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Background Platelet-rich plasma (PRP) injections have been proposed as an additional therapy in the treatment of chronic midsubstance Achilles tendinopathy (AT). The use of PRP injections as pharmacological treatment added to a conservative approach has gained growing interest, but the efficacy remains highly debated. The varying methodological quality of the available studies may contribute to these contradictory results. The aim of this systematic review with meta-analysis was to establish the existing evidence of PRP injections for chronic midsubstance AT on the functional outcome, with a risk of bias assessment of each included study. Methods According to the PRISMA guidelines systematic searches were performed in Embase, the Cochrane library and Pubmed on June 12, 2020 for relevant literature. Only clinical trials comparing PRP injections with placebo, additional to an eccentric training program, in midsubstance AT were included. The primary outcome was Victorian Institute of Sport Assessment - Achilles (VISA-A) score at 3, 6 and 12 months post-injection. Risk of bias was assessed using the Cochrane risk-of-bias tool for randomized trials (Rob 2). As secondary outcome we assessed reported changes in tendon structure after PRP injections. Results A total of 367 studies were identified with the initial database search. Finally, four randomized controlled trials (RCTs) met inclusion criteria for systematic review and meta-analysis with data of 170 patients available for pooling. Results showed no difference in clinical outcome between the PRP and placebo group at different points in time using the VISA-A score as outcome parameter (3 months 0.23 (CI -0.45, 0.91); 6 months 0.83 (CI -0.26, 1.92); 12 months 0.83 (CI -0.77, 2.44)). The bias analysis showed a low or intermediate risk of bias profile for all studies which supports the good methodological quality of each included article. Finally, it is unclear whether PRP injections cause an improvement in tendon structure. However, no direct relationship between tendon structure and clinical presentation of AT could be found. Conclusion PRP has no clear additional value in management of chronic midsubstance Achilles tendinopathy and therefore should not be used as a first-line treatment option.

Lateral elbow pain caused by tendinopathy – tendinosis – or tennis elbow is a highly prevalent problem. Unfortunately, no treatment method can guarantee clinical success. Inspired by the lithotripsy technique used for kidney stones, extracorporeal shock wave therapy (ESWT) has been introduced as an alternative to surgical treatment 25 years ago. In a randomized prospective study, we compared 15 patients with lateral elbow tendinopathy who were operated and 14 who underwent ESWT. Almost all patients had good or excellent outcomes according to the criteria by Verhaar. Subjective improvement was 57% for the ESWT group and 76% for the surgery group. No significant differences between both groups were found (p = 0.07). We therefore recommend considering non-invasive techniques such as ESWT treatment prior to surgery in tennis elbow.

Background: Nine core domains for tendinopathy have been identified. For Achilles tendinopathy there is large variation in outcome measures used, and how these fit into the core domains has not been investigated. Objective: To identify all available outcome measures outcome measures used to assess the clinical phenotype of Achilles tendinopathy in prospective studies and to map the outcomes measures into predefined health-related core domains. Design: Systematic review. Data Sources: Embase, MEDLINE (Ovid), Web of Science, CINAHL, The Cochrane Library, SPORTDiscus and Google Scholar. Eligibility Criteria for Selecting Studies: Clinical diagnosis of Achilles tendinopathy, sample size ��� ten participants, age ��� 16 years, and the study design was a randomized or non-randomized clinical trial, observational cohort, single-arm intervention, or case series. Results: 9376 studies were initially screened and 307 studies were finally included, totaling 13,248 participants. There were 233 (177 core domain) different outcome measures identified across all domains. For each core domain outcome measures were identified, with a range between 8 and 35 unique outcome measures utilized for each domain. The proportion of studies that included outcomes for predefined core domains ranged from 4% for the psychological factors domain to 72% for the disability domain. Conclusion: 233 unique outcome measures for Achilles tendinopathy were identified. Most frequently, outcome measures were used within the disability domain. Outcome measures assessing psychological factors were scarcely used. The next step in developing a core outcome set for Achilles tendinopathy is to engage patients, clinicians and researchers to reach consensus on key outcomes measures. Prospero Registration: CRD42020156763.

To evaluate the effectiveness of rehabilitation strategies on disability, pain, pain-related fear, and return-to-work in patients undergoing lumbar fusion surgery for degenerative conditions or adult isthmic spondylolisthesis.Six electronic databases were systematically searched for randomized controlled trials (RCTs) evaluating the effect of rehabilitation (unimodal or multimodal). The estimated effect size was calculated for interventions with homogeneous content using a random-effects model. Certainty of evidence was assessed by GRADE.In total, 18 RCTs, including 1402 unique patients, compared specific rehabilitation to other rehabilitation strategies or usual care. Most described indications were degenerative disc disease and spondylolisthesis. All rehabilitation interventions were delivered in the postoperative period, and six of them also included a preoperative component. Intervention dose and intensity varied between studies (ranging from one session to daily sessions for one month). Usual care consisted mostly of information and postoperative mobilization. At short term, low quality of evidence shows that exercise therapy was more effective for reducing disability and pain than usual care (standardized mean difference [95% CI]: -0.41 [-0.71; -0.10] and -0.36 [-0.65; -0.08], four and five studies, respectively). Multimodal rehabilitation consisted mostly of exercise therapy combined with cognitive behavioral training, and was more effective in reducing disability and pain-related fear than exercise therapy alone (-0.31 [-0.49; -0.13] and -0.64 [-1.11; -0.17], six and four studies, respectively). Effects disappeared beyond one year. Rehabilitation showed a positive tendency towards a higher return-to-work rate (pooled relative risk [95% CI]: 1.30 [0.99; 1.69], four studies).There is low-quality evidence showing that both exercise therapy and multimodal rehabilitation are effective for improving outcomes up to six months after lumbar fusion, with multimodal rehabilitation providing additional benefits over exercise alone in reducing disability and pain-related fear. Additional high-quality studies are needed to demonstrate the effectiveness of rehabilitation strategies in the long term and for work-related outcomes.

OBJECTIVE: Decisions concerning the rehabilitation process and return to play (RTP) after cervical spine surgery in a general sporting population can be difficult and may be influenced by several factors. Moreover, no clear guidelines for this are currently available. The aim of this study was to create tentative guidelines for rehabilitation and RTP after cervical surgery in a general sporting population. DESIGN: Five-step Delphi analysis. SETTINGS: Primary, secondary, and tertiary medical practitioners. PARTICIPANTS: Panel of Belgian neurosurgeons, orthopedic surgeons, physiotherapists, and physical and rehabilitation medicine practitioners. ASSESSMENT: Round 1 (R1) was a brainstorm phase. A comprehensive list of answers from R1 was validated in round 2 (R2). In round 3 (R3), experts ranked these items in a chronological order. Contraindications and criteria to start each rehabilitation step were linked in round 4 (R4). In round 5 (R5), panelists ranked theses about contraindications and criteria on a 5-point Likert scale. MAIN OUTCOME MEASURES: Theses scoring ≥10% "oppose" or "strongly oppose" were rejected. RESULTS: The response rate was 100% (n = 15) for R1, 93% (n = 14) for R2, 73% (n = 11) for R3, 53% (n = 8) for R4, and 67% (n = 10) for R5. In R5, 25 theses on absolute and relative contraindications and criteria were endorsed. CONCLUSIONS: This Delphi analysis resulted in contraindications and criteria for the rehabilitation process and RTP after cervical surgery in a general athletic population. Tentative guidelines and timetable are proposed. Key messages from these guidelines are (1) Rehabilitation should start before surgery with education; (2) Rehabilitation should be patient-tailored; and (3) An unstable arthrodesis is an absolute contraindication for RTP. ispartof: Clin J Sport Med vol:31 issue:2 pages:145-150 ispartof: location:United States status: published

BACKGROUND: Non-inflammatory thickening of the subsynovial connective tissue is a common histological finding in carpal tunnel syndrome. This subsynovial connective tissue thickening may precede changes in electrodiagnostic testing. Therefore, measuring subsynovial connective tissue thickness may help in detecting early changes in carpal tunnel syndrome. METHODS: To provide an overview of subsynovial connective tissue thickness characteristics in subjects with and without carpal tunnel syndrome, a systematic review of articles, assessing human subsynovial connective tissue, was performed using MEDLINE, CENTRAL and EMBASE. FINDINGS: Seven studies were included for qualitative analysis. Measurements were done ex vivo (laser (n = 3), photographic (n = 1), micrometric (n = 1)) and in vivo (ultrasound (n = 3)). All four case-control studies showed a significant difference in subsynovial connective tissue thickness between subjects with and without carpal tunnel syndrome. One study showed good correlation between ultrasound and anatomical measurements. No correlation was found between subsynovial connective tissue thickness and symptom duration, electrodiagnostic changes, age and sex. INTERPRETATION: Subsynovial connective tissue thickness may be a valuable aid in diagnosing carpal tunnel syndrome. No factors influencing subsynovial connective tissue thickness are identified, although they are not well investigated. ispartof: CLINICAL BIOMECHANICS vol:75 ispartof: location:England status: published

OBJECTIVES: To investigate the temporal relationship between two-dimensional measured frontal plane joint angles and three-dimensional measured kinematic profiles during the stance phase of running, and to assess the intra- and intertester reliability of the two-dimensional angles. DESIGN: Observational study. SETTING: Research laboratory. PARTICIPANTS: Fifteen injury-free elite athletes. MAIN OUTCOME MEASURES: Contralateral pelvic drop (CPD), femoral adduction (FA), hip adduction (HA) and knee valgus (KV) were measured at the deepest landing position during midstance with two-dimensional video analysis during running. CPD, HA and knee abduction were measured continuously during the entire stance phase through three-dimensional motion analysis. One-dimensional statistical parametric mapping was used to examine the temporal relationships between the two-dimensional angles and three-dimensional kinematic profiles. In addition, intra-class correlation coefficients (ICC) were calculated to assess the intra- and intertester reliability of the two-dimensional angles. RESULTS: Two-dimensional CPD, FA and HA were significantly related to the three-dimensional HA kinematic profile. Two-dimensional CPD was significantly related to the three-dimensional CPD kinematic profile. No significant relationship was found between two-dimensional KV and three-dimensional knee abduction. Excellent intra- and intertester reliability was found for the two-dimensional angles (ICC 0.90-0.99). CONCLUSIONS: These findings support implementing two-dimensional video analysis to evaluate CPD and HA during running. ispartof: PHYSICAL THERAPY IN SPORT vol:29 pages:84-92 ispartof: location:England status: published

Achilles tendinopathy remains one of the most prevalent overuse injuries in elite as well as recreational athletes. Regardless of the fact that the aetiology of tendinopathy has not been fully understood, therapeutic mechanical loading programs have emerged as being the treatment of choice. In this light, mechanical properties of the tendon and their response to changes in loading or unloading have been the subject of many previous investigations. One of these properties often investigated is strain, a measure of relative deformation. By means of a systematic review, an overview was given of research in this field, with a primary objective to list the methods used and secondary aim to synthesize data on strain mapping in the Achilles tendon. Following the guidelines of the PRISMA statement, 47 articles were found appropriate for qualitative assessment. Achilles tendon strain has been investigated across a variety of contexts, including the response to exercise, walking, unloading, ageing, hormonal changes and weight. Only three studies investigated the effect of the presence of tendinopathy on strain. Ultrasound was the most often used imaging modality to measure or estimate strain. Further methodological parameters, e.g. the location of measurement, differed greatly between all different studies. Nearly all studies considered global strain. Some studies investigated the transverse strain response of the Achilles tendon. Recently, however, the role of local - intratendinous - strain distribution has been found to be of critical importance and further studies should focus on imaging modalities to investigate these local changes.

PURPOSE: Bracing is frequently prescribed following lumbar surgery for degenerative conditions. However, previous studies failed to demonstrate the advantage of postoperative lumbar bracing in both short- and long-term outcome in terms of pain, quality of life and fusion rate. The purpose of this study was to assess the prescription patterns and rationale for postoperative bracing amongst spinal surgeons in Belgium. METHODS: A 16-item online survey was distributed by email to spinal surgeons affiliated to the Spine Society of Belgium (N = 252). RESULTS: A total of 105 surgeons (42%) completed the survey. The overall bracing frequency following lumbar surgery was 38%. A brace was more often prescribed following the fusion procedures (52%) than after the non-fusion procedures (21%) (p

Achilles tendinopathy remains a prevalent condition among recreational and high-level athletes. Mechanical loading has become the gold standard in managing these injuries, but exercises are often generic and prescribed in a "one-size-fits-all" principle. The aim of this study was to evaluate the impact of knee angle changes and different levels of force production on the non-uniform behavior in the Achilles tendon during isometric contractions. It was hypothesized that a flexed knee position would lead to a more distinct non-uniform behavior, due to greater differential loading of soleus vs gastrocnemius, and that this effect would be attenuated by higher levels of force production. Contrary to the hypotheses, it was found that the non-uniform deformation, that is, superficial-to-deep variation in displacement with highest displacement in the deep layer, is consistently present, irrespective of the level of force production and knee angle (n = 19; mean normalized displacement ratio 6.32%, 4.88%, and 4.09% with extended knee vs 5.47%, 2.56%, and 6.01% with flexed knee, at 25%, 50%, and 75% MVC, respectively; P > .05). From tendon perspective, aside from the influence on muscle behavior, this might question the mechanical rationale for a change in knee angle during eccentric heel drops. Additionally, despite reaching high levels of plantar flexion force, the relative contribution of the AT sometimes appears to be decreased, potentially due to compensatory actions by agonist muscle groups. These results are relevant for optimizing AT rehabilitation as the goal is to reach specific local tendon loading. ispartof: SCANDINAVIAN JOURNAL OF MEDICINE & SCIENCE IN SPORTS vol:28 issue:11 pages:2322-2329 ispartof: location:Denmark status: published

Introduction/Background Decisions concerning the rehabilitation process and return to play (RTP) after cervical spine surgery in a general sporting population can be difficult and may be influenced by several factors. Moreover, no guidelines are present for this. The aim of this study was to create a consensus on this topic. Material and method A 5-step Delphi analysis with panels of neurosurgeons, orthopaedic surgeons, physiotherapists and physical and rehabilitation medicine practitioners in Belgium was conducted. The first round (R1) was a brainstorm phase. A comprehensive list of answers from R1 was validated in round 2 (R2). In round 3 (R3) experts ranked these items in a chronological order. Next, contraindications and criteria to start each rehabilitation step were linked by experts in round 4 (R4). In round 5 (R5) panellists ranked theses about contraindications and criteria on a 5-point Likert scale. Results The response rate was 100% (n = 15) for R1, 93% (n = 14) for R2, 73% (n = 11) for R3, 53% (n = 8) for R4 and 67% (n = 10) for R5. In R5, 25 theses on absolute and relative contraindications and criteria were endorsed. Conclusion This Delphi analysis resulted in contraindications and criteria for the rehabilitation process and return to play after cervical surgery. Tentative guidelines and timetable are proposed.

A traumatic pedicle fracture in association with pre-existing bilateral spondylolysis and anterolisthesis has never been described. A 27-year-old male professional football player presented with acute gluteal pain caused by a traumatic fracture of the left pedicle L5 missed on plain radiographs, but seen on CT-scan and confirmed on bone scintigraphy. Instability caused by this fracture in association with pre-existing bilateral spondylolysis and grade I-anterolisthesis required immobilization of the lumbar spine. Since no neurological deficit was observed, it was decided not to operate but to treat the patient with analgesics and with a lumbar orthosis which would provide unilateral hip fixation in extension during walking. We report here on the difficulties of diagnosis and on the successful treatment by means of immobilization in a lumbar orthosis. A rehabilitation program with specific sports-related exercises was devised.

Background Impaired muscle activation may predispose subjects to develop chronic ankle instability. It has been suggested that impairments are found not only in structures around the injured ankle but also around the more proximal joint complexes. Hypothesis Subjects with chronic ankle instability were expected to show later onset times for lower limb and trunk muscle activation when compared with control subjects. They were expected to show less variability in muscle activation patterns compared with the control group. Study Design Controlled laboratory study. Methods Thirty control subjects and 10 subjects with chronic ankle instability participated in the study. The onset of muscle activity of 14 muscles of the lower limb and trunk was measured during the transition from a double-leg stance position to a single-leg stance position in eyes-open and eyes-closed test conditions. Results Subjects with chronic ankle instability showed significantly later onset times for the ankle, hip, and hamstring muscles compared with control subjects. They used a similar muscle activation pattern in both test conditions, whereas control subjects adjusted their activation pattern according to the condition. Conclusions Differences in muscle activation patterns between subjects with chronic ankle instability and control subjects occur not only around the ankle but also around other joints. Subjects with chronic ankle instability show less variability in muscle activation patterns between test conditions. Clinical Relevance Knowledge of muscle activation patterns in the whole lower limb and trunk in noninjured subjects and the differences found in chronic ankle instability subjects broadens the physical therapy approach to the treatment of chronic ankle instability.

Background Previous studies showed that the amount of hip flexion and the combination of knee valgus and lateral trunk motion, measured with two-dimensional video analysis, were related to three-dimensional measured knee joint moments during single-leg drop vertical jumps, but it remains unclear whether these measurements can be used to identify non-contact knee injury risk. Methods Fifty injury-free female athletes participated in the study. Two-dimensional video analysis was used to measure hip flexion, knee valgus and lateral trunk motion angles during single-leg drop vertical jumps. Time loss non-contact knee injuries were registered during a one-year follow-up. Independent t-tests and receiver operating characteristic analysis were used to analyze the predictive ability of the two-dimensional angles. Findings Seven participants sustained a time loss non-contact knee injury. Hip flexion was not significantly different between groups ( P > .05). The combination of knee valgus and lateral trunk motion was significantly smaller in the injured ( P = .036) and non-injured legs ( P = .009) of the future injured group compared with the respective matched leg of the non-injured group. The receiver operating characteristic analysis showed a significant discriminative accuracy between groups for the combination of knee valgus and lateral trunk motion of the uninjured leg of the future injured group with the matched leg of the non-injured group (area under curve = 0.803; P = .012). Interpretation The measurement of a combination of increased knee valgus and ipsilateral trunk motion during the single-leg drop vertical jump with two-dimensional video analysis can be used to help identify female athletes with increased non-contact knee injury risk.

Formerly known as 'jumper's knee', patellar tendinopathy gives rise to considerable functional deficit and disability in recreational as well as professional athletes. It can interfere with their performance, often perseveres throughout the sporting career and may be the primary cause to end it. The diagnosis of patellar tendinopathy is primarily a clinical one but new imaging techniques, such as Doppler ultrasonography, may provide additional diagnostic value. Current therapeutic protocols are characterised by wide variability ensuing from anecdotal experience rather than evidence. Moreover, numerous reports in recent years have shattered previous doctrines and dogmatic belief on tendon overuse. Histopathological and biochemical evidence has indicated that the underlying pathology of tendinopathy is not an inflammatory tendinitis but a degenerative tendinosis. Consequently, pain in chronic patellar tendinopathy is not inflammatory in nature, but its exact origin remains unexplained. In pursuit of pathology- and evidence-based management, conservative therapy should be shifted from anti-inflammatory strategies towards a complete rehabilitation with eccentric tendon strengthening as a key element. If conservative management fails, surgery is opted for. However, considering the heterogeneity of surgical procedures and the absence of randomised studies, no conclusive evidence can be drawn from the literature regarding the effectiveness of surgical treatment for patellar tendinopathy. Parallel with the improved knowledge on the pathophysiology and pain mechanisms in patellar tendinopathy, new treatment strategies are expected to emerge in the near future.

Twenty-five patients with chronic Achilles tendinopathy were clinically and ultrasonographically evaluated. A positive correlation existed between power Doppler ultrasonography (PDU) and tendon thickness (r=0.63, p

The goal of this prospective study was to evaluate the efficacy of open versus closed kinetic chain exercises in the nonoperative management of patellofemoral pain. Sixty patients were randomized into a 5-week program that consisted of only closed kinetic chain exercises or only open kinetic chain exercises. Muscle characteristics, subjective symptoms, and functional performance were evaluated in this study at the time of the initial physical examination, at the end of the treatment period, and 3 months later. Both groups experienced a statistically significant decrease in pain and an increase in functional performance. This study shows that both open and closed kinetic chain exercise programs lead to an improved subjective and clinical outcome in patients with anterior knee pain. The few significantly better functional results for some of the tested parameters in the closed kinetic chain group suggest that this type of treatment is a little more effective than the open kinetic chain program in the treatment of these patients.

To compare the outcome of chronic patellar tendinopathy treated surgically and by extracorporeal shock wave therapy.Cross-sectional outcome analysis.University Hospital Pellenberg, Leuven, Belgium.Of a total of 27 patients (28 knees) with chronic patellar tendinopathy, 13 were treated surgically, and 14 (15 knees) received extracorporeal shock wave therapy.Functional outcome questionnaire: Victorian Institute of Sport Assessment score, Visual Analog Scale, and Roles and Maudsley classification.At an average of 6 months of follow-up, the mean Victorian Institute of Sport Assessment and Visual Analog Scale scores for the extracorporeal shock wave therapy group were 78.8 +/- 28.7 and 9 +/- 2, respectively, which improved to 83.9 +/- 28.6 and 9 +/- 2, respectively, at 22.1 months. The surgery group scored 70.7 +/- 22.2 points on the Victorian Institute of Sport Assessment at an average of 26.3 months of follow-up (p = 0.41 and p = 0.18) and 8 +/- 3 on the Visual Analog Scale (p = 0.14). In the extracorporeal shock wave therapy group, 5 (33%) patients rated their pain status at 22.1 months as excellent, 5 (33%) as good, 2 (13%) as fair, and 2 (13%) as poor. In the surgery group, 4 (33%) evaluated the result as excellent, 3 (25%) as good, 3 (25%) as fair, and 2 as poor (17%).Extracorporeal shock wave therapy shows a comparable functional outcome to surgery in a cross-sectional analysis of patients with chronic proximal patellar tendinopathy resistant to conservative treatment.

Background Eccentric exercises have proven to be an effective management option and prevention strategy in tendon overuse injuries (a challenging sport pathology). However, till date, these exercise protocols are undifferentiated and certainly don9t take subregional stress and strain differences, which have frequently been mentioned as important etiological factors, in account. Knowledge on these biomechanical parameters, obtained by in vivo experiments, could optimise the exercise protocols. Objective The present experiment evaluates the feasibility of automatic, intensity-based, spatio-temporal elastic registration for non-invasive local strain measurement by speckle tracking on dynamic ultrasound movies. Methods An isolated porcine patellar tendon (tendon length of 60 mm) with bone parts at each side was placed in a loading frame with an ultrasound transducer orientated along the long axis of the tendon. Ultrasound recordings were made while the tendon was cyclically loaded at two different velocities (1 mm/s and 2 mm/s) and three different displacements (1.5 mm, 3 mm and 5 mm). Afterwards a precalibrated strain-gauge extensometer was inserted in the central 2.5 cm of the tendon and the same loading scheme was applied while recording ultrasound movies. The movies were processed, based on non-rigid elastic registration and speckle tracking, and these results were compared with the extensometer data. Results Ultrasound strain values were comparable to extensometer strain data in four measurements (a- velocity 1.0 mm/s, displacement 1.5 mm: 0.8% strain difference; b- velocity 1.0 mm/s, displacement 3.0 mm: 0.6% strain difference; c- velocity 1.0 mm/s displacement 5.0 mm: 0.7% strain difference; d- velocity 2.0 mm/s, displacement 1.5 mm: strain difference 0.1%) resulting in a mean strain difference of 0.55%. The measurements at velocity 2 mm/s and 3.00 and 5.00 mm displacement were left out because of poor tracking in these recordings due to more out of plane movement. Conclusion It seems feasible to obtain comparable strain values between extensometer measurements and speckle tracking on non-invasive ultrasound recordings.

Introduction Achilles tendinopathies continue to present in epidemic-like proportions. Due to its multifactorial aetiology and its fragmentarily understood pathophysiology, the management of Achilles tendinopathy is time-consuming and therefore often frustrating. Nevertheless, eccentric exercises have emerged as the key element in the treatment of these tendinopathies. However, to date, there is no general agreement on the optimal eccentric exercise protocol as subregional strain differences within the Achilles tendon are not taken into account. The purpose of this paper is therefore to critically review the published literature that currently exists on Achilles tendon strain in normal Achilles tendons as well as in Achilles tendons with tendinosis. Knowledge on subregional Achilles tendon strain differences may enhance our understanding of the aetiology, pathophysiology and management of Achilles tendinopathy. Methods The following three databases were examined on November 1 st 2012 using strict search criteria: PubMed, Cochrane Library and CINAHL. The following main keywords were used: “Achilles tendon”, “Tendinopathy” and “Strain”. These keywords were then expanded to aim for an inclusion of all the relevant literature. Results Discussion All included studies in this review concerned global 2D strain measurements. Great variation exists in the measurement technique (ultrasound versus MRI), the location of measurement and the procedure of activation. In the vast majority of the cases, strain is measured in a longitudinal direction over the entire length of the Achilles tendon. Only three studies investigated Achilles tendon strain in transverse direction over the entire thickness of the tendon [Grigg, 2012; Wearing, 2011; Park, 2011]. Values for strain found in literature ranged from 2.1 to 9.2% in the longitudinal direction and from -19.5 to -8.3% in the transverse direction. Moreover, global 2D in vivo Achilles tendon strain in response to Achilles tendinopathy is investigated in only three studies [Grigg, 2012; Arya 2010; Child 2010]. Two-dimensional ultrasound imaging is the preferred imaging technique and maximum voluntary isometric contraction testing is the preferred measurement procedure to assess Achilles tendon strain. Taking into account that strain is a three-dimensional parameter as indicated by subregional strain differences on cadaveric Achilles tendons [Lersch, 2012; Wren, 2003; Lyman, 2004] and considering that Achilles tendinosis can occur at different subregional locations, it is clear that further research regarding non-invasive in vivo intratendinous strain mapping of the healthy and sick Achilles tendon is warranted. References Arya et al . J Appl Physiol . 2010;108:670–675 Child et al . Am J Sports Med . 201038:1885–1893 Grigg et al . Med Sci Sports Exerc . 2012;44:12–17 Lersch et al . Clin Biomech . 2012;27:955–961 Lyman et al . Am J Sports Med . 2004;32:457–461 Park et al . Foot Ankle Int . 32:407–413 Wearing et al . J Appl Physiol . 2011;110:1384–89 Wren et al . Ann Biomed Eng . 2003;31:710–717

BACKGROUND: There is limited evidence on neuromuscular risk factors for anterior cruciate ligament (ACL) injuries, with most work mainly focusing on hamstrings and quadriceps muscle strength. This prospective pilot study explored if neuromuscular activation patterns of the quadriceps and hamstrings during a drop vertical jump influence ACL injury risk. METHODS: Forty-six female athletes performed a drop vertical jump at baseline. Injuries were monitored throughout a one-year follow-up. Neuromuscular activation patterns of the vastus medialis, vastus lateralis, hamstrings medialis and hamstrings lateralis, and selected landing kinematic and kinetic profiles (knee flexion, knee abduction and hip flexion angles, and knee abduction moments), were compared between athletes who sustained a non-contact ACL injury and those who remained injury free. Electromyogram vector fields were created to represent neuromuscular activation patterns of muscle pairs around the knee joint rather than only considering individual muscle activations, and compared using Statistical Parametric Mapping. RESULTS: Four athletes sustained an ACL injury. Significantly greater {hamstrings medials, hamstrings lateralis}, {vastus lateralis, hamstrings lateralis} and {hamstrings lateralis, vastus medialis} activations, mainly due to greater hamstrings lateralis activation, were found in the injured group around peak loading and just before take-off (P