INCLINOMETERS AND APPS ARE BETTER THAN GONIOMETERS. MEASURING KNEE EXTENSION RANGE OF MOTION IN ANTERIOR CRUCIATE LIGAMENT PATIENTS. RELIABILITY AND MINIMAL DETECTABLE CHANGE FOR THE THREE DEVICES

INTRODUCTION

Knee extension range of motion (ROM) measurement is important in patients with anterior cruciate ligament (ACL) injury. The main objective is to evaluate the reliability and the minimal detectable change (MDC) of three methods of measuring knee extension ROM in ACL patients.

MATERIALS

Three common goniometric devices: a universal goniometer, an inclinometer, and a Smartphone app.

METHODS

During a single visit, knee extension ROM was measured in both knees of 92 ACL injured or reconstructed patients by two testers blinded to the other's measures. Intra-rater, inter-rater, and test-retest Intraclass Correlation Coefficients (ICC2,1) were calculated.

RESULTS

Intra-rater ICC(2,1) was excellent for the three devices ranging from 0.93-0.96, with the smartphone app yielding the best results (ICC(2,1)=0.96, [95%CI:0.89-0.95]). Inter-rater ICC(2,1), however, varied from 0.36 to 0.80. The inclinometer and the smartphone app yielded similar results 0.80 (95%CI:0.71-0.86) and 0.79 (95%CI:0.70-0.86) respectively, whereas the universal goniometer was 0.36 (95%CI:0.17-0.53). Test-retest ICC(2,1) for the inclinometer was 0.89 (95%CI:0.84-0.93), 0.86 (95%CI:0.79-0.91) for the app, and 0.83 (95%CI:0.74-0.89) for the goniometer. The intra-rater, inter-rater, and test-retest MDC95 values ranged from 1.6° to 3.5°, 3.7° to 10.4 and 2.6° to 5.4° respectively.

CONCLUSIONS

The goniometer was the least reliable. The inclinometer is the recommended device due to its ease of use compared to the smartphone app.

Beware of the "Moving Target" - Uninvolved Limb Strength Increases to Exceed Preoperative Values During Rehabilitation After ACL Reconstruction in Male Professional and Recreational Athletes

OBJECTIVE: To describe the changes in quadriceps and hamstrings muscle strength in the uninvolved limb of male professional and recreational athletes during rehabilitation after anterior cruciate ligament reconstruction (ACLR) and compare to preoperative strength values. DESIGN: Prospective longitudinal study. METHODS: During rehabilitation, 665 participants who underwent unilateral ACLR performed a strength test preoperatively and every 6 weeks after surgery for up to 9 months. Isokinetic quadriceps and hamstrings strength of the uninvolved limb were measured at an angular velocity of 60°/s and normalized to body weight (N·m/kg). RESULTS: Quadriceps and hamstrings strength of the uninvolved limb gradually increased during rehabilitation until 6 months post-ACLR, and plateaued thereafter. Postoperative quadriceps' strength significantly exceeded preoperative values by 3 months for professional (2.99 N·m/kg; 95% confidence interval [CI]: 2.93, 3.04; P = .007) and by 6 months for recreational athletes (2.77 N·m/kg; 95% CI: 2.71, 2.83; P<.001), and hamstrings exceeded presurgery levels by 4.5 months (1.71 N·m/kg; 95% CI: 1.67, 1.74; P<.001 and 1.43 N·m/kg; 95% CI: 1.40, 1.46; P = .002, professional and recreational athletes respectively). CONCLUSION: In male professional and recreational athletes, uninvolved limb quadriceps and hamstrings strength gradually improved after ACLR, until 6 months after surgery. The uninvolved limb's strength may present as a "moving target" that requires consistent monitoring during rehabilitation. J Orthop Sports Phys Ther 2024;54(4):1-9. Epub 14 December 2023. doi:10.2519/jospt.2023.11961.

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

Background

After Anterior Cruciate Ligament Reconstruction (ACLR) athletes face the challenge of regaining their previous competitive level while avoiding re-injury and early knee joint cartilage degeneration. Quadriceps and hamstrings strength reductions and neuromuscular alterations potentially related to risk of re-injury are present after ACLR and relate to deficits in muscle activation.

Design

Cross-sectional laboratory study.

Purpose

To examine quadriceps and hamstrings muscle activation during repeated hops in healthy pivoting-sport athletes and those who had undergone ACLR (bone-tendon-bone and semitendinosus graft) who had met functional criteria allowing return to training.

Methods

Surface electromyography (SEMG) was recorded from vastus medialis and lateralis and medial and lateral hamstrings bilaterally during 30 seconds' repeated hopping in male athletes on average eight months after ACLR surgery (5-12 months). All patients underwent hamstring (HS) (n=24) or bone-tendon-bone (BTB) reconstruction (n=20) and were compared to healthy controls (n=31). The SEMG signals were normalized to those obtained during maximal voluntary isometric contraction.

Results

A significant time shift in peak muscle activation (earlier) was seen for: vastus medialis and vastus lateralis activation in the control group, in the BTB group's healthy (but not injured) leg and both legs of the HS group. A significant time shift in peak muscle activation was seen for lateral hamstrings (earlier) in all but the BTB group's injured leg and the medial hamstrings in the control group only. Lower peak activation levels of the vastus lateralis (p\<0.001) and vastus medialis (p\<0.001) were observed in the injured compared to healthy legs and lower peak lateral hamstrings activity (p\<0.009) in the injured leg compared to control leg. Decline in medial hamstring peak activation (p\<0.022) was observed between 1st and 3rd phase of the hop cycle in all groups.

Conclusion

Repeated hop testing revealed quadriceps and hamstring activation differences within ACLR athletes, and compared to healthy controls, that would be missed with single hop tests.

Level of evidence

3.

Lower Patellofemoral Joint Contact Force During Side-Step Cutting After Return-to-Sports Clearance Anterior Cruciate Ligament Reconstruction

BACKGROUND

Low patellofemoral joint (PFJ) contact force has been associated with PFJ osteoarthritis. Quadriceps force and knee flexion angles, which are typically altered after an anterior cruciate ligament reconstruction (ACLR), primarily influence PFJ contact forces. It is still inconclusive whether differences in PFJ contact forces are present during high knee flexion tasks such as side-step cutting after clearance to return to sports (RTS) after ACLR.

PURPOSE

To explore PFJ contact forces in the ACLR limb and compare them with those of the contralateral and control limbs during side-step cutting tasks after clearance to RTS.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 26 male athletes with ACLR who were previously cleared to RTS were matched with 23 healthy men serving as the control group. Three-dimensional motion capture and force plate data were collected while both groups performed anticipated side-step cutting tasks. Joint kinematics, kinetics, muscle forces, and PFJ contact forces were calculated using musculoskeletal modeling.

RESULTS

Peak PFJ force was lower in the ACLR limbs compared with the contralateral limbs (mean difference [MD], 5.89 body weight [BW]; 95% CI, 4.7-7.1 BW; P < .001) and the control limbs (MD, 4.44 BW; 95% CI, 2.1-6.8 BW; P < .001). During peak PFJ force, knee flexion angle was lower in ACLR limbs compared with the contralateral (MD, 4.88°; 95% CI, 3.0°-6.7°; P < .001) and control (MD, 6.01°; 95% CI, 2.0°-10.0°; P < .002) limbs. A lower quadriceps force compared with the contralateral (MD, 4.14 BW; 95% CI, 3.4-4.9 BW; P < .001) and control (MD, 2.83 BW; 95% CI, 1.4-4.3 BW; P < .001) limbs was also found.

CONCLUSION

Lower PFJ contact forces and a combination of quadriceps force deficits and smaller knee flexion angle were found in the ACLR compared with the contralateral and control limbs even after clearance to RTS.

CLINICAL RELEVANCE

Despite rehabilitation and subsequent clearance to RTS, differences in PFJ contact forces are present after ACLR. Current rehabilitation and RTS battery may not be effective and sensitive enough to identify and address these differences.

The dose-response of pain throughout a Nordic hamstring exercise intervention

The Nordic hamstring exercise (NHE) reduces hamstring injury incidence. Compliance to large exercise volumes of the NHE is poor, with exercise related soreness often seen as a contributing factor. We investigated the dose-response of NHE exposure with delayed onset muscle soreness (DOMS) and non-DOMS pain. Forty males were randomized to a 6-week intervention of four different NHE dosages: Group 1: very low volume; Group 2: low volume; Group 3: initial high to low volume; Group 4: low to high volume. Group 4 experienced more DOMS (p < 0.05) and non-DOMS pain (p = 0.030) than other groups. High volumes of NHE increase DOMS and non-DOMS pain while lower volume protocols have lesser DOMS and non-DOMS pain responses.

Understanding Fear after an Anterior Cruciate Ligament Injury: A Qualitative Thematic Analysis Using the Common-Sense Model

Fear is a significant factor affecting successful return to sport following an anterior cruciate ligament (ACL) injury. However, there is a lack of understanding of the emotional drivers of fear and how fear beliefs are formed. This study qualitatively explored the contextual and emotional underpinnings of fear and how these beliefs were formed, with reference to the Common-Sense Model of Self-Regulation. Face-to-face online interviews were conducted with ACL-injured participants (n = 18, 72% female) with a mean age of 28 years (range 18-50 years). Participants were either 1 year post ACL reconstruction surgery (n = 16) or at least 1 year post injury without surgery (n = 2) and scored above average on a modified Tampa Scale of Kinesiophobia. Four participants were playing state-level sport or higher. Five themes emerged describing factors contributing to fear: 'External messages', 'Difficulty of the ACL rehabilitation journey', 'Threat to identity and independence', 'Socioeconomic factors', and 'Ongoing psychological barriers'. A sixth theme, 'Positive coping strategies', provided insight into influences that could reduce fear and resolve negative behaviors. This study identified a broad range of contextual biopsychosocial factors which contribute to fear, supporting the notion that ACL injuries should not be treated through a purely physical lens. Furthermore, aligning the themes to the common-sense model provided a conceptual framework conveying the inter-related, emergent nature of the identified themes. The framework provides clinicians with a means to understanding fear after an ACL injury. This could guide assessment and patient education.

Aspetar clinical practice guideline on rehabilitation after anterior cruciate ligament reconstruction

This guideline was developed to inform clinical practice on rehabilitation after anterior cruciate ligament reconstruction (ACLR) and was performed in accordance with the Appraisal of Guidelines for REsearch & Evaluation II (AGREE II) instrument and used the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. A Guideline Development Group systematically searched and reviewed evidence using randomised clinical trials and systematic reviews to evaluate the effectiveness of rehabilitation interventions and guide clinicians and patients on the content of the optimal rehabilitation protocol after ACLR.The guideline targets patients during rehabilitation after ACLR and investigates the effectiveness of the available interventions to the physiotherapist, alone or in combination (eg, exercise, modalities, objective progression criteria). Exercise interventions should be considered the mainstay of ACLR rehabilitation. However, there is little evidence on the dose-response relationship between volume and/or intensity of exercise and outcomes. Physical therapy modalities can be helpful as an adjunct in the early phase of rehabilitation when pain, swelling and limitations in range of motion are present. Adding modalities in the early phase may allow earlier pain-free commencement of exercise rehabilitation. Return to running and return to training/activity are key milestones for rehabilitation after ACLR. However, there is no evidence on which progression or discharge criteria should be used.While there is a very low level of certainty for most components of rehabilitation, most of the recommendations provided in this guideline were agreed to by expert clinicians. This guideline also highlights several new elements of ACLR management not reported previously.

An Investigation of the Nature of Fear within ACL-Injured Subjects When Exposed to Provocative Videos: A Concurrent Qualitative and Quantitative Study

Fear is a factor contributing to poor return to sport after an anterior cruciate (ACL) injury, however the identification and assessment of fear is challenging. To improve understanding of fear, this study qualitatively and quantitatively assessed responses to videos depicting threat to knee stability in people who had experienced an ACL injury. ACL-injured participants who had above average fear on the Tampa Scale of Kinesiophobia and were at least 1-year post-injury/surgery were eligible. Participants were shown four videos depicting sequentially increasing threat to their knee stability (running, cut-and-pivot, feigned knee injury during cut-and-pivot, series of traumatic knee injuries). Qualitative interviews explored participants feeling related to viewing the videos. Participants quantitatively self-rated fear and distress in response to each video. Seventeen participants were included in this study (71% female, with an average time since last ACL injury of 5 ½ years). Five themes were identified: (1) Evoked physiological responses, (2) Deeper contextualisation of the meaning of an ACL injury influencing bodily confidence, (3) Recall of psychological difficulties, (4) Negative implications of a re-injury, and (5) Change to athletic identity. Quantitatively, direct proportionality was noticed between threat level and reported fear and distress. Specifically, participants reported increasing levels of fear and distress as the videos progressed in threat level, with the largest increase seen between a cut-and-pivot movement to a feigned injury during a cut and pivot. The results support the notion that in addition to being a physical injury, an ACL injury has more complex neurophysiological, psychological, and social characteristics which should be considered in management. Using video exposure in the clinic may assist identification of underlying psychological barriers to recovery following an ACL injury, facilitating person-centred care.

Symmetry in Triple Hop Distance Hides Asymmetries in Knee Function After ACL Reconstruction in Athletes at Return to Sports

BACKGROUND

After anterior cruciate ligament reconstruction (ACLR), a battery of strength and hop tests is frequently used to determine the readiness of an athlete to successfully return to sports. However, the anterior cruciate ligament reinjury rate remains alarmingly high.

PURPOSE

To evaluate the lower limb function of athletes after ACLR at the time when they had been cleared to return to sports (RTS). We aimed to evaluate if passing discharge criteria ensures restoration of normal lower limb biomechanics in terms of kinematics, kinetics, work, and percentage work contribution during a triple hop for distance.

STUDY DESIGN

Controlled laboratory study.

METHODS

Integrated 3-dimensional motion analysis was performed in 24 male athletes after ACLR when cleared to RTS and 23 healthy male controls during the triple-hop test. The criteria for RTS were (1) clearance by the surgeon and the physical therapist, (2) completion of a sports-specific on-field rehabilitation program, and (3) limb symmetry index >90% after quadriceps strength and hop battery tests. Lower limb and trunk kinematics, as well as knee joint moments and work, were calculated. Between-limb differences (within athletes after ACLR) and between-group differences (between ACLR and control groups) were evaluated using mixed linear models.

RESULTS

Although achieving 97% limb symmetry in distance hopped and displaying almost 80% symmetry for knee work absorption in the second rebound and third landing, the ACLR cohorts demonstrated only 51% and 66% limb symmetry for knee work generation in the first and second rebound phases, respectively. During both work generation phases of the triple hop, the relative contribution of the involved knee was significantly smaller, with a prominent compensation from the hip joint (P < .001, for all phases) as compared with the uninvolved limb and the controls. In addition, patients deployed a whole body compensatory strategy to account for the between-limb differences in knee function, mainly at the hip, pelvis, and trunk.

CONCLUSION

Symmetry in the triple hop for distance masked important deficits in the knee joint work. These differences were more prominent during work generation (concentric-propulsive) than work absorption (eccentric-landing).

CLINICAL RELEVANCE

Symmetry in hop distance during the triple hop test masked significant asymmetries in knee function after ACLR and might not be the appropriate outcome to use as a discharge criterion. Differences between limbs in athletes after ACLR were more prominent during the power generation than the absorption phase.

Match High-Speed Running Distances Are Often Suppressed After Return From Hamstring Strain Injury in Professional Footballers

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 (r2 = 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.

Effect of speed and gradient on plantar force when running on an AlterG® treadmill

BACKGROUND

Anti-gravity treadmills are used to decrease musculoskeletal loading during treadmill running often in return to play rehabilitation programs. The effect different gradients (uphill/downhill running) have on kinetics and spatiotemporal parameters when using an AlterG® treadmill is unclear with previous research focused on level running only.

METHODS

Ten well-trained healthy male running athletes ran on the AlterG® treadmill at varying combinations of bodyweight support (60, 80, and 100% BW), speed (12 km/hr., 15 km/hr., 18 km/hr., 21 km/hr., and 24 km/hr), and gradients (- 15% decline, - 10, - 5, 0, + 5, + 10 + 15% incline), representing a total of 78 conditions performed in random order. Maximum plantar force and contact time were recorded using a wireless in-shoe force sensor insole system.

RESULTS

Regression analysis showed a linear relationship for maximum plantar force with bodyweight support and running speeds for level running (p < 0.0001, adj. R² = 0.604). The linear relationship, however, does not hold for negative gradients at speeds 12 & 15 km/h, with a relative 'dip' in maximum plantar force across all assisted bodyweight settings.

CONCLUSIONS

Maximum plantar force peaks are larger with faster running and smaller with more AlterG® assisted bodyweight support (athlete unweighing). Gradient made little difference except for a downhill grade of - 5% decreasing force peaks as compared to level or uphill running.

Lower medial hamstring activity after ACL reconstruction during running: a cross-sectional study

Objective

Anterior cruciate ligament reconstruction (ACLR) predisposes footballers for subsequent ACL and hamstring (HS) injury. This case series examines HS muscle activation patterns during the running in ACLR patients (bone-patellar tendon-bone (BTB) and (HS) graft) after completion of functional criteria allowing return to training.

Methods

Electromyography (EMG) recorded from medial and lateral HS bilaterally during treadmill running (12, 14 and 16 km/hour) from 21 male ACLR patients on average 7 months from surgery (5-9) that underwent (HS) (n=12) or BTB reconstruction (n=9) were compared with 19 healthy runners. Main outcome measures: EMG signal was normalised to peak during the running. Pairwise comparisons were made for each muscle group examining stance and swing activation for mean and peak EMG for each patient group and leg.

Results

Significantly lower relative peak activation in stance (not swing) phase for medial HS was seen for all conditions with effect sizes ranging from −0.63 (controls, BTB non-injured leg) to −1.09 (HS injured). For lateral HS only BTB injured were significantly lower in stance phase (−1.05)

Conclusion

ACLR patients show neuromuscular alterations during different phases of running. The finding of reduced medial HS activity in stance phase might have implications for knee instability and HS muscle injury on resumption of sport.

Participant characteristics are poorly reported in exercise trials in tendinopathy: A systematic review

OBJECTIVE

To evaluate the reporting of eligibility criteria and baseline participant characteristics in randomised controlled trials investigating the effects of exercise interventions in tendinopathy.

METHODS

Randomised controlled trials investigating the effects of exercise therapy compared to a non-exercising intervention in upper and lower limb tendinopathy were included. Data extraction was categorised into the following domains: participant demographics, tendinopathy descriptors, general health, participant recruitment and eligibility criteria.

RESULTS

The review included the following tendinopathies: Achilles (n = 9), gluteal (n = 2), lateral elbow tendinopathy (n = 15), patellar (n = 3) plantar (n = 3), and rotator cuff (n = 13). Age, sex, duration of symptoms and symptom severity were commonly reported across the review, while prior history of tendinopathy was poorly reported (6/45). Variables such as physical activity level (17/45), sleep (0/45), psychological factors (2/45), medication at baseline (8/45), co morbid health complaints (10/45) and sociodemographic factors (11/45) were poorly reported across the included studies. Substantial variation existed between studies in the specific eligibility criteria used.

CONCLUSION

The findings of this systematic review demonstrate that participant characteristics are poorly reported in exercise trials in tendinopathy. To improve effectiveness of exercise interventions in tendinopathy, improved reporting of participant characteristics may allow better comparisons and targeted interventions for specific subgroups.

Subacromial Impingment Syndrome does not alter muscle onset activation patterns during shoulder cardinal movement at different speed and load

This study examines neuromuscular firing patterns in healthy and subjects diagnosed with SIS of the periscapular, prime-moving, and rotator cuff muscles during "clinical" cardinal plane physiological movements at different speeds and loads. EMG recordings were taken in 34 healthy and 34 subjects diagnosed with Subacromial Impingement Syndrome (SIS) of the prime movers, periscapular, and rotator cuff muscles during flexion, scaption, and abduction performed at fast, medium, and slow speeds with a loaded (3 kg) and unloaded arm. Differences in firing patterns between groups were analyzed by fitting mixed linear models with random intercepts per subject, and fixed factors for group, muscle, movement type, speed, and load. No difference in timing of activation was seen between the healthy and SIS. Onset timing of prime movers, periscapular, and rotator cuff muscles were prior to movement in all scenarios studied, with rotator cuff muscles firing last. Speed and load appear to independently vary muscle activation timing in a non-intuitive manner in both healthy and SIS. The lack of different firing neuromuscular patterns in subjects diagnosed with SIS and healthy subjects raises the need to consider individual assessment of motor patterns rather than generalized patterns.

No association between perceived exertion and session duration with hamstring injury occurrence in professional football

Training and competition loads have emerged as modifiable composite risk factors of non-contact injury. Hamstring strains are the most common injuries in football with substantial burden on the individual player and club. Nevertheless, robust evidence of a consistent load-hamstring injury relationship in professional football is lacking. Using available data from the Qatar Stars League over three competitive seasons, this study investigated the separate and combined effects of perceived exertion and session duration on hamstring injury occurrence in a sample of 30 outfield football players. Load variables were calculated into 7-day, 14-day, 21-day, 28-day periods of data, and week-to-week changes for average ratings of perceived exertion (RPE; au) score and session-RPE (s-RPE; session-duration  ×  score), plus the cumulative training and match minutes and s-RPE, respectively. Conditional logistic regression models estimated load-injury relationships per 2-within-subject standard deviation increments in each candidate variable. Associations were declared practically important based on the location of the confidence interval in relation to thresholds of 0.90 and 1.11 defining small beneficial and harmful effects, respectively. The uncertainty for the corrected odds ratios show that typically high within-subject increments in each candidate variable were not practically important for training- and match-related hamstring injury (95% confidence intervals range: 0.85 to 1.16). We found limited exploratory evidence regarding the value of perceived exertion and session duration as etiological factors of hamstring injury in Middle-East professional football. Monitoring remains valuable to inform player load management strategies, but our exploratory findings suggest its role for type-specific injury risk determination appears empirically unsupported.

Translation into modern standard Arabic, cross-cultural adaptation and psychometric properties' evaluation of the Lower Extremity Functional Scale (LEFS) in Arabic-speaking athletes with Anterior Cruciate Ligament (ACL) injury

BACKGROUND

The Lower Extremity Functional Scale evaluates the functional status of patients that have lower extremity conditions of musculoskeletal origin. Regional Arabic dialects often create barriers to clear communication and comparative research. We aimed to cross-culturally adapt the Lower Extremity Functional Scale in modern standard Arabic that is widely used and understood in the Middle East and North Africa region, and assess its psychometric properties.

METHODS

Cross-cultural adaptation followed a combination of recommended guidelines. For psychometric evaluation 150 patients with anterior cruciate ligament injury and 65 asymptomatic individuals were recruited. All measurement properties as indicated by the Consensus-based Standards for the selection of health status Measurement Instruments recommendations were evaluated, including content-relevance analysis, structural validity, longitudinal reproducibility, anchor- and distribution-based methods of responsiveness, as well as the longitudinal pattern of change of Lower Extremity Functional Scale in anterior cruciate ligament injured patients' functional status.

RESULTS

The questionnaire presented excellent internal consistency (α = 0.96), reliability (0.80-0.98), and good convergent validity (ρ = 0.85). For reproducibility testing: minimal detectable change was 9.26 points; for responsiveness assessment: minimal clinically important difference was 9 points and presented moderate effect sizes (Glass'Δ = 0.71, Cohen's d = 0.81). Its unidimensionality was not confirmed and an exploratory factor analysis indicated a 2-factor solution explaining 78.1% of the variance.

CONCLUSION

The Arabic Lower Extremity Functional Scale presented acceptable psychometric properties comparable to the original version. The Arabic version of Lower Extremity Functional Scale can be used in research and clinical practice to assess the functional status of Arabic-patients suffering an anterior cruciate ligament injury.

Six different football shoes, one playing surface and the weather; Assessing variation in shoe-surface traction over one season of elite football

INTRODUCTION

An optimal range of shoe-surface traction (grip) exists to improve performance and minimise injury risk. Little information exists regarding the magnitude of traction forces at shoe-surface interface across a full season of elite football (soccer) using common football shoes.

OBJECTIVE

To assess variation in shoe-surface traction of six different football shoe models throughout a full playing season in Qatar encompassing climatic and grass species variations.

METHODS

Football shoes were loaded onto a portable shoe-surface traction testing machine at five individual testing time points to collect traction data (rotational and translational) on a soccer playing surface across one season. Surface mechanical properties (surface hardness, soil moisture) and climate data (temperature and humidity) were collected at each testing time point.

RESULTS

Peak rotational traction was significantly different across shoe models (F = 218, df = 5, p <0.0001), shoe outsole groups (F = 316.2, df = 2, p < .0001), and grass species (F = 202.8, df = 4, p < 0.0001). No main effect for shoe model was found for translational traction (F = 2.392, p = 0.07).

CONCLUSIONS

The rotational (but not translational) traction varied substantially across different shoe types, outsole groups, and grass species. Highest rotational traction values were seen with soft ground outsole (screw-in metal studs) shoes tested on warm season grass. This objective data allows more informed footwear choices for football played in warm/hot climates on sand-based elite football playing surfaces. Further research is required to confirm if these findings extend across other football shoe brands.

Beighton scoring of joint laxity and injury incidence in Middle Eastern male youth athletes: a cohort study

Objectives

To examine the association between generalised joint laxity (GJL) and injury rates in Middle Eastern male youth athletes.

Design

Prospective observational study consisting of GJL screen and injury audit (season 2009/2010).

Setting

Aspire Sports Academy Doha, Qatar.

Participants

A total of 226 adolescent male athletes (mean age: 14.2 years; SD: 1.7; range: 10–18) involved in 15 sporting activities were grouped into contact and non-contact sports. All available athletes were included in this study.

Outcome measures

A seasonal injury audit, athletes’ anthropometric characteristics, for example, weight, height and body mass index and screen for GJL to determine Beighton Score (BS).

Results

The 226 athletes sustained 596 injuries and 75% reported at least one injury over a seasonal injury audit. Players in contact sports were injured more often than players in non-contact sports (more frequent injuries than injury-free time in contact sports; 127 days (95% CI 93 to 160) vs 176 days in non-contact sports (95% CI 118 to 234) (p<0.001). Survival analysis showed that gradient BS was not associated with injury HR=1.004 (95% CI 0.95 to 1.06) in the overall cohort. However, BS was associated with a greater injury risk in contact sports (HR: 1.29; 95% CI 1.05 to 1.59; p=0.015).

Conclusion

Greater GJL, defined by gradient BS, plus involvement in contact sports together influence injury risk in youth athletes. Preseason documentation of GJL scoring should be considered specifically for contact sports as injury pre-emptive measure.

[A video-based analysis to classify shoulder injuries during the Handball World Championships 2015]

Injuries play a major role in high-performance sports and occur in training and competition. Handball is a team sport with high physical demands, and the measurement of specific loads has the potential to identify risk factors for injuries. Few studies have identified this in handball during a World Cup. This study aims to record shoulder injuries that occurred during the 88 games of the 2015 Men's World Cup and to discuss position-specific differences. Players from 24 national teams were analysed using a camera system and special software (Prozone Handball V. 1.2, Prozone, Leeds, UK). In total, nine shoulder injuries were recorded. Three out of these nine injuries were non-contact injuries. The number of passes and throws is position-dependent, and the highest load was documented for the back players. The two back players who suffered a non-contact injury have an increased play time and an increased number of throws compared to their peers. To reduce the risk of injury, the load should be monitored (during training and tournament), and a targeted injury prevention should be performed to prepare the players for the requirements of the game/tournament.

Dual Kinect v2 system can capture lower limb kinematics reasonably well in a clinical setting: concurrent validity of a dual camera markerless motion capture system in professional football players

Objectives

To determine whether a dual-camera markerless motion capture system can be used for lower limb kinematic evaluation in athletes in a preseason screening setting.

Design

Descriptive laboratory study.

Setting

Laboratory setting.

Participants

Thirty-four (n=34) healthy athletes.

Main outcome measures

Three dimensional lower limb kinematics during three functional tests: Single Leg Squat (SLS), Single Leg Jump, Modified Counter-movement Jump. The tests were simultaneously recorded using both a marker-based motion capture system and two Kinect v2 cameras using iPi Mocap Studio software.

Results

Excellent agreement between systems for the flexion/extension range of motion of the shin during all tests and for the thigh abduction/adduction during SLS were seen. For peak angles, results showed excellent agreement for knee flexion. Poor correlation was seen for the rotation movements.

Conclusions

This study supports the use of dual Kinect v2 configuration with the iPi software as a valid tool for assessment of sagittal and frontal plane hip and knee kinematic parameters but not axial rotation in athletes.

Fifth metatarsal stress fracture in elite male football players: an on-field analysis of plantar loading

Objective

Evaluate plantar loading during ‘on-field’ common football movements in players after fifth metatarsal (MT-5) stress fracture and compare with matched healthy players.

Methods

Fourteen elite male soccer players participated in the study conducted on a natural grass playing surface using firm ground football boots. Seven players who had suffered a primary stress fracture (MT-5 group) and seven matched healthy players (controls, CON) performed three common football movements while in-shoe plantar loading data were collected.

Results

Large between-group differences exist for maximal vertical force normalised to bodyweight (F_max) at the lateral toes (2-5) of the stance leg during a set-piece kick (MT-5: 0.2±0.06 bodyweight (BW), CON: 0.1±0.05 BW, effect size (ES) 1.4) and the curved run where the MT-5 group showed higher F_max with very large effect size at the lateral forefoot of the injured (closest to curve) limb when running a curve to receive a pass (MT-5 injured−CON=0.01 BW, ES 1.5). Small between-group differences were evident during straight-line running. However, between-limb analysis of MT-5 group showed significant unloading of the lateral forefoot region of the involved foot.

Conclusions

Elite male football players who have returned to play after MT-5 stress fracture display significantly higher maximum plantar force at the lateral forefoot and lateral toes (2-5) compared with healthy matched control players during two football movements (kick and curved run) with the magnitude of these differences being very large. These findings may have important implications for manipulating regional load during rehabilitation or should a player report lateral forefoot prodromal symptoms.

Muscle Injuries in Sports: A New Evidence-Informed and Expert Consensus-Based Classification with Clinical Application

Muscle injuries are among the most common injuries in sport and continue to be a major concern because of training and competition time loss, challenging decision making regarding treatment and return to sport, and a relatively high recurrence rate. An adequate classification of muscle injury is essential for a full understanding of the injury and to optimize its management and return-to-play process. The ongoing failure to establish a classification system with broad acceptance has resulted from factors such as limited clinical applicability, and the inclusion of subjective findings and ambiguous terminology. The purpose of this article was to describe a classification system for muscle injuries with easy clinical application, adequate grouping of injuries with similar functional impairment, and potential prognostic value. This evidence-informed and expert consensus-based classification system for muscle injuries is based on a four-letter initialism system: MLG-R, respectively referring to the mechanism of injury (M), location of injury (L), grading of severity (G), and number of muscle re-injuries (R). The goal of the classification is to enhance communication between healthcare and sports-related professionals and facilitate rehabilitation and return-to-play decision making.

Blood Flow Restriction induces hypoalgesia in recreationally active adult male anterior knee pain patients allowing therapeutic exercise loading

OBJECTIVE

To evaluate if a single blood flow restriction (BFR)-exercise bout would induce hypoalgaesia in patients with anterior knee pain (AKP) and allow painless application of therapeutic exercise.

DESIGN

Cross-sectional repeated measures design.

SETTING

Institutional out-patients physiotherapy clinic.

PATIENTS

Convenience sample of 30 AKP patients.

INTERVENTION

BFR was applied at 80% of complete vascular occlusion. Four sets of low-load open kinetic chain knee extensions were implemented using a pain monitoring model.

MAIN OUTCOME MEASUREMENTS

Pain (0-10) was assessed immediately after BFR application and after a physiotherapy session (45 min) during shallow and deep single-leg squat (SSLS, DSLS), and step-down test (SDT). To estimate the patient rating of clinical effectiveness, previously described thresholds for pain change (≥40%) were used, with appropriate adjustments for baseline pain levels.

RESULTS

Significant effects were found with greater pain relief immediate after BFR in SSLS (d = 0.61, p < 0.001), DSLS (d = 0.61, p < 0.001), and SDT (d = 0.60, p < 0.001). Time analysis revealed that pain reduction was sustained after the physiotherapy session for all tests (d_(SSLS) = 0.60, d_(DSLS) = 0.60, d_(SDT) = 0.58, all p < 0.001). The reduction in pain effect size was found to be clinically significant in both post-BFR assessments.

CONCLUSION

A single BFR-exercise bout immediately reduced AKP with the effect sustained for at least 45 min.

A valid and reliable method to measure jump-specific training and competition load in elite volleyball players

Use of a commercially available wearable device to monitor jump load with elite volleyball players has become common practice. The purpose of this study was to evaluate the validity and reliability of this device, the Vert, to count jumps and measure jump height with professional volleyball players. Jump count accuracy was determined by comparing jumps recorded by the device to jumps observed through systematic video analysis of three practice sessions and two league matches performed by a men's professional volleyball team. Jumps performed by 14 players were each coded for time and jump type and individually matched to device recorded jumps. Jump height validity of the device was examined against reference standards as participants performed countermovement jumps on a force plate and volleyball-specific jumps with a Vertec. The Vert device accurately counted 99.3% of the 3637 jumps performed during practice and match play. The device showed excellent jump height interdevice reliability for two devices placed in the same pouch during volleyball jumps (r = .99, 95% CI 0.98-0.99). The device had a minimum detectable change (MDC) of 9.7 cm and overestimated jump height by an average of 5.5 cm (95% CI 4.5-6.5) across all volleyball jumps. The Vert device demonstrates excellent accuracy counting volleyball-specific jumps during training and competition. While the device is not recommended to measure maximal jumping ability when precision is needed, it provides an acceptable measure of on-court jump height that can be used to monitor athlete jump load.

The effectiveness of extracorporeal shockwave therapy in common lower limb conditions: a systematic review including quantification of patient-rated pain reduction

OBJECTIVE

To evaluate extracorporeal shockwave therapy (ESWT) in treating Achilles tendinopathy (AT), greater trochanteric pain syndrome (GTPS), medial tibial stress syndrome (MTSS), patellar tendinopathy (PT) and proximal hamstring tendinopathy (PHT).

DESIGN

Systematic review.

ELIGIBILITY CRITERIA

Randomised and non-randomised studies assessing ESWT in patients with AT, GTPS, MTSS, PT and PHT were included. Risk of bias and quality of studies were evaluated.

RESULTS

Moderate-level evidence suggests (1) no difference between focused ESWT and placebo ESWT at short and mid-term in PT and (2) radial ESWT is superior to conservative treatment at short, mid and long term in PHT. Low-level evidence suggests that ESWT (1) is comparable to eccentric training, but superior to wait-and-see policy at 4 months in mid-portion AT; (2) is superior to eccentric training at 4 months in insertional AT; (3) less effective than corticosteroid injection at short term, but ESWT produced superior results at mid and long term in GTPS; (4) produced comparable results to control treatment at long term in GTPS; and (5) is superior to control conservative treatment at long term in PT. Regarding the rest of the results, there was only very low or no level of evidence. 13 studies showed high risk of bias largely due to methodology, blinding and reporting.

CONCLUSION

Low level of evidence suggests that ESWT may be effective for some lower limb conditions in all phases of the rehabilitation.

Peak medial (but not lateral) hamstring activity is significantly lower during stance phase of running. An EMG investigation using a reduced gravity treadmill

The hamstrings are seen to work during late swing phase (presumably to decelerate the extending shank) then during stance phase (presumably stabilizing the knee and contributing to horizontal force production during propulsion) of running. A better understanding of this hamstring activation during running may contribute to injury prevention and performance enhancement (targeting the specific role via specific contraction mode). Twenty active adult males underwent surface EMG recordings of their medial and lateral hamstrings while running on a reduced gravity treadmill. Participants underwent 36 different conditions for combinations of 50%-100% altering bodyweight (10% increments) & 6-16km/h (2km/h increments, i.e.: 36 conditions) for a minimum of 6 strides of each leg (maximum 32). EMG was normalized to the peak value seen for each individual during any stride in any trial to describe relative activation levels during gait. Increasing running speed effected greater increases in EMG for all muscles than did altering bodyweight. Peak EMG for the lateral hamstrings during running trials was similar for both swing and stance phase whereas the medial hamstrings showed an approximate 20% reduction during stance compared to swing phase. It is suggested that the lateral hamstrings work equally hard during swing and stance phase however the medial hamstrings are loaded slightly less every stance phase. Likely this helps explain the higher incidence of lateral hamstring injury. Hamstring injury prevention and rehabilitation programs incorporating running should consider running speed as more potent stimulus for increasing hamstring muscle activation than impact loading.

Interseason variability of a functional movement test, the 9+ screening battery, in professional male football players

BACKGROUND

The Nine Plus screening battery test (9+) is a functional movement test intended to identify limitations in fundamental movement patterns predisposing athletes to injury. However, the interseason variability is unknown.

AIM

To examine the variability of the 9+ test between 2 consecutive seasons in professional male football players.

METHODS

Asymptomatic Qatar Star League players (n=220) completed the 9+ at the beginning of the 2013 and 2014 seasons. Time-loss injuries in training and matches were obtained from the Aspetar Injury and Illness Surveillance Program. No intervention was initiated between test occasions.

RESULTS

A significant increase in the mean total score of 1.6 points (95% CI 1.0 to 2.2, p<0.001) was found from season 1 (22.2±4.1 (SD)) to season 2 (23.8±3.3). The variability was large, as shown by an intraclass correlation coefficient (ICC) of 0.24 (95% CI 0.11 to 0.36) and a minimal detectable change (MDC) of 8.7 points. Of the 220 players, 136 (61.8%) suffered a time-loss injury between the 2 tests. There was an improvement in mean total scores in the injured (+2.0±0.4 (SE), p<0.001) group but not in the uninjured group (+0.9±0.5, p=0.089). The variability from season 1 to season 2 was large both in the injured (ICC 0.25, 0.09 to 0.40, MDC 8.3) and uninjured (ICC 0.24, 0.02 to 0.43, MDC 9.1) groups.

CONCLUSIONS

The 9+ demonstrated substantial intraindividual variability in the total score between 2 consecutive seasons, irrespective of injury. A change above 8 points is necessary to represent a real change in the 9+ test between seasons.

Hamstring and Quadriceps Isokinetic Strength Deficits Are Weak Risk Factors for Hamstring Strain Injuries: A 4-Year Cohort Study

BACKGROUND

A hamstring strain injury (HSI) has become the most common noncontact injury in soccer. Isokinetic muscle strength deficits are considered a risk factor for HSIs. However, underpowered studies with small sample sizes unable to determine small associations have led to inconclusive results regarding the role of isokinetic strength and strength testing in HSIs.

PURPOSE

To examine whether differences in isokinetic strength measures of knee flexion and extension represent risk factors for hamstring injuries in a large cohort of professional soccer players in an adequately powered study design.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 614 professional soccer players from 14 teams underwent isokinetic strength testing during preseason screening. Testing consisted of concentric knee flexion and extension at 60 deg/s and 300 deg/s and eccentric knee extension at 60 deg/s. A clustered multiple logistic regression analysis was used to identify variables associated with the risk of HSIs. Receiver operating characteristic (ROC) curves were calculated to determine sensitivity and specificity.

RESULTS

Of the 614 players, 190 suffered an HSI during the 4 seasons. Quadriceps concentric strength at 60 deg/s (odds ratio [OR], 1.41; 95% CI, 1.03-1.92; P = .03) and hamstring eccentric strength at 60 deg/s (OR, 1.37; 95% CI, 1.01-1.85; P = .04) adjusted for bodyweight were independently associated with the risk of injuries. The absolute differences between the injured and uninjured players were 6.9 N·m and 9.1 N·m, with small effect sizes (d < 0.2). The ROC analyses showed an area under the curve of 0.54 and 0.56 for quadriceps concentric strength and hamstring eccentric strength, respectively, indicating a failed combined sensitivity and specificity of the 2 strength variables identified in the logistic regression models.

CONCLUSION

This study identified small absolute strength differences and a wide overlap of the absolute strength measurements at the group level. The small associations between lower hamstring eccentric strength and lower quadriceps concentric strength with HSIs can only be considered as weak risk factors. The identification of these risk factors still does not allow the identification of individual players at risk. The use of isokinetic testing to determine the association between strength differences and HSIs is not supported.