Control Limbs Research Articles

Evaluating massage therapy for radiation-induced fibrosis in rats: preliminary findings and palpation results

ABSTRACT Radiation-induced fibrosis (RIF) is a common side effect of cancer treatment, but can manifest into a devastating syndrome for which there is no preventive measure or cure. In rats who perform a repetitive work task, who left untreated develop signs and symptoms that resemble repetitive motion disorders in humans, we have shown that manual therapy prevents the development of fibrosis and other key biomarkers. The fibrosis of RIF and repetitive motion disorders has similar biomarkers. In rats, we sought to determine if manual therapy would alter key biomarkers of post-irradiation fibrosis following X-ray irradiation given to the rat forelimb. One limb of rats was given a damaging dose of X-ray irradiation. Some limbs were massaged using a protocol previously described and characterized. Serum inflammatory markers, histological assays of tissue fibrosis and nerve pathology, and electrophysiology for neuropathic discharge were assayed after 8 weeks. We also tested if an experienced therapist could identify the irradiated limb using blinded palpation at the 8 week end-point. While preliminary assays showed robust changes compared to control limbs, the other assays did not show similar pathology. Our therapist could detect each irradiated limb. Serum inflammatory markers were reduced by massage to the irradiated limb. We conclude that blinded palpation is sensitive to detect subtle changes in tissue following irradiation. In contrast to the preliminary studies, the dose of irradiation used was insufficient to induce long-lasting deep fibrosis or nerve degeneration. We suspect that a difference in housing, and thus physical activity, was the plausible reason for this difference.

Assessing Femoral Anteversion in Patients With Bilateral Recurrent Patellar Dislocations.

After first-time lateral patellar dislocation, 44% to 70% of patients sustain redislocations. Increased femoral anteversion (FA) is considered to result in increased lateralizing forces on the patella, which might predispose one to patellar instability. When recurrent patellar dislocations (RPDs) are bilateral, it is unclear if the FA is even more increased. Patients with bilateral RPD would have greater FA than patients with unilateral RPD. Case-control study; Level of evidence, 3. A total of 52 skeletally mature patients with RPD and a clinical suspicion of rotational malalignment underwent rotational computed tomography or magnetic resonance imaging. The uni- or bilaterality of the RPD was determined. A control group comprising 54 adult patients with trauma underwent computed tomography of both lower extremities as part of a multitrauma protocol. The FA values of both lower extremities were evaluated separately. In total, 20 of 52 (38.5%) patients in the study group had a history of unilateral RPD and 32 of 52 (61.5%) patients had a bilateral RPD diagnosis. The mean FA of the asymptomatic limb in unilaterally symptomatic patients was 18.0° (SD, 11.2°; range, 0.5°-40.0°; median, 16.5°). In the symptomatic limb, the mean FA was 19.2° (SD, 9.1°; range, 2.0°-33.0°; median, 19.0°) (mean difference, 1.2°; 95% CI -1.3° to 3.8°). In bilaterally symptomatic patients, the mean FA on the right side was 23.2°, and 22.5° on the left. The mean differences between the symptomatic limbs in the unilateral RPD group and the right or left limbs in the bilateral RPD group were 4.0° (P = .263) and 3.3° (P = .326), respectively. In the control group without RPD, the mean FA was 12.5° (SD, 8.5°; range, 0.8°-33.0°; median, 10.9°). The mean difference between right limbs of the patients with bilateral RPD and right limbs of controls was 10.8° (P = .001). Patients with bilateral RPD have bilaterally greater FA than patients without a history of RPD. Patients with unilateral RPD have greater FA on both sides compared with the control group without a history of lateral patellar dislocation. No statistically significant difference of FA can be seen between patients with bilateral or unilateral RPD.

Fibular reduction and the evolution of theropod locomotion.

Since Hampé's classic developmental experiments in the mid-twentieth century1,2, the reduced avian fibula has sparked sustained curiosity3-6. The fibula transformed throughout dinosaur evolution from a columnar structure into its splint-like avian form, a change long thought to be of little biomechanical consequence3,6. Here we integrated comparative three-dimensional kinematic analyses with transitional morphologies from the fossil record to refute this assumption and show that the reduced fibula serves a crucial function in enabling extreme knee long-axis rotation (LAR). Extreme LAR is fundamental to avian locomotion and is regularly exploited by living birds to execute complex terrestrial manoeuvres7. We infer that the evolution of this capacity was preceded by restriction of the knee to hinge-like motion in early theropod dinosaurs, driven by the origin of a mid-shank articulation8 that precluded ancestral patterns of tibiofibular motion. Freeing of the fibula from the ankle joint later enabled mobilization of this initially static articulation and, in doing so, established a novel pattern of tibiofibular kinematics essential to the extreme levels of LAR retained by modern birds. Fibular reduction thus ushered in a transition to LAR-dominated three-dimensional limb control, profoundly altering the course of theropod locomotor evolution.

Rapid eye and hand responses in an interception task are differentially modulated by context-dependent predictability.

When catching a falling ball or avoiding a collision with traffic, humans can quickly generate eye and limb responses to unpredictable changes in their environment. Mechanisms of limb and oculomotor control when responding to sudden changes in the environment have mostly been investigated independently. Here, we investigated eye-hand coordination in a rapid interception task where human participants used a virtual paddle to intercept a moving target. The target moved vertically down a computer screen and could suddenly jump to the left or right. In high-certainty blocks, the target always jumped; in low-certainty blocks, the target only jumped in a portion of the trials. Further, we manipulated response urgency by varying the time of target jumps, with early jumps requiring less urgent responses and late jumps requiring more urgent responses. Our results highlight differential effects of certainty and urgency on eye-hand coordination. Participants initiated both eye and hand responses earlier for high-certainty compared with low-certainty blocks. Hand reaction times decreased and response vigor increased with increasing urgency levels. However, eye reaction times were lowest for medium-urgency levels and eye vigor was unaffected by urgency. Across all trials, we found a weak positive correlation between eye and hand responses. Taken together, these results suggest that the limb and oculomotor systems use similar early sensorimotor processing; however, rapid responses are modulated differentially to attain system-specific sensorimotor goals.

Decoding multi-limb movements from two-photon calcium imaging of neuronal activity using deep learning

Objective.Brain-machine interfaces (BMIs) aim to restore sensorimotor function to individuals suffering from neural injury and disease. A critical step in implementing a BMI is to decode movement intention from recorded neural activity patterns in sensorimotor areas. Optical imaging, including two-photon (2p) calcium imaging, is an attractive approach for recording large-scale neural activity with high spatial resolution using a minimally-invasive technique. However, relating slow two-photon calcium imaging data to fast behaviors is challenging due to the relatively low optical imaging sampling rates. Nevertheless, neural activity recorded with 2p calcium imaging has been used to decode information about stereotyped single-limb movements and to control BMIs. Here, we expand upon prior work by applying deep learning to decode multi-limb movements of running mice from 2p calcium imaging data.Approach.We developed a recurrent encoder-decoder network (LSTM-encdec) in which the output is longer than the input.Main results.LSTM-encdec could accurately decode information about all four limbs (contralateral and ipsilateral front and hind limbs) from calcium imaging data recorded in a single cortical hemisphere.Significance.Our approach provides interpretability measures to validate decoding accuracy and expands the utility of BMIs by establishing the groundwork for control of multiple limbs. Our work contributes to the advancement of neural decoding techniques and the development of next-generation optical BMIs.

Effect of a Sensorimotor Training Program for Aerial Maneuvers in Junior Surfers

The purpose of this study was to examine the impact of a sensorimotor training program on maximum ankle dorsiflexion (ankle DF), coordination, dynamic balance and postural control, and lower-limb muscle power, in competitive junior surfers, and its relation to parameters of sensorimotor control required to perform aerial maneuvers. Twelve junior competitive surfers followed a 7-week sensorimotor training program, being assessed pre- and post-program with the knee-to-wall test (KW), Y-Balance test—lower quarter (YBT-LQ), and the countermovement jump test (CMJ). Post-training assessment revealed positive effects on the KW (ankle DF) distance, which increased approximately 2 cm (p < 0.001) for both ankles, and all scores for the YTB-LQ (coordination, dynamic balance, and postural control) variables increased, being significant (p < 0.005) for some reach distances (YBT-LQ—Anterior Left, YBT-LQ—Postero-medial Left, and YTB-LQ Anterior Right). YBT-LQ Anterior Reach Asymmetry also improved by decreasing 1.62 cm (p < 0.001) and the CMJ height (lower limb muscle power) increased 2.89 cm (p < 0.001). The training program proved to effectively enhance parameters of physical performance for this sample, including ankle DF, coordination, dynamic balance, postural control, and lower limb muscle power. This tailored-made task approach can help to optimize surfing performance capabilities and contribute to reducing the risk of injuries while performing aerials.

Intrathecal enalapril reduces adhesion formation in experimentally induced digital flexor tendon sheath injuries in horses.

The objectives of the study were to describe a standing percutaneous adhesion induction model in the digital flexor tendon sheath (DFTS) of horses and to evaluate the effect of intrathecal administration of the angiotensin-converting enzyme (ACE) inhibitor enalapril on tendon healing and adhesion formation. Randomized, blinded, controlled experimental study. Eight healthy horses. A collagenase-induced adhesion model was implemented in the deep digital flexor tendon (DDFT) of both forelimbs under standing ultrasonographic guidance. Daily intrathecal injections of 5 mg enalapril (the treatment condition) were administered to a randomly assigned forelimb for 5 days, with the contralateral limb receiving an equivalent volume of 0.9% NaCl (the control). Lameness and limb circumference were recorded weekly. Horses were euthanized after 8 weeks and evaluated for gross digital flexor tendon sheath (DFTS) adhesions. Tendons were collected for histopathologic scoring of DDFT healing. Paired data were analyzed using a one-sided alternative sign test and longitudinal regression. Multiple DFTS adhesions were formed in control limbs of all horses. The median number of gross DFTS adhesions in treated limbs was less than in control limbs (p = .0039). The average reduction in limb circumference and lameness scores over time occurred faster in treated versus control limbs (p < .025). There were no differences in DDFT histopathologic scores between groups. The standing percutaneous DFTS adhesion induction model demonstrated that intrathecal enalapril reduced DFTS adhesion formation, lameness scores, and limb circumference over time. Intrathecal enalapril administration may reduce morbidity in horses with naturally occurring tendon injuries.

Lower limb biomechanics and control of center of mass during turning phases in daily gait

This study aims to elucidate the biomechanical characteristics of turning in daily life by analyzing the three-step process of approach, turn, and departure phases. The research involved ten healthy young individuals performing straight walking and 90° turns, categorized into Side-Step (SS) and Cross-Step (CS) turns. Using a 17-camera motion capture system and force plates, the study measured joint angles, moments, and center of mass (COM) variations. The results indicated that turning involves rotational movements of the lower limbs across three phases, with distinct biomechanical roles for each step. From the perspective of COM control, instability increased at the departure foot in SS, while in CS, stability was maintained at both the approach and departure foot.This study emphasized the importance of rotational movements and rotational forces in the lower limb joints during turning. It also revealed that the center of mass is controlled across three steps. These findings highlight the need for a comprehensive analysis of turning and add a new perspective to gait analysis during turning.

Deep Learning and Human-machine Integration in Smart Prosthetic Control: Process and Perspectives

With the rapid development of science and technology and the maturity of deep learning technology, intelligent prosthetic limb control has made significant progress in human-machine integration. While traditional prosthetic technology has seen improvements in form and function, it still faces challenges in user experience and physiological adaptability. Deep learning, with its powerful pattern recognition and decision-making capabilities, offers new possibilities to address these issues. This paper reviews the current status and future development of the application of deep learning in intelligent prosthetic limb control, emphasizing its close relationship with the concept of human-machine integration. Intelligent prosthetic control involves not only mechanical engineering and bioengineering, but also interdisciplinary integration of the fields of neural engineering, electrical engineering, motion control and computer science. This paper reviews the limitations in traditional prosthetic technology, such as accuracy and user adaptability, introduces the successful cases and latest research results of deep learning in the medical field, and explores the potential of deep reinforcement learning in optimizing complex movements and adapting to different environments. Finally, the future direction of deep learning technology in smart prosthetic limb control is envisioned, and research challenges and recommendations are presented in the hope of providing theoretical support for the innovative development of smart prosthetic limb technology and improving the quality of life of people with disabilities.

Transforming Stroke Recovery: The Bobath Concept in a Case Study of Middle Cerebral Artery Infarction

Stroke remains a major cause of long-term disability, necessitating effective rehabilitation strategies. This case study examines the rehabilitation of a 57-year-old male patient recovering from a middle cerebral artery (MCA) infarction, utilising the Model of Bobath Clinical Practice (MBCP). The patient underwent interventions based on the Bobath concept, focusing on selective activation of trunk muscles, core engagement, and pelvic alignment to enhance postural control. Assessments revealed significant improvements in both sitting and standing postures, with reductions in compensatory fixation strategies. The targeted therapeutic exercises facilitated better trunk control and lower limb weight-bearing, resulting in overall enhanced stability. The findings underscore the importance of individualised approaches in stroke rehabilitation aligned with Bobath principles. While the outcomes are promising, further research is needed to confirm the effectiveness of the MBCP model across varied patient populations. This study highlights the potential of the Bobath Concept in improving functional recovery and quality of life for stroke survivors.

A novel biomechanical model of the mouse forelimb predicts muscle activity in optimal control simulations of reaching movements.

Mice are key model organisms in neuroscience and motor systems physiology. Fine motor control tasks performed by mice have become widely used in assaying neural and biophysical motor system mechanisms. Although fine motor tasks provide useful insights into behaviors which require complex multi-joint motor control, there is no previously developed physiological biomechanical model of the adult mouse forelimb available for estimating kinematics nor muscle activity or kinetics during behaviors. Here, we developed a musculoskeletal model based on high-resolution imaging of the mouse forelimb that includes muscles spanning the neck, trunk, shoulder, and limbs. Physics-based optimal control simulations of the forelimb model were used to estimate in vivo muscle activity present when constrained to the tracked kinematics during reaching movements. The activity of a subset of muscles was recorded and used to assess the accuracy of the muscle patterning in simulation. We found that the synthesized muscle patterning in the forelimb model had a strong resemblance to empirical muscle patterning, suggesting that our model has utility in providing a realistic set of estimated muscle excitations over time when given a kinematic template. The strength of the similarity between empirical muscle activity and optimal control predictions increases as mice performance improves throughout learning of the reaching task. Our computational tools are available as open-source in the OpenSim physics and modeling platform. Our model can enhance research into limb control across broad research topics and can inform analyses of motor learning, muscle synergies, neural patterning, and behavioral research that would otherwise be inaccessible.

Underpowered studies in muscle metabolism research: Determinants and considerations

Biomedical research frequently employs null hypothesis testing to determine whether an observed difference in a sample is likely to exist in the broader population. Null hypothesis testing generally assumes that differences between groups or interventions are non-existent, unless proven otherwise. Because biomedical studies with human subjects are often limited by financial and logistical resources, they tend to have low statistical power, i.e. a low probability of statistically confirming a true difference. As a result, small but potentially clinically important differences may be overseen or ignored simply due to the absence of a statistically significant difference. This absence is often misinterpreted as ‘equivalence’ of treatments. In this educational paper, we will use practical examples related to the effects of exercise and nutrition on muscle protein metabolism to illustrate the most important determinants of statistical power, as well as their implications for both investigators and readers of scientific articles.Changes in muscle mass occur at a relatively slow rate, making it practically challenging to detect differences between treatment groups in a long-term setting. One way to make it ‘easier’ to differentiate between groups and hence increase statistical power is to have a sufficiently long study duration to allow treatment effects to become apparent. This is especially relevant when comparing treatments with relatively small expected differences such as the effect of modest changes in daily protein intake. Secondly, one could try to minimize the variance and response heterogeneity within groups, for example by using strict inclusion criteria and standardization protocols (e.g., meal provision), by using cross-over designs, or even within-subject designs where two interventions are compared simultaneously (e.g., studying an exercised limb vs a contralateral control limb) although this might limit the generalizability of the findings (e.g. such single-limb exercise training is not common in practice). In terms of data interpretation, investigators should obviously refrain from drawing strong conclusions from underpowered studies. Yet, such studies still provide valuable data for meta-analyses. Finally, because muscle protein synthesis rates are highly responsive to anabolic stimuli, acute metabolic studies are more sensitive to detect potentially clinically relevant differences in the anabolic response between treatments. Apart from further elaborating on these topics, this educational article encourages readers to more critically question null findings and scientists to more clearly discuss limitations that may have compromised statistical power.

EFFECTS OF LOCAL HYPOTHERMIA ON LIMB VIABILITY IN A SWINE MODEL OF ACUTE LIMB ISCHEMIA DURING PROLONGED DAMAGE-CONTROL RESUSCITATION.

Background : New strategies are needed to mitigate further tissue injury during traumatic limb ischemia in cases requiring damage control resuscitation (DCR). Little is known about the pathophysiology and injury course in acute limb ischemia (ALI) with DCR in polytraumatized casualties. We therefore investigated the effects of therapeutic limb hypothermia in a swine model of ALI and DCR. Methods : Fifteen swine underwent a published 6-h DCR protocol of hemorrhage and then resuscitation. After hemorrhage, animals were randomized to 5°C or 15°C cooling of one hindlimb; the contralateral limb serving as an uncooled control. Physiologic variables, limb temperature, and limb tissue metabolites (glucose, lactate, and pyruvate) were measured throughout the DCR protocol. Muscle and nerve biopsies were obtained after the 6-h protocol. Results : Lactate and pyruvate levels were significantly lower in the cooled limbs than in the uncooled control limbs but did not differ between the 5°C and 15°C groups. Tissue glucose levels did not differ between the 5°C group, the 15°C group, and controls. Mean histologic muscle score was significantly higher in the 5°C group than in controls ( P = 0.03). Mean nerve histology scores did not differ between the 5°C and paired control limbs, or between the mean muscle and nerve histology scores of the 15°C and paired control limbs. Conclusion : Cooling to 15°C significantly reduced local tissue metabolites compared to paired controls, while producing no significant increase in histologic damage, whereas cooling to 5°C increased histologic muscle damage. These results suggest an approach to prevention of ischemic injury through local hypothermia but warrant further functional testing.

High-Definition Trans-Spinal Current Stimulation Improves Balance and Somatosensory Control: A Randomised, Placebo-Controlled Trial.

To investigate and compare the effects of three different high-definition (HD) non-invasive current stimulation (NICS) protocols on the spinal cord on support balance and somatosensory abilities in healthy young people. Fifty-eight students were enrolled in this crossover study. All participants underwent application of (i) 1.5 mA anodal high-definition trans spinal direct current stimulation (HD-tsDCS), (ii) 1.5 mA cathodal HD-tsDCS, (iii) 1.5 mA high-definition trans spinal alternating current stimulation (HD-tsACS), and (iv) sham HD-tsDCS/ACS over the eighth thoracic vertebra in a randomised order. Balance (Y Balance test), deep sensitivity (Tuning Fork Test), and superficial sensitivity (Monofilament Test) of the lower limbs were tested immediately before and after each intervention. Balance ability improved significantly following anodal HD-tsDCS and HD-tsACS compared with that following sham HD-tsDCS/ACS. Similarly, deep sensitivity increased significantly with anodal HD-tsDCS and HD-tsACS compared to that with sham HD-tsDCS/ACS and cathodal HD-tsDCS. Furthermore, superficial sensitivity improved significantly following anodal HD-tsDCS compared with that after HD-tsACS and cathodal HD-tsDCS. Our data show that HD-tsNICS effectively modulates the balance and somatosensory control of the lower limbs. Several diseases are associated with illness-induced changes in the spinal network in parallel with sensorimotor disabilities. Non-invasive spinal modulation may be a favourable alternative to conventional brain applications in rehabilitation. Future studies should therefore investigate these promising approaches among cohorts of patients with disabilities.

Hop to It! A Systematic Review and Longitudinal Meta-analysis of Hop Performance After ACL Reconstruction.

Hop testing is widely used by clinicians to monitor rehabilitation and decide when to return to sport following anterior cruciate ligament reconstruction (ACLR); however, the trajectory of long-term hop performance has not been summarised. To investigate hop performance change over time after ACLR. Systematic review with longitudinal meta-analysis. MEDLINE, EMBASE, CINAHL, Scopus, Cochrane CENTRAL and SPORTDiscus to 28 February 2023. Studies with ≥ 50 participants following primary ACLR, with mean participant age of 18-40years, reporting a quantitative measure of hop performance (e.g. single forward hop distance). Results had to be reported for the ACLR limb and compared with (1) the contralateral limb (within person) and/or (2) an uninjured control limb (between person). We included 136 studies of 23,360 participants. Performance was similar across different hop tests, with steep initial improvements in within-person symmetry, tailing off after 18-24months. ACLR limb hop performance was 5-10% lower compared with the contralateral limb at 1year post-surgery, with largest deficits observed for vertical hop [87.0% contralateral limb (95% CI 85.3-88.8) compared with single forward hop 93.8% (95% CI 92.8-94.9)]. By 3-5years, results were similar between ACLR and contralateral limbs. There were limited data for between-person comparisons (n = 17 studies). Exploratory analyses showed deficits in all forward hopping tests to be very strongly correlated with each other [e.g. single forward and triple hop rho = 0.96 (95% CI 0.90-0.99)], though there was discordance in the relationship between single forward hop and vertical hop performance [rho = 0.27 (95% CI - 0.53 to 0.79)]. Hop performance is comparable to the uninjured limb by 3-5years post-ACLR, with the greatest deficits in within-person symmetry present in vertical and side hop tests. Assessment of hopping in multiple planes and comparison with uninjured controls, may provide the most complete evaluation of functional performance.

Reducing phantom limb pain using phantom motor execution enabled by augmented and virtual reality: participants’ perspectives on an innovative treatment

Purpose Phantom limb pain (PLP) is a condition that greatly diminishes quality of life. Phantom motor execution (PME), enabled by myoelectric pattern recognition combined with virtual and augmented reality, is a novel treatment for PLP. Here we, aimed to describe patients’ experiences of this treatment. Material and Methods Qualitative, using semi-structured interviews one month after completed PME treatment. Twenty-one Swedish and Dutch patients (mean age 57, 16 males, 16 lower limb amputations) participated. The analysis followed the framework approach. Results The main themes were 1) treatment effects on the perception of the phantom limb, 2) living with PLP before and after treatment, and 3) facilitators and barriers to treatment. Most participants learned to control their phantom limb, perceived it more positively and as more complete. This control over the phantom limb became a tool for managing PLP. Most participants’ outlook on life and energy levels improved after treatment. Being mentally focused during treatment was important. Therapists were pivotal to the success of the treatment. Conclusion Controlling the phantom limb improved their perception of it and pain management, self-agency, and quality of life. The therapists’ role was invaluable. We suggest training for patients in phantom limb control before and after amputation.

Kinematic-Muscular Synergies Describe Human Locomotion with a Set of Functional Synergies.

Kinematics, kinetics and biomechanics of human gait are widely investigated fields of research. The biomechanics of locomotion have been described as characterizing muscle activations and synergistic control, i.e., spatial and temporal patterns of coordinated muscle groups and joints. Both kinematic synergies and muscle synergies have been extracted from locomotion data, showing that in healthy people four-five synergies underlie human locomotion; such synergies are, in general, robust across subjects and might be altered by pathological gait, depending on the severity of the impairment. In this work, for the first time, we apply the mixed matrix factorization algorithm to the locomotion data of 15 healthy participants to extract hybrid kinematic-muscle synergies and show that they allow us to directly link task space variables (i.e., kinematics) to the neural structure of muscle synergies. We show that kinematic-muscle synergies can describe the biomechanics of motion to a better extent than muscle synergies or kinematic synergies alone. Moreover, this study shows that at a functional level, modular control of the lower limb during locomotion is based on an increased number of functional synergies with respect to standard muscle synergies and accounts for different biomechanical roles that each synergy may have within the movement. Kinematic-muscular synergies may have impact in future work for a deeper understanding of modular control and neuro-motor recovery in the medical and rehabilitation fields, as they associate neural and task space variables in the same factorization. Applications include the evaluation of post-stroke, Parkinson's disease and cerebral palsy patients, and for the design and development of robotic devices and exoskeletons during walking.

Tale of quadriceps and hamstring muscle strength after ACL reconstruction: a systematic review with longitudinal and multivariate meta-analysis

ObjectiveThis study aimed to investigate how knee extensor and flexor strength change over time after anterior cruciate ligament reconstruction (ACLR).DesignSystematic review with longitudinal meta-analysis.Data sourcesMedline, Embase, CINAHL, Scopus, Cochrane CENTRAL...

Porcine blast injury model achieves prolonged elevation of intra-compartmental pressures without exogenous pressure manipulation

BackgroundMost existing animal models of acute compartment syndrome (ACS) rely on exogenous manipulation of intra-compartmental pressures to model ACS. The purpose of the current study was to evaluate the endogenous effect of a blast injury on porcine lower leg intra-compartmental pressures (ICP).MethodsThe hindlimb of juvenile Landrace pigs was fractured at the diaphyseal tibia and subjected to blasts of compressed air to mimic a blast injury. Injured and control legs underwent pre-operative continuous ICP monitoring. At 4.5 h post injury, the fracture was stabilized followed by closure of the anterior compartment fascia (continued compartment pressure model, CCPM) or four compartment fasciotomy. Pressure measurements were made after operative fixation. Select pigs in CCPM were harvested between 48 and 72 h post-injury to evaluate the duration of ICP elevation.ResultsPost-injury, the model created significantly elevated ICP compared to control limbs (54.5 ± 18.2 vs. 18.2 ± 4.9 mmHg; p < 0.001). Operative fixation and anterior compartment fascial closure further increased the ICP (Mean: 87.4 ± 42.5 mmHg) relative to the pre-operative state (p = 0.037). Fasciotomy returned baseline compartment pressures (Mean: 13.7 ± 10.2 mmHg) which were equivalent to control limbs (p = 0.117). Pressure measurements at the time of delayed harvest (48–72 h) demonstrated that elevated ICP persisted following injury (69.7 ± 55.12 mmHg).ConclusionThe current study demonstrates that a pilot porcine blast model elevates ICP comparable to existing animal models of compartment syndrome without exogenous ICP manipulation. ICP remained elevated at 48–72 h in the absence of fasciotomy.

Sensorimotor adaptation to a nonuniform formant perturbation generalizes to untrained vowels.

When speakers learn to change the way they produce a speech sound, how much does that learning generalize to other speech sounds? Past studies of speech sensorimotor learning have typically tested the generalization of a single transformation learned in a single context. Here, we investigate the ability of the speech motor system to generalize learning when multiple opposing sensorimotor transformations are learned in separate regions of the vowel space. We find that speakers adapt to a nonuniform "centralization" perturbation, learning to produce vowels with greater acoustic contrast, and that this adaptation generalizes to untrained vowels, which pattern like neighboring trained vowels and show increased contrast of a similar magnitude.NEW & NOTEWORTHY We show that sensorimotor adaptation of vowels at the edges of the articulatory working space generalizes to intermediate vowels through local transfer of learning from adjacent vowels. These results extend findings on the locality of sensorimotor learning from upper limb control to speech, a complex task with an opaque and nonlinear transformation between motor actions and sensory consequences. Our results also suggest that our paradigm has potential to drive behaviorally relevant changes that improve communication effectiveness.