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Prostate-specific membrane antigen (PSMA) imaging has become a mainstay diagnostic tool in staging unfavorable primary prostate cancer (PC) and identifying sites of recurrence in previously treated PC. One of the biggest pitfalls of PSMA imaging is rapid radionucleotide excretion in the urine via the​ kidneys, ureters, and bladder.​ The positron-emission tomography (PET) images obtained show increased radiotracer activity in these structures, which can occlude or even mimic true malignant disease. We describe the diagnostic challenges encountered in differentiating benign versus malignant disease with PSMA scans. A 78-year-old male presented ​to our outpatient radiation oncology office ​with high-risk prostate cancer. His medical history was significant for ulcerative colitis (UC). Magnetic resonance imaging (MRI) revealed an enlarged prostate and a Prostate Imaging Reporting and Data System (PI-RADS) class 4 lesion. A subsequent transperineal biopsy confirmed unilateral Gleason 8 adenocarcinoma. A PSMA PET scan was read as increased uptake in the right prostate and a left external iliac node. The patient, having been initially informed of a positive lymph node metastasis, sought a second opinion,​resulting in​​ ​a CT urogram that revealed physiologic ureteral uptake. We were thus able to avoid lymph node radiation and morbidity to the surrounding bowel, already chronically inflamed with ulcerative colitis. This study ​demonstrates the ​potential for misinterpretation of PSMA uptake in the ureter as lymph node metastases. We discuss how peri-uretic activity can hinder accurate visualization of pelvic lymph node metastases. This study highlights the need for careful image interpretation of PSMA uptake patterns in order to avoid diagnostic errors and unnecessary radiation to ​at-risk​​ ​organs in prostate cancer management.

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A single depth camera provides a fast and easy approach to performing biomechanical assessments in a clinical setting; however, there are currently no established methods to reliably determine joint angles from these devices. The primary aim of this study was to compare joint angles as well as the between-day reliability of direct kinematics to model-constrained inverse kinematics recorded using a single markerless depth camera during a range of clinical and athletic movement assessments.A secondary aim was to determine the minimum number of trials required to maximize reliability. Eighteen healthy participants attended two testing sessions one week apart. Tasks included treadmill walking, treadmill running, single-leg squats, single-leg countermovement jumps, bilateral countermovement jumps, and drop vertical jumps. Keypoint data were processed using direct kinematics as well as in OpenSim using a full-body musculoskeletal model and inverse kinematics. Kinematic methods were compared using statistical parametric mapping and between-day reliability was calculated using intraclass correlation coefficients, mean absolute error, and minimal detectable change. Keypoint-derived inverse kinematics resulted in significantly smaller hip flexion (range = -9 to -2°), hip abduction (range = -3 to -2°), knee flexion (range = -5° to -2°), and greater dorsiflexion angles (range = 6-15°) than direct kinematics. Both markerless kinematic methods had high between-day reliability (inverse kinematics ICC 95 %CI = 0.83-0.90; direct kinematics ICC 95 %CI = 0.80-0.93). For certain tasks and joints, keypoint-derived inverse kinematics resulted in greater reliability (up to 0.47 ICC) and smaller minimal detectable changes (up to 13°) than direct kinematics. Performing 2-4 trials was sufficient to maximize reliability for most tasks. A single markerless depth camera can reliably measure lower limb joint angles, and skeletal model-constrained inverse kinematics improves lower limb joint angle reliability for certain tasks and joints.

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OBJECTIVES: To evaluate the concurrent validity and test-retest reliability of common movement, strength, and balance tests using portable uniaxial dual force plates. DESIGN: Repeated measures cross-sectional study. METHODS: Sixteen healthy individuals participated in two testing sessions, where they performed 12 different movement, strength, and balance tests. Vertical ground reaction force and centre of pressure data were collected using the VALD ForceDecks simultaneously with ground-embedded laboratory force plates. Concurrent validity was assessed using root mean square error for raw time-series data and Bland-Altman plots for discrete metrics. Test-retest reliability was assessed using intraclass correlation coefficients and minimal detectable changes. RESULTS: ForceDecks recorded vertical ground reaction forces and center of pressure with high accuracy compared to laboratory force plates. The mean bias between systems was negligible (<2 N or 0.1 mm), with small limits of agreement (<5 N or 1 mm). Overall, 530/674 (79%) showed good or excellent validity (<10% difference) and 611/773 (79%) had good or excellent reliability (intraclass correlation coefficient >0.75). ForceDecks reliability was similar to laboratory force plates (<0.07 intraclass correlation coefficient median difference for all metrics). CONCLUSIONS: Portable uniaxial force plates record highly accurate vertical ground reaction forces and center of pressure during a range of movement, strength, and balance tests. The VALD ForcDecks are a valid and reliable alternative to laboratory force plates when strict standardized testing and data analysis procedures are followed. Users should be aware of the validity and reliability characteristics of the tests and metrics they choose.

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OBJECTIVES: Hamstring strain injuries (HSIs) commonly affect the proximal biceps femoris long head (BFlh) musculotendinous junction. Biomechanical modeling suggests narrow proximal BFlh aponeuroses and large muscle-to-aponeurosis width ratios increase localized tissue strains and presumably risk of HSI. This study aimed to determine if BFlh muscle and proximal aponeurosis geometry differed between limbs with and without a history of HSI. METHODS: Twenty-six recreationally active males with (n = 13) and without (n = 13) a history of unilateral HSI in the last 24 months underwent magnetic resonance imaging of both thighs. BFlh muscle and proximal aponeurosis cross-sectional areas, length, volume, and interface area between muscle and aponeurosis were extracted. Previously injured limbs were compared to uninjured contralateral and control limbs for discrete variables and ratios, and along the relative length of tissues using statistical parametric mapping. RESULTS: Previously injured limbs displayed significantly smaller muscle-to-aponeurosis volume ratios (p = 0.029, Wilcoxon effect size (ES) = 0.43) and larger proximal BFlh aponeurosis volumes (p = 0.019, ES = 0.46) than control limbs with no history of HSI. No significant differences were found between previously injured and uninjured contralateral limbs for any outcome measure (p = 0.216-1.000, ES = 0.01-0.36). CONCLUSIONS: Aponeurosis geometry differed between limbs with and without a history of HSI. The significantly larger BFlh proximal aponeuroses and smaller muscle-to-aponeurosis volume ratios in previously injured limbs could alter the strain experienced in muscle adjacent to the musculotendinous junction during active lengthening. Future research is required to determine if geometric differences influence the risk of re-injury and whether they can be altered via targeted training.

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Altered semitendinosus (ST) morphology and distal tendon insertion following anterior cruciate ligament reconstruction (ACLR) may reduce knee flexion torque generating capacity of the hamstrings via impaired ST force generation and/or moment arm. This study used a computational musculoskeletal model to simulate mechanical consequences of tendon harvest for ACLR on ST function by modeling changes in ST muscle tendon insertion point, moment arm, and torque generating capacity across a physiological range of motion. Simulated ST function was then compared between ACLR and uninjured contralateral limbs. Magnetic resonance imaging from 18 individuals with unilateral history of ACLR involving a hamstring autograft was used to analyse bilateral hamstring muscle (ST, semimembranosus, bicep femoris long head and short head) morphology and distal ST tendon insertion. The ACLR cohort was sub-grouped into those with and without ST regeneration. For each participant with ST regeneration (n = 7), a personalized musculoskeletal model was created including postoperative remodeling of ST using OpenSim 4.1. Knee flexion and internal rotation moment arms and torque generating capacities of hamstrings were evaluated. Bilateral differences were calculated with an asymmetry index (%) ([unaffected limb-affected limb]/[unaffected limb + affected limb]*100%). Smaller moment arms or knee torques within injured compared to uninjured contralateral limbs were considered a deficit. Compared to uninjured contralateral limbs, ACLR limbs with tendon regeneration (n = 7) had minor reductions in knee flexion (5.80% [95% confidence interval (CI) = 3.97-7.62]) and internal rotation (4.92% [95% CI = 2.77-7.07]) moment arms. Decoupled from muscle morphology, altered ST moment arms in ACLR limbs with tendon regeneration resulted in negligible deficits in knee flexion (1.20% [95% CI = 0.34-2.06]) and internal rotation (0.24% [95% CI = 0.22-0.26]) torque generating capacity compared to uninjured contralateral limbs. Coupled with muscle morphology, ACLR limbs with tendon regeneration had substantial deficits in knee flexion (19.32% [95% CI = 18.35-20.28]) and internal rotation (15.49% [95% CI = 14.56-16.41]) torques compared to uninjured contralateral limbs. Personalized musculoskeletal models with measures of ST distal insertion and muscle morphology provided unique insights into post-ACLR ST and hamstring function. Deficits in knee flexor and internal rotation moment arms and torque generating capacities were evident in those with ACLR even when tendon regeneration occurred. Future studies may wish to implement this framework in personalized musculoskeletal models following ACLR to better understand individual muscle function for injury prevention and treatment evaluation.

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OBJECTIVES: This study investigated relationships between isometric trunk and hip extensor strength, lumbar muscle morphology, and the risk of hamstring and knee ligament injuries in Australian Football League and National Rugby League players. DESIGN: Prospective cohort study. METHODS: Trunk and hip extensor strength, multifidus and quadratus lumborum cross-sectional area were measured during the 2020 pre-season. Logistic regressions and decision trees were employed to explore associations between maximum strength, strength endurance, multifidus and quadratus lumborum cross-sectional area, age, previous injuries, and hamstring and knee ligament injury risk. RESULTS: Greater strength endurance [odds ratio = 0.42 (0.23-0.74), p = 0.004] and maximum strength [odds ratio = 0.55 (0.31-0.94), p = 0.039] reduced hamstring injury risk. Increased risk of knee ligament injuries was associated with larger multifidus [odds ratio = 1.66 (1.14-2.45), p = 0.008] and higher multifidus to quadratus lumborum ratio (odds ratio = 1.57 (1.13-2.23), p = 0.008]. Decision tree models indicated that low strength endurance (< 99 Nm) characterised hamstring strains, while high (≥ 1.33) multifidus to quadratus lumborum ratio mitigated risk. Knee ligament injuries were associated with larger (≥ 8.49 cm2) multifidus, greater (≥ 1.25) multifidus to quadratus lumborum ratio, and lower maximum strength (< 9.24 N/kg). CONCLUSIONS: Players with lower trunk and hip extensor maximum strength and strength endurance had increased risk of hamstring injuries, while knee ligament injury risk was elevated with larger multifidus cross-sectional area, higher multifidus to quadratus lumborum ratio, and lower maximum trunk and hip extensor strength.

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INTRODUCTION: Recently, there has been a call for vertical jump testing via force-plate analysis to be included in the assessment of individuals after anterior cruciate ligament reconstruction (ACLR) and as part of return-to-play criteria. However, a synthesis of current literature is needed to help guide clinicians on what tests to perform, which force-plate metrics to assess, and how these may change over the time course of rehabilitation. METHODS: Four online databases were searched from inception to July 2022. The Downs and Black checklist was used to assess study quality. Multilevel meta-analyses and meta-regressions were undertaken in conjunction with a best evidence synthesis. RESULTS: Forty-two articles were included, capturing 2375 participants with a history of ACLR. Reconstructed limbs displayed 1) lower peak eccentric forces, concentric forces, landing forces, and lower eccentric and concentric impulses (standardized means difference [SMD] = -1.84 to -0.46) than uninjured contralateral limbs during bilateral countermovement jumps (CMJ) and drop vertical jumps (DVJ); 2) lower jump heights and reactive strength indices (RSI), and longer contact times than uninjured contralateral limbs during unilateral CMJ and DVJ (SMD = -0.86 to 0.26); and 3) lower jump heights, RSI, and longer contact times during bilateral and unilateral CMJ, and unilateral DVJ, than uninjured controls (SMD = -1.19 to 1.08). Meta-regression revealed that time postsurgery was a significant moderator ( P < 0.05) for 1) bilateral CMJ height, peak concentric force, and peak landing force; 2) between-limb differences in unilateral CMJ height; and 3) differences in unilateral DVJ height, RSI, and contact time between reconstructed limbs and healthy controls with no history of injury. CONCLUSIONS: Individuals with a history of ACLR display chronic deficits in vertical jumping performance during a range of bilateral and unilateral tasks, which may have implications for return-to-play criteria and the design of interventions targeted at restoring long-term deficits in explosive lower limb strength after ACLR.

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OBJECTIVES: The purpose of this prospective cohort study was to assess the associations between lower limb injuries in female team-sport athletes and a number of factors. The potential risk factors explored included (1) lower limb strength, (2) history of life-event stress, (3) family history of ACL injuries, (4) menstrual history, and (5) history of oral contraception use. METHODS: One hundred and thirty-five female athletes aged between 14 and 31 years (mean: 18.8 ± 3.6 years) from rugby union (n = 47), soccer (n = 72), and netball (n = 16) volunteered to participate in this study. Demographics, history of life-event stress, injury history and baseline data were obtained prior to the competitive season. The following strength measures were collected: isometric hip adductor and abductor strength, eccentric knee flexor strength and single leg jumping kinetics. Athletes were then followed for 12 months, and all lower limb injuries sustained were recorded. RESULTS: One hundred and nine athletes provided one-year follow-up injury data, of whom, 44 suffered at least one lower limb injury. All athletes who reported high scores for negative life-event stress sustained lower limb injuries. Non-contact lower limb injury was positively associated with weak hip adductor strength (OR: 0.88; 95%CI: 0.78-0.98; p = 0.017), and between-limb adductor (OR: 5.65; 95%CI: 1.61-19.7.; p = 0.007) and abductor (OR: 1.95; 95%CI: 1.03-3.71; p = 0.039) strength asymmetries. CONCLUSION: History of life event stress, hip adductor strength, and between-limb adductor and abductor strength asymmetries offer potential novel avenues for investigating injury risk factors in female athletes.

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BACKGROUND: One mechanism by which exercise interventions may be effective in reducing anterior cruciate ligament (ACL) injury risk is through changes in lower limb biomechanics. Understanding how training programmes affect lower-limb kinematics and kinetics may help refine injury prevention programmes. OBJECTIVE: The aim of this systematic review and meta-analysis was to assess the effect of injury prevention programmes on kinematics and kinetics during tasks related to ACL injury in female team field and court sports. DATA SOURCES: Five databases were searched in October 2022. ELIGIBILITY CRITERIA: Randomised controlled trials assessing the effect of injury prevention programmes compared with usual training/no training on lower limb kinematics and kinetics in female team field and court sports were eligible for review. RESULTS: Sixteen studies were included. A total of 976 female athletes were included. Most of the studies included interventions with multiple components (12/16). Commonly used components were plyometrics (12/16), strength (8/16), and balance/stability (7/16). Thirteen studies had routine training or sham interventions as the control group and three studies had no training. Very low certainty evidence suggests that injury prevention programmes increase knee flexion angles (mean difference = 3.1° [95% confidence interval 0.8-5.5]); however, very low to low certainty evidence suggests no effect on hip flexion angles/moments, knee flexion moments, hip adduction angles/moments, knee adduction angles/moments, hip internal rotation angles/moments, ankle dorsiflexion angles, and ground reaction forces, compared with usual training/no training. CONCLUSION: Injury prevention programmes may be effective in increasing knee flexion angles during dynamic landing and cutting tasks but may have no effect on other lower limb biomechanical variables. As such, the benefits of injury prevention programmes may be mediated by factors other than altered biomechanics and/or may happen through other biomechanical measures not included in this review.

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PURPOSE: To examine the association between muscle fiber typology and match running performance in professional Australian football (AF) athletes. METHODS: An observational time-motion analysis was performed on 23 professional AF athletes during 224 games throughout the 2020 competitive season. Athletes were categorized by position as hybrid, small, or tall. Athlete running performance was measured using Global Navigation Satellite System devices. Mean total match running performance and maximal mean intensity values were calculated for moving mean durations between 1 and 10 minutes for speed (in meters per minute), high-speed-running distance (HSR, >4.17 m·s-1), and acceleration (in meters per second squared), while intercept and slopes were calculated using power law. Carnosine content was quantified by proton magnetic resonance spectroscopy in the gastrocnemius and soleus and expressed as a carnosine aggregate z score (CAZ score) to estimate muscle fiber typology. Mixed linear models were used to determine the association between CAZ score and running performance. RESULTS: The mean (range) CAZ score was -0.60 (-1.89 to 1.25), indicating that most athletes possessed a greater estimated proportion of type I muscle fibers. A greater estimated proportion of type I fibers (ie, lower CAZ score) was associated with a larger accumulation of HSR (>4.17 m·s-1) and an increased ability to maintain HSR as the peak period duration increased. CONCLUSION: AF athletes with a greater estimated proportion of type I muscle fibers were associated with a greater capacity to accumulate distance running at high speeds, as well as a greater capacity to maintain higher output of HSR running during peak periods as duration increases.

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CONTEXT: Hamstring strain injuries (HSIs) are the most frequently sustained injury in Major League Baseball (MLB). However, the beliefs and practices of MLB practitioners regarding HSI risk factors and prevention strategies in baseball athletes, have not been documented. OBJECTIVE: To document the current beliefs and practices of MLB practitioners in relation to HSI prevention. DESIGN: cross-sectional study. SETTING: Major League Baseball via an online survey. PARTICIPANTS: Athletic trainers, physical therapists and strength and conditioning coaches employed in MLB during the 2021 season. DATA COLLECTION AND ANALYSIS: An online survey was conducted with participants completing the survey once. Questions pertained to risk factor identification, the use and perceived effectiveness of preventative strategies, and barriers to implementation. Descriptive statistics were calculated for each question. RESULTS: 91 responses were received featuring respondents from 28 of 30 MLB organizations. The perceived most important intrinsic risk factor for first-time HSI was tolerance to high-speed running and previous HSI for recurrent injury. The perceived most important extrinsic risk factor for both first-time and recurrent HSI was internal communication between staff.The perceived most effective prevention strategies were managing overall workload, exposure to high-speed running, and periodization. The most used prevention strategies were core/lumbopelvic strengthening, resistance training and workload management.Approximately half (53%) of respondents reported barriers to effective implementation of HSI prevention strategies, including player and coach buy-in, compliance, training time constraints, and in-season scheduling/reduced recovery time. CONCLUSIONS: This was the first survey to investigate MLB practitioner beliefs and practices regarding HSI prevention. Responses from practitioners regarding their beliefs about risk factors and appropriate prevention strategies were varied, and discrepancies existed between the perceived most effective strategies and those most frequently employed.

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OBJECTIVES: The physical demands of military service place soldiers at risk of musculoskeletal injuries and are major concerns for military capability. This paper outlines the development new training technologies to prevent and manage these injuries. DESIGN: Narrative review. METHODS: Technologies suitable for integration into next-generation training devices were examined. We considered the capability of technologies to target tissue level mechanics, provide appropriate real-time feedback, and their useability in-the-field. RESULTS: Musculoskeletal tissues' health depends on their functional mechanical environment experienced in military activities, training and rehabilitation. These environments result from the interactions between tissue motion, loading, biology, and morphology. Maintaining health of and/or repairing joint tissues requires targeting the "ideal" in vivo tissue mechanics (i.e., loading and strain), which may be enabled by real-time biofeedback. Recent research has shown that these biofeedback technologies are possible by integrating a patient's personalised digital twin and wireless wearable devices. Personalised digital twins are personalised neuromusculoskeletal rigid body and finite element models that work in real-time by code optimisation and artificial intelligence. Model personalisation is crucial in obtaining physically and physiologically valid predictions. CONCLUSIONS: Recent work has shown that laboratory-quality biomechanical measurements and modelling can be performed outside the laboratory with a small number of wearable sensors or computer vision methods. The next stage is to combine these technologies into well-designed easy to use products.

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PURPOSE: This study aimed to compare and rank gluteal muscle forces in eight hip-focused exercises performed with and without external resistance and describe the underlying fiber lengths, velocities, and muscle activations. METHODS: Motion capture, ground reaction forces, and electromyography (EMG) were used as input to an EMG-informed neuromusculoskeletal model to estimate gluteus maximus, medius, and minimus muscle forces. Participants were 14 female footballers (18-32 yr old) with at least 3 months of lower limb strength training experience. Each participant performed eight hip-focused exercises (single-leg squat, split squat, single-leg Romanian deadlift [RDL], single-leg hip thrust, banded side step, hip hike, side plank, and side-lying leg raise) with and without 12 repetition maximum (RM) resistance. For each muscle, exercises were ranked by peak muscle force, and k-means clustering separated exercises into four tiers. RESULTS: The tier 1 exercises for gluteus maximus were loaded split squat (95% confidence interval [CI] = 495-688 N), loaded single-leg RDL (95% CI = 500-655 N), and loaded single-leg hip thrust (95% CI = 505-640 N). The tier 1 exercises for gluteus medius were body weight side plank (95% CI = 338-483 N), loaded single-leg squat (95% CI = 278-422 N), and loaded single-leg RDL (95% CI = 283-405 N). The tier 1 exercises for gluteus minimus were loaded single-leg RDL (95% CI = 267-389 N) and body weight side plank (95% CI = 272-382 N). Peak gluteal muscle forces increased by 28-150 N when exercises were performed with 12RM external resistance compared with body weight only. Peak muscle force coincided with maximum fiber length for most exercises. CONCLUSIONS: Gluteal muscle forces were exercise specific, and peak muscle forces increased by varying amounts when adding a 12RM external resistance. These findings may inform exercise selection by facilitating the targeting of individual gluteal muscles and optimization of mechanical loads to match performance, injury prevention, or rehabilitation training goals.

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PURPOSE: The aim of this systematic review was to (1) determine the muscle fiber-type composition (or muscle fiber typology [MFT]) of team-sport athletes and (2) examine associations between MFT and the physical characteristics and performance tasks in team-sport athletes. METHODS: Searches were conducted across numerous databases-PubMed, SPORTDiscus, MEDLINE, and Google Scholar-using consistent search terms. Studies were included if they examined the MFT of team-sport athletes. Included studies underwent critical appraisal using the McMasters University critical appraisal tool for quantitative research. RESULTS: A total of 10 studies were included in the present review, wherein the MFT of athletes was measured from 5 different team sports (soccer, rugby union, rugby league, handball, and volleyball). There was large variability in the MFT of team-sport athletes both within (up to 27.5%) and between sports (24.0% relative difference). Male football players with a higher proportion of type II fibers had faster 10- and 30-m sprint times, achieved a greater total distance sprinting (distance at >6.67 m·s-1), and a greater peak 1-minute sprint distance. CONCLUSIONS: MFT varies considerably between athletes both within and between different team sports. The results from some studies suggest that variation in MFT is associated with high-intensity running performance in a football match, as well as 10- and 30-m sprint times. Further experimental studies should focus on how determination of the MFT of team-sport athletes could be utilized to influence talent identification, team selection, and the individualization of training.

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The objective of this study is to assess the initial perception of referring providers and radiologists to a virtual consultation solution (the Virtual Radiology Reading Room, VR3). VR3 is specifically designed to replace the radiology reading room phone and enable the radiologist to continue to work as part of the clinical care team fielding radiology consults without being confined to the same physical space. Surveys of providers' and radiologists' initial experience were conducted approximately 6 months after initial deployment. Users were asked about their overall impression, and how well the solution integrates with their workflow as well as how it compares to traditional phone calls to the reading room. Forty of 71 referring providers and 27 of 44 radiologists responded to our survey. VR3 was rated 4.7 out of 5 stars by referrers and 4.1 by radiologists. Seventy percent of referrers and radiologists preferred VR3 to the phone while 4.5% of referrers and 11% of radiologists preferred the phone. Referring providers and radiologists expressed a positive initial perception of the Virtual Radiology Reading Room and prefer it to traditional phone calls to the reading room.

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Following hamstring autograft anterior cruciate ligament reconstruction (ACLR), muscle length, cross-sectional area, and volume are reduced. However, these discrete measures of morphology do not account for complex three-dimensional muscle shape. The primary aim of this study was to determine between-limb semitendinosus (ST) shape and regional morphology differences in young adults following tendon harvest for ACLR and to compare these differences with those in healthy controls. In this cross-sectional study, magnetic resonance imaging was performed on 18 individuals with unilateral ACLR and 18 healthy controls. Bilaterally, ST muscles were segmented, and shape differences assessed between limbs and compared between groups using Jaccard index (0-1) and Hausdorff distance (mm). Length (cm), peak cross-sectional area (cm2 ), and volume (cm3 ) were measured for the entire muscle and proximal, middle, and distal regions, and compared between limbs and groups. Compared to healthy controls, the ACLR group had significantly (p < 0.001, Cohen's d = -2.33) lower bilateral ST shape similarity and shape deviation was significantly (p < 0.001, d = 2.12) greater. Shape deviation was greatest within the distal region of the ACLR (Hausdorff: 23.1 ± 8.68 mm). Compared to both the uninjured contralateral limb and healthy controls, deficits in peak cross-sectional area and volume in ACLR group were largest in proximal (p < 0.001, d = -2.52 to -1.28) and middle (p < 0.001, d = -1.81 to -1.04) regions of the ST. Overall, shape analysis provides unique insight into regional adaptations in ST morphology post-ACLR. Findings highlight morphological features in distal ST not identified by traditional discrete morphology measures. Clinical significance: Following ACLR, risk of a secondary knee or primary hamstring injury has been reported to be between 2-to-5 times greater compared to those without ACLR. Change in semitendinosus (ST) shape following ACLR may affect force transmission and distribution within the hamstrings and might contribute to persistent deficits in knee flexor and internal rotator strength.

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INTRODUCTION: Anterior cruciate ligament (ACL) rupture is debilitating, often requiring surgical reconstruction. An ACL reconstruction (ACLR) using a tendon autograft harvested from the semitendinosus results in substantial injury to the donor muscle. Following ACLR, patients rarely return to their preinjury level of physical activity, are at elevated risk of secondary lower limb injuries and early onset knee osteoarthritis. To date, no randomised controlled trial has evaluated the efficacy of platelet-rich plasma (PRP) in aiding knee function and semitendinosus morphology of following ALCR. METHODS AND ANALYSIS: This is a multicentre double-blind randomised placebo-controlled trial. Fifty-four ACLR patients aged 18-50 years will be randomised to receive either a single application of PRP (ACLR+) or placebo saline (ACLR) into the semitendinosus harvest zone at the time of surgery. All patients will undergo normal postoperative rehabilitation recommended by the attending orthopaedic surgeon or physiotherapist. The primary outcome measure is between-limb difference (ACLR compared with intact contralateral) in isometric knee flexor strength at 60o knee flexion, collected 10-12 months postsurgery. This primary outcome measure will be statistically compared between groups (ACLR+ and standard ACLR). Secondary outcome measures include bilateral assessments of hamstring muscle morphology via MRI, biomechanical and electromyographic parameters during an anticipated 45° running side-step cut and multidirectional hopping task and patient-reported outcomes questionaries. Additionally, patient-reported outcomes questionaries will be collected before (baseline) as well as immediately after surgery, and at 2-6 weeks, 3-4 months, 10-12 months and 22-24 months postsurgery 10-12 months following surgery. ETHICS AND DISSEMINATION: Ethics approval has been granted by Griffith University Human Research Ethics Committee, Greenslopes Research and Ethics Committee, and Royal Brisbane & Women's Hospital Human Research Ethics Committee. Results will be submitted for publication in a peer-reviewed medical journal. TRIAL REGISTRATION NUMBER: ACTRN12618000762257p.

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PURPOSE: This study aimed to investigate hamstring architectural, strength, and morphological adaptations after an eccentric or isometric hip extension exercise intervention. METHODS: Twenty-four recreationally active males performed either an eccentric ( n = 12) or an isometric hip extension ( n = 12) exercise intervention, twice per week for 6 wk, followed by a 4-wk detraining period. Biceps femoris long head (BFlh) architecture was assessed pre-intervention, mid-intervention, post-intervention, and post-detraining via two-dimensional ultrasound. Strength was assessed pre-intervention, post-intervention, and post-detraining during an isokinetic knee flexion, an isometric hip extension, a Nordic hamstring exercise, and a single-leg hamstring bridge repetition to fatigue test. Hamstring muscle morphology was assessed via magnetic resonance imaging before strength testing sessions. RESULTS: The eccentric hip extension exercise intervention significantly lengthened BFlh fascicles (+19.7%, P < 0.001, d = 1.57), increased eccentric knee flexion torque (ECC 60°·s -1 , +12%, P < 0.005, d = 0.66; ECC 180°·s -1 , +8.3%, P < 0.05, d = 0.41), and increased BFlh (+13.3%, P < 0.001, d = 1.96) and semimembranosus (SM) muscle volume (+12.5%, P < 0.001, d = 2.25). After 4 wk of detraining, BFlh fascicles were significantly shortened in the eccentric group (-14.8%, P < 0.005, d = -1.25), whereas eccentric knee flexion torque and BFlh and SM volumes were unchanged. The isometric hip extension exercise intervention significantly increased isometric knee flexion torque (+10.4%, P < 0.05, d = 0.54), isometric hip extension force (+12.4%, P < 0.05, d = 0.41), and semitendinosus volume (+15%, P = 0.054, d = 1.57). All other outcome measures saw no significant changes. After 4 wk of detraining, no significant changes to any variables were observed in the isometric group. CONCLUSIONS: The eccentric but not isometric hip extension exercise intervention significantly increased BFlh fascicle length. Both exercise interventions demonstrated contraction mode-specific increases in strength. However, the eccentric hip extension exercise intervention resulted in preferential hypertrophy of BFlh and SM, and the isometric hip extension exercise intervention led to selective hypertrophy of semitendinosus.

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To assess the validity and between-unit agreement of velocity monitoring devices during incrementally-loaded countermovement jumps (CMJ), 16 males (24.0 ± 3.5 yr) completed 12 CMJs on a force plate (FP). Performance variables were collected through two linear position transducers (GymAware [GA]) and four accelerometer-based devices (two PUSH units, two Bar Sensei units). Pearson correlations (r) and coefficients of variation (CV) demonstrated strong to very-strong relationships (r = 0.60-0.88) and poor agreement (CV = 11.7-25.3%) between FP and GA, and moderate to very-strong relationships (r = 0.31-0.81) and poor agreement (CV = 10.1-24.2%) between FP and PUSH. Between-unit comparisons demonstrated moderate to very-strong relationships (r = 0.50-0.88) with poor agreement (CV = 10.8-26.6%) for GA, and very weak to very-strong relationships (r = 0.01-0.87) with moderate to poor agreement (CV = 9.1-24.1%) for PUSH. Bar Sensei units were excluded from analyses. Loaded CMJ data collected with either device displayed poor agreement with a FP. Velocity monitoring devices demonstrate poor validity across all loads; however, GA demonstrated strong between-unit agreement. A FP should be utilised to accurately assess CMJ performance at all times.

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OBJECTIVES: Compare hamstring strength between Australian Football League (AFL) players with and without a prior hamstring injury and determine the effect of the number of previous hamstring injuries, time since the last injury, and injury severity, on hamstring strength. DESIGN: Cross-sectional, retrospective. SETTING: AFL clubs. PARTICIPANTS: 124 AFL players. MAIN OUTCOME MEASURES: Bilateral hamstring strength was assessed on a Nordbord (Vald Performance) during the Nordic Hamstring Exercise. Self-reported questionnaires were used to record previous hamstring injuries. Players were categorized into No Injury or Hamstring Injury groups. Previously injured players were subgrouped based on number of prior hamstring injuries (single or multiple), time since the last hamstring injury (≤1 or > 1-year ago), and hamstring injury severity (≤3 or > 3 matches missed). RESULTS: 19 hamstring injuries were reported. Hamstring strength was not different between players with and without a history of hamstring injury when assessed in absolute (N) or relative (i.e., N.kg-1) terms. No differences in strength were detected between hamstring injury subgroups when assessed in absolute or relative terms. CONCLUSIONS: AFL players that experienced a previous hamstring injury did not exhibit deficits in hamstring strength relative to their uninjured limb or players without a previous hamstring injury.