Can real-time feedback improve the simulated infant cardiopulmonary resuscitation performance of basic life support and lay rescuers?

BACKGROUND: Performing high-quality chest compressions during cardiopulmonary resuscitation (CPR) requires achieving of a target depth, release force, rate and duty cycle. OBJECTIVE: This study evaluates whether 'real time' feedback could improve infant CPR performance in basic life support-trained (BLS) and lay rescuers. It also investigates whether delivering rescue breaths hinders performing high-quality chest compressions. Also, this study reports raw data from the two methods used to calculate duty cycle performance. METHODOLOGY: BLS (n=28) and lay (n=38) rescuers were randomly allocated to respective 'feedback' or 'no-feedback' groups, to perform two-thumb chest compressions on an instrumented infant manikin. Chest compression performance was then investigated across three compression algorithms (compression only; five rescue breaths then compression only; five rescue breaths then 15:2 compressions). Two different routes to calculate duty cycle were also investigated, due to conflicting instruction in the literature. RESULTS: No-feedback BLS and lay groups demonstrated <3% compliance against each performance target. The feedback rescuers produced 20-fold and 10-fold increases in BLS and lay cohorts, respectively, achieving all targets concurrently in >60% and >25% of all chest compressions, across all three algorithms. Performing rescue breaths did not impede chest compression quality. CONCLUSIONS: A feedback system has great potential to improve infant CPR performance, especially in cohorts that have an underlying understanding of the technique. The addition of rescue breaths-a potential distraction-did not negatively influence chest compression quality. Duty cycle performance depended on the calculation method, meaning there is an urgent requirement to agree a single measure.

Biomechanical properties and microstructure of neonatal porcine ventricles.

Neonatal heart disorders represent a major clinical challenge, with congenital heart disease alone affecting 36,000 new-borns annually within the European Union. Surgical intervention to restore normal function includes the implantation of synthetic and biological materials; however, a lack of experimental data describing the mechanical behaviour of neonatal cardiac tissue is likely to contribute to the relatively poor short- and long-term outcome of these implants. This study focused on characterising the mechanical behaviour of neonatal cardiac tissue using a porcine model, to enhance the understanding of how this differs to the equivalent mature tissue. The biomechanical properties of neonatal porcine cardiac tissue were characterised by uniaxial tensile, biaxial tensile, and simple shear loading modes, using samples collected from the anterior and posterior walls of the right and left ventricles. Histological images were prepared using Masson's trichrome staining, to enable assessment of the microstructure and correlation with tissue behaviour. The mechanical tests demonstrated that the neonatal cardiac tissue is non-linear, anisotropic, viscoelastic and heterogeneous. Our data provide a baseline describing the biomechanical behaviour of immature porcine cardiac tissue. Comparison with published data also indicated that the neonatal porcine cardiac tissue exhibits one-half the stiffness of mature porcine tissue in uniaxial extension testing, one-third in biaxial extension testing, and one-fourth stiffness in simple shear testing; hence, it provides an indication as to the relative change in characteristics associated with tissue maturation. These data may prove valuable to researchers investigating neonatal cardiac mechanics.

Does the new rugby union scrum sequence positively influence the hooker's in situ spinal kinematics?

BACKGROUND: Scrummaging is unique to rugby union and involves 2 'packs' of 8 players competing to regain ball possession. Intending to serve as a quick and safe method to restart the game, injury prevalence during scrummaging necessitates further evaluation of this environment. AIMS: The aim of this study was to determine the effect of scrummage engagement sequences on spinal kinematics of the hooker. The conditions investigated were: (1) live competitive scrummaging using the new 'crouch, bind, set' sequence; (2) live competitive scrummaging using the old 'crouch touch pause engage' sequence and (3) training scrummaging using a scrum machine. METHODS: Inertial sensors provided three-dimensional kinematic data across 5 spinal regions. Participants (n=29) were adult, male community club and university-level hookers. RESULTS: Engagement sequence had no effect on resultant kinematics of any spinal region. Machine scrummaging resulted in lesser magnitudes of motion in the upper spinal regions. Around two-thirds of the total available cervical motion was utilised during live scrummaging. CONCLUSIONS: This study indicates that the most recent laws do not influence the spinal kinematics of the hooker during live scrummaging; however, there may be other benefits from these law changes that fall outside the scope of this investigation.

The prediction of neck extensor force using surface electromyography.

BACKGROUND: The relationship between muscular force and electromyography (EMG) has been investigated by numerous researchers. EMG has not previously been used as a means of estimating force in the cervical erector spinae (CES). OBJECTIVE: Use EMG of the CES musculature to indirectly predict neck extension force. METHODS: Isometric contractions of the CES muscles were studied at increasing levels of contractile force across all participants (n= 12) to produce an individualised force-EMG relationship. The method of least squares was used to determine the linear regression trend line for the force-EMG relationship. The validity of these individual `correlation curves' was demonstrated through further, blinded, investigation. RESULTS: A linear relationship was identified for the individualised correlation curves that gained in strength for < 50% maximum voluntary contraction (MVC; R2> 0.8 for 80% of trials). The prediction of muscle force from the correlation curves was found to be statistically similar to the equivalent experimental data (p> 0.05). Given the tendency of EMG to slightly overestimate force in most cases, an adjustment coefficient was calculated to reduce the error in the predicted force data. CONCLUSIONS: This study reports a validated method using EMG to indirectly acquire CES muscular force, which has application for clinicians and research scientists working in fields including sport and rehabilitation.

Investigating the contribution of the upper and lower lumbar spine, relative to hip motion, in everyday tasks.

BACKGROUND: It is commonplace for clinicians to measure range of motion (ROM) in the assessment of the lumbar spine. Traditional single 'joint' models afford measuring only a limited number of regions along the spine and may, therefore, over-simplify the description of movement. It remains to be determined if additional, useful information can be gleaned by considering the traditional 'lumbar region' as two regions. OBJECTIVE: The aim of this study was to determine whether modelling the lumbar spine as two separate regions (i.e. upper and lower), yields a different understanding of spinal movement relative to hip motion, than a traditional single-joint model. This study is unique in adopting this approach to evaluate a range of everyday tasks. METHOD: Lumbar spine motion was measured both by being considered as a whole region (S1 to T12), and where the lumbar spine was modelled as two regions (the upper (L3-T12) and lower (S1-L3)). RESULTS: A significant difference was evident between the relative contribution from the lower and upper spine across all movements, with the lower lumbar spine consistently contributing on average 63% of the total ROM. A significant difference was also evident between the whole lumbar spine-hip ratio, and the lower lumbar spine-hip ratio, for the movement of lifting only. The lower lumbar spine achieved greater velocity for all tasks, when compared to the upper lumbar spine. CONCLUSION: This study has consistently demonstrated differences in the contribution of the upper and lower spinal regions across a range of everyday tasks; hence, it would appear that greater focus should be given to performing more detailed assessments to fully appreciate spinal movement.

A kinematic analysis of the spine during rugby scrummaging on natural and synthetic turfs.

Artificial surfaces are now an established alternative to grass (natural) surfaces in rugby union. Little is known, however, about their potential to reduce injury. This study characterises the spinal kinematics of rugby union hookers during scrummaging on third-generation synthetic (3G) and natural pitches. The spine was sectioned into five segments, with inertial sensors providing three-dimensional kinematic data sampled at 40 Hz/sensor. Twenty-two adult, male community club and university-level hookers were recruited. An equal number were analysed whilst scrummaging on natural or synthetic turf. Players scrummaging on synthetic turf demonstrated less angular velocity in the lower thoracic spine for right and left lateral bending and right rotation. The general reduction in the range of motion and velocities, extrapolated over a prolonged playing career, may mean that the synthetic turf could result in fewer degenerative injuries. It should be noted, however, that this conclusion considers only the scrummaging scenario.

Correlation of lumbar-hip kinematics between trunk flexion and other functional tasks.

OBJECTIVE: The purpose of this study was to explore the relationship between the kinematic profiles of flexion of the upper lumbar and lower lumbar (LL) spine and hip and 3 sagittally dominant functional tasks (lifting, stand-to-sit, and sit-to-stand). METHODS: Fifty-three participants were recruited for this study. Four sensors were attached to the skin over the S1, L3, T12, and lateral thigh. Relative angles between adjacent sensors were used to quantify the motion for the hip, LL, and upper lumbar spine. Pearson correlation coefficients were used to explore the relationship between the movements and more functional tasks. One-way analysis of variance was used to determine the significance of differences between the variables. RESULTS: Flexion resulted in a greater or similar range of motion (ROM) to the other tasks investigated for both spinal regions but less ROM for the hip. Strong correlations for ROM are reported between forward flexion tasks and lifting for the LL spine (r = 0.83) and all regions during stand-to-sit and sit-to-stand (r = 0.70-0.73). No tasks were strongly correlated for velocity (r = 0.03-0.55). CONCLUSION: Strong correlations were only evident for the LL spine ROM between lifting and flexion; all other tasks afforded moderate or weak correlations. This study suggests that sagittal tasks use different lumbar-hip kinematics and place different demands on the lumbar spine and hip.

Reliability of an accelerometer-based system for quantifying multiregional spinal range of motion.

OBJECTIVES: The purpose of this study was to investigate the reliability of a novel motion analysis device for measuring the regional breakdown of spinal motion and describing the relative motion of different segments of the thoracolumbar (TL) spine. METHODS: Two protocols were applied to 18 healthy participants. In protocol 1, 2 sensors were placed on the forehead and T1 to measure cervical range of motion (ROM). In protocol 2, 6 sensors were placed on the spinous processes of T1, T4, T8, T12, L3, and S1 to measure TL regional ROM. Intraclass correlation coefficients were used to evaluate the repeatability of movement, whereas SEM was used to define the extent of error. Ranges of motion were demonstrated in flexion extension, right-left lateral flexion, and right-left rotation of the head-cervical, upper thoracic, middle thoracic, lower thoracic, upper lumbar, and lower lumbar. RESULTS: The intraclass correlation coefficient values, for all regions, were found to be high, ranging from 0.88 to 0.99 for all movements, and regions of the spine and SEM values ranged from 0.4° to 5.2°. Multiregional spine ROM ranged from 3° in the upper thoracic and mid-thoracic during flexion and 80° at head cervical during right rotation. CONCLUSION: The described methodology was reliable for assessing regional spinal ROM across multiple spinal regions while providing the relative motions of different segments of the TL spine.

The change in energy absorbed post removal of metalwork in a simulated paediatric long bone fracture.

PURPOSE: The surgical treatment of paediatric fractures is increasing. Open reduction and internal fixation (ORIF) with plates and screws is long established, whilst the use of elastic stable intramedullary nailing (ESIN) has become increasingly popular. This study quantifies, in terms of the energy required to produce a fracture, the biomechanical sequelae of both techniques post removal of metalwork, to provide clinicians with evidence to guide post-operative advice. METHODS: An immature bovine model was adopted to ascertain whether these techniques exposed the bone to a greater re-fracture risk following removal of the device. Bones were prepared to reflect ORIF or ESIN techniques, or prepared intact for the acquisition of control data. Each bone was tested to failure at 90 °/s, with the absorbed energy then being calculated to determine the relative difference between each technique and versus control data. Data describing peak shear stress and torque were recorded. RESULTS: Absorbed energy was reduced by 47 % in the ORIF group compared to both the control (p = 0.011) and ESIN (p = 0.018) groups. The peak shear stress and torque were also significantly different. All ORIF bones failed through drill holes, suggesting stress localisation around the defects. CONCLUSION: This study suggests that there is a significantly higher re-fracture risk following the removal of ORIF plates when compared to both ESIN and the control environment. Whilst this may reflect the intuitive view of many clinicians, this study provides a quantitative value of the reduction in strength and should help clinicians to appropriately caution patients and parents prior to surgery.

Does the presence of a vertical barrier influence sagittal spinal curvature or range of motion in young females?

BACKGROUND AND OBJECTIVES: Lifting presents a significant risk for the development of low back pain. It is not known what effect lifting from a supermarket shopping trolley has on sagittal spinal curvature. The aim of this study is to determine the effect of lifting from a shopping trolley on sagittal spinal curvature. METHODS: Fifteen female subjects (height 1.67 ± 0.04 m, weight 64.3 ± 5.0 kg) completed lifts of 9 kg from a shopping trolley and a surface matched for height whilst sagittal spinal curvature was measured using Qualysis motion analysis system. Seven retro-reflective markers were placed along spine with angle between three markers representing regional curvature. No constraints on lifting technique were instigated. RESULTS: Results demonstrate no difference in sagittal range of motion or spinal curvature across the two lifts. A small but significant difference in knee flexion angle was observed. These results demonstrate that the chosen lifting strategy was not influenced by the constraint imposed by the shopping trolley. Furthermore the function of knee flexion did not result in change in sagittal curvature during the lifts. CONCLUSION: Lifting from a shopping trolley has no effect of sagittal spinal curvature.

Development of a methodology for the standardisation and improvement of 'Smartphone' photography of patterned bruises and other cutaneous injuries.

Human bite-mark analyses can play a prominent role in forensic case investigations, including those involving sexual assault. High-quality photographs routinely secure a link between a bite-mark and an individual's dentition. Access to around the clock forensic photography, however, is often limited, resulting in delay and/or missed opportunities to record valuable evidence. The emergence of Smartphone high-quality photographic technology now provides a previously unimagined opportunity to gather timely forensic photographic evidence. Problems can arise, however, due to the relatively poor quality of the photographs, as a result of many of those taking photographs having received little or no forensic photography training. This study compares unassisted photography with assisted photography, by a specifically developed camera application (App), to provide a standardised method for taking forensic photographs. An App, written in Java, was hosted on the Google Android Operating System, on a Samsung Galaxy SII Smartphone. Twenty-four volunteers participated in a study to photograph a pseudo bite-mark using three methods, (1) unassisted (as a control), (2) assisted by an ABFO No.2 right-angled photographic reference scale and (3) assisted by the App. The App, method (3), was shown to consistently outperform methods (1) and (2), demonstrating greater standardisation and precision (p<0.001). Analysis of the data showed the extent to which acquiring an accurate photograph depends on the image being orthogonal to the camera. It appears likely that the relatively inaccurate photographs acquired by methods (1) and (2), were as a result of deviation from the plane, orthogonal to the bite-mark. Therefore, the App was successful in ensuring that the camera was both orthogonal and at an appropriate distance, relative to the bite-mark. Thus, the App enhanced the abilities of non-experts to acquire more accurate photographs and created the potential to significantly improve the quality of forensic photographs.

Does a more "physiological" infant manikin design effect chest compression quality and create a potential for thoracic over-compression during simulated infant CPR?

Poor survivability following infant cardiac arrest has been attributed to poor quality chest compressions. Current infant CPR manikins, used to teach and revise chest compression technique, appear to limit maximum compression depths (CDmax) to 40 mm. This study evaluates the effect of a more "physiological" CDmax on chest compression quality and assesses whether proposed injury risk thresholds are exceeded by thoracic over-compression. A commercially available infant CPR manikin was instrumented to record chest compressions and modified to enable compression depths of 40 mm (original; CDmax40) and 56 mm (the internal thoracic depth of a three-month-old male infant; CDmax56). Forty certified European Paediatric Life Support instructors performed two-thumb (TT) and two-finger (TF) chest compressions at both CDmax settings in a randomised crossover sequence. Chest compression performance was compared to recommended targets and compression depths were compared to a proposed thoracic over-compression threshold. Compressions achieved greater depths across both techniques using the CDmax56, with 44% of TT and 34% of TF chest compressions achieving the recommended targets. Compressions achieved depths that exceeded the proposed intra-thoracic injury threshold. The modified manikin (CDmax56) improved duty cycle compliance; however, the chest compression rate was consistently too high. Overall, the quality of chest compressions remained poor in comparison with internationally recommended guidelines. This data indicates that the use of a modified manikin (CDmax56) as a training aid may encourage resuscitators to habitually perform deeper chest compressions, whilst avoiding thoracic over-compression and thereby improving current CPR quality. Future work will evaluate resuscitator performance within a more realistic, simulated CPR environment.

Do chest compressions during simulated infant CPR comply with international recommendations?

BACKGROUND: Morbidity and mortality remain high following infant cardiac arrest. Optimal cardiopulmonary resuscitation (CPR) is therefore imperative. OBJECTIVE: Comparison of two-thumb (TT) and two-finger (TF) infant chest compression technique compliance with international recommendations. DESIGN: Randomised cross-over experimental study. METHODS: Twenty-two certified Advanced Paediatric Life Support (APLS) instructors performed 2 min continuous TT and TF chest compressions on an instrumented infant CPR manikin. Compression depth (CD), release force (RF), compression rate (CR) and duty cycles (DCs) were recorded. Quality indices were developed to calculate the proportion of compressions that complied with internationally recommended targets, and an overall quality index was used to calculate the proportion that complied with all four targets. RESULTS: Mean CD was 33 mm and 26 mm (p<0.001; target ≥36.7 mm), mean RF was 0.8 kg and 0.2 kg (p<0.001; target <2.5 kg), mean CR was 128/min and 131/min (p=0.052; target 100-120/min) and mean DCs was 61% and 53% (p<0.001; target 30-50%) for the TT and TF techniques, respectively. With the exception of RF, the majority of compressions failed to comply with targets. The TT technique improved median CD compliance (6% vs 0% (p<0.001)), while the TF technique improved median DC compliance (23% vs 0% (p<0.001)). Overall compliance with all four targets was <1% for both techniques (p=0.14). CONCLUSIONS: Compliance of APLS instructors with current international recommendations during simulated infant CPR is poor. The TT technique provided improved CD compliance, while the TF technique provided superior DC compliance. If this reflects current clinical practice, optimisation of performance to achieve international recommendations during infant CPR is called for.

In vitro growth factor-induced bio engineering of mature articular cartilage.

Articular cartilage maturation is the postnatal development process that adapts joint surfaces to their site-specific biomechanical demands. Maturation involves gross morphological changes that occur through a process of synchronised growth and resorption of cartilage and generally ends at sexual maturity. The inability to induce maturation in biomaterial constructs designed for cartilage repair has been cited as a major cause for their failure in producing persistent cell-based repair of joint lesions. The combination of growth factors FGF2 and TGFß1 induces accelerated articular cartilage maturation in vitro such that many molecular and morphological characteristics of tissue maturation are observable. We hypothesised that experimental growth factor-induced maturation of immature cartilage would result in a biophysical and biochemical composition consistent with a mature phenotype. Using native immature and mature cartilage as reference, we observed that growth factor-treated immature cartilages displayed increased nano-compressive stiffness, decreased surface adhesion, decreased water content, increased collagen content and smoother surfaces, correlating with a convergence to the mature cartilage phenotype. Furthermore, increased gene expression of surface structural protein collagen type I in growth factor-treated explants compared to reference cartilages demonstrates that they are still in the dynamic phase of the postnatal developmental transition. These data provide a basis for understanding the regulation of postnatal maturation of articular cartilage and the application of growth factor-induced maturation in vitro and in vivo in order to repair and regenerate cartilage defects.

Tribological characteristics of healthy tendon.

Tendons transfer muscular forces efficiently and painlessly, facilitating joint motion. Whilst the tribology of articular cartilage is constantly explored, a poorer understanding remains of tendon lubrication and friction. This study reports experimental data describing the tribological characteristics of tendon and its surrounding tissue, before presenting an arithmetic solution to facilitate numerical modelling. The experimental characteristics of the tensile (i.e. mid-substance) and compressive (i.e. fibrocartilaginous) regions of bovine flexor tendon were investigated using a pin-on-plate tribometer, with immunofluroscence analysis describing the relative intensity and distribution of surface-bound lubricin. Arithmetic analysis considering the digital extensor tendon determined that, in physiological conditions, the tensile tendon region was able to generate elastohydrodynamic lubrication (EHL). The equivalent region of compressive tendon exhibited a higher intensity of surface-bound lubricin which, it is hypothesised, serves to minimise the increased frictional resistance due to generating only mixed or boundary lubrication regimes. Arithmetic analysis indicates that, given a more favourable biomechanical environment, this region can also generate EHL. Whilst acknowledging the limitations of transferring data from an animal model to a clinical environment, by providing the first data and equations detailing the film thicknesses and lubrication regime for these two tendon regions it is hoped that clinicians, engineers and scientists can consider improved clinical strategies to tackle both tendinopathy and tendon rupture.

The bio-tribological properties of anti-adhesive agents commonly used during tendon repair.

Frictional resistance to tendon gliding is minimized by surrounding loose areolar tissue. During periods of prolonged immobilization, for example, post-tendon-repair, adhesions can form between these two adjacent tissues, thereby limiting tendon function. Anti-adhesive agents can be applied during surgery to prevent adhesion formation, whilst reportedly providing some reduction in friction during in vitro tendon-bony pulley investigations. This bio-tribological study evaluates whether application of these agents can improve the lubrication between the tendon and surrounding tissue, thus potentially reducing the risk of re-rupturing the tendon at the repair site. The use of bovine synovial fluid (BSF) enabled an approximation of the in vivo lubrication regime, and subsequent comparison of the performance of three synthetic agents (50 mg/ml 5-fluorouracil; 5 mg/ml hyaluronic acid; ADCON-T/N). Coefficient of friction data was recorded and then compared with the Stribeck curve. BSF generated a fluid film that separated the two surfaces, giving rise to optimal lubrication conditions. This efficient regime was also generated following application of each anti-adhesion agent. The use of phosphate-buffered saline solution in generating only a boundary lubrication regime highlighted the effectiveness of the agents in reducing friction. Hyaluronic acid (5 mg/ml) was marginally deemed the most effective anti-adhesive agent at lubricating the tendon. Subsequently, it is concluded that the application of anti-adhesive agents post-surgery has secondary, tribological benefits that serve to reduce friction, and thus potentially the risk of failure, at the tendon repair site.

Do inertial sensors represent a viable method to reliably measure cervical spine range of motion?

A rise in neck pain cases has initiated an exponential interest in the assessment and treatment of cervical spine range of motion (CROM). Experimental limitations, however, have been reported as therapists strive to collect continuous, dynamic data to aid prognosis. This technical report seeks to explore the viability of using inertial sensors to reliably assess CROM. In recognition of the need for secure skin-sensor attachment, four combinations of sensor pairings were established and investigated based upon four clinically identifiable surface landmarks. Twelve participants were recruited and asked to perform three specific movement cycles in each plane (i.e. flexion-extension; rotation; lateral bending). The reliability of the peak CROM, and the movement pattern, recorded in each of the three movement cycles was statistically analysed using the intra-class correlation coefficient (ICC) and coefficient of multiple correlations (CMC). It was determined that the most reliable positions of the orientation sensors, with one adhered to the forehead and the other representing T4, enables data to be recorded with a reliability that is comparable to other CROM measuring techniques. Subsequently, it is concluded that inertial sensors represent a viable method to assess CROM.

Biomechanical investigation into the torsional failure of immature long bone.

Approximately 50% of infant and toddler long bone fractures are attributed to non-accidental trauma; however, differentiating from benign mechanisms is subjective, due to an absence of evidence-based diagnostic tools. Previous studies investigated small ranges of rotational velocities in animal long bone models, although did not report the variation in the spiral fracture angle. This study considered the fracture angle as a potential clinical measure, correlating this data with a wider range of rotational velocities. The spiral fracture angle was measured relative to the long axis, whilst noting the narrowest diaphysial diameter, location of the fracture, and the extent of comminution and periosteal disruption. Twenty-six bones failed in spiral fracture, with the potting material failing in the remaining tests. All spiral fractures centred on the narrowest diaphysial diameter. Slower rotational velocities caused fracture angles approaching 45°, whereas fractures at greater velocities caused fracture angles nearer 30°. A relatively strong trend (R (2) = 0.78) is reported when the normalised fracture angle (against the narrowest diaphysial dimension) was plotted against the rotational rate. A relationship has been identified between the angle of spiral fracture and the rotational velocity using the immature bovine metatarsal model. This trend forms a scientific foundation from which to explore developing a diagnostic, evidence-based tool that may ultimately serve to assist differentiating between accidental and non-accidental injury.

Panoramic ultrasound to measure in vivo tendo Achilles strain.

BACKGROUND: The tendo Achilles (TA) is a tendon very susceptible to injury. Biomechanical methodologies for exploring tendon strain are limited, however, as they are typically performed in vitro or by indirectly measuring the displacement of reference markers. By using panoramic ultrasound, this study reports a novel approach to acquire direct, in vivo tendon extension data. MATERIALS AND METHODS: Sonographic scans were acquired between two in vivo landmarks following a consistent pathway along the long axis of the distal TA. Ten subjects were scanned with an unloaded tendon and then when resisting a range of loads. Tendon cross-sectional area was measured following coronal scans of the TA in three subjects, allowing for calculation and plotting of stress versus strain. Coefficients of variation were also calculated to measure the reliability and robustness of the protocol. RESULTS: Data from all ten subjects were found to fit with classic tendon force versus extension trend. The stress versus strain plot indicated that the wavy collagen fibers were fully straightened at 4% to 6% strain, which is comparable to results reported in other studies. The Young's modulus of 0.5 to 2.1 GPa also compared favorably to published data. CONCLUSION: Coefficients of variation indicated that the protocol was repeatable, although the technique for measuring cross-sectional area could be improved. CLINICAL RELEVANCE: As the reported data is comparable to previous invasive and in vitro studies, we believe sports medicine specialists and orthopaedic surgeons can utilize panoramic ultrasound to directly measure in vivo tendon strain.