 years old were recruited. All participants are professional athletes; mainly participating in above-head sports such as volleyball and basketball. The patients were randomly allocated into two treatment groups: Group I (control group): 15 patients received a conventional physical therapy program of structured therapeutic exercise program, manual therapy and land-based exercises, in addition to external support, and Group II (Aquatic therapy group): 15 patients received aquatic training. Visual Analog Scale (VAS) was used to measure the pain intensity, while the dynamic balance was measured by the Star Excursion Balance Test. Athletic performance was measured by HOP Tests (Single, Triple, 6-m, and Cross-over hops) aided by the Agility T-Test (ATT) and Illinois Agility Test (IAT). Muscle power was tested by a Single Leg Press. Finally, back to sports time was recorded for each participant in both groups., Results: There was a significant interaction effect of Aquatic therapy and time for VAS (p < 0.001), single hop (p < 0.001), triple hop (p < 0.001), cross-over hop (p < 0.001), IAT (p = 0.019) and ATT (p < 0.001) of both affected and nonaffected. There was no significant interaction effect of Aquatic therapy and time for 6-MHT of affected (p = 0.923), and nonaffected (p = 0.140). There was a significant main effect of time for all dependent variables (p < 0.001) except for 6-MHT of affected (p = 0.939), nonaffected (p = 0.109), and IAT (p = 0.099). The Star excursion dynamic balance test (SEBT) and Single leg press revealed a significant difference between groups on affected and non-affected sides (p < 0.001*). Lastly and most importantly the back-to-sport time revealed a significant difference in the return-to-sport time in favor of the Aquatic therapy group who returned faster than the control group (p < 0.001*)., Conclusion: Aquatic therapy is more effective than traditional protocols regarding early rehabilitation of acute ankle sprain grade III in Elite professional athletes for reducing pain intensity, improving dynamic balance and athletic performance and power and accelerating their return to sports time. Because aquatic therapy produces better outcomes, it is advised to be included in the rehabilitation programs of athletic patients with acute ankle sprains grade III., (© 2024. The Author(s).)

Background: Acute lateral ankle sprains (ALAS) are associated with long-term impairments and instability tied to altered neural excitability. Arthrogenic muscle inhibition (AMI) has been observed in this population; however, relationships with injury-related impairments are unclear, potentially due to the resting, prone position in which AMI is typically measured. Assessing AMI during bipedal stance may provide a better understanding of this relationship., Methods: AMI was assessed in 38 young adults (19 ALAS within 72 h of injury: 10 males, 21.4 ± 2.7 years; 19 healthy controls: 10 males, 21.9 ± 2.2 years; mean ± SD) using the Hoffmann reflex (H-reflex) during bipedal stance. Electrical stimulation was administered to identify the maximal H-reflex (H max ) and maximal motor response (M max ) from the soleus, fibularis longus, and tibialis anterior muscles. The primary outcome measure was the H max /M max ratio. Secondary outcomes included acute symptoms (pain and swelling), postural control during bipedal stance, and self-reported function., Results: No significant group-by-limb interactions were observed for any muscle. However, a significant group main effect was observed in the soleus muscle (F (1,35)  = 6.82, p = 0.013), indicating significantly lower H max /M max ratios following ALAS (0.38 ± 0.20) compared to healthy controls (0.53 ± 0.16). Furthermore, lower H max /M max ratios in the soleus significantly correlated with acute symptoms and self-reported function but not with postural control., Conclusion: This study supports previous evidence of AMI in patients with ALAS, providing insight into neurophysiologic impacts of musculoskeletal injury. Our results suggest that assessing AMI in a standing position following acute injury may provide valuable insight into how AMI develops and guide potential therapeutic options to curb and offset the formation of joint instability., (Copyright © 2024. Production and hosting by Elsevier B.V.)

Purpose : Acute ankle sprain may affect ankle function during sport and daily activities. This study aimed to use vector coding technique to analyze the difference over time between injured and healthy lower limb during the first week of acute ankle sprain phase (P1) and post a 1-month recovery phase (P2) to understand the return-to-play coordination strategy in the lower extremity. Methods : Six females attended the gait experiments with attached 40 reflective markers using eight-camera Vicon motion capture system. All participants walked barefoot while turning in four directions (T0°, T45°, T90°, T135°) at their self-selected speed. Coordination patterns were classified as in-phase, anti-phase, proximal or distal dominancy between lower limb joints involving hip, knee, ankle, subtalar, metatarsophalangeal (MTP) joint and tarsometatarsal (TMT) joint. Results : P1 showed more proximal joint dominant in Hip-Knee coupling angles but P2 displayed more distal joint dominant in Knee-Ankle joint coordination pattern and mainly distal joint dominant in Ankle-MTP coupling angle mapping. The Ankle-TMT1 and Ankle-TMT5 coordination patterns matched best in straight walking but worst in T135 walking. Conclusions : Investigating inter-segmental coordination in different turning movements could provide insights into gait changes from acute ankle sprain from one-month return-to-play recovery. Knowledge of lower limb coordination pattern may provide clinical implications to improve dynamic balance and gait stability for individuals with acute ankle sprain., (© 2023 Xiaoyi Yang et al., published by Sciendo.)

Background: In a closed claims study, most patients experiencing cervical spinal cord injury had stable cervical spines. This raises two questions. First, in the presence of an intact (stable) cervical spine, are there tracheal intubation conditions in which cervical intervertebral motions exceed physiologically normal maximum values? Second, with an intact spine, are there tracheal intubation conditions in which potentially injurious cervical cord strains can occur?, Methods: This study utilized a computational model of the cervical spine and cord to predict intervertebral motions (rotation, translation) and cord strains (stretch, compression). Routine (Macintosh) intubation force conditions were defined by a specific application location (mid-C3 vertebral body), magnitude (48.8 N), and direction (70 degrees). A total of 48 intubation conditions were modeled: all combinations of 4 force locations (cephalad and caudad of routine), 4 magnitudes (50 to 200% of routine), and 3 directions (50, 70, and 90 degrees). Modeled maximum intervertebral motions were compared to motions reported in previous clinical studies of the range of voluntary cervical motion. Modeled peak cord strains were compared to potential strain injury thresholds., Results: Modeled maximum intervertebral motions occurred with maximum force magnitude (97.6 N) and did not differ from physiologically normal maximum motion values. Peak tensile cord strains (stretch) did not exceed the potential injury threshold (0.14) in any of the 48 force conditions. Peak compressive strains exceeded the potential injury threshold (-0.20) in 3 of 48 conditions, all with maximum force magnitude applied in a nonroutine location., Conclusions: With an intact cervical spine, even with application of twice the routine value of force magnitude, intervertebral motions during intubation did not exceed physiologically normal maximum values. However, under nonroutine high-force conditions, compressive strains exceeded potentially injurious values. In patients whose cords have less than normal tolerance to acute strain, compressive strains occurring with routine intubation forces may reach potentially injurious values., (Copyright © 2021, the American Society of Anesthesiologists. All Rights Reserved.)

Purpose: This study aimed 1) to determine whether talar cartilage deformation measured via ultrasonography (US) after standing and hopping loading protocols differs between chronic ankle instability (CAI) patients and healthy controls and 2) to determine whether the US measurement of cartilage deformation reflects viscoelasticity between standing and hopping protocols., Methods: A total of 30 CAI and 30 controls participated. After a 60-min off-loading period, US images of the talar cartilage were acquired before and after static (2-min single-leg standing) and dynamic (60 single-leg forward hops) loading conditions. We calculated cartilage deformation by assessing the change in average thickness (mm) for overall, medial, and lateral talar cartilage. The independent variables include time (Pre60 and postloading), condition (standing and dynamic loading), and group (CAI and control). A three-way mixed-model repeated-measures ANCOVA and appropriate post hoc tests were used to compare cartilage deformation between the groups after static and dynamic loading., Results: After the static loading condition, those with CAI had greater talar cartilage deformation compared with healthy individuals for overall (-10.87% vs -6.84%, P = 0.032) and medial (-12.98% vs -5.80%, P = 0.006) talar cartilage. Similarly, the CAI group had greater deformation relative to the control group for overall (-8.59% vs -3.46%, P = 0.038) and medial (-8.51% vs -3.31%, P = 0.043) talar cartilage after the dynamic loading condition. In the combined cohort, cartilage deformation was greater after static loading compared with dynamic in overall (-8.85% vs -6.03%, P = 0.003), medial (-9.38% vs -5.91%, P = 0.043), and lateral (-7.90% vs -5.65%, P = 0.009) cartilage., Conclusion: US is capable of detecting differences in cartilage deformation between those with CAI and uninjured controls after standardized physiologic loads. Across both groups, our results demonstrate that static loading results in greater cartilage deformation compared with dynamic loading., (Copyright © 2021 by the American College of Sports Medicine.)

Background: High-speed running is commonly implicated in the genesis of hamstring injury. The success of hamstring injury management is typically quantified by the duration of time loss or reinjury rate. These metrics do not consider any loss in performance after returning to play from hamstring injury. It is not known to what extent high-speed running is altered on return to play after such injury., Hypothesis: Match high-speed running distance will change after returning from hamstring injury., Study Design: Non-randomized cohort., Level of Evidence: Level 3., Methods: Match high-speed running distance in highest level professional football (soccer, Rugby League, Rugby Union, and Australian Rules) were examined for a minimum of 5 games prior and subsequent to hamstring strain injury for individual differences using a linear regression models approach. A total of 22 injuries in 15 players were available for analysis., Results: Preinjury cumulative high-speed running distances were strongly correlated for each individual ( r 2 = 0.92-1.0; P < 0.0001). Pre- and postinjury high-speed running data were available for a median of 15 matches (range, 6-15). Variance from the preinjury high-speed running distance was significantly less ( P = 0.0005) than the post injury values suggesting a suppression of high-speed running distance after returning from injury. On return to play, 7 of the 15 players showed a sustained absolute reduction in preinjury high-speed running distance, 7 showed no change, and 1 player (only) showed an increase. Analysis of subsequent (second and third injury) return to play showed no differences to return from the index injury., Conclusion: Return to play was not associated with return to high-speed running performance for nearly half of the players examined, although the same number showed no difference. Persisting deficits in match high-speed running may exist for many players after hamstring strain injury., Clinical Relevance: Returning to play does not mean returning to (high-speed running) performance for nearly half of the high-level professional football players examined in this study. This suggests that successful return to play metrics should be expanded from simple time taken and recurrence to include performance.

This review aimed to investigate characteristics of muscle activation and ground reaction force (GRF) patterns in patients with ankle instability (AI). Relevant studies were sourced from PubMed, CINAHL, SPORTDiscus, and Web of Science through December 2019 for case-control study in any laboratory setting. Inclusion criteria for study selection were (1) subjects with chronic, functional, or mechanical instability or recurrent ankle sprains; (2) primary outcomes consisted of muscle activation of the lower extremity and GRF during landing; and (3) peer-reviewed articles with full text available, including mean, standard deviation, and sample size, to enable data reanalysis. We evaluated four variables related to landing task: (1) muscle activation of the lower extremity before landing, (2) muscle activation of the lower extremity during landing, (3) magnitude of GRF, and (4) time to peak GRF. The effect size using standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated for these variables to make comparisons across studies. Patients with AI had a lower activation of peroneal muscles before landing (SMD = -0.63, p < 0.001, CI = -0.95 to -0.31), greater peak vertical GRF (SMD = 0.21, p = 0.03, CI = 0.01 to 0.40), and shorter time to peak vertical GRF (SMD = -0.51, p < 0.001, CI = -0.72 to -0.29) than those of normal subjects during landing. There was no significant difference in other muscle activation and GRF components between the patients with AI and normal subjects ( p > 0.05). Altered muscle activation and GRF before and during landing in AI cases may contribute to both recurrent ankle and ACL injuries and degenerative change of articular., (© Journal of Sports Science and Medicine.)

Context: Approximately 72% of patients with an ankle sprain report residual symptoms 6 to 18 months later. Although 44% of patients return to activity in less than 24 hours after experiencing a sprain, residual symptoms should be evaluated in the long term to determine if deficits exist. These residual symptoms may be due to the quality of ligament tissue and motion after injury., Objective: To compare mechanical laxity of the talocrural joint and dorsiflexion range of motion (DFROM) over time (24 to 72 hours, 2 to 4 weeks, and 6 months) after an acute lateral ankle sprain (LAS)., Design: Cross-sectional study., Setting: Athletic training research laboratory., Patients or Other Participants: A total of 108 volunteers were recruited. Fifty-five participants had an acute LAS and 53 participants were control individuals without a history of LAS., Main Outcome Measure(s): Mechanical laxity (talofibular interval and anterior talofibular ligament length) was measured in inversion (INV) and via the anterior drawer test. The weight-bearing lunge test was conducted and DFROM was measured. The data were analyzed using repeated-measures analysis of variance, independent-samples t tests, and 1-way analysis of variance., Results: Of the 55 LASs, 21 (38%) were grade I, 27 (49%) were grade II, and 7 (13%) were grade III. Increases were noted in DFROM over time, between 24 and 72 hours, at 2 to 4 weeks, and at 6 months (P < .05). The DFROM was less in participants with grade III than grade I LASs (P = .004) at 24 to 72 hours; INV length was greater at 24 to 72 hours than at 2 to 4 weeks (P = .023) and at 6 months (P = .035) than at 24 to 72 hours. The anterior drawer length (P = .001) and INV talofibular interval (P = .004) were greater in the LAS group than in the control group at 6 months., Conclusions: Differences in range of motion and laxity were evident among grades at various time points and may indicate different clinical responses after an LAS., (© by the National Athletic Trainers' Association, Inc.)

Recently, coupled musculoskeletal-finite element modelling approaches have emerged as a way to investigate femoral neck loading during various daily activities. Combining personalised gait data with finite element models will not only allow us to study changes in motion/movement, but also their effects on critical internal structures, such as the femur. However, previous studies have been hampered by the small sample size and the lack of fully personalised data in order to construct the coupled model. Therefore, the aim of this study was to build a pipeline for a fully personalised multiscale (body-organ level) model to investigate the strain levels at the femoral neck during a normal gait cycle. Five postmenopausal women were included in this study. The CT and MRI scans of the lower limb, and gait data were collected for all participants. Muscle forces derived from the body level musculoskeletal models were used as boundary constraints on the finite element femur models. Principal strains were estimated at the femoral neck region during a full gait cycle. Considerable variation was found in the predicted peak strain among individuals with mean peak first principal strain of 0.24% ± 0.11% and mean third principal strain of -0.29% ± 0.24%. For four individuals, two overall peaks of the maximum strains were found to occur when both feet were in contact with the floor, while one individual had one peak at the toe-off phase. Both the joint contact forces and the muscular forces were found to substantially influence the loading at the femoral neck. A higher correlation was found between the predicted peak strains and the gluteus medius (R2 ranged between 0.95 and 0.99) than the hip joint contact forces (R2 ranged between 0.63 and 0.96). Therefore, the current findings suggest that personal variations are substantial, and hence it is important to consider multiple subjects before deriving general conclusions for a target population., Competing Interests: The authors have declared that no competing interests exist.

Background: Unexplained pain in the medial proximal tibia frequently leads to revision after unicondylar knee arthroplasty (UKA). As one of the most important factors for osteogenic adaptive response, increased bone strain following UKA has been suggested as a possible cause., Questions/purposes: In this study we: (1) performed a cadaver-based kinematic analysis on paired cadaveric specimens before and after mobile-bearing and fixed-bearing UKA; and (2) simultaneously characterized the strain distribution in the anterior and posterior proximal tibia during squatting., Methods: Five pairs of fresh, frozen full-leg cadaver specimens (four male, one female, 64 years to 87 years) were subjected to a dynamic squatting motion on a kinematic rig to simulate joint loading for a large ROM. Forces were applied to the quadriceps and hamstrings during the simulation while an infrared camera system tracked the location of reflective markers attached to the tibia and femur. Tibial cortical bone strain was measured with stacked strain gauge rosettes attached at predefined anterior and posterior positions on the medial cortex. Pairwise implantation of mobile-bearing (UKAMB) and fixed-bearing implants (UKAFB) allowed a direct comparison of right and left knees from the same donor through a linear mixed model., Results: UKAMB more closely replicated native kinematics in terms of tibial rotation and in AP and mediolateral translation. Maximum principal bone strain values were consistently increased compared with native (anteromedial, mean [± SD] peak strain: 311 µε ± 190 and posterior, mean peak strain: 321 µε ± 147) with both designs in the anteromedial (UKAFB, mean peak strain: 551 µε ± 381, Cohen's d effect size 1.3 and UKAMB, mean peak strain: 596 µε ± 564, Cohen's d effect size 1.5) and posterior (UKAFB, mean peak strain: 505 µε ± 511, Cohen's d effect size 1.3 and UKAMB, mean peak strain: 633 µε ± 424, Cohen's d effect size 2.1) region. However, in the anterolateral region of the medial tibial bone, UKAFB demonstrated the overall largest increase in strain (mean peak strain: 1010 µε ± 787, Cohen's d effect size 1.9), while UKAMB (613 µε ± 395, Cohen's d effect size 0.2) closely replicated values of the native knee (563 µε ± 234)., Conclusion: In this in vitro cadaver study both UKAMB and UKAFB led to an increase in bone strain in comparison with the native knee. However, in the anterolateral region of the medial tibial plateau, proximal tibial bone strain was lower after UKAMB and UKAFB. Both UKAMB and UKAFB lead to comparable increases in anteromedial and posterior tibial strain in comparison with the native knee. In the anterolateral region of the medial tibial plateau UKA, proximal tibial bone strain was closer to the native knee after UKAMB than after UKAFB. In an attempt to link kinematics and strain behavior of these designs there seemed to be no obvious relation., Clinical Relevance: Further clinical research may be able to discern whether the observed differences in cortical strain after UKA is associated with unexplained pain in patients and whether the observed differences in cortical bone strain between mobile-bearing and fixed unicondylar designs results in a further difference in unexplained pain.

Introduction: There is a lack of definitive evidence supporting deficits in voluntary activation in participants with prior hamstring injury; moreover, it remains unknown if spinal mechanisms contribute to suspected deficits., Purpose: This study aimed to determine the effect of prior hamstring strain injury on knee flexor concentric and eccentric strength, voluntary activation, surface electromyographic (sEMG) activity, and stretch and tendon reflex amplitudes., Methods: Twenty-five participants were recruited, 12 with a history of unilateral hamstring strain injury of at least moderate severity. Voluntary activation, strength, and sEMG activity were recorded during maximal eccentric and concentric knee flexor contractions at 60°·s. Stretch and tendon reflexes were also recorded at rest., Results: Previously injured limbs exhibited lower levels of voluntary activation (mean difference = -24.1%, 95% confidence interval [CI] = -34.1% to -14.0%, P < 0.001), strength (mean difference vs control group = -0.37 Nm·kg, 95% CI = -0.71% to -0.03 N·m·kg, P = 0.03), and normalized sEMG (mean difference = -17%, 95% CI = -32% to -2%, P = 0.02) during maximal eccentric knee flexor contractions compared with control group. No such differences were seen in concentric contractions. Stretch reflexes (mean difference = -3.8%, 95% CI = -6.8 to -0.8, P = 0.02) and tendon reflexes (mean difference = -13%, 95% CI = -26% to 0%, P = 0.04) were also lower in previously injured compared with control biceps femoris muscles., Conclusion: Moderate to severe hamstring strain injury is associated with long-term deficits in voluntary activation during maximal eccentric contraction. Hamstring injury history is also associated with deficits in stretch reflex and tendon reflex amplitude.

Background: The interaction of functional and mechanical deficits in chronic ankle instability remains a major issue in current research. After an index sprain, some patients develop sufficient coping strategies, while others require mechanical support. This study aimed to analyze persisting functional deficits in mechanically unstable ankles requiring operative stabilization., Methods: We retrospectively analyzed the functional testing of 43 patients suffering from chronic, unilateral mechanical ankle instability (MAI) and in which long-term conservative treatment had failed. Manual testing and arthroscopy confirmed mechanical instability. The functional testing included balance test, gait analysis, and concentric-concentric, isokinetic strength measurements and was compared between the non-affected and the MAI ankles., Results: Plantarflexion, supination, and pronation strength was significantly reduced in MAI ankles. A sub-analysis of the strength measurement revealed that in non-MAI ankles, the peak pronation torque was reached earlier during pronation (maximum peak torque angle at 20° vs. 14° of supination, p < 0.001). Furthermore, active range of motion was reduced in dorsiflexion and supination. In balance testing, patients exhibited a significant increased perimeter for the injured ankle (p < 0.02). During gait analysis, we observed an increased external rotation in MAI (8.7 vs. 6.8°, p<0.02)., Conclusions: This study assesses functional deficits existent in a well-defined population of patients suffering from chronic MAI. Impairments of postural sway, gait asymmetries, and asymmetric isokinetic strength can be observed despite long-term functional treatment. The finding that pronation strength is particularly reduced with the foot in a close-to-accident position indicates potential muscular dysfunction in MAI. Possibly, these deficits alongside the underlying mechanical instability characterize patients requiring mechanical stabilization.

Introduction: Chronic ankle instability (CAI) is known to induce impairments throughout the lower quarter kinetic chain, however there is currently no synthesized information on proximal adaptations of the trunk, hip, thigh, and knee for neuromuscular and biomechanical outcomes during strength, balance, jumping, and gait among CAI patients. The purpose of this systematic review and meta-analysis was to synthesize trunk, hip, thigh and knee neuromuscular and biomechanical outcome measures during functional assessments when comparing CAI to healthy groups., Methods: Cumulative Index of Nursing and Allied Health Literature and Medical Literature Analysis and Retrieval System Online with PubMed databases were searched on June 3, 2019. Studies comparing outcomes at the trunk, hip, thigh, or knee regardless of assessment type in CAI versus healthy groups were considered for inclusion. Assessment categories were used to differentiate adaptations by assessment type after inclusion. Two independent reviewers assessed methodological quality using the Physiotherapy Evidence Database scoring criteria. Data pertaining to study methodology and primary proximal adaptation outcomes were extracted. Separate random effects meta-analyses were performed for consistently reported outcome measures., Results: Pooled estimates reflected that CAI patients had decreased triplanar isometric hip strength outcomes (P < 0.001, effect size range: 0.52-0.93). Knee kinematics did not differ from healthy groups during dynamic balance testing (P = 0.26). Few studies found CAI patients have altered knee kinematics during jumping tasks. The remaining findings were isolated to individual studies and thus inconclusive., Conclusions: The CAI groups demonstrated triplanar hip strength deficits and altered knee flexion angles during jumping assessments. Clinicians should consider proximal evaluations and interventions for CAI patients.

Purpose: The sudden rise in the injury incidence during adolescence is also evident in soccer-related injuries to the groin. Submaximal passing applies high stress on the adductor muscles and pubic symphysis and is therefore likely to be connected to the occurrence of groin injuries. Therefore, the purpose of the study was to compare hip joint kinematics and adductor muscle forces of different adolescent age groups during submaximal soccer passing., Methods: Sixty participants, in four groups, younger than 12, 15, 16. and 23 yr (U12, U15, U16, U23), were analyzed. A Footbonaut, equipped with a 3D motion capture system consisting of 16 cameras, was used to capture kinematic data of short passes. Inverse dynamic analysis was performed to calculate muscle forces of 10 passes of each subject., Results: The U15 group showed reduced angular velocities. A rise in hip adductor muscle forces was evident from the youngest group up to the oldest groups. The largest increase (49%) was found between U12 and U15. Lower-limb mass was identified as the best predictor for the increasing adductor force., Conclusions: The reduced angular velocities of the U15 and the increase in muscle forces between all age groups were attributed to the increasing segment masses and length. This increases the moments of inertia of the leg segments thereby demanding higher forces to accelerate the segments. Most likely, the stress put upon the adductors apophyses increases during adolescence, as tendons are known to adapt slower than muscles, increasing the risk for overuse injuries. Coaches could use lower-limb mass as an indicator for fast increases in the force demand to identify players who would benefit from a reduced training volume.

Patients with chronic ankle instability (CAI) have postural-control deficits during center-of-pressure excursions than do healthy individuals. While an external analysis of center-of-pressure excursions in CAI has been performed, a quantitative analysis of center-of-gravity movements, to detect the balance deficits associated with CAI, has yet to be performed. Therefore, the aim of the study is to quantify the balance deficits in patients with unilateral CAI.Forty-four patients with unilateral CAI (24 men; age, 31.7 ± 5.5 years) and 26 uninjured volunteers (12 men; age, 28.6 ± 5.9 years) underwent Neurocom Balance Manager assessments of dynamic and static balance responses in limits of stability, unilateral stance, and forward lunge tests.In the limits of stability test, there were no significant group differences in the forward direction; however, reaction times were longer in the CAI group than in the control group in the backward (P = .037, effect size [ES] = 0.49) and rightward directions (P = .032, ES  = 0.47). Furthermore, the CAI group showed more excursions in the rightward (P = .046, ES = 0.50) and leftward directions (P = .002, ES = 0.80), and less directional control in the leftward direction (P = .036, ES = 0.59). In the unilateral stance test, the center of gravity sway velocity was faster in the CAI group than in the control group, whether eyes were opened or closed (P < .05). There were no significant group differences in forward lunge-test outcomes.Patients with CAI have poor static and dynamic balance performance compared to that in healthy counterparts. Thus, balance retraining should be an essential component of rehabilitation programs for patients with CAI.

Background: Repetitive microtrauma can result in a hypertrophied ATFL. Previous studies have found that the anterior talofibular ligament thickness (ATFLT) is correlated with lateral ankle sprains, ligament injuries and chronic stroke in patients, and thickened anterior talofibular ligament (ATFL) has been considered to be a major morphologic parameter of hypertrophied ATFL. However, hypertrophy is different from thickness. Thus, we devised the anterior talofibular ligament area (ATFLA) as a new morphological parameter to evaluate the hypertrophy of the whole ATFL., Methods: ATFL samples were collected from 53 patients with sprain group and from 50 control subjects who underwent magnetic resonance imaging (MRI) of the ankle and revealed no evidence of lateral ankle injury. Axial T1-weighted MRI images were collected at the ankle level from all subjects. We measured the ATFLA and ATFLT at the anterior margin of the fibular malleolus to the talus bone on the MRI using a picture archiving and communications system. The ATFLA was measured as the whole cross-sectional ligament area of the ATFL that was most hypertrophied in the axial MR images. The ATFLT was measured as the thickest point between the lateral malleolus and the talus of the ankle., Results: The average ATFLA was 25.0 ± 6.0 mm 2 in the control group and 47.1 ± 10.4 mm 2 in the sprain group. The average ATFLT was 2.3 ± 0.6 mm in the control group and 3.8 ± 0.6 mm in the hypertrophied group. Patients in sprain group had significantly greater ATFLA (p < 0.001) and ATFLT (p < 0.001) than the control subjects. A Receiver Operator Characteristics curve analysis showed that the best cut-off point of the ATFLA was 34.8 mm 2 , with 94.3% sensitivity, 94.0% specificity, and an AUC of 0.97 (95% CI, 0.94-1.00). The optimal cut-off point of the ATFLT was 3.1 mm, with 86.8% sensitivity, 86.0% specificity, and AUC of 0.95 (95% CI, 0.92-0.99)., Conclusion: ATFLA is a new morphological parameter for evaluating chronic ankle sprain, and may even be more sensitive than ATFLT., (Copyright © 2019 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Little is known about the strains at the glenoid near the bone-implant interface in reverse shoulder arthroplasty. The purpose of the current study was to evaluate the strains on the glenoid bone under a compressive load after implantation of three different sizes of metal-backed baseplates in either inferior or superior position in combination with three different sizes of glenospheres and three different glenosphere designs., Methods: Three sizes of baseplates (small, medium, large) were implanted in thirty-six paired human cadaveric scapulae either inferior, flush with the glenoid neck, or with a 5 mm superior offset. Glenospheres were available in three sizes (36 mm, 39 mm, 42 mm) and designs (standard, 4 mm lateralized, 2.5 mm inferiorized). Specimens were mounted in a servo-hydraulic testing apparatus at a 60° angle between the glenoid and actuator holding the humeral component. Four strain-gauge rosettes were placed around the glenoid rim to measure strains transferred to the scapular bone under a compressive load (750 N) relative to the various baseplate-glenosphere combinations. Following repeated compression, a load-to-failure test was performed., Results: Mean overall registered strains were 161με (range: - 1165 to 2347) at the inferior sensor, -2με (range: - 213 to 90) at the superior sensor, -95με (range: - 381 to 254) at the anterior sensor, and 13με (range: - 298 to 128) at the posterior sensor. Measured bone strains did not show any significant differences across tested baseplate and glenosphere design, size, or positioning combinations (p > 0.05 for all sensors). Furthermore, linear regression analysis did not identify any of the evaluated parameters as an independent influential factor for strains (p > 0.05 for all sensors). Mean load-at-failure was significantly higher in the group of inferior (3347.0 N ± 704.4 N) compared to superior (2763.8 N ± 927.8 N) positioned baseplates (p = 0.046)., Conclusion: Different baseplate positions, baseplate sizes, glenosphere sizes, and glenosphere design or various combinations of these parameters did not significantly influence the measured bone strains at the glenoid near the bone-implant interface in a contemporary reverse shoulder arthroplasty system., Level of Evidence: Basic Science Study, Biomechanical Study.

This study analyzed landing strategies used by athletes with chronic ankle instability (CAI) and copers compared to uninjured controls. Thirty participants were asked to perform a single-leg forward jump followed by a single-leg landing. Compared to uninjured controls, those with CAI athletes had significantly greater hip flexion and ankle eversion angles at initial landing, suggesting preference for using hip movements and extra ankle eversion angles to avoid ankle inversion when landing. CAI athletes were also found to have significantly decreased peroneus longus activation and higher ankle inversion velocity were both found during descending phase. And these were potential contributors to cause ankle inversion injury as there were likely many others. Based on these findings, CAI athletes may need to utilize more multi-joint or multi-muscle strategies during landing to maintain stability and prevent re-injury., (© Journal of Sports Science and Medicine.)

Introduction: Hamstring strain injuries typically occur in the proximal biceps femoris long head (BFlh) at high running speeds. Strain magnitude seems to be the primary determinant of strain injury, and may be regulated by muscle activation. In running, BFlh strain is largest in the proximal region, especially at high speeds. However, region-specific activity has not been examined. This study examined the proximal-distal and intermuscular activity of BFlh and semitendinosus (ST) as a function of increasing running speed., Methods: Thirteen participants ran at steady speeds of 4.1 (slow), 5.4 (moderate), and 6.8 m·s (fast) on a treadmill. Region- and muscle-specific EMG activity were recorded at each speed using high-density EMG, and were normalized to maximal voluntary isometric activity. Muscle-tendon unit lengths were calculated from kinematic recordings. Speed effects, regional, and intermuscular differences were tested with Statistical Parametric Mapping., Results: With increasing running speed, EMG activity increased in all regions of both muscles to a similar extent in the clinically relevant late swing phase. Increases in muscle-tendon unit lengths in late swing as a function of running speed were comparatively small. In fast running, EMG activity was highest in late swing in all regions, and reached 115% ± 20% (proximal region, mean ± 95% confidence limit), 106% ± 11% (middle), and 124% ± 16% (distal) relative to maximal voluntary isometric activity in BFlh. Regional and intermuscular EMG patterns were highly individual, but each individual maintained similar proximal-distal and intermuscular EMG activity patterns across running speeds., Conclusions: Running is associated with highly individual hamstring activity patterns, but these patterns are similar across speeds. It may thus be crucial to implement running at submaximal speeds early after hamstring injury for restoration of normal neuromuscular function.

The evaluation of brain changes to a specific pain condition in pediatric and adult patients allows for insights into potential mechanisms of pain chronicity and possibly long-term brain changes. Here we focused on the primary somatosensory system (SS) involved in pain processing, namely the ventroposterolateral thalamus (VPL) and the primary somatosensory cortex (SI). We evaluated, using MRI, three specific processes: (a) somatotopy of changes in the SS for different pain origins (viz., foot vs. arm); (b) differences in acute (ankle sprain versus complex regional pain syndrome-CRPS); and (c) differences of the effects of CRPS on SS in pediatric versus adult patients. In all cases, age- and sex-matched individuals were used as controls. Our results suggest a shift in concurrent gray matter density (GMD) and resting functional connectivity strengths (rFC) across pediatric and adult CRPS with (a) differential patterns of GMD (VPL) and rFC (SI) on SS in pediatric vs. adult patterns that are consistent with upper and lower limb somatotopical organization; and (b) widespread GMD alterations in pediatric CRPS from sensory, emotional and descending modulatory processes to more confined sensory-emotional changes in adult CRPS and rFC patterns from sensory-sensory alterations in pediatric populations to a sensory-emotional change in adult populations. These results support the idea that pediatric and adult CRPS are differentially represented and may reflect underlying differences in pain chronification across age groups that may contribute to the well-known differences between child and adult pain vulnerability and resilience., (© 2019 Wiley Periodicals, Inc.)

With the development of wearable devices, strain sensors have attracted large interest for the detection of human motion, movement, and breathing. Various strain sensors consisting of stretchable conductive materials have been investigated based on resistance and capacitance differences according to the strain. However, this method requires multiple electrodes for multipoint detection. We propose a strain sensor capable of multipoint detection with a single electrode, based on the ultrasound pulse-echo method. It consists of several transmitters of carbon nanotubes (CNTs) and a single polyvinylidene fluoride receiver. The strain sensor was fabricated using CNTs embedded in stretchable polydimethylsiloxane. The received data are characterized by the different times of transmission from the CNTs of each point depending on the strain, i.e., the sensor can detect the positions of the CNTs. This study demonstrates the application of the multipoint strain sensor with a single electrode for measurements up to a strain of 30% (interval of 1%). We considered the optical and acoustic energy losses in the sensor design. In addition, to evaluate the utility of the sensor, finger bending with three-point CNTs and flexible phantom bending with six-point CNTs for the identification of an S-curve having mixed expansion and compression components were carried out.

Lateral ankle sprains are a common injury with an estimated occurrence rate of 23 000 per day in the USA. Prolonged immobilisation and delayed referral to physical therapy are associated with poorer outcomes. The patient was a 49-year-old woman working as a surgical technologist. She sustained an inversion injury to her left ankle while descending from a stool. Her primary care physician examined her, issued a Controlled Ankle Movement (CAM) walking boot and immobilised her ankle for 6 weeks. Patients with grade I and II lateral ankle sprains who are treated with early mobilisation and referral to physical therapy have demonstrated earlier return to function compared with patients who are treated with prolonged immobilisation and delayed referral. Nevertheless, it remains common for individuals who have sustained a lateral ankle sprain to be immobilised. This case study highlights the importance of early mobilisation and early physical therapy referral for patients with lateral ankle sprains., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Context: Despite the prevalence of ankle sprains and the potential for developing chronic ankle instability and ankle osteoarthritis, ankle sprains are often perceived as an innocuous injury., Objective: To understand the initial management and treatment sought by patients after a lateral ankle sprain (LAS) and to identify any differences in subjective function and self-reported injury., Design: Cross-sectional study., Setting: Research laboratory., Patients or Other Participants: A total of 175 participants with chronic ankle instability (73 men, 102 women; age = 20.9 ± 3.4 years, height = 173.5 ± 13.2 cm, mass = 81.4 ± 24.6 kg) were involved in the study., Main Outcome Measure(s): Participants were administered a questionnaire regarding their initial LAS. All participants also completed the Foot and Ankle Ability Measure (FAAM). The primary questions of interest were (1) Did the participants seek treatment from a medical professional for their initial LAS? (2) Did the participants perform rehabilitation? (3) Was the initial LAS immobilized? and (4) Did the participants use crutches? The other variables measured were scores on the FAAM and the FAAM Sports subscale, total number of ankle sprains, and incidents of giving way., Results: Sixty-four percent of participants did not seek medical treatment after their LAS. Those who did not seek medical treatment scored worse on the FAAM (81.21% ± 3.1% versus 89.23% ± 2.8%, P = .03) and the FAAM Sports subscale (72.34% ± 5.3% versus 81.26% ± 3.1%, P = .001). Those not seeking treatment also reported more ankle sprains since the initial injury (4.7 ± 2.4 versus 1.9 ± 0.90, P = .02) and more incidents of giving way each month (3.8 ± 1.9 versus 1.1 ± 0.87, P = .04)., Conclusions: It is not surprising that those who did not seek medical treatment for their LASs had worse subjective function, more ankle sprains, and more incidents of the ankle giving way. The public needs to be educated on the significance of ankle sprains and the need for medical attention to provide appropriate management. However, we also need to continue to evaluate initial management and rehabilitation to ensure that those who seek treatment receive the best care in order to reduce reinjury rates.

Context: Exposure to game conditions and previous injury are known to increase the risk of injury, but little available evidence pertains to modifiable factors that may mediate dynamic control of body segments, such as core muscle endurance and neurocognitive capabilities., Objective: To identify potentially modifiable factors associated with the occurrence of a core or lower extremity sprain or strain during participation in football., Design: Prospective cohort study., Setting: National Collegiate Athletic Association Division I Football Bowl Subdivision football program., Patients or Other Participants: All team members who participated for the duration of 1 season or both of 2 consecutive seasons (n = 142)., Main Outcome Measure(s): Predictors of injury occurrence were derived from analysis of preparticipation data that included the results of front plank hold (FPH) and neurocognitive tests. Receiver operating characteristic analysis was used to establish binary classifications of injury risk. Logistic regression analyses were conducted to build multivariable injury-prediction models for optimal discriminatory power., Results: Exceptionally good discrimination between injured and noninjured participants was provided by models that included the results of the FPH and ImPACT neurocognitive tests. A high level of exposure to game conditions and injury during the preceding year magnified the effects of other risk factors. A model for identifying players with an elevated risk for injury occurrence during both of 2 consecutive seasons included FPH ≤120 seconds, verbal memory score ≤87, composite reaction time ≥560 milliseconds, and starter status. Having ≥2 of the 4 risk factors demonstrated 44% sensitivity and 91% specificity, with an odds ratio = 8.40., Conclusions: Core muscle endurance and neurocognitive processes may both play important roles in generating anticipatory muscle stiffness during participation in collegiate football. These factors may be particularly important for players who sustained an injury during the previous year and those who have a high level of game exposure.

Ankle sprains and their common sequalae are thought to negatively affect physical activity levels and health-related quality of life among active populations, but limited evidence has described this among younger populations. This study aimed to determine the prevalence rate of ankle sprain and chronic ankle instability among rural adolescents and subsequently compare their physical activity levels based on ankle injury status. The study was conducted in a rural high school in North Carolina. High school students completed an online survey that assessed ankle injury history, perception of ankle instability and function, and physical activity. Respondents were categorized into one of four groups based on ankle injury history and complaints of instability: 1) uninjured (no history of injury); 2) unstable (history of injury >1 year and recurrent instability); 3) copers (history of injury >1 year and no recurrent instability); and 4) potentially unstable (injury within the past year). Frequency of physical activity was compared across groups using analysis of variance, Kruskall-Wallis test (α = 0.05), and responses to activity type were assessed using chi-square. Physical activity was found to differ significantly between the four groups [Formula: see text] with unstable respondents reporting more physical activity than uninjured respondents (unstable = 4706.05 ± 4610.56 MET-minutes/week; uninjured = 2592.93 ± 2946.02 MET-minutes/week). No differences were found between other groups. Despite injury history and sensations of instability, respondents with chronic ankle instability reported greater physical activity levels than uninjured participants. As this is contrary to pre-existing hypotheses, it is possible that continued physical activity after injury among adolescents may contribute to deleterious outcomes such as increased frequency of chronic instability., Competing Interests: The authors have declared that no competing interests exist.

Hamstring strain injury is a multifactorial and complex problem involving interactions among various factors. Information about risk factors for this injury is inconsistent among studies because the strong effects of confounding factors and injury situations are often ignored. We investigated the relationship between hamstring strain induced by high-speed running and intrinsic risk factors, including hip muscle morphology and function, by excluding the influences of confounding factors. Sixty-one male track and field athletes (age, 19.6 ± 1.1 years; 95% confidence interval, 19.3-19.9) who often performed high-speed running were monitored throughout one season. Before the season, we measured hip and knee strength, muscle thickness of the gluteus maximus and biceps femoris, and hip and knee joint range of motion (ROM). We also obtained information about each athlete's history of hamstring injury by questionnaire. Eighteen athletes sustained hamstring strain injuries induced by high-speed running. Eighteen uninjured athletes who had the same profile of confounding factors as the injured athletes were selected as controls. Previously injured athletes had a significantly higher injury rate than uninjured athletes (p < .05; odds ratio, 2.85). No other measurements had a significant relationship with the occurrence of injury. However, passive hip ROM (flexion and extension) tended to be larger in the injured than control group. A history of hamstring strain was a strong risk factor for hamstring strain injury, and it may affect other factors. Therefore, the risk factors for hamstring strain injury should be investigated by eliminating the impact of a history of hamstring strain.

Objectives: To develop and externally validate a prognostic model for poor recovery after ankle sprain., Setting and Participants: Model development used secondary data analysis of 584 participants from a UK multicentre randomised clinical trial. External validation used data from 682 participants recruited in 10 UK emergency departments for a prospective observational cohort., Outcome and Analysis: Poor recovery was defined as presence of pain, functional difficulty or lack of confidence in the ankle at 9 months after injury. Twenty-three baseline candidate predictors were included together in a multivariable logistic regression model to identify the best predictors of poor recovery. Relationships between continuous variables and the outcome were modelled using fractional polynomials. Regression parameters were combined over 50 imputed data sets using Rubin's rule. To minimise overfitting, regression coefficients were multiplied by a heuristic shrinkage factor and the intercept re-estimated. Incremental value of candidate predictors assessed at 4 weeks after injury was explored using decision curve analysis and the baseline model updated. The final models included predictors selected based on the Akaike information criterion (p<0.157). Model performance was assessed by calibration and discrimination., Results: Outcome rate was lower in the development (6.7%) than in the external validation data set (19.9%). Mean age (29.9 and 33.6 years), body mass index (BMI; 26.3 and 27.1 kg/m 2 ), pain when resting (37.8 and 38.5 points) or bearing weight on the ankle (75.4 and 71.3 points) were similar in both data sets. Age, BMI, pain when resting, pain bearing weight, ability to bear weight, days from injury until assessment and injury recurrence were the selected predictors. The baseline model had fair discriminatory ability (C-statistic 0.72; 95% CI 0.66 to 0.79) but poor calibration. The updated model presented better discrimination (C-statistic 0.78; 95% CI 0.72 to 0.84), but equivalent calibration., Conclusions: The models include predictors easy to assess clinically and show benefit when compared with not using any model., Trial Registration Number: ISRCTN12726986; Results., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY. Published by BMJ.)

Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disease with no effective treatment. Multiple mechanisms are thought to contribute to muscle wasting, including increased susceptibility to contraction-induced damage, chronic inflammation, fibrosis, altered satellite stem cell (SSC) dynamics, and impaired regenerative capacity. The goals of this project were to 1) develop an agent-based model of skeletal muscle that predicts the dynamic regenerative response of muscle cells, fibroblasts, SSCs, and inflammatory cells as a result of contraction-induced injury, 2) calibrate and validate the model parameters based on comparisons with published experimental measurements, and 3) use the model to investigate how changing isolated and combined factors known to be associated with DMD (e.g., altered fibroblast or SSC behaviors) influence muscle regeneration. Our predictions revealed that the percent of injured muscle that recovered 28 days after injury was dependent on the peak SSC counts following injury. In simulations with near-full cross-sectional area recovery (healthy, 4-wk mdx, 3-mo mdx), the SSC counts correlated with the extent of initial injury; however, in simulations with impaired regeneration (9-mo mdx), the peak SSC counts were suppressed relative to initial injury. The differences in SSC counts between these groups were emergent predictions dependent on altered microenvironment factors known to be associated with DMD. Multiple cell types influenced the peak number of SSCs, but no individual parameter predicted the differences in SSC counts. This finding suggests that interventions to target the microenvironment rather than SSCs directly could be an effective method for improving regeneration in impaired muscle. NEW & NOTEWORTHY A computational model predicted that satellite stem cell (SSC) counts are correlated with muscle cross-sectional area (CSA) recovery following injury. In simulations with impaired CSA recovery, SSC counts are suppressed relative to healthy muscle. The suppressed SSC counts were an emergent model prediction, because all simulations had equal initial SSC counts. Fibroblast and anti-inflammatory macrophage counts influenced SSC counts, but no single factor was able to predict the pathological differences in SSC counts that lead to impaired regeneration.

A healthy 19-year-old male college student (height = 177.8 cm, mass = 64.3 kg, body mass index = 20.3 kg/m 2 , Foot Posture Index = -1) participating in a study sustained a grade 2 inversion lateral ankle sprain 3 days after completing patient-reported outcome measures. A treatment protocol including therapeutic exercises and midfoot mobilizations was provided. Patient-reported outcomes assessing physical health, mental health, and foot-ankle function were completed 3 days preinjury and 1, 3, and 12 weeks postinjury. Substantial postinjury changes in function, physical health, and kinesiophobia reflected functional limitations that improved with treatment and time. This level 3 exploration case report provides a rare opportunity to highlight preinjury-to-postinjury changes in patient-reported physical and psychological measures caused by a lateral ankle sprain.

Background: The purpose of this study was to assess the frequency of superior labrum anterior posterior (SLAP) lesions, long head of biceps tendon (LHBT) pathologies, and superior rotator cuff tears accompanying subscapularis tears. We hypothesised that LHBT lesions, superior rotator cuff tears, and especially SLAP lesions were very frequent with subscapularis tears., Methods: The digital files of patients who underwent shoulder arthroscopy were reviewed retrospectively. One hundred and eleven patients with subscapularis tears evident on surgery videos were examined. Superior labrum, LHBT, and superior rotator cuff lesions were investigated by the authors of this study. The statistical analyses were made with SPSS statistics software, and significance was set at P < 0.05 value., Results: There were 111 patients with both subscapularis tears and surgery videos. The mean age was 58.09 ± 10.21, and 63.1% of the patients were female. 98.2% of the 111 patients had a SLAP lesion. 7.2% of those were SLAP I and 91% were SLAP II lesions while 1.8% were healthy. The 75.7% of the patients had a LHBT pathology, and 83.8% had superior cuff tear., Conclusions: Subscapularis tears were almost always accompanied by SLAP lesions. On the other hand, biceps tendon pathologies and superior rotator cuff tears were also very frequent with subscapularis tears., Level of Evidence: Prognostic study, Level IV (retrospective cohort study)., (Copyright © 2017 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Context:   Ankle sprains are the most common orthopaedic injury that occurs during sport and physical activity. Many individuals who sprain their ankles develop chronic ankle instability (CAI), a condition characterized by recurrent injury, decreased physical activity, and decreased quality of life. These residual impairments are believed to persist for the remainder of the patient's life, in part due to the link between CAI and posttraumatic ankle osteoarthritis. However, this belief remains speculative due to the lack of long-term prospective investigations., Objective:   To use a mouse model of mild (MILD) and severe (SEVERE) ankle sprains to quantify balance and locomotor adaptations across the lifespan., Design:   Cohort study., Setting:   University research laboratory., Patients or Other Participants:   Fifty male mice (CBA/J) were randomly placed into a control (SHAM), MILD, or SEVERE group and housed individually., Intervention(s):   The MILD group underwent surgical transection of a single right hind-limb lateral ankle ligament, and the SEVERE group had 2 of the lateral ligaments transected. The SHAM group underwent a sham surgery during which no lateral ligaments were transected., Main Outcome Measure(s):   After surgically inducing the ankle sprain, we measured balance and gait using a balance beam and footprint test before and every 6 weeks for 78 weeks., Results:   Age-related declines in balance but not stride length were exacerbated by an ankle sprain ( P < .001). Balance and stride lengths changed with age ( P < .001). Foot slips were worse in the SEVERE (4.32 ± 0.98) and MILD (3.53 ± 0.98) groups than in the SHAM group (2.16 ± 0.99; P < .001). Right-limb stride length was shorter in the SEVERE group (6.45 cm ± 0.41 cm) than in the SHAM group (6.87 cm ± 0.40 cm; P = .04)., Conclusions:   Transecting the lateral ligaments of a mouse hind foot resulted in lifelong sensorimotor dysfunction. Declines starting at 42 weeks postinjury may have represented the onset of posttraumatic osteoarthritis.

Context: High ankle "syndesmosis" injuries are common in American football players relative to the general population. At the professional level, syndesmotic sprains represent a challenging and unique injury lacking a standardized rehabilitation protocol during conservative management., Evidence Acquisition: PubMed, Biosis Preview, SPORTDiscus, PEDro, and EMBASE databases were searched using the terms syndesmotic injuries, American football, conservative management, and rehabilitation., Study Design: Clinical review., Level of Evidence: Level 3., Results: When compared with lateral ankle sprains, syndesmosis injuries result in significantly prolonged recovery times and games lost. For stable syndesmotic injuries, conservative management features a brief period of immobilization and protected weightbearing followed by progressive strengthening exercises and running, and athletes can expect to return to competition in 2 to 6 weeks. Further research investigating the efficacy of dry needling and blood flow restriction therapy is necessary to evaluate the benefit of these techniques in the rehabilitation process., Conclusion: Successful conservative management of stable syndesmotic injuries in professional American football athletes requires a thorough understanding of the anatomy, injury mechanisms, diagnosis, and rehabilitation strategies utilized in elite athletes.

Context:   Diminished hip-abductor strength has been suggested to increase the risk of noncontact lateral ankle sprains., Objective:   To determine prospectively whether baseline hip-abductor strength predicts future noncontact lateral ankle sprains in competitive male soccer players., Design:   Prospective cohort study., Setting:   Athletic training facilities and various athletic fields., Patients or Other Participants:   Two hundred ten competitive male soccer players., Main Outcome Measure(s):   Before the start of the sport season, isometric hip-abductor strength was measured bilaterally using a handheld dynamometer. Any previous history of ankle sprain, body mass index, age, height, and weight were documented. During the sport season (30 weeks), ankle injury status was recorded by team medical providers. Injured athletes were further classified based on the mechanism of injury. Only data from injured athletes who sustained noncontact lateral ankle sprains were used for analysis. Postseason, logistic regression was used to determine whether baseline hip strength predicted future noncontact lateral ankle sprains. A receiver operating characteristic curve was constructed for hip strength to determine the cutoff value for distinguishing between high-risk and low-risk outcomes., Results:   A total of 25 noncontact lateral ankle sprains were confirmed, for an overall annual incidence of 11.9%. Baseline hip-abductor strength was lower in injured players than in uninjured players ( P = .008). Logistic regression indicated that impaired hip-abductor strength increased the future injury risk (odds ratio = 1.10 [95% confidence interval = 1.02, 1.18], P = .010). The strength cutoff to define high risk was ≤33.8% body weight, as determined by receiver operating characteristic curve analysis. For athletes classified as high risk, the probability of injury increased from 11.9% to 26.7%., Conclusions:   Reduced isometric hip-abductor strength predisposed competitive male soccer players to noncontact lateral ankle sprains.

Reference:  Schiftan GS, Ross LA, Hahne AJ. The effectiveness of proprioceptive training in preventing ankle sprains in sporting populations: a systematic review and meta-analysis. J Sci Med Sport. 2015;18(3):238-244., Clinical Question:   Does the use of proprioceptive training as a sole intervention decrease the incidence of initial or recurrent ankle sprains in the athletic population?, Data Sources:   The authors completed a comprehensive literature search of MEDLINE, CINAHL, SPORTDiscus, and Physiotherapy Evidence Database (PEDro) from inception to October 2013. The reference lists of all identified articles were manually screened to obtain additional studies. The following key words were used. Phase 1 population terms were sport*, athlet*, and a combination of the two. Phase 2 intervention terms were propriocept*, balance, neuromusc* adj5 train*, and combinations thereof. Phase 3 condition terms were ankle adj5 sprain*, sprain* adj5 ankle, and combinations thereof., Study Selection:   Studies were included according to the following criteria: (1) the design was a moderate- to high-level randomized controlled trial (>4/10 on the PEDro scale), (2) the participants were physically active (regardless of previous ankle injury), (3) the intervention group received proprioceptive training only, compared with a control group that received no proprioceptive training, and (4) the rate of ankle sprains was reported as a main outcome. Search results were limited to the English language. No restrictions were placed on publication dates., Data Extraction:   Two authors independently reviewed the studies for eligibility. The quality of the pertinent articles was assessed using the PEDro scale, and data were extracted to calculate the relative risk. Data extracted were number of participants, intervention, frequency, duration, follow-up period, and injury rate., Main Results:   Of the initial 345 studies screened, 7 were included in this review for a total of 3726 participants. Three analyses were conducted for proprioceptive training used (1) to prevent ankle sprains regardless of history (n = 3654), (2) to prevent recurrent ankle sprains (n = 1542), or (3) as the primary preventive measure for those without a history of ankle sprain (n = 946). Regardless of a history of ankle sprain, participants had a reduction in ankle-sprain rates (relative risk [RR] = 0.65, 95% confidence interval [CI] = 0.55, 0.77; numbers needed to treat [NNT] = 17, 95% CI = 11, 33). For individuals with a history of ankle sprains, proprioceptive training demonstrated a reduction in repeat ankle sprains (RR = 0.64, 95% CI = 0.51, 0.81; NNT = 13, 95% CI = 7, 100). Proprioceptive training as a primary preventive measure demonstrated significant results (RR = 0.57, 95% CI = 0.34, 0.97; NNT = 33, 95% CI = 16, 1000)., Conclusions:   Proprioceptive training programs were effective in reducing the incidence rates of ankle sprains in the athletic population, including those with and those without a history of ankle sprains.

Background: Anterior cruciate ligament (ACL) injures incur over USD 2 billion in annual medical costs and prevention has become a topic of interest in biomechanics. However, literature conflicts persist over how knee rotations contribute to ACL strain and ligament injury. To maximize the efficacy of ACL injury prevention, the effects of underlying mechanics need to be better understood., Questions/purposes: We applied robotically controlled, in vivo-derived kinematic stimuli to the knee to assess ligament biomechanics in a cadaver model. We asked: (1) Does the application of abduction rotation increase ACL and medial collateral ligament (MCL) strain relative to the normal condition? (2) Does the application of internal tibial rotation impact ACL strain relative to the neutral condition? (3) Does combined abduction and internal tibial rotation increase ligament strain more than either individual contribution?, Methods: A six-degree-of-freedom robotic manipulator was used to position 17 cadaveric specimens free from knee pathology outside of low-grade osteoarthritis (age, 47 ± 8 years; 13 males, four females) into orientations that mimic initial contact recorded from in vivo male and female drop vertical jump and sidestep cutting activities. Four-degree rotational perturbations were applied in both directions from the neutral alignment position (creating an 8° range) for each frontal, transverse, and combined planes while ACL and MCL strains were continuously recorded with DVRT strain gauges implanted directly on each ligament. Analysis of variance models with least significant difference post hoc analysis were used to assess differences in ligament strain and joint loading between sex, ligament condition, or motion task and rotation type., Results: For the female drop vertical jump simulation in the intact knee, isolated abduction and combined abduction/internal rotational stimuli produced the greatest change in strain from the neutral position as compared with all other stimuli within the ACL (1.5% ± 1.0%, p ≤ 0.035; 1.8% ± 1.3%, p ≤ 0.005) and MCL (1.8% ± 1.0%, p < 0.001; 1.6% ± 1.3%, p < 0.001) compared with all other applied stimuli. There were no differences in mean peak ACL strain between any rotational stimuli (largest mean difference = 2.0%; 95% confidence interval [CI], -0.9% to 5.0%; p = 0.070). These trends were consistent for all four simulated tasks. Peak ACL strain in the intact knee was larger than peak MCL strain for all applied rotational stimuli in the drop vertical jump simulations (smallest mean difference = 2.1%; 95% CI, -0.4% to 4.5%; p = 0.047)., Conclusions: Kinematically constrained cadaveric knee models using peak strain as an outcome variable require greater than 4° rotational perturbations to elicit changes in intraarticular ligaments., Clinical Relevance: Because combined rotations and isolated abduction produced greater change in strain relative to the neutral position for the ACL and MCL than any other rotational stimuli in this cadaver study, hypotheses for in vivo investigations aimed toward injury prevention that focuses on the reduction of frontal plane knee motion should be considered. Furthermore, reduced strain in the MCL versus the ACL may help explain why only 30% of ACL ruptures exhibit concomitant MCL injuries.

Purpose: To assess in-season alterations of biceps femoris long head (BFlh) fascicle length in elite Australian footballers with and without a history of unilateral hamstring strain injury (HSI) in the past 12 months., Methods: Thirty elite Australian football players were recruited. Twelve had a history of unilateral HSI. Eighteen had no HSI history. All had their BFlh architecture assessed at approximately monthly intervals, six times across a competitive season., Results: The previously injured limb's BFlh fascicles increased from the start of the season and peaked at week 5. Fascicle length gradually decreased until the end of the season, where they were shortest. The contralateral uninjured limb's fascicles were the longest when assessed at week 5 and showed a reduction in-season where weeks 17 and 23 were shorter than week 1. Control group fascicles were longest at week 5 and reduced in-season. The previously injured limb's BFlh fascicles were shorter than the control group at all weeks and the contralateral uninjured limb at week 5. Compared with the control group, the contralateral uninjured limb had shorter fascicles from weeks 9 to 23., Conclusions: Athletes with a history of HSI end the season with shorter fascicles than they start. Limbs without a history of HSI display similar BFlh fascicle lengths at the end of the season as they begin with. All athletes increase fascicle length at the beginning of the season; however, the extent of the increase differed based on history of HSI. These findings show that a HSI history may influence structural adaptation of the BFlh in-season.

The aim of this study was to quantify the contributions of lower extremity joint torques and the mechanical power of lower extremity muscle groups to further elucidate the loadings on hamstring and the mechanics of its injury. Eight national-level male sprinters performed maximum-velocity sprint running on a synthetic track. The 3D kinematic data and ground reaction force (GRF) were collected synchronously. Intersegmental dynamics approach was used to analyze the lower extremity joint torques and power changes in the lower extremity joint muscle groups. During sprinting, the GRF during the stance phase and the motion-dependent torques (MDT) during the swing phase had a major effect on the lower extremity movements and muscle groups. Specifically, during the stance phase, torque produced and work performed by the hip and knee muscles were generally used to counteract the GRF. During the swing phase, the role of the muscle torque changed to mainly counteract the effect of MDT to control the movement direction of the lower extremity. Meanwhile, during the initial stance and late swing phases, the passive torques, namely, the ground reaction torques and MDT produced by the GRF and the inertial movement of the segments of the lower extremity, applied greater stress to the hamstring muscles.

Context: The mechanisms that contribute to the development of chronic ankle instability are not understood. Investigators have developed a hypothetical model in which neuromuscular alterations that stem from damaged ankle ligaments are thought to affect periarticular and proximal muscle activity. However, the retrospective nature of these studies does not allow a causal link to be established., Objective: To assess temporal alterations in the activity of 2 periarticular muscles of the rat ankle and 2 proximal muscles of the rat hind limb after an ankle sprain., Design: Controlled laboratory study., Setting: Laboratory., Patients or Other Participants: Five healthy adult male Long Evans rats (age = 16 weeks, mass = 400.0 ± 13.5 g)., Intervention(s): Indwelling fine-wire electromyography (EMG) electrodes were implanted surgically into the biceps femoris, medial gastrocnemius, vastus lateralis, and tibialis anterior muscles of the rats. We recorded baseline EMG measurements while the rats walked on a motor-driven treadmill and then induced a closed lateral ankle sprain by overextending the lateral ankle ligaments. After ankle sprain, the rats were placed on the treadmill every 24 hours for 7 days, and we recorded postsprain EMG data., Main Outcome Measure(s): Onset time of muscle activity, phase duration, sample entropy, and minimal detectable change (MDC) were assessed and compared with baseline using 2-tailed dependent t tests., Results: Compared with baseline, delayed onset time of muscle activity was exhibited in the biceps femoris (baseline = -16.7 ± 54.0 milliseconds [ms]) on day 0 (5.2 ± 64.1 ms; t 4 = -4.655, P = .043) and tibialis anterior (baseline = 307.0 ± 64.2 ms) muscles on day 3 (362.5 ± 55.9 ms; t 4 = -5.427, P = .03) and day 6 (357.3 ± 39.6 ms; t 4 = -3.802, P = .02). Longer phase durations were observed for the vastus lateralis (baseline = 321.9 ± 92.6 ms) on day 3 (401.3 ± 101.2 ms; t 3 = -4.001, P = .03), day 4 (404.1 ± 93.0 ms; t 3 = -3.320, P = .048), and day 5 (364.6 ± 105.2 ms; t 3 = -3.963, P = .03) and for the tibialis anterior (baseline = 103.9 ± 16.4 ms) on day 4 (154.9 ± 7.8 ms; t 3 = -4.331, P = .050) and day 6 (141.9 ± 16.2 ms; t 3 = -3.441, P = .03). After sprain, greater sample entropy was found for the vastus lateralis (baseline = 0.7 ± 0.3) on day 6 (0.9 ± 0.4; t 4 = -3.481, P = .03) and day 7 (0.9 ± 0.3; t 4 = -2.637, P = .050) and for the tibialis anterior (baseline = 0.6 ± 0.4) on day 4 (0.9 ± 0.5; t 4 = -3.224, P = .03). The MDC analysis revealed increased sample entropy values for the vastus lateralis and tibialis anterior., Conclusions: Manually inducing an ankle sprain in a rat by overextending the lateral ankle ligaments altered the complexity of muscle-activation patterns, and the alterations exceeded the MDC of the baseline data.

Introduction: The repeated bout effect characterizes the protective adaptation after a single bout of unaccustomed eccentric exercise that induces muscle damage. Sarcomerogenesis and increased tendon compliance have been suggested as potential mechanisms for the repeated bout effect by preventing muscle fascicles from being stretched onto the descending limb of the length-tension curve (the region where sarcomere damage is thought to occur). In this study, evidence was sought for three possible mechanical changes that would support either the sarcomerogenesis or the increased tendon compliance hypotheses: a sustained rightward shift in the fascicle length-tension relationship, reduced fascicle strain amplitude, and reduced starting fascicle length., Methods: Subjects (n = 10) walked backward downhill (5 km·h, 20% incline) on a treadmill for 30 min on two occasions separated by 7 d. Kinematic data and medial gastrocnemius fascicle lengths (ultrasonography) were recorded at 10-min intervals to compare fascicle strains between bouts. Fascicle length-torque curves from supramaximal tibial nerve stimulation were constructed before, 2 h after, and 2 d after each exercise bout., Results: Maximum torque decrement and elevated muscle soreness were present after the first, but not the second, backward downhill walking bout signifying a protective repeated bout effect. There was no sustained rightward shift in the length-torque relationship between exercise bouts, nor decreases in fascicle strain amplitude or shortening of the starting fascicle length., Conclusions: Protection from a repeated bout of eccentric exercise was conferred without changes in muscle fascicle strain behavior, indicating that sarcomerogenesis and increased tendon compliance were unlikely to be responsible. As fascicle strains are relatively small in humans, we suggest that changes to connective tissue structures, such as extracellular matrix remodeling, are better able to explain the repeated bout effect observed here.

Background: The drop vertical jump (DVJ) task has previously been used to identify movement patterns associated with a number of injury types. However, no current research exists evaluating people with chronic ankle instability (CAI) compared with people coping with lateral ankle sprain (LAS) (referred to as "LAS copers") during this task., Objective: The aim of this study was to identify the coping movement and motor control patterns of LAS copers in comparison with individuals with CAI during the DVJ task., Design: This was a case-control study., Methods: Seventy individuals were recruited at convenience within 2-weeks of sustaining a first-time acute LAS injury. One year following recruitment, these individuals were stratified into 2 groups: 28 with CAI and 42 LAS copers. They attended the testing laboratory to complete a DVJ task. Three-dimensional kinematic and sagittal-plane kinetic profiles were plotted for the lower extremity joints of both limbs for the drop jump phase (phase 1) and drop landing phase (phase 2) of the DVJ. The rate of impact modulation relative to body weight during both phases of the DVJ also was determined., Results: Compared with LAS copers, participants with CAI displayed significant increases in hip flexion on their "involved" limb during phase 1 of the DVJ (23° vs 18°) and bilaterally during phase 2 (15° vs 10°). These movement patterns coincided with altered moment-of-force patterns at the hip on the "uninvolved" limb., Limitations: It is unknown whether these movement and motor control patterns preceded or occurred as a result of the initial LAS injury., Conclusions: Participants with CAI displayed hip-centered changes in movement and motor control patterns during a DVJ task compared with LAS copers. The findings of this study may give an indication of the coping mechanism underlying outcome following initial LAS injury., (© 2016 American Physical Therapy Association.)

Chronic fatigue syndrome (CFS) is a complex, multisystem disorder that can be disabling. CFS symptoms can be provoked by increased physical or cognitive activity, and by orthostatic stress. In preliminary work, we noted that CFS symptoms also could be provoked by application of longitudinal neural and soft tissue strain to the limbs and spine of affected individuals. In this study we measured the responses to a straight leg raise neuromuscular strain maneuver in individuals with CFS and healthy controls. We randomly assigned 60 individuals with CFS and 20 healthy controls to either a 15 minute period of passive supine straight leg raise (true neuromuscular strain) or a sham straight leg raise. The primary outcome measure was the symptom intensity difference between the scores during and 24 hours after the study maneuver compared to baseline. Fatigue, body pain, lightheadedness, concentration difficulties, and headache scores were measured individually on a 0-10 scale, and summed to create a composite symptom score. Compared to individuals with CFS in the sham strain group, those with CFS in the true strain group reported significantly increased body pain (P = 0.04) and concentration difficulties (P = 0.02) as well as increased composite symptom scores (all P = 0.03) during the maneuver. After 24 hours, the symptom intensity differences were significantly greater for the CFS true strain group for the individual symptom of lightheadedness (P = 0.001) and for the composite symptom score (P = 0.005). During and 24 hours after the exposure to the true strain maneuver, those with CFS had significantly higher individual and composite symptom intensity changes compared to the healthy controls. We conclude that a longitudinal strain applied to the nerves and soft tissues of the lower limb is capable of increasing symptom intensity in individuals with CFS for up to 24 hours. These findings support our preliminary observations that increased mechanical sensitivity may be a contributor to the provocation of symptoms in this disorder.

Context: Lateral ankle ligamentous sprain (LAS) is one of the most common injuries in recreational activities and competitive sports. Many studies have attempted to determine whether there are certain intrinsic factors that can predict LAS. However, no consensus has been reached on the predictive intrinsic factors., Objective: To identify the intrinsic risk factors of LAS by meta-analysis from data in randomized control trials and prospective cohort studies., Data Sources: A systematic computerized literature search of MEDLINE, CINAHL, ScienceDirect, SPORTDiscus, and Cochrane Register of Clinical Trials was performed., Study Selection: A computerized literature search from inception to January 2015 resulted in 1133 studies of the LAS intrinsic risk factors written in English., Study Design: Systematic review., Level of Evidence: Level 4., Data Extraction: The modified quality index was used to assess the quality of the design of the papers and the standardized mean difference was used as an index to pool included study outcomes., Results: Eight articles were included in this systematic review. Meta-analysis results showed that body mass index, slow eccentric inversion strength, fast concentric plantar flexion strength, passive inversion joint position sense, and peroneus brevis reaction time correlated with LAS., Conclusion: Body mass index, slow eccentric inversion strength, fast concentric plantar flexion strength, passive inversion joint position sense, and the reaction time of the peroneus brevis were associated with significantly increased risk of LAS.

Context: The first step to identifying factors that increase the risk of recurrent ankle sprains is to identify impairments after a first sprain and compare performance with individuals who have never sustained a sprain. Few researchers have restricted recruitment to a homogeneous group of patients with first sprains, thereby introducing the potential for confounding., Objective: To identify impairments that differ in participants with a recent index lateral ankle sprain versus participants with no history of ankle sprain., Design: Cross-sectional study., Patients or Other Participants: We recruited a sample of convenience from May 2010 to April 2013 that included 70 volunteers (age = 27.4 ± 8.3 years, height = 168.7 ± 9.5 cm, mass = 65.0 ± 12.5 kg) serving as controls and 30 volunteers (age = 31.1 ± 13.3 years, height = 168.3 ± 9.1 cm, mass = 67.3 ± 13.7 kg) with index ankle sprains., Main Outcome Measure(s): We collected demographic and physical performance variables, including ankle-joint range of motion, balance (time to balance after perturbation, Star Excursion Balance Test, foot lifts during single-legged stance, demi-pointe balance test), proprioception, motor planning, inversion-eversion peak power, and timed stair tests. Discriminant analysis was conducted to determine the relationship between explanatory variables and sprain status. Sequential discriminant analysis was performed to identify the most relevant variables that explained the greatest variance., Results: The average time since the sprain was 3.5 ± 1.5 months. The model, including all variables, correctly predicted a sprain status of 77% (n = 23) of the sprain group and 80% (n = 56) of the control group and explained 40% of the variance between groups ([Formula: see text] = 42.16, P = .03). Backward stepwise discriminant analysis revealed associations between sprain status and only 2 tests: Star Excursion Balance Test in the anterior direction and foot lifts during single-legged stance ([Formula: see text] = 15.2, P = .001). These 2 tests explained 15% of the between-groups variance and correctly predicted group membership of 63% (n = 19) of the sprain group and 69% (n = 48) of the control group., Conclusions: Balance impairments were associated with a recent first ankle sprain, but proprioception, motor control, power, and function were not.

Context: Individuals with chronic ankle instability (CAI) have deficits in neuromuscular control and altered movement patterns. Ankle-destabilization devices have been shown to increase lower extremity muscle activity during functional tasks and may be useful tools for improving common deficits and self-reported function., Objective: To determine whether a 4-week rehabilitation program that includes destabilization devices has greater effects on self-reported function, range of motion (ROM), strength, and balance than rehabilitation without devices in patients with CAI., Design: Randomized controlled clinical trial., Setting: Laboratory., Patients or Other Participants: A total of 26 patients with CAI (7 men, 19 women; age = 21.34 ± 3.06 years, height = 168.96 ± 8.77 cm, mass = 70.73 ± 13.86 kg)., Intervention(s): Patients completed baseline measures and were randomized into no-device and device groups. Both groups completed 4 weeks of supervised, impairment-based progressive rehabilitation with or without devices and then repeated baseline measures., Main Outcome Measure(s): We assessed self-reported function using the Foot and Ankle Ability Measure. Ankle ROM was measured with an inclinometer. Ankle strength was assessed using a handheld dynamometer during maximal voluntary isometric contractions. Balance was measured using a composite score of 3 reach directions from the Star Excursion Balance Test and a force plate to calculate center of pressure during eyes-open and eyes-closed single-limb balance. We compared each dependent variable using a 2 × 2 (group × time) analysis of variance and post hoc tests as appropriate and set an a priori α level at .05. The Hedges g effect sizes and associated 95% confidence intervals were calculated., Results: We observed no differences between the no-device and device groups for any measure. However, both groups had large improvements in self-reported function and ankle strength., Conclusions: Incorporating destabilization devices into rehabilitation did not improve ankle function more effectively than traditional rehabilitation tools because both interventions resulted in similar improvements. Impairment-based progressive rehabilitation improved clinical outcomes associated with CAI.

Introduction: Longitudinal analyses of participants with a history of lateral ankle sprain are lacking. This investigation combined measures of lower limb interjoint coordination and stabilometry to evaluate static unipedal stance with the eyes open (condition 1) and closed (condition 2) in a group of participants with chronic ankle instability (CAI) compared to lateral ankle sprain "copers" (both recruited 12 months after sustaining an acute first-time lateral ankle sprain) and a group of noninjured controls., Methods: Twenty-eight participants with CAI, 42 lateral ankle sprain "copers," and 20 noninjured controls completed three 20-s single-limb stance trials in conditions 1 and 2. An adjusted coefficient of multiple determination statistic was used to compare stance limb three-dimensional kinematic data for similarity to establish patterns of interjoint coordination. The fractal dimension of the stance limb center of pressure path was also calculated., Results: Between-group analyses revealed that participants with CAI displayed notable increases in ankle-hip linked coordination compared with both lateral ankle sprain "copers" (-0.52 (1.05) vs 0.28 (0.9), P = 0.007) and controls (-0.52 (1.05) vs 0.63 (0.64), P = 0.006) in condition 1 and compared with controls only (0.62 (1.92) vs 0.1 (1.0) P = 0.002) in condition 2. Participants with CAI also exhibited a decrease in the fractal dimension of the center-of-pressure path during condition 2 compared with both controls and lateral ankle sprain "copers.", Conclusions: Participants with CAI present with a hip-dominant strategy of eyes-open and eyes-closed static unipedal stance. This coincided with reduced complexity of the stance limb center of pressure path in the eyes-closed condition.

Objective: To observe the effect of electroacupuncture (EA) on force-displacement value (FDV) of muscle state and the temperature index of infrared thermogram in patients with acute lumbar muscle sprain., Methods: Patients with acute lumbar muscle sprain were randomly divided into a medication group and an EA group. The medication group (n = 60) were treated with diclofenac sodium dual release enteric-coated capsules, 75 mg per day for 7 days. The EA group (n = 60) received EA at bilateral Houxi (SI 3), Jiaji (EX-B2), and Ashi points, at 20-30 mm depth and 10-25 Hz frequency for 20 min daily for 7 days. Muscle states were determined by measuring FDVs of the bilateral lumbar muscle with a Myotonometer fast muscle state detector. The temperature index of the lumbar skin was measured before and after treatment with a Fluke Ti30 non-refrigerated focal plane infrared thermal imaging detector., Results: There were no significant pre-treatment differences between the medication group and the EA group in mean FDV (P = 0.052) or temperature index of the lumbar skin (P = 0.25). The cure rate was 63.3% in the EA group and 53.3% in the medication group. The total efficacy in the EA group (93.3 %) was not significantly different from that in the medication group (86.6 %, P = 0.204). After treatment, the mean FDV of the lumbar muscle significantly increased in both groups (P < 0.05 for both groups); the FDV increase in the EA group was significantly higher than in the medication group (P = 0.015). The temperature index was also significantly increased in both groups (P < 0.05 for both groups); the infrared thermogram in the EA group indicated significantly greater recovery compared to the medication group (P = 0.026)., Conclusion: Both EA and diclofenac sodium markedly improved acute lumbar sprain, but EA better improved the rehabilitation and regeneration of FDVs and temperature index of infrared thermogram of the muscle.