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Comparison of knee flexor strength limb symmetry index (LSI) between the NordBord-test and the Biodex-test, and to determine the relationship between knee flexor strength and function in patients 2 and 5 years after anterior cruciate ligament reconstruction (ACL-R) with hamstring tendon (HT) autografts. Observational registry study. Primary care. Cross-sectional data from 96 patients (55% women) participating in a rehabilitation-registry after ACL-R with HT autografts. Comparison of knee flexor strength symmetry between the Biodex-test and the NordBord-test. Secondly, the relationship between knee flexor strength test and perceived knee function, activity level, and hop performance. The NordBord-test demonstrated greater strength deficits compared to the Biodex-test with a mean difference of 12.5% ± 15.1% 95 % CI [8.1; 16.9%] at 2 years, and 11.1% ± 11.9% 95 % CI [7.7; 14.6 %] at 5 years after ACL-R. Relative concentric knee flexor strength (Nm/kg) in the Biodex demonstrated significant weak-to-moderate correlations with activity level and hop performance (r = 0.33–0.67) at 2 and 5 years. The NordBord-test identified deficits in knee flexor strength LSI not seen with the Biodex-test at 2 and 5 years after ACL-R. No significant correlations were found between the persistent knee flexor strength asymmetry and perceived function, activity level or hop performance. • Knee flexor strength deficits persists in the NordBord-test at 2 and 5 years. • Knee flexor strength LSI displayed weak relationships with knee function. • Relative knee flexor strength in the Biodex appears more relevant for function. [ABSTRACT FROM AUTHOR]

The lower kinetic chain is known to be affected by hamstring tightness which causes biomechanical alterations. As per the literature, short hamstring might cause prolonged forefoot loading, which can cause higher repeated stress on the plantar fascia. There is evidence supporting the use of various stretching and myofascial release techniques for hamstring tightness, further research is needed to investigate their impact on plantar pressure. Hence the study aims to determine combined effect of myofascial release and passive stretching on plantar pressure in individual with hamstring tightness. This was an experimental pre-post study design with 67 randomised screenings from asymptomatic health care science students aged 18 to 25. From this scientific survey, a sample size of 47 students having HMS tightness based on the popliteal angle were recruited using a universal goniometer. An intervention was proposed that included MFR and passive stretching in 3 sessions on alternate days. Plantar pressure of these individuals was noted by using the "Harris and Beath foot printing mat" before and after the intervention. Significant pressure changes were observed after intervention: great toe of right side (p = 0.001), toes 2 to 5 of right side (p = 0.010) and left side (p = 0.008), first metatarsal of left side (p = 0.010), lateral forefoot of right side (p = 0.019) and left (p = 0.018), medial heel (p = 0.044), and lateral heel of right side (p = 0.025). These values substantiate the enhancement in plantar pressure. The combined effect of Myofascial release and passive stretching in an individual with hamstring tightness resulted in a significant increase in popliteal angle and plantar pressure. [ABSTRACT FROM AUTHOR]

Muskelverletzungen im Profisport haben eine große Bedeutung und gehören zu den häufigsten Diagnosen. Entscheidend ist eine schnelle, vollständige Genesung unter Vermeidung von Re-Verletzungen. Es gibt zahlreiche Muskelverletzungen mit unterschiedlichen Prognosen/Ausfallzeiten, daher ist die richtige Primäreinschätzung, Erstversorgung und die sofortige Einleitung der entsprechenden Therapie und Rehabilitation von großer Bedeutung. Muskelverletzungen werden in der Regel konservativ behandelt. Bei nicht strukturellen Verletzungen werden primär physio- und manualtherapeutische Maßnahmen durchgeführt – im Falle von rückenbedingten neurogenen Muskelläsionen kann eine infiltrative Mitbehandlung der LWS sinnvoll sein. Bei strukturellen Verletzungen stehen unterschiedliche infiltrative Behandlungsoptionen zur Verfügung, die jedoch kontrovers diskutiert werden und eine geringe Evidenz aufweisen. In der Rehabilitation ist ein schrittweiser Belastungsaufbau, zeitlich orientiert an der jeweiligen Diagnose, von großer Bedeutung. Dieser Artikel gibt einen Überblick über die Klassifikation, Prognose und Therapie der unterschiedlichen Muskelverletzungen. Treatment of muscle injuries in professional sports. Muscle injuries are a substantial problem in professional sports and they are one of the most common injuries. A quick and complete healing is essential – a re-injury has to be prevented. There are several different muscle injuries with different prognoses and time of absence. Therefore the correct primary assessment of the injury and the initiation of the correct treatment and rehabilitation are very important. Most of the muscle injuries can be treated conservatively. Functional muscle disorders and neuromuscular muscle injuries are treated with physio- and manualtherapeutic techniques – in lumbar spine related neurogenic muscle injuries an infiltration treatment of the lower back can be helpful. Various infiltrative treatments are available in structural muscle injuries – they are discussed controversialy and scientific studies show a low level of evidence. In the rehabilitation process a gradual increase of the intensities and load is essential. This article gives an overview of the classification, prognosis and therapy of different muscle injuries. [ABSTRACT FROM AUTHOR]

Copyright of Sport-Orthopadie - Sport-Traumatologie is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The validity and reliability of 3-D ultrasound (US) in estimation of muscle and tendon volume was assessed in a very limited number of muscles that can be easily immersed. The objective of the present study was to assess the validity and reliability of muscle volume measurements for all hamstring muscle heads and gracilis (GR), as well as tendon volume for the semitendinosus (ST) and GR using freehand 3-D US. Three-dimensional US acquisitions were performed for 13 participants in two distinct sessions on separate days, in addition to one session dedicated to magnetic resonance imaging (MRI). Volumes of ST, semimembranosus (SM), biceps femoris short (BFsh) and long (BFlh) heads, and GR muscles and from the tendon from semitendinosus (STtd) and gracilis (GRtd) were collected. The bias and the 95% confidence intervals of 3-D US compared with MRI ranged from –1.9 mL (–0.8%) to 1.2 mL (1.0%) for muscle volume and from 0.01 mL (0.2%) to –0.03 mL (–2.6%) for tendon volume. For muscle volume assessed using 3-D US, intraclass correlation coefficients (ICCs) ranged from 0.98 (GR) to 1.00, and coefficients of variation (CV) from 1.1% (SM) to 3.4% (BFsh). For tendon volume, ICCs were 0.99, and CVs between 3.2% (STtd) and 3.4% (GRtd). Three-dimensional US can provide a valid and reliable inter-day measurement of hamstrings and GR for both muscle and tendon volumes. In the future, this technique could be used as an outcome for strengthening interventions and potentially in clinical environments. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the intra- and inter-muscular differences of the hamstring muscles using textural analysis of ultrasound (US) images, and the relationship between textural indicators with hamstring torque. Transverse US scans were obtained from 10 young males from four different measurement sites along the thigh of each individual hamstring muscle at rest. Maximum-knee-flexion isometric torque measurements were also obtained. Texture analysis was applied to US images, and five gray-level co-occurrence matrix (GLCM) features were quantified: entropy (ENT), angular second moment (ASM), inverse difference moment (IDM), contrast (CON) and correlation (COR). The intraclass correlation coefficients ranged from 0.77 to 0.99, and the standard error of measurement ranged from 0.06 to 10.05%, indicating high test-retest reliability. Analysis of the variance indicated significant differences between measurement sites and individual muscles, with the proximal measurement sites having greater values for ASM, IDM and COR and lower values for ENT and CON compared with the distal sites. Additionally, only the COR at the proximal measurement site exhibited a significant relationship (r = -0.66) with strength. The present study indicated significant differences among hamstrings and measurement locations with respect to the textural analysis and may provide a novel indicator of hamstring functional properties. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MRI) is an integral component of the treatment algorithm for proximal hamstring avulsion injuries. The purpose of this study was to survey orthopedic surgeons and musculoskeletal radiologists on the reporting and analysis of proximal hamstring avulsions on MRI. Two online surveys were developed to evaluate musculoskeletal radiologists' and orthopedic surgeons' perceptions of MRI-reporting for proximal hamstring avulsion injuries. Each survey was designed to provide information on physicians' best practices with respect to four primary questions (1) ischial tuberosity landmark determination (2) difficulties associated with measuring tendon retraction, (3) important ancillary findings, and (4) perceived clinical impact of measured retraction. Descriptive statistics were calculated for all categorical variables, which were reported as frequencies with percentages. Chi-squared test was utilized to compare rates of responses between surgeons and radiologists. Statistically significant differences were analyzed with post-hoc Fisher's exact tests; p < 0.05 considered statistically significant. 218-Musculoskeletal radiologists and 33-orthopedic surgeons responded to their respective surveys. There were statistically significant differences with responses to two of the questions asked in both surveys; (1) in cases of complete hamstring avulsion (avulsion of both the semimembranosus and conjoint tendon), which arrow represents the tendon gap measurement used for planning surgery? p = 0.028; (2) in cases of avulsion of only the conjoint tendon, which arrow represents the tendon gap measurement used for planning surgery? p = 0.013. Post-hoc testing demonstrated that for either partial or complete hamstring avulsions, more surgeons use the conjoint tendon origin to measure tendon retraction than radiologists (p < 0.05 for both). Significantly more radiologists use the semimembranosus origin to measure hamstring retraction for partial or complete hamstring tears (p < 0.05 for both). However, for each of these questions, both radiologists and surgeons most frequently stated that the conjoint tendon landmark should be used for surgical planning. Musculoskeletal radiologists and orthopedists frequently utilize the conjoint tendon origin as an anatomic landmark for measuring complete and partial proximal hamstring avulsion injuries; though, orthopedists are more likely to utilize this landmark. Additionally, the broad surface area of the ischial tuberosity may lead to variability in measurement. Standard landmarks at the ischial tuberosity and/or detailed descriptions of tendon retractions would improve communication between radiologists and surgeons for proximal hamstring avulsions. • Many orthopedic surgeons and radiologists frequently use the conjoint tendon as a radiographic landmark for measuring the extent of proximal hamstring avulsion injuries. • However, there is significant variability in the radiographic landmarks used to quantify these injuries, and this has an impact on the interventions and clinical outcomes for these patients. [ABSTRACT FROM AUTHOR]

Objectives: Many studies have investigated the relationship between muscle activation and tensile force of the anterior cruciate ligament. These studies lacked a holistic representation of the muscle status. For instance, they were limited with respect to the peak muscle forces, number of muscles, and possible muscle activation patterns.Design: This study used a knee surrogate including ten muscles with motor-controlled muscle force activation crossing the knee joint, thus providing a fully muscle-supported knee joint.Methods: Anterior cruciate ligament tensile force is measured in different knee flexion and extension movements to evaluate ratios of quadriceps/hamstring muscle activations in low hip angle setups.Results: Increasing the extension of the leg increased anterior cruciate ligament tension forces. Different quadriceps/hamstring ratios had different effects on anterior cruciate ligament tension forces during unrestricted flexion and extension movements. This was dependent on the direction of movement. Sole hamstring activation increased the anterior cruciate ligament tensile forces in extension movements compared with flexion movements. Sole quadriceps activation provoked greater anterior cruciate ligament tensile forces in flexion than in extension. This was not prominent in the test in which the other muscle groups counteracted the dominant muscle group.Conclusions: The findings from the present study demonstrate that active hamstring activation can reduce the load on the anterior cruciate ligament, and the dominant quadriceps increase anterior cruciate ligament loads for knee flexions of less than 40°. Moreover, the anterior cruciate ligament is loaded differently in flexion or extension movements with flexion movements, resulting in higher anterior cruciate ligament loads. [ABSTRACT FROM AUTHOR]

The semitendinosus tendon is one of the most used autografts in anterior cruciate ligament reconstruction. Although recent evidence indicates that young patients, especially in females, may experience high rates of revision and residual instability, the reasons for the inferior outcomes in these patients remain unclear. To address this issue, we aimed to compare the mechanical properties of the semitendinosus tendon used for anterior cruciate ligament reconstruction in male and female patients of various ages. The semitendinosus tendons harvested from 31 male and 29 female patients who underwent anterior cruciate ligament reconstruction surgery using the semitendinosus tendon autografts were used in this study. Using the distal part of the harvested semitendinosus tendon, the extent of cyclic loading-induced elongation (i.e., the extent of the increase in slack length) and the Young's modulus were measured during cyclic tensile testing. Spearman correlation analyses revealed that the Young's modulus (|ρ| = 0.725, P < 0.001), but not elongation (|ρ| ≤ 0.036, P ≥ 0.351) positively correlated with the patient age in male tendon samples. In contrast, for female tendon samples, the elongation (|ρ| ≥ 0.415, P ≤ 0.025), but not the Young's modulus (|ρ| = 0.087, P = 0.655) negatively correlated with the patient age. These results indicate that the semitendinosus tendon used for anterior cruciate ligament reconstruction in young male patients is compliant, whereas that in young female patients is susceptible to elongation induced by cyclic loading. • The semitendinosus tendons used for surgery were assessed. • The semitendinosus tendon in young male patients is compliant. • The semitendinosus tendon in young female patients is susceptible to elongation. [ABSTRACT FROM AUTHOR]

To explore the incidence, burden, and pattern of injuries in Spanish male youth soccer players during a 9-month competitive season (from September to May–June). Prospective cohort study. 314 young (10–19 years) soccer players. Incidence, burden, location, type, severity, mechanism, and circumstance of injuries, as well as potential differences by tactical position, month of the year, age group, and maturity status. A total of 146 time-loss injuries were sustained by 101 different players. This resulted in an overall injury incidence of 3.1 injuries per 1000 h, a training injury incidence of 1.8 injuries per 1000 h, and a match injury incidence of 11.2 injuries per 1000 h. The probability of injury over the season was 34%. Most of the injuries affected the lower extremity and were classified as muscle/tendon injuries, with hamstring muscle injuries representing the most burdensome diagnosis. The incidence of injuries increased with age and maturation, but a heightened risk of overuse injuries during periods around peak height velocity was also identified. These findings suggest a need for implementing specific injury prevention measures. Due to the high burden shown, these measures should mainly focus on reducing the number and severity of hamstring muscle injuries. • One out of three boys is likely to sustain a time-loss injury during a season in Spain. • Hamstring muscle injuries represent the most burdensome diagnosis. • The incidence of injuries is higher in older age groups (U15–16 and U17-19). • There is an increased risk of overuse injuries during the adolescent growth spurt. • Players around the peak height velocity suffer the greatest injury burden. [ABSTRACT FROM AUTHOR]

Stretching and strengthening exercises are commonly used to improve muscle shortness. Consequently, the aim of this trial was to compare the flexion-relaxation response (electromyography activities of shortened hamstring and back muscles) in chronic nonspecific LBP patients. In this randomized controlled clinical trial, forty-five eligible patients were randomly categorized into three groups; static stretching (n = 15), strengthening exercise in lengthened hamstring position (n = 15) and control (n = 15). All groups received conventional physical therapy for LBP and the two intervention groups received special exercise programs as well. Each group performed three treatment sessions for a week, a total of 12 sessions. The flexion-relaxation ratio (FRR) for knee and back muscles were assessed as the primary outcome measure. Pain and functional disability for participants were also assessed. The results indicated non-significant differences between the three groups regarding the changes of FRR (mean between-group differences ranged over 0.69 to 39.1; p > 0.05), pain and disability (mean between-group differences ranged over 0.15 to 5.96; p > 0.05). Within-group analysis for each group, revealed statistically significant improvement in the patients' score of either pain (mean within-group differences ranged over −27.20 to −35.76; p < 0.001) or disability (mean within-group differences ranged over −16.17 to 24.95; p < 0.001) as secondary outcomes. In other words, the scores of pain and disability decreased in all treatment groups as compared to the baseline. Neither static stretching nor strengthening exercises in lengthened hamstring position affected FRR more than the control group. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the reliability of distal hamstring tendon morphology using freehand 3-D ultrasound (US). Freehand 3-D US scans were acquired for 16 young males and females, in two sessions, spaced a week apart. The length, volume, cross-sectional area (CSA) and echo intensity (EI) of the semitendinosus (ST), biceps femoris long and short head and semimembranosus (SM) tendons were acquired. Measurements of the CSA and EI were obtained from three sites along each tendon. The intra-class correlation coefficients ranged from 0.88-0.99 of the examined variables, indicating high test-retest reliability. In addition, the minimal detectable change (MDC) ranged from 0.255-3.766 mm (MDC% of the mean: 0.406%-12.558%) for hamstring tendon length, from 0.036-0.077 mL (MDC%: 1.548%-3.178%) for tendon volume, from 0.512-1.948 mm2 (MDC%: 0.702%-3.586%) for CSA and from 0.898-2.586 au (MDC%: 1.145%-3.325%) for EI. Of the four hamstring tendons, ST had the greatest length (141.587 ± 10.701 mm) and EI (94.637 ± 5.536 au), while SM had the greatest volume (3.056 ± 0.421 mL) and CSA (115.277 ± 16.442 mm2) relative to other tendons. Freehand 3-D US appears to be a reliable tool for the evaluation of hamstring distal tendon morphology; hence, its use for in vivo evaluation of tendon properties is promising. [ABSTRACT FROM AUTHOR]

To investigate the relationship between: (1) knee flexor strength, rate of torque development (RTD), and flexibility with pain level; (2) knee flexor strength and RTD with the performance in the single leg bridge test (SLBT) in women and men with patellofemoral pain (PFP). Cross-sectional. Laboratory-based study. 39 women and 36 men with PFP. Knee flexor strength, RTD, and flexibility; performance in the SLBT, current, and worst pain level. Moderate to strong significant negative relationships were identified between the current pain level with knee flexor strength (r = −0.57 to −0.34) and flexibility (r = −0.44 to −0.35); and between knee flexor strength and RTD with the performance in the SLBT (r = 0.34 to 0.57) in women and men with PFP. Knee flexor RTD was not related to any pain level and no significant relationships were identified between the worst pain level with knee flexor strength and flexibility in women and men with PFP. Our results support the potential value of assessing knee flexor strength and flexibility in women and men with PFP. The SLBT may be a useful tool to assess knee flexor muscle capacity in individuals with PFP in a clinical setting. • Clinicians should consider knee flexor strength and flexibility when assessing women and men with patellofemoral pain • The single leg bridge test may be a useful tool to assess knee flexor muscle capacity in individuals with patellofemoral pain [ABSTRACT FROM AUTHOR]

Proximal hamstring injuries can present as chronic tendinosis, acute strain, partial tendinous avulsions, or complete 3-tendon rupture. Nonoperative management for chronic insertional tendinosis and low-grade tears includes activity modification, anti-inflammatories, and physical therapy. Platelet-rich plasma injections, corticosteroid injections, dry needling, and shock wave therapy are newer therapies that also may provide benefit. Surgical indications include complete, proximal avulsions; partial avulsions with least 2 tendons injured with more than 2 cm of retraction in young, active patients; and partial avulsion injuries or chronic tendinosis that have failed nonoperative management. Surgical management entails open primary repair, endoscopic primary repair, or augmentation/reconstruction. [ABSTRACT FROM AUTHOR]

To explore and summarise expert physiotherapists' perceptions on their assessment, management and prevention of proximal hamstring tendinopathy (PHT). We conducted semi-structured interviews with expert physiotherapists until data saturation was met (n = 13). Interviews were transcribed verbatim and data were analysed systematically and organised into categories and sub-categories according to study aims. Experts report using a clinical reasoning-based approach, incorporating information from the patient interview and results of clinical load-based provocation tests, in the physical examination to diagnose PHT. Experts manage the condition through education and progressive loading targeting the hamstring unit and kinetic chain, avoiding provocative activities in positions of compression in early-mid stage rehab and a gradated and controlled return to sport. Passive therapies including injection therapies and surgery were believed to have limited utility. Prevention of recurrence primarily involved continuation of hamstring and kinetic chain strengthening programs and management of physical workload. Experts rely on a combination of information from the patient interview and a battery of pain provocation tests to diagnose PHT. Education and graded exercise of the hamstring group and synergists, minimising early exposure to hip flexion, were the foundation of management of the condition. • Expert physiotherapists use a battery of diagnostic tests - implying no one test is adequate. • Progressive exercise should minimise early exposure to provocative ranges of hip flexion. • Exercise of the hamstring musculotendinous unit and synergists should be the first line of care. • Passive therapies including injection therapies and surgery are thought to have limited utility. [ABSTRACT FROM AUTHOR]

The purpose of this study was to establish beliefs and practices of physical performance coaches regarding sprinting and Hamstring Strain Injury (HSI) in Australian Rules football. Delphi-validated questionnaire. Online. Eighteen high-performance managers of the Australian Football League. Descriptive statistics were collected to establish experience; central themes were established for the analyses of the beliefs and practices. Nine (50%) physical performance coaches responded to an invitation to complete the questionnaire. Participants held an undergraduate degree and had 9.2 ± 4.3 years of experience. Accelerations (n = 9), maximum speed sprints (n = 9) and running with hip flexion (n = 7) were the most common activities associated with HSI. Coaches believed sprinting, eccentric strength training and proper periodisation were effective strategies to reduce HSI risk. There's a disparity between beliefs and practices when using GPS to monitor sprinting, however, all coaches reported regular exposure to sprint training across both pre and in-season. Overstriding (n = 9) and pelvic instability (n = 6) were identified as key flaws in running mechanics. This information can be used to improve training strategies, whilst these findings indicate further investigations into sprint training and running mechanics for HSI risk reduction. • Athletes are regularly exposed to sprinting for HSI prevention, but the fear of injury is prominent, possibly because of consequences for players and staff. • There is a disparity between beliefs and practices of coaches when using GPS to monitor HSR, however the solution for this problem remains unclear. • Assessing and training running mechanics is common practice in Professional ARF, however, the link to hamstring strain injury is not yet well established. [ABSTRACT FROM AUTHOR]

Background: The head, arms and trunk segment constitute a large proportion of the body's mass. Therefore, small alterations in trunk inclination may affect lower limb joint moments and muscle activation patterns. Although previous research has investigated the effect of changing frontal plane inclination of the trunk, it is not clear how increasing trunk flexion will impact on the activation of the lower limb muscles.Research Question: What is the effect of independently manipulating trunk flexion angle on lower limb kinematics, moments and muscle function?Methods: Gait analysis was carried out on 20 healthy people under four trunk flexion conditions: normal walking (NW), NW-5°, NW+5° and NW+10°. For the latter three conditions, a biofeedback approach was used to tightly control trunk flexion angle. A linear mixed model was used to investigate the effect of changing trunk flexion on joint angles, moments, and knee muscle activation.Results: There were clear increases in hip and ankle moments as trunk flexion was increased, but no change in knee moments. The results also showed a linear increase in knee flexor muscle activity and a corresponding increase in co-contraction as trunk flexion increased. Interestingly, there was a dramatic change in the profile of hamstring activity. In the medial hamstrings, this change led to a 100% increase in activation during early stance as flexion was increased by 5° from NW.Significance: This is the first study to demonstrate a strong dependence of knee flexor muscle activity on trunk flexion. This is important as people with knee osteoarthritis have been observed to walk with elevated muscle activation and this has been linked to increased joint loads. It is possible that these altered muscle patterns may result from increased trunk flexion during walking. [ABSTRACT FROM AUTHOR]

Background: Deficits in knee flexor strength and rate of torque development (RTD) might be present in women with patellofemoral pain (PFP). In addition, maximal strength and RTD of the knee flexors and extensors might be related with subjective and objective function in women with PFP. However, both conjectures are still poorly understood.Research Question: Do women with PFP have deficits in the maximal strength and RTD of the knee flexors and extensors during isometric, concentric, and eccentric contractions? Is there a relationship between maximal strength and RTD of the knee flexors and extensors with subjective and objective function in women with PFP?Methods: Fifty-six women with, and 46 women without, PFP participated. Maximal strength and RTD (to 30% and 60% maximal torque) during isometric, concentric, and eccentric contractions of the knee flexors and extensors were assessed using an isokinetic dynamometer. Objective assessment included single leg hop test (SLHT) and forward step-down test (FSDT). Subjective assessment involved the anterior knee pain scale.Results: Women with PFP had small to large deficits in maximal strength and RTD of the knee flexors and extensors during isometric, concentric and eccentric contractions (Effect sizes: -0.43 to -1.10; p ≤ 0.016). Small to moderate correlations of maximal concentric and eccentric knee flexor strength and RTD with SLHT and FSDT (r = 0.28 to 0.41; p ≤ 0.037) were identified. Subjective or objective function were not correlated with maximal isometric knee flexor strength and RTD, or any knee extensor measures (p > 0.05).Significance: Maximal strength and RTD deficits of the knee flexors and extensors were identified in this female PFP cohort, but they were unrelated to subjective function. The relationship of concentric and eccentric knee flexor strength and RTD deficits with poor objective function should be considered in future exercise trials for women with PFP. [ABSTRACT FROM AUTHOR]

Copyright of Revista Española de Cirugía Ortopédica y Traumatologia (English Edition) is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Stretching and strengthening exercises are commonly used to improve muscle shortness of the hamstring as any tension in this muscle can have an effect on the pelvic posture. Thus, the aim of this study was to evaluate the effects of two methods of improving short hamstring on the angle of pelvic tilt in LBP sufferers. Forty-five low back pain patients aged 19–59 years with hamstring tightness participated in this clinical trial. The patients were categorized randomly into three groups: 1- static stretching, 2-strengthening exercise and 3-control group. The two intervention groups received physical therapy and special exercise program thrice a week in a total of 12 sessions, while the control group received only conventional physical therapy. Before and after the treatment implementation, the pelvic tilt and straight leg raising (SLR) degree were assessed for each group. After 12 sessions of treatment, the ANCOVA models indicated non-significant differences in pelvic tilt angle and SLR score changes (p > 0.05), among the three groups. In addition, no statistically significant correlation was observed between the pelvic tilt and SLR test [except for the strengthening exercise group (Pearson correlation coefficient = −0.54, P < 0.05)]. In LBP sufferers, both static stretching and strengthening of hamstring muscle in its lengthened position caused elongation and extensibility in the hamstring muscle and increased SLR test score, but did not change pelvic tilt angle. [ABSTRACT FROM AUTHOR]

This novel study aims to provide unique data on eccentric hamstring strength in elite track and field athletes. Clinical measurement, cross-sectional study. Across two British Athletics performance centres. 44 elite British track and field athletes. Eccentric hamstring force and torque were evaluated using the Nordbord device. Injury history and demographic data was collected to assess whether differences between gender, event group, limb symmetry and previous injury history were present. Average peak force for males and females was 418.38N and 318.54N. Relative to body weight there were no gender differences (Male 5.21N.kg−1, Female 4.99N.kg−1) (p = 0.62). The right limb was significantly stronger in long sprint (400m athletes) (p = 0.00018) (d = 0.56). No differences in relative force or torque were observed between previously injured and non-injured limbs. This study provides unique data in elite track and field athletes. Relative force per kilogram should be used when comparing male and female athletes. Unlike other studies, we found no difference in eccentric strength between previously injured and non-injured limbs. The novel finding of increased eccentric strength demonstrated in the right limb in 400m sprinters may be due to the asymmetric demands of bend running and may be considered normal. • Asymmetry of eccentric hamstring strength may be a normal finding. • No association between previous injury and hamstring strength. • No gender difference in relative eccentric hamstring strength. [ABSTRACT FROM AUTHOR]

Objectives: Investigate the determinants of hamstring fascicle length in professional rugby league players.Design: Retrospective cohort study METHODS: Thirty-three elite male athletes underwent testing in the pre-season and in-season periods. Fascicle length measurements of the biceps femoris long head, 3D kinematics and elapsed time-periods at thigh angular velocities between 20°/s to peak velocity during a single-leg Nordic hamstring strength test, GPS-derived running loads, age and previous injury history were all recorded. Fixed effect determinants for fascicle length were analyzed using multiple linear regression.Results: Significant determinants of hamstring fascicle length were observed. Multivariate regression analysis showed modifiable factors including chronic (56 days) running volumes >80% of measured peak velocity and maximum velocity itself collectively explained 43% of the variability in the fascicle length data, whilst peak eccentric strength and elapsed time under load from 20°/s to peak thigh angular velocity collectively contributed an additional 44%. Chronic running volumes >90% of individually measured peak velocity and the 'break angle' during a Nordic eccentric contraction were not significant contributors to the final model. Non-modifiable risk factors (age and previous injury) contributed the remaining 13%.Conclusions: Managing high velocity running exposure as well as eccentric strength allows for ˜90% of the controllable determinants in fascicle length within elite athlete populations. An important contributor to the explained variability within fascicle length (superseded only by chronic velocity exposure and peak eccentric strength) was an athletes ability to achieve a prolonged contraction at long lengths during eccentric strength training rather than the angle of failure during the contraction in itself. [ABSTRACT FROM AUTHOR]

• The ratio of vastus medialis (VM) cross-sectional area (CSA) to quadriceps muscle and that of semi-membranosus (SM) CSA to hamstring were low in individuals with medial knee osteoarthritis. • The thigh region to evaluate muscle atrophy differed by muscles. • The thigh region around the mid-thigh should be analyzed for the VM CSA ratio. • The thigh region at the muscle belly should be analyzed for the SM CSA ratio. • The therapeutic effect of VM and SM hypertrophy on knee osteoarthritis is worth testing. The characteristics of thigh-muscle cross-sectional area (CSA) in older adults with knee osteoarthritis (KOA) remain controversial. This study aimed to evaluate atrophy of individual thigh muscles in older adults with KOA and to determine which muscle CSA should be measured to detect KOA-related muscle atrophy of the thigh. In older adults, individual thigh-muscle CSA measured by 1.5 Tesla MRI was analyzed at 5% intervals of the femoral length (FL) around the mid-thigh between the proximal 25% of the FL and the distal 25%. Participants with KOA grade ≤ 1 and grade ≥ 2 were compared for ratios of quadriceps muscle (QM) CSA to total thigh, individual QM CSA to QM, and individual hamstring (HAM) CSA to HAM at 5% intervals. We included 40 older adults [20 males; mean (SD) age 73.3 (4.7) years; 20 with KOA grade ≤ 1 and 20 with KOA grade ≥ 2]. The ratio of vastus medialis (VM) CSA to QM from the proximal 25% to distal 15% and the ratio of semi-membranosus (SM) CSA to HAM at the distal 10% to 25% were significantly lower with KOA grade ≥ 2 than grade ≤ 1; the effect sizes were 0.34 to 0.67 for VM and 0.40 to 0.60 for SM. The effect sizes were greatest for the ratios of VM CSA to QM at the mid-thigh with 5% intervals and the ratio of SM CSA to HAM at the distal 25%. The ratio of VM CSA to QM and/or that of SM CSA to HAM were low and were the best indicators to detect KOA-related muscle atrophy of the thigh. However, to detect KOA-related muscle atrophy, the VM CSA ratio should be analyzed in the thigh region around the mid-thigh, whereas the SM CSA ratio should be analyzed in the thigh region at the muscle belly. [ABSTRACT FROM AUTHOR]

To compare traditional and angle-specific isokinetic strength of eccentric knee flexors and concentric knee extensors in female senior professional and youth soccer players. Cross-sectional study design. University's Laboratory. A total of 34 players (17 seniors [age 25.31 ± 4.51 years; height 167.89 ± 7.04 cm; mass 63.12 ± 7.79 kg] and 17 youths [16.91 ± 1.16 years; height 165.92 ± 4.42 cm; mass 60.07 ± 4.48 kg]) from the Women's Super League 1 completed strength assessments at 180, 270 and 60°∙s−1. Peak torque (PT), dynamic control ratio (DCR), angle of peak torque (APT), functional range (FR), angle-specific torque (AST) and angle-specific DCR (DCR AST) were compared between age groups. The PT (P = 0.016) AST (P = 0.041) were significantly higher in seniors compared to youths; however APT (P = 0.141), DCR (P = 0.524) FR (P = 0.821) and DCR AST (P = 0.053) were not significant between playing age. The use of absolute and angle-specific strength measures were able to distinguish between female playing ages, whereas DCR and DCR AST was unable to identify differences. The PT and AST metrics may be the most useful metrics to help identify and inform training needs, particularly in youths. • Thigh musculature strength of female soccer players influenced by playing age. • No differences in strength ratios across female soccer playing age. • These metrics can inform training and better prepare youths for senior match-play. [ABSTRACT FROM AUTHOR]

To investigate the influence of internal and external foot rotation on medial and lateral hamstring electromyographic (EMG) activity during conventional hamstring exercises in patients following anterior cruciate ligament (ACL) reconstruction. Cross-sectional study. EMG activity of medial and lateral hamstrings was recorded during prone leg curl, single-leg bridge and Nordic hamstring exercises with three different foot positions (neutral, internal rotation, external rotation), randomly presented. Twenty patients 9–15 months after ACL reconstruction with the semitendinosus-gracilis graft. Concentric and eccentric EMG activity normalized to the EMG activity recorded during a maximal voluntary contraction (MVC). Compared to the neutral position, the EMG activity of the medial hamstring during prone leg curl exercise was significantly increased by internal foot rotation (concentric: +8.7% MVC; eccentric: +5.9% MVC; p < 0.01; d = 0.88–0.99) and decreased by external rotation (concentric: 5.8% MVC; eccentric: 5.2% MVC; p < 0.05; d = 0.67–0.92). Foot position did not significantly affect hamstring EMG activity during single-leg bridge and Nordic hamstring exercises. Active internal rotation of the foot during prone leg curl exercise can help selectively maximize muscle activity of the medial hamstring portion. This may have implications for post-operative rehabilitation of ACL patients with a semitendinosus-gracilis graft. • Internal foot rotation during leg curl exercise increases MH activity. • External foot rotation during leg curl exercise decreases MH activity and increases LH activity. • Foot rotation during single-leg bridge and Nordic hamstring exercises has no effect on hamstring muscle activity. • The prone leg curl exercise with active foot rotation could be implemented in rehabilitation following ACL reconstruction. [ABSTRACT FROM AUTHOR]

• Performing intermittent cycling increases the level of oxygenation in hamstring muscle. • Oxygenation have no beneficial effect on recovery kinetics of hamstring force. • Muscle performance recovery is influenced by several factors. The aim of this study was to analyze the effects of inducing muscle oxygenation using an intermittent cycling exercise on recovery kinetics after exercise-induced muscle damage. Ten soccer players performed single-leg knee flexors exercise: 75 eccentric contractions. The day after, subjects performed an intermittent cycling exercise of 12 min (15 s work - 15 s rest) or recovered passively in a balanced and randomized cross-over design. Force, single and double-leg countermovement jumps, muscle soreness, perceived recovery and creatine kinase concentrations were assessed through a 72 h period. Oxygenation during cycling was assessed using Near Infrared Spectroscopy. Results showed an increase in knee flexors oxygenation using intermittent cycling (ΔHbO 2 = 70.2 ± 19.8% ; ΔHHb = 68.2 ± 14.1%). Possibly small detrimental effect of cycling on eccentric force was found (ES = -0.58, 90% CI: -1.33 to 0.17). Small detrimental effects of cycling were found for soreness and perceived recovery. Implementing intermittent cycling exercise the day after muscle damage may be detrimental for recovery. [ABSTRACT FROM AUTHOR]

• Active unilateral knee extension in sitting (AKEiSit) was compared between two interventions. • Jack-knife stretching (JKS) or active knee extension stretching (AKES) was conducted. • There was no difference in the AKEiSit changes between the two interventions. [ABSTRACT FROM AUTHOR]

We report the case of a 32-year-old basketball player who presented with an acute flatfoot deformity after performing a unipodal power jump. Rupture of the posterior tibial tendon within the foot was diagnosed and then treated by hamstring tendon transfer combined with application of autologous biologic preparations. The functional outcome at 18 months was good. To our knowledge, this is the first reported case of posterior tibial tendon rupture treated by hamstring tendon transfer. [ABSTRACT FROM AUTHOR]

To determine eccentric knee flexor strength in elite female Australian Rules Football (ARF) players with and without a history of unilateral anterior cruciate ligament reconstruction (ACLR) using an ipsilateral semitendinosus graft. Case-control. Elite ARF Women's competition. Eighty-four elite female ARF players (mean age, 25 ± 4.9 years; height, 1.71 ± 0.73 m; weight, 67 kg ± 7.4 kg) with (n = 12) and without (n = 72) a history of unilateral ACLR in the previous 10 years. Peak eccentric knee flexor force during the Nordic hamstring exercise (NHE). Players with a history of unilateral ACLR displayed lower levels of eccentric knee flexor strength in their surgically reconstructed limb than their uninjured contralateral limb (mean difference −53.77 N, 95% CI = −85.06 to −24.27, d = −0.51) and compared to the limbs of players with no history of injury (mean difference = −46.32 N, 95% CI = −86.65 to −11.13, d = −0.73). Elite female ARF players with a history of unilateral ACLR display deficits in eccentric knee flexor strength in their surgically reconstructed limb for up to 10 years following surgery. • Elite female ARF players display deficits in eccentric knee flexor strength 1-10 years post-ACLR compared to uninjured limbs. • Conventional rehabilitation may not adequately restore knee flexor strength to the ACLR limb. • Future research should explore if hamstring strength deficits are a risk factor for ACL re-injury. [ABSTRACT FROM AUTHOR]

The habitual use of resistance exercises involving concentric and eccentric contractions can increase muscle strength, speed and endurance. However, current knowledge has limited potential to fully understand the application of such resistance training and the muscle changes that occur to differentiate these two types of training. The aim of this study was to compare the effects of concentric contraction (CON) and eccentric contraction (ECC) during an acute bout of resistance training on the hamstring contractile properties. A group of 20 female recreational athletes were divided into two equal groups, CON training and ECC training. The contractile properties of the muscles on both sides of the body were assessed using tensiomyography (TMG): biceps femoris (BF) and semitendinosus (ST). The muscles were assessed twice, before and after 10 maximal repetitions of either concentric or eccentric isotonic contractions. The results indicate a greater change in TMG parameters with ECC training, with p < 0.001 (Td and Tc). An acute bout of resistance training induces changes in the muscle hamstrings contractile properties in both CON and ECC training. Eccentric training causes greater changes than concentric training, shortening contraction time (Td, Tc), increase radial displacement velocity (Vrd) and affecting changes in muscle belly displacement (Dm), so may be more effective in training. [ABSTRACT FROM AUTHOR]

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Hamstring injuries occur commonly in athletes participating in sports that require sprinting/high velocity running, kicking a ball or agility. In the first instance, clinical assessment and management play a pivotal role in managing these injuries. Radiological investigations such as ultrasonography (US) and magnetic resonance imaging (MRI) are also recommended to confirm one or more parameters related to hamstring injury (the location, length, cross-sectional area, volume, edema, hemorrhage, etc.) and predicting return-to-play. However, hamstring injuries that are minor in nature, diagnosed clinically, may not be discernible on conventional US or MRI in some cases. Certain reasons for these paradoxical (clinical vs. radiological) findings may include pain referral to the posterior thigh from lumbosacral dysfunction or sciatic nerve pathoneurodynamics. Conversely, minor hamstring injuries might remain indiscernible within the threshold of conventional MRI sensitivity. To date, there is neither clear consensus on a standardized criteria nor strong evidence for using MRI to prognosticate return-to-play following hamstring injuries. This paper briefly discusses the controversy between contradicting clinical and radiological findings encountered by clinicians in the diagnosis of minor hamstring injuries. If posterior thigh pain appears with clinical signs and symptoms of a minor hamstring injury without pain referral from neighboring structures, but presents with negative findings on US or MRI, the diagnosis remains a challenge. However, such conditions are pragmatically treated as (nonstructural) hamstring injuries unless certain differential diagnoses can be established. [ABSTRACT FROM AUTHOR]

Background: Acute proximal hamstring ruptures can be a diagnostic challenge in the emergency department. The revealing sign of large posterior thigh ecchymosis is typically not yet present; the physical examination is limited due to pain, radiographs can be unremarkable, and definitive testing with magnetic resonance imaging is not practical. These avulsions are often misdiagnosed as hamstring strains and treated conservatively. The diagnosis is made after failed treatment, often months after the injury. Surgical repair at that time can be technically challenging and higher risk due to tendon retraction and adhesion of the tendon stump to the sciatic nerve.Case Reports: The first case illustrates an example of how delay in diagnosis can occur in both emergency medicine and outpatient primary care settings. It also shows complications and morbidity potential for patients who warrant and do not receive timely surgical repair. The second case illustrates physical examination findings obtainable during the acute setting, and the use of point-of-care ultrasound (POCUS) in facilitating an expedited diagnosis and treatment plan. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Timely diagnosis of hamstring rupture is paramount to optimize patient outcomes for this serious injury. The best results are obtained with surgical repair within 3-6 weeks of injury. POCUS evaluation can aid significantly in the timely diagnosis of this injury. If the POCUS examination raises clinical concern for a proximal hamstring rupture, this may allow for earlier diagnosis and definitive treatment of proximal hamstring rupture. [ABSTRACT FROM AUTHOR]

Background Hamstring Injuries commonly cause missed training and competition time in elite sports. Injury surveillance studies have demonstrated high injury and re-injury rates, which have not improved across sports despite screening and prevention programmes being commonplace. The most commonly suggested intervention for hamstring prevention and rehabilitation is eccentric strength assessment and training. Case description This case study describes the management of an elite sprinter with a history of hamstring injury. A multi-variate screening process based around lumbar-pelvic dysfunction and hamstring strength assessment using the Nordbord is employed. The effect of external pelvic compression using a taping technique, on eccentric hamstring strength is evaluated. Outcomes A persistent eccentric strength asymmetry of 17% was recorded as well as lumbar-pelvic control deficits. Pelvic taping appears to improve load transfer capability across the pelvis, resulting in correction of eccentric strength asymmetry. Discussion Screening strategies and interventions to prevent hamstring injury have failed to consistently improve injury rates across various sports. In this case study external pelvic compression resulted in normalising eccentric strength deficits assessed using the Nordbord. The inclusion of lumbar-pelvic motor control assessment, in relation to hamstring strength and function, as part of a multi-variate screening strategy requires further research. [ABSTRACT FROM AUTHOR]

Background Ulnar collateral ligament reconstruction (UCLR) has become a common procedure among baseball players of all levels. There are several graft choices in performing UCLR, one of which is a hamstring (gracilis or semitendinosus) autograft. It is unclear whether the hamstring muscle from a pitcher's drive leg (ipsilateral side of the UCLR) or landing leg (contralateral side of the UCLR) is more active during the pitching motion. We hypothesized that the landing leg semitendinosus will be more electromyographically active than the drive leg. Methods Healthy, elite male pitchers aged 16-21 years were recruited. Sixteen pitchers (average age, 17.6 ± 1.6 years; 67% threw right handed) underwent electromyographic analysis. Pitchers threw 5 fastballs at 100% effort from the wind-up with electromyographic analysis of every pitch. Activation of the semitendinosus and biceps femoris in both legs was compared within pitchers and between pitchers. Results Hamstring activity was higher in the drive leg than in the landing leg during each phase and in sum, although the difference was significant only during the double support phase ( P  = .021). On within-pitcher analysis, 10 of 16 pitchers had significantly more sum hamstring activity in the drive leg than in the landing leg, while only 4 of 16 had more activity in the landing leg ( P  = .043). Conclusion During the baseball pitch, muscle activity of the semitendinosus was higher in the drive leg than in the landing leg in most pitchers. Surgeons performing UCLR using hamstring autograft should consider harvesting the graft from the pitcher's landing leg to minimize disruption to the athlete's pitching motion. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the intra-rater, inter-examiner and inter-observer reliability of biceps femoris long head (BFlh) tendon strain using ultrasound imaging. Nineteen patients (age: 20.4 ± 0.35 y) were tested twice with a 1-wk interval. Each session included passive stretching from three different hip positions. Tests were performed independently by two examiners while BFlh tendon displacement (mm) and strain (%) were manually extracted from ultrasound video footages by two observers. Intra-rater comparisons revealed an intra-class correlation coefficient (ICC2,1) range of 0.87 to 0.98 and a variability less than 4.74%. Inter-examiner comparisons revealed an ICC2,1 range of 0.83 to 0.99 and less than 4.69% variability. Inter-observer ICCs ranged from 0.93 to 0.97 with variability less than 4.89%. Using a well-defined scanning protocol, two experienced examiners attained high levels of intra-rater agreement, with similarly excellent results for inter-rater and inter-observer reliability for BFlh tendon displacement and strain. [ABSTRACT FROM AUTHOR]

Zusammenfassung Komplette Sehnenabrisse im Bereich der Hüfte und des Oberschenkels führen oft zu einem Funktionsverlust des betroffenen Muskels. Aktuell besteht noch keine Einigkeit über die bestmögliche Versorgung, da evidenzbasierte Daten fehlen. Es gibt jedoch basierend auf der klinischen Erfahrung gute Richtlinien für eine Therapieempfehlung. In Abhängigkeit der Retraktion der Sehnenenden können Sehnenabrisse des M. adductor longus und des M. gluteus medius konservativ behandelt werden, während Abrisse der ischiokruralen Muskulatur, des M. rectus femoris und der Quadrizepssehne überwiegend operativ versorgt werden. Ziel der vorliegenden Übersichtsarbeit ist es, die funktionelle Bedeutung relevanter Muskeln im Bereich der Hüfte und des Oberschenkels darzustellen. Im Anschluss daran werden das diagnostische Vorgehen und die aktuelle Therapieempfehlung der häufigsten Sehnenrupturen dargelegt. Summary Tendon injuries in the pelvic and in the thigh often result in a loss of function of the affected muscle. Currently based on a lack of level I and II evidence, there is no common consensus on which treatment strategy is most successful. There are, however, useful guidelines based on clinical experience. Depending on the degree of tendon retraction, ruptures of the M. adductor longus tendon and of the M. gluteus medius can be treated conservatively. In contrast, rupture of the hamstring muscles, the rectus femoris or the quadriceps tendon require surgical repair in the majority of cases. It is the goal of this review, to explain the functional relevance of the key muscles in the pelvic and the thigh region. Subsequent to this, the suggested diagnostic strategy and current treatment recommendations regarding the most prevalent tendon ruptures are explained. [ABSTRACT FROM AUTHOR]

Objectives To investigate the effect of two hamstring training protocols on eccentric peak torque before and after soccer specific fatigue. Participants Twenty-two university male soccer players. Design Isokinetic strength tests were performed at 60°/s pre and post fatigue, before and after 2 different training interventions. A 45-min soccer specific fatigue modified BEAST protocol (M-BEAST) was used to induce fatigue. Players were randomly assigned to a 4 week hamstrings conditioning intervention with either a maximum strength (STR) or a muscle endurance (END) emphasis. Main outcome measures The following parameters were evaluated: Eccentric peak torque (EccPT), angle of peak torque (APT), and angle specific torques at knee joint angles of 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80° and 90°. Results There was a significant effect of the M-BEAST on the Eccentric torque angle profile before training as well as significant improvements in post-fatigue torque angle profile following the effects of both strength and muscle endurance interventions. Conclusions Forty-five minutes of simulated soccer activity leads to reduced eccentric hamstring torque at longer muscle lengths. Short-term conditioning programs (4-weeks) with either a maximum strength or a muscular endurance emphasis can equally reduce fatigue induced loss of strength over this time period. [ABSTRACT FROM AUTHOR]

A retrospective analysis of computational gait studies performed in a single lab over a 12 year period was undertaken to characterize how recommendations to perform or not to perform hamstring lengthenings were utilized by physicians and the effect on outcomes. 131 Subjects were identified as either having hamstring lengthening considered by the referring surgeon, recommended by gait analysis data, or performed. A subset of this data meeting inclusion criteria for pre- and post-surgical timeframes, and bilateral diagnosis was further analyzed to assess the efficacy of the recommendations. There was initial agreement between planned procedures and recommended procedures in just 41% of the cases. Including the cases where there was agreement, gait analysis altered the initial procedure in 54%. In the cases where the initial plan was not supported by gait data, surgeons followed gait recommendations in 77%. In subjects who underwent hamstring lengthening, when surgeons followed or agreed with gait recommendations, patients were 3.6 times more likely to experience a positive outcome. [ABSTRACT FROM AUTHOR]

Objectives: To describe in detail the anatomic distribution of acute hamstring injuries in football players, and to assess the relationship between location and extent of edema and tears, all based on findings from MRI. Design: Retrospective observational study. Methods: We included 275 consecutive male football players who had sustained acute hamstring injuries and had positive findings on MRI. For each subject, lesions were recorded at specific locations of the hamstring muscles, which were divided into proximal or distal: free tendon, myotendinous junction, muscle belly, and myofascial junction locations. For each lesion, we assessed the largest cross-sectional area of edema and/or tears. We calculated the prevalence of injuries by location. The relationships between locations and extent of edema and tears were assessed using a one-sample t-test, with significance set at p<0.05. Results: The long head of biceps femoris (LHBF) was most commonly affected (56.5%). Overall, injuries were most common in the myotendinous junction and in proximal locations. The proximal myotendinous junction was associated with a greater extent of edema in the LHBF and semitendinosus (ST) muscles (p<0.05). Proximal locations in the LHBF had larger edema than distal locations (p<0.05). Distal locations in the ST muscle had larger tears than proximal locations (p<0.05). Conclusions: The proximal myotendinous junction (LHBF and ST muscles) and proximal locations (LHBF muscle) are more commonly affected and are associated with a greater extent of edema in acute hamstring muscle injury. Distal locations (ST muscle), however, seem to be more commonly associated with larger tears. [ABSTRACT FROM AUTHOR]

Background Chronic rupture of the Achilles tendon (delayed diagnosis of more than 4 weeks) can result in retraction of the tendon and inadequate healing. Direct repair may not be possible and augmentation methods are challenging when the defect exceeds 5–6 cm, especially if the distal stump is grossly tendinopathic. Methods We describe our method of Achilles tendon reconstruction with ipsilateral semitendinosis autograft and interference screw fixation in a patient with chronic rupture, a 9 cm defect and gross distal tendinopathy. Results Patient reported outcome measures consistently demonstrated improved health status at 12 months post surgery: MOXFQ-Index 38–25, EQ5D-5L 18–9, EQ VAS 70–90 and VISA-A 1–64. The patient was back to full daily function, could single leg heel raise and was gradually returning to sport. No complications or adverse events were recorded. Conclusion Reconstruction of chronic tears of the Achilles tendon with large defects and gross tendinopathy using an ipsilateral semitendinosis autograft and interference screw fixation can achieve satisfactory improvements in patient reported outcomes up to 1 year post-surgery. [ABSTRACT FROM AUTHOR]

Objectives: To investigate inter and intra-tester reliability of an externally fixed dynamometry unilateral hamstring strength test, in the elite sports setting.Design: Reliability study.Methods: Sixteen, injury-free, elite male youth football players (age=16.81±0.54 years, height=180.22±5.29cm, weight 73.88±6.54kg, BMI=22.57±1.42) gave written informed consent. Unilateral maximum isometric peak hamstring force was evaluated by externally fixed dynamometry for inter-tester, intra-day and intra-tester, inter-week reliability. The test position was standardised to correlate with the terminal swing phase of the gait running cycle.Results: Inter and intra-tester values demonstrated good to high levels of reliability. The intra-class coefficient (ICC) for inter-tester, intra-day reliability was 0.87 (95% CI=0.75-0.93) with standard error of measure percentage (SEM%) 4.7 and minimal detectable change percentage (MDC%) 12.9. Intra-tester, inter-week reliability results were ICC 0.86 (95% CI, 0.74-0.93), SEM% 5.0 and MDC% 14.0.Conclusions: This study demonstrates good to high inter and intra-tester reliability of isometric externally fixed dynamometry unilateral hamstring strength testing in the regular elite sport setting involving elite male youth football players. The intra-class coefficient in association with the low standard error of measure and minimal detectable change percentages suggest that this procedure is appropriate for clinical and academic use as well as monitoring hamstring strength in the elite sport setting. [ABSTRACT FROM AUTHOR]

Objectives: To assess the inter-machine reliability of the Biodex System 3 Pro and Cybex Humac Norm Model 770 dynamometers for knee extensor and knee flexor peak torque measurements in isometric, concentric and eccentric tests. Design: Randomized/crossover. Setting: Exercise Research Laboratory, Federal University of Rio Grande do Sul (Brazil). Participants: 25 healthy male subjects. Main outcome measures: Isometric, concentric and eccentric knee extensor and knee flexor peak torques recorded in the same test procedure performed on both isokinetic dynamometers. One-way ANOVA, intraclass correlation coefficient (ICC), standard error of measurement (SEM) and coefficient of variation (CV) were used to verify significant differences, relative and absolute reliability between devices. Results: No significant differences were found between tests performed on Biodex and Cybex (p > 0.05). ICC values indicated a high to very high reproducibility for isometric, concentric and eccentric peak torques (0.88-0.92), and moderate to high reliability for agonist-antagonist strength ratios (0.62-0.73). Peak torque did not show great difference between dynamometers for SEM (3.72-11.27 Nm) and CV (5.27-7.77%). Strength ratios presented CV values of 8.57-10.72%. Conclusion: Maximal knee extensor and knee flexor tests performed in isometric (60° of knee flexion), concentric and eccentric modes at 60°/s in Biodex and Cybex dynamometers present similar values. [ABSTRACT FROM AUTHOR]

Background: A significant decrease in deep knee flexion torque has been reported after harvesting the semitendinosus tendon for anterior cruciate ligament (ACL) reconstruction. Thus, we have developed a partial harvesting technique that leaves part of the width of the insertion of semitendinosus tendon by splitting it. Our hypothesis was that the partial harvesting technique would reduce postoperative functional deficits in deep knee flexion by achieving regeneration of harvested tendon without shortening. Methods: A total of 36 patients who underwent ACL reconstruction with an autologous semitendinosus tendon by means of either the conventional whole harvesting technique (whole-ST group, n = 16) or the partial harvesting technique (partial-ST group, n = 20) were included in this study. Clinical outcome, semitendinosus muscle length, and deep knee flexion torque were assessed 2 years after surgery. Results: No significant group differences were found in terms of range of motion, Lysholm score, or anterior knee laxity. Shortening of the semitendinosus muscle was significantly less in the partial-ST group (mean 8 mm) than in the whole-ST group (mean 36 mm; P < 0.001). The side-to-side ratio of isometric knee flexion torque in the prone position with 90° of knee flexion was statistically different between the partial-ST (87.0 ± 20.4%) and whole-ST (55.3 ± 13.9%; P < 0.001) groups. Conclusions: The present partial harvesting technique not only prevented shortening of the semitendinosus muscle, but also reduced the deficit in the maximum knee flexion angle in the standing position and a decrease in the deep knee flexion torque in the prone position with the partial harvesting technique compared to the nonoperated side with good clinical outcomes. Level of evidence: Case-control study, Level III. [ABSTRACT FROM AUTHOR]

The mechanisms underlying cranial cruciate ligament rupture (CCLR) in dogs are poorly understood. In this study hamstring muscle reflexes in response to cranial tibial translation were analysed to determine whether these active stabilisers of the stifle joint are differently activated in dogs with CCLR compared to control dogs. In a prospective clinical study reflex muscle activity from the lateral and medial hamstring muscles (biceps femoris and semimembranosus) was recorded using surface electrodes in control dogs (n = 21 ) and dogs with CCLR (n = 22). These electromyographic recordings were analysed using an algorithm previously validated in humans. The hamstring reflex was reliably and reproducibly recorded in normal dogs. Both a short latency response (SLR, 17.6 ± 2.1 ms) and a medium latency response (MLR, 37.7 ± 2.7 ms) could be identified. In dogs with unilateral CCLR, the SLR and MLR were not significantly different between the affected and the unaffected limbs, but the MLR latency of both affected and unaffected limbs in CCLR dogs were significantly prolonged compared to controls. In conclusion, the hamstring reflex can be recorded in dogs and the MLR is prolonged in dogs with CCLR. Since both affected and unaffected limbs exhibit prolonged MLR, it is possible that abnormal hamstring reflex activation is a mechanism by which progressive CCL damage may occur. The methodology allows for further investigation of the relationship between neuro-muscular imbalance and CCLR or limitations in functional recovery following surgical intervention. [ABSTRACT FROM AUTHOR]

Abstract: Background: The human biceps femoris long head is susceptible to injury, especially when sprinting. The potential mechanical action of this muscle at a critical stage in the stride cycle was evaluated by calculating three-dimensional lines-of-action and moment arms about the hip and knee joints in vivo. Methods: Axial magnetic resonance images of the right lower-limb (pelvis to proximal tibia) were recorded from four participants under two conditions: a reference pose, with the lower-limb in the anatomical position and the hamstrings relaxed; and a terminal swing pose, with the hip and knee joints flexed to mimic the lower-limb orientation during the terminal swing phase of sprinting and the hamstrings isometrically activated. Images were used to segment biceps femoris long head and the relevant bones. The musculotendon path and joint coordinate systems were defined from which lines-of-action and moment arms were computed. Findings: Biceps femoris long head displayed hip extensor and adductor moment arms as well as knee flexor, abductor and external-rotator moment arms. Sagittal-plane moment arms were largest, whereas transverse-plane moment arms were smallest. Moment arms remained consistent in polarity across all participants and testing conditions, except in the transverse-plane about the hip. For the terminal swing pose compared to the reference pose, sagittal-plane moment arms for biceps femoris long head increased by 19.9% to 48.9% about the hip and 42.3% to 93.9% about the knee. Interpretation: Biceps femoris long head has the potential to cause hip extension and adduction as well as knee flexion during the terminal swing phase of sprinting. [Copyright &y& Elsevier]

Background: The hamstring tendons, gracilis and semitendinosus are widely used in ligament and reconstructive surgery. Their accessory bands or insertions are technical pitfalls during harvesting. Methods: Thirty fresh cadaver knees have been studied, in order to 1) determine the anatomy of the bands of the gracilis and semitendinosus tendons, and, 2) to identify risk factors for failure during harvesting. Results: Semitendinosus always had at least one band, sometimes two, strong, tendinous, and generally running to the fascia of gastrocnemius medialis to which they are attached, at an acute angle in a distal direction. Their presence is constant and they are only exceptionally found more than 100 mm from the tendon's tibial insertion. Gracilis shows the greatest anatomical variability, and over one quarter have no bands (although there may be as many as three). Their location, destination and angle of attachment to the tendon vary greatly. These bands are mainly aponeurotic and less strong, but must be carefully and widely dissected. Conclusion: Anatomical variability makes harvesting of pes anserinus tendons difficult. Three simple anatomical criteria have been highlighted that can be assessed by the surgeon during harvesting. The criteria are the insertion, the direction and the anatomical type of the bands. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: This study used serial MRI to assess the absorption of a poly l-lactide Bioabsorbable interference screw used in the anterior cruciate ligament reconstruction with a 4-strand hamstring technique. Methods: A consecutive series of ten patients undergoing anterior cruciate ligament reconstruction a 4-strand hamstring technique were assessed with magnetic resonance imaging (MRI) scans at 1, 2, 4, 7 and 10years postoperatively. Results: No resorption had occurred after 4years in any of the patients. By 7years screw absorption was complete in seven patients and had progressed in three. New cyst formation occurred in 3 patients between 5 and 7years. Half the patients displayed small fluid collections within the tibial tunnels. At 10years all screws were fully absorbed; however cyst formation was common, including the development of a new cyst in the period between 7 and 10years in one patient. None of the patients had instability, persistent effusions, or clinically detectable adverse reactions to the screws. Conclusions: This study has shown that poly l-lactide bioabsorbable screws take longer to resorb than initial in vitro data suggested. It is unclear whether ganglion formation within the tibial tunnel is related to screw resorption or the hamstring graft. The theoretical advantages of bioabsorbable screws must be weighed against these findings. [Copyright &y& Elsevier]

Summary: Inter-muscular coordination has an important role in proper function and prevention of injuries in the knee joint. The purpose of this study was to characterize the effect of velocity and fatigue on the relative activation onset of hamstring to quadriceps muscles during knee extension. Thirty one healthy and non-athletic volunteers (24 women, 7 men) were recruited for the study. The onset time of vastus medialis, vastus lateralis, rectus femoris, medial and lateral hamstring were measured during maximum voluntary extension of the knee joint at velocities of 45°/s, 150°/s & 300°/s before and after fatigue and the mean delay onset of all pairs of H-Q were measured. A two-way repeated measures ANOVA test was used to compare across the mean delayed onset of hamstring related to quadriceps muscles at various velocities. Hamstring muscle showed a delayed activation related to quadriceps and increasing the velocity of shortening has a prominent effect on the inter-muscular coordination with early activation of hamstring related to quadriceps muscles (F = 6.7, p < 0.002 for Biceps-rectus femoris, F = 6.31, p < 0.003 for semitendinosus-rectus femoris, F = 6.26, p < 0.003 for biceps-vastus lateralis, F = 5.98, p < 0.004 for semitendinosus-vastus lateralis, F = 3.19, p < 0.04 for biceps-vastus medialis and F = 3.2, p < 0.04 for semitendinosus-vastus medialis). This could predispose these muscles to over strain and possible injuries. The main effect of fatigue condition and its interaction with velocity however, showed statistically nonsignificant result. [Copyright &y& Elsevier]