Muscle Contracture Research Articles

Congenital Torticollis : Surgical Approach and Outcome

Introduction. Torticollis, also known as crooked neck, is a contraction or contracture of the neck muscles that causes the head to tilt to one side. This is accompanied by rotation of the chin to the opposite side with flexion. The congenital form of torticollis usually appears within a few weeks of birth. The basis of diagnosis is clinical examination findings, and the mainstay of treatment is physical therapy. Surgical management is an option only when medical and physical treatments are not producing the desired results or for cosmetic reasons. Case Report. A-11 year young girl came with a chief complaints of a tilted head to the right, she also had difficulty shaking her head and nodding and had an asymmetrical face. This has been experienced since birth. Result. The patient underwent bipolar removal of the lower end of the sternocleidomastoideus muscle (SCM). The patient’s neck was extended with a sandbag, and then the patient’s head was turned toward the shoulder on the opposite, uninvolved side. First, the distal portion of the SCM was released by making a skin incision 3 to 5 cm long on the medial end of the clavicle, with consideration given to palpable fibrous bands, and then deepening the incision to the tendons of the sternal and clavicular attachments of the SCM. The tight band and muscle tendon were dissected to pass a right angle instrument posterior to the tendons and were then resected by electrocautery near the insertion site to the clavicle. The SCM was then carefully dissected and released near the bone, while checking the nearby nerves and vessels. Outcomes were assessed using the cervicalmandibular angle (CMA), calculated using the radiological head tilt, which was defined as the angle between the line crossing the upper border of the C7 vertebral body and another line connecting the lower border of the mandibular angle. Conclusion. Release of the bipolar CMT in the patient in this study increased head tilt, leading to a better quality of life since surgery, and the patient adapted fairly well to her new neck position.

Traumatology and functional recovery of the shoulder specific to the game of Volleyball

Abstract: Worldwide, the game of volleyball is a very popular sport regardless of the demographic categories analyzed. In recent years, the dynamics of the game of volleyball is continuously increasing, notable increases being observed among the female gender. Shoulder injuries are common among athletes, for example in baseball, 12% to 19% of injuries encountered are located in the shoulder, while in swimming, the percentage of shoulder injuries is estimated to be between 23% and 38%. The research is based on the case study carried out on a 28-year-old male subject, with 15 years of sports experience, a volleyball player, with a previous history of shoulder joint through the presence of bicipital tendinitis, contractures in the trapezius muscle, as well as in the the sternocleidomastoid muscle. The analysis of the dynamics of the evolution of the subject included in the research and the interpretation of the results led to the confirmation of the hypothesis, so that, reaching all the well-established recovery objectives, we can conclude that the symptomatology, in our case, rotator cuff muscle injury, can be combated by using kinetotherapeutic methods , which demonstrated the highest level of success achieved, when the subject can be taken even from the immobilization stage. Also, a much faster progress was observed from the point of view of socio-professional reintegration. Keywords: Volleyball, Shoulder, Recovery.

Rat Model of Quadriceps Contracture by Joint Immobilization.

Muscle contracture is an abnormal pathologic process resulting in fibrosis and muscle atrophy, which can lead to limitation of joint motion. To establish a diagnostic method to detect muscle contracture and a method to control its progression, we investigated an appropriate method to create an animal model of quadriceps contracture using rats. Eighteen Wistar rats were divided into three groups, and bilateral hindlimbs were immobilized with either a cast (Group I), a Velcro hook-and-loop fastener (Group V), or steel wire (Group S) with the knee and ankle joints in extension position for two weeks. Five rats in a control group (Group C) were not immobilized. After two weeks, the progression of quadriceps contracture was assessed by measuring the range of joint motion and pathohistological changes. Muscle atrophy and fibrosis were observed in all immobilization groups. The knee joint range of motion, quadriceps muscle weight, and muscle fiber size decreased only in Group S compared to the other immobilization groups. Stress on rats due to immobilization was less in Group S. These results indicate that Group S is the superior quadriceps contracture model. This model aids research investigating diagnostic and therapeutic methods for muscle contracture in humans and animals.

Vascular malformation in the hand causing adduction contracture of the thumb: a case report

Vascular malformations of the muscle are rare non-proliferative vascular lesions, and few case reports have described intramuscular vascular malformations in the upper extremities. Vascular malformations of the muscle may produce musculoskeletal deformities due to muscle contracture. Symptomatic intramuscular vascular malformations are commonly treated with surgery and interventional management. We report a vascular malformation that could not be completely resected. It caused adduction contracture of the thumb in the hand. Sclerotherapy was performed before surgery, but the contracture did not improve. Thus, we additionally performed adductor tenotomy. There was no evidence of recurrence during 6 months of follow-up.

Factors associated with balance ability in Duchenne and Becker muscular dystrophies

BackgroundProblems such as progressive muscle function loss, postural deteriorations, and contractures seen in patients with Duchenne and Becker muscular dystrophies (D/BMD) may affect children's balance ability, and impaired balance ability may lead to limitations in children's functional level. Research questionWhat factors are associated with balance ability in children with D/BMD? MethodsTwenty participants with D/BMD were included in the study. Participants' ages were asked; height, body weight, and body mass index (BMI) were recorded. Children's functional level was assessed with the Motor Function Measurement-32 (MFM-32), Brooke and Vignos Scales. Muscle strength of hip flexion and extension, knee flexion and extension, and ankle dorsiflexion was measured with a handheld dynamometer. Balance measurements were performed using the Balance Master System. The relationship between balance and continuous independent variables was determined using Spearman's test. ResultsThe mean age of the participants was 8.57 ± 3.27 years. The balance abilities of children with BMD were better than those of children with DMD (p < 0.05). The balance diminished with age (p < 0.05), while there was a positive correlation between balance and weight, height, BMI (p < 0.05). There was a positive correlation between the balance and the MFM-32 total and subsection scores. Muscle strength was positively related to balance (p < 0.05). SignificanceThe results showed the balance ability in children with D/BMD was affected by age, height, weight, BMI, functional level, and muscle strength. Based on the results of this study, balance and strength training should be an integral part of the rehabilitation of children with D/BMD.

Association of the CKM rs8111989 Polymorphism with Injury Epidemiology in Football Players.

The influence of the rs8111989 polymorphism in the muscle-specific creatine kinase gene (CKM) on injury incidence is unknown. The aim was to investigate CKM polymorphism on injury incidence in high-performance football players. A cohort of 109 high-performance players was genotyped by using saliva samples. Injury incidence was similar in players with the GG, GA, and AA genotypes and did not modify incidence during training or match exposure (p=0.583 and p=0.737 respectively). GG players had a higher frequency of slight-severity injuries (60.0 vs. 10.2 vs. 24.2%, p<0.001), while GA players had a higher frequency of severe injuries (16.7 vs. 30.8 vs. 10.0%, p=0.021). GA players also had a higher frequency of muscle tears (34.8 vs. 59.0 vs. 20.0%, p<0.001). Muscle contracture was a more frequent injury in players with the GG genotype (40.0%, p<0.001). G allele carriers had lower frequencies of gradual-onset injuries (4.1 vs. 16.7%, p=0.035) and recurrent injuries (6.1 vs. 16.7%, p=0.003) than AA players. A allele carriers had higher frequency of severe injuries (10.0 vs. 21.9%, p=0.044) than GG players. Genotypes in the CKM rs8111989 polymorphism did not affect injury incidence in high-performance football players. Players with the GA genotype were more prone to severe injuries and muscle tears when compared to GG and AA players.

Sex-specific role of myostatin signaling in neonatal muscle growth, denervation atrophy, and neuromuscular contractures.

Neonatal brachial plexus injury (NBPI) causes disabling and incurable muscle contractures that result from impaired longitudinal growth of denervated muscles. This deficit in muscle growth is driven by increased proteasome-mediated protein degradation, suggesting a dysregulation of muscle proteostasis. The myostatin (MSTN) pathway, a prominent muscle-specific regulator of proteostasis, is a putative signaling mechanism by which neonatal denervation could impair longitudinal muscle growth, and thus a potential target to prevent NBPI-induced contractures. Through a mouse model of NBPI, our present study revealed that pharmacologic inhibition of MSTN signaling induces hypertrophy, restores longitudinal growth, and prevents contractures in denervated muscles of female but not male mice, despite inducing hypertrophy of normally innervated muscles in both sexes. Additionally, the MSTN-dependent impairment of longitudinal muscle growth after NBPI in female mice is associated with perturbation of 20S proteasome activity, but not through alterations in canonical MSTN signaling pathways. These findings reveal a sex dimorphism in the regulation of neonatal longitudinal muscle growth and contractures, thereby providing insights into contracture pathophysiology, identifying a potential muscle-specific therapeutic target for contracture prevention, and underscoring the importance of sex as a biological variable in the pathophysiology of neuromuscular disorders.

Double Fascicular Nerve Transfer to Restore Elbow Flexion Following Neuralgic Amyotrophy: A Case Report

Double fascicular nerve transfer (DFNT) involves transferring fascicles from the median and ulnar nerves to the musculocutaneous nerve to restore elbow flexion. We performed this procedure on a patient who was diagnosed with neuralgic amyotrophy (NA) 2 years previously. We aimed to investigate the short-term outcomes and feasibility of DFNT applied to non-traumatic neuropathy. A 63-year-old, right-handed man presented to us with persistent right elbow flexion weakness 24 months after receiving the diagnosis of NA. On examination, biceps strength was 0/5, and shoulder abduction strength was 3/5. Magnetic resonance neurography demonstrated muscle atrophy in the upper trunk. DFNT was considered to restore elbow flexion. The donor and recipient fascicles were then coapted (flexor digitorum superficialis to biceps brachii, flexor carpi ulnaris to brachialis). Postoperatively, paresthesia was reported in the area of ulnar innervation, and the patient complained of hand clumsiness. From postoperative day 10 onward, biceps muscle contracture was identified and on the 14th day, grade 3 elbow flexion strength was observed. We suggest that DFNT may be a safe and effective method to restore elbow flexion in patients with NA.

P.74 Using high-field magnetic resonance spectroscopy to measure muscle glycogen in patients with McArdle disease

Glycogen plays a critical role as an energy source in skeletal muscle. McArdle disease is a recessively inherited disorder in which muscle glycogen breakdown is blocked due to myophosphorylase deficiency. The patients suffer from severe exercise intolerance marked by premature fatigue with muscle contractures and episodic rhabdomyolysis. Additionally, some patients show progressive muscular atrophy when they get older, mainly in lumbar paraspinal muscles but not in thigh or calf muscles. The cause of fat replacement in older McArdle patients is unknown but could relate to a higher glycogen accumulation in their muscles. Utilizing the high sensitivity of 13C magnetic resonance spectroscopy at 7 Tesla field strength, we wanted to quantify muscle glycogen in lumbar, thigh and calf muscles in young McArdle patients as well as healthy controls to test the hypothesis of variable glycogen content in muscles of patients with McArdle disease. Preliminary results from 5 patients and 8 controls, show increased muscle glycogen concentration in the calf (4.4 times normal levels, p = 0.002), hamstrings (2.7 times normal levels, p = 0.02) and anterior thigh compartment (3.2 times normal levels, p = 0.01), while there was no difference in the lumbar muscle glycogen content vs. healthy (p = 0.6). No clear pattern of muscle glycogen distribution was seen in neither the McArdle nor the control groups. Our results are in line with previous studies in that we see a 3-5 times increase in glycogen compared to control. Surprisingly, this is not seen in the lumbar muscle group, which is the muscle group most prone to fat replacement with age. Thus, it does not appear that a difference in glycogen concentration between muscles of McArdle patients can explain the fat replacement seen in specific muscles groups of older patients.

TARGETED ULTRASOUND-GUIDED PERINEURAL HYDRODISSECTION OF THE SCIATIC NERVE AND CORTICOSTEROID INJECTION FOR THE TREATMENT OFPIRIFORMIS SYNDROME

Piriformis syndrome is a common cause of lumbar, gluteal, and thigh pain frequently associated with sciatic nerve symptoms. Etiology depends on individual predisposition or congenital anomalies. The mechanism is sciatic nerve impingement under the tendinous portion of the piriformis muscle due to spasm of the muscle. There is a common pathological end pathway involving hypertrophy, spasm, contracture, inammation, and scarring of the piriformis muscle, leading to impingement of the sciatic nerve. Ultrasound guided piriformis injection is frequently used in the treatment of piriformis syndrome, with most of the published literature describing injection of the muscle. We described a safe, effective ultrasound-guided injection technique for the treatment of piriformis syndrome among patients attending Physical Medicine &amp; Rehabilitation (PMR) outpatient and inpatient departments in SSKM hospital, Kolkata (December 2019-June 2021) not responding to conservative management by using the targeted sciatic perineural hydrodissection followed by therapeutic corticosteroid injection.

P.168 Observational study: The quality of life in patients with alpha-sarcoglycan, beta-sarcoglycan and gamma-sarcoglycan gene mutation

LGMDR3, LGMDR4, LGMDR5 are recessive autosomal diseases, there are no specific treatments, except for some physical therapies that prevent worsening of muscle contractures and therapies associated with cardiac and respiratory problems. In 2013 the volunteer organization named Family Group of Beta-sarcoglycanopathy (GFB ODV; www.lgmd2e.org) was established to stimulate and support basic and clinical research on these diseases. Since 2012, families of the GFB ODV funded a research project of gene therapy for LGMDR4, under the supervision of Prof. J. Mendell, at the Ohio State University (Columbus, Ohio, USA). The first clinical trial, conducted by Sarepta Therapeutics, is currently underway. In 2018 GFB Odv promoted a natural history study on Italian patients "Clinical Determinants of disease progression in patients with beta-sarcoglycan gene mutations", led by Prof. Yvan Torrente, of the University of Milan, Ospedale Maggiore Policlinico in Milan, Italy. Since 2021 GFB Odv has started an ongoing observational study on the quality of life in patients with beta-sarcoglycan, alpha-sarcoglycan, and gamma-sarcoglycan gene mutation, again in collaboration with Prof. Yvan Torrente. The study is aimed at international GFB patients. At this time 139 patients from 45 countries have joined the Project: in particular, 68 with LGMDR4, 32 with LGMDR5, 39 with LGMDR3. 201 questionnaires have already been filled out. The ACTIVLIM, ABILHAND, EK, PEDSQL and PROMIS scales are used in the study, both in paper and electronic format. The study will run for 3 years and the scales will be given to patients every 6 months.

LESÕES NO EXERCÍCIO AERÓBICO: CAUSAS E PREVENÇÃO

ABSTRACT Introduction: Professional aerobic exercises require high performance from exercisers. Injuries are common during their execution. Understanding the causal reasons is essential for prevention methods to reduce athletes’ injuries. Objective: Investigate the influential factors of ligament injuries caused by aerobic exercise. Methods: This paper analyzes the injuries caused by aerobic exercise through mathematical statistics. Time, course, degree of injury, location of the injury, cause, early treatment time, primary approach, treatment methods, recovery conditions, and speed in recovery time of sports injuries were investigated. Results: Injuries are mainly concentrated at the hip, knee, and ankle joint level; sprains are the first injuries, followed by muscle strains, lower back muscle contractures, kneecap deformities, and joint ligament injuries. The leading causes of injuries were poor warm-up, excessive load, technical errors, and fatigue. Conclusion: Various physiotherapy methods can improve the recovery rate from ligament injuries. This method can also improve sports ligament injuries’ prevention and treatment effects. Evidence Level II; Therapeutic Studies - Investigating the result.

Muscle contractile exercise through a belt electrode device prevents myofiber atrophy, muscle contracture, and muscular pain in immobilized rat gastrocnemius muscle.

Immobilization of skeletal muscles causes muscle atrophy, muscle contracture, and muscle pain, the mechanisms of which are related to macrophage accumulation. However, muscle contractile exercise through a belt electrode device may mitigate macrophage accumulation. We hypothesized that such exercise would be effective in preventing myofiber atrophy, muscle contracture, and muscular pain. This study tested this hypothesis in immobilized rat gastrocnemius muscle. A total of 32 rats were divided into the following control and experimental groups: immobilization (immobilized treatment only), low-frequency (LF; immobilized treatment and muscle contractile exercise with a 2 s (do) /6 s (rest) duty cycle), and high-frequency (HF; immobilized treatment and muscle contractile exercise with a 2 s (do)/2 s (rest) duty cycle). Electrical stimulation was performed at 50 Hz and 4.7 mA, and muscle contractile exercise was applied to the lower limb muscles for 15 or 20 min/session (once daily) for 2 weeks (6 times/week). After the behavioral tests, the bilateral gastrocnemius muscles were collected for analysis. The number of macrophages, the Atrogin-1 and MuRF-1 mRNA expression, and the hydroxyproline content in the HF group were lower than those in the immobilization and LF groups. The cross-sectional area (CSA) of type IIb myofibers in the superficial region, the PGC-1α mRNA expression, and the range of motion of dorsiflexion in the HF group were significantly higher than those in the immobilization and LF groups. The pressure pain thresholds in the LF and HF groups were significantly higher than that in the immobilization group, and the nerve growth factor (NGF) content in the LF and HF groups was significantly lower than that in the immobilization group. Muscle contractile exercise through the belt electrode device may be effective in preventing immobilization-induced myofiber atrophy, muscle contracture, and muscular pain in the immobilized rat gastrocnemius muscle.

Stance and swing phase ankle phenotypes in youth with Charcot-Marie-Tooth type 1: An evaluation using comprehensive gait analysis techniques

BackgroundCharcot-Marie-Tooth disease (CMT) results in muscle weakness and contracture leading to a wide variety of gait issues including atypical ankle kinematics in both stance and swing. Knowledge of the stance and swing phase kinematic patterns for CMT type 1 (CMT1), the most common CMT type, will improve our understanding of expected gait outcomes and treatment needs to improve gait function. Research questionWhat are the stance/swing phase ankle phenotypes in CMT1? MethodsA prospective convenience sample of 25 participants with CMT1, ages 7–19 years, underwent comprehensive gait analysis following standard procedures. Ankle phenotypes based on peak ankle dorsiflexion in terminal stance and mid-swing were defined and compared using linear mixed models. ResultsPatients with CMT1 presented with three stance phase ankle phenotypes: 21 limbs (42 %) with reduced (mean 5°, SD 2°), 19 limbs (38 %) with typical (mean 11°, SD 1°) and 10 limbs (20 %) with excessive (mean 15°, SD 2°) peak dorsiflexion in terminal stance (p < 0.05). There were two swing phase phenotypes: 19 limbs (38 %) with typical (mean −1.7°, SD 1.5°) and 31 limbs (62 %) with excessive (mean −5.6°, SD 1.4°) plantarflexion in mid-swing (p < 0.002). Eleven patients (44 %) had ankles that were classified into different stance groups, and 9 patients (36 %) had ankles that were classified into different swing groups. The most common combination of stance/swing ankle phenotypes was decreased dorsiflexion in terminal stance with increased plantarflexion in mid-swing (16 sides, 32 %). SignificanceThis study shows that youth with CMT1 have multiple combinations of combined ankle kinematics for stance and swing. The ankle phenotypes identified in this study reflect contributions of both dorsi/plantarflexor weakness and plantarflexor contracture, which require different treatment approaches. Comprehensive gait analysis can distinguish between multiple ankle phenotypes to assist in determining the most appropriate treatment to improve gait for individual patients.

Acute Effects of Static and Proprioceptive Neuromuscular Facilitation Stretching of the Plantar Flexors on Ankle Range of Motion and Muscle-Tendon Behavior in Children with Spastic Cerebral Palsy-A Randomized Clinical Trial.

Stretching is considered a clinically effective way to prevent muscle contracture development in children with spastic cerebral palsy (CP). Therefore, in this study, we assessed the effects of a single session of proprioceptive neuromuscular facilitation (PNF) or static stretching (SS) on ankle joint range of motion (RoM) and gastrocnemius muscle-tendon behavior in children with CP. During the SS (n = 8), the ankle joint was held in maximum dorsiflexion (30 s). During the PNF stretching (n = 10), an isometric contraction (3–5 s) was performed, followed by stretching (~25 s). Ten stretches were applied in total. We collected data via dynamometry, 3D motion capture, 2D ultrasound, and electromyography, before and after the stretching sessions. A mixed ANOVA was used for the statistical analysis. Both ankle RoM and maximum dorsiflexion increased over time (F(1,16) = 7.261, p < 0.05, η² = 0.312; and F(1,16) = 4.900, p < 0.05, η² = 0.234, respectively), without any difference between groups. An interaction effect (F(1,12) = 4.768, p = 0.05, η² = 0.284) was observed for muscle-tendon unit elongation (PNF: −8.8%; SS: +14.6%). These findings suggest a positive acute effect of stretching on ankle function. However, SS acutely increased muscle-tendon unit elongation, while this decreased after PNF stretching, indicating different effects on the spastic muscles. Whether PNF stretching has the potential to cause positive alterations in individuals with CP should be elucidated in future studies.

Comparative Study of Multimodal Therapy in Facial Palsy Patients.

Introduction In chronic facial palsy, synkinetic muscle overactivity and shortening causes muscle stiffness resulting in reduced movement and functional activity. This article studies the role of multimodal therapy in improving outcomes. Methods Seventy-five facial palsy patients completed facial rehabilitation before being successfully discharged by the facial therapy team. The cohort was divided into four subgroups depending on the time of initial attendance post-onset. The requirement for facial therapy, chemodenervation, or surgery was assessed with East Grinstead Grade of Stiffness (EGGS). Outcomes were measured using the Facial Grading Scale (FGS), Facial Disability Index, House-Brackmann scores, and the Facial Clinimetric Evaluation scale. Results FGS composite scores significantly improved posttherapy (mean-standard deviation, 60.13 ± 23.24 vs. 79.9 ± 13.01; confidence interval, –24.51 to –14.66, p < 0.0001). Analysis of FGS subsets showed that synkinesis also reduced significantly ( p < 0.0001). Increasingly, late clinical presentations were associated with patients requiring longer durations of chemodenervation treatment ( p < 0.01), more chemodenervation episodes ( p < 0.01), increased doses of botulinum toxin ( p < 0.001), and having higher EGGS score ( p < 0.001). Conclusions This study shows that multimodal facial rehabilitation in the management of facial palsy is effective, even in patients with chronically neglected synkinesis. In terms of the latency periods between facial palsy onset and treatment initiation, patients presenting later than 2 years were still responsive to multimodal treatment albeit to a lesser extent, which we postulate is due to increasing muscle contracture within their facial muscles.

Complication of lengthening and the role of post-operative care, physical and psychological rehabilitation among fibula hemimelia.

There is a clear clinical need for efficient physiotherapy and rehabilitation programs during and after bone lengthening and reconstruction for gaining the optimal effect and also prevention or treatment of lengthening side effects. Pin tract infection is the most prevalent side effect during lengthening which could be prevented and treated initially via proper wound care. Muscle contractures are typically a consequence of the generated tension on the distracted muscle. It can be managed by physiotherapy initially and surgically in later severe stages. Furthermore, it is essential to avoid muscle contracture development, which is the demonstration of the imbalanced muscle appeals on the joint to inhibit the following subluxation. The knee is the furthermost affected joint by the aforementioned problem due to the inherent lack of ligamentous and bony stability. Joint stiffness is the other possible unfavorable effect of lengthening. It happens because of extensive muscle contractures or may possibly be attributed to rigidity of the joint following the amplified pressure on the joint surface during the process of lengthening. Physiotherapy and occupational therapy including endurance and strength exercise as well as stretching play an important role during the rehabilitation periods for the prevention and also the treatment of muscle contracture and the following deformity and also joint stiffness. Likewise, the effect of mental and physical rehabilitation programs should not be overlooked.

Brachial plexus birth injury and cerebral palsy lead to a common contracture phenotype characterized by reduced functional muscle length and strength.

IntroductionBrachial plexus birth injury (BPBI) and cerebral palsy (CP) both cause disabling contractures for which no curative treatments exist, largely because contracture pathophysiology is incompletely understood. The distinct neurologic nature of BPBI and CP suggest different potential contracture etiologies, although imbalanced muscle strength and insufficient muscle length have been variably implicated. The current study directly compares the muscle phenotype of elbow flexion contractures in human subjects with BPBI and CP to test the hypothesis that both conditions cause contractures characterized by a deficit in muscle length rather than an excess in muscle strength.MethodsSubjects over 6 years of age with unilateral BPBI or hemiplegic CP, and with elbow flexion contractures greater than 10 degrees on the affected side, underwent bilateral elbow flexion isokinetic strength testing to identify peak torque and impulse, or area under the torque-angle curve. Subjects then underwent needle microendoscopic sarcomere length measurement of bilateral biceps brachii muscles at symmetric joint angles.ResultsIn five subjects with unilateral BPBI and five with hemiplegic CP, peak torque and impulse were significantly lower on the affected versus unaffected sides, with no differences between BPBI and CP subjects in the percent reduction of either strength measurement. In both BPBI and CP, the percent reduction of impulse was significantly greater than that of peak torque, consistent with functionally shorter muscles. Similarly, in both conditions, affected muscles had significantly longer sarcomeres than unaffected muscles at symmetric joint angles, indicating fewer sarcomeres in series, with no differences between BPBI and CP subjects in relative sarcomere overstretch.DiscussionThe current study reveals a common phenotype of muscle contracture in BPBI and CP, with contractures in both conditions characterized by a similar deficit in muscle length rather than an excess in muscle strength. These findings support contracture treatments that lengthen rather than weaken affected muscles. Moreover, the discovery of a common contracture phenotype between CP and BPBI challenges the presumed dichotomy between upper and lower motor neuron lesions in contracture pathogenesis, instead revealing the broader concept of “myobrevopathy”, or disorder of short muscle, warranting increased investigation into the poorly understood mechanisms regulating muscle length.

Rheumatoid arthritis – symptoms, diagnosis, treatment

Rheumatoid arthritis is a systemic autoimmune disease of connective tissue of unknown etiology. Specific for it is the involvement of symmetrically small and medium-sized joints, leading to degradation of their structure, stiffening and muscle contractures. It is also characterized by extra-articular and generalized symptoms, such as fatigue, low-grade fever and sweating. It can occur with or without elevated RF and / or ACPA antibodies, causes disability and contributes to premature death. Drugs for this disease can be categorized into disease-modifying drugs as well as glucocorticosteroids and non-steroidal anti-inflammatory drugs. The first-line drug is methotrexate. In case of ineffectiveness of the treatment, biological treatment can be started.

The Sex-Dependent Role of Myostatin Signaling in Contractures Following Neonatal Brachial Plexus Injury

Purpose: Neonatal brachial plexus injury (NBPI) causes disabling and incurable muscle contractures, arising from impaired longitudinal growth of denervated muscles. This growth impairment is caused by dysregulation of muscle proteostasis characterized by increased proteasome-mediated protein degradation. Myostatin (MSTN), a secreted growth differentiation factor and prominent muscle-specific negative regulator of proteostasis, drives muscle protein degradation. MSTN signaling is thus a possible pathway through which denervation impairs muscle growth and a potential muscle-specific molecular target for preventing contractures. This study uses pharmacologic inhibition of MSTN signaling in a mouse model of NBPI to test the hypothesis that NBPI induces contractures through MSTN-dependent impairment of longitudinal muscle growth. Methods: Unilateral NBPI was generated in postnatal day (P)5 mice. Mice were treated weekly with Dulbecco’s phosphate-buffered saline (DPBS) or ACVR2B-Fc, a soluble inhibitory decoy receptor for MSTN, starting at P4. Mice were sacrificed at P33, whereupon elbow and shoulder range of motion were measured to assess contractures. Brachialis muscles were prepared for microCT assessment of cross-sectional area (CSA) and volume, then processed for sarcomere length measurement as a readout of longitudinal muscle growth. Total protein content in biceps was assessed via Bradford assay. Protein degradation in triceps was quantified via 20S proteasome β1 subunit activity assay. Results: In female mice, myostatin inhibition with ACVR2B-Fc enhanced muscle weight and total protein content of denervated biceps (Figure 1), increased cross-sectional and volumetric growth of denervated brachialis (Figure 2), preserved longitudinal growth in denervated brachialis (Figure 3), and reduced elbow and shoulder contracture severity in the denervated limbs (Figure 4). Analysis of protein dynamics demonstrates the improvements in female denervated muscles were associated with a reduction in proteasome β1 subunit activity (Figure 5). However, no such improvements in denervated muscles occurred in male mice with ACVR2B-Fc. Conversely, myostatin inhibition increased muscle weight, CSA, volume, and total protein content of the normally innervated, contralateral control muscles in both male and female mice (Figures 1 and 2). Conclusion: Our findings reveal MSTN as a driver of impaired muscle growth and contracture formation in female but not male mice. This sex dimorphism lies in the pathophysiology of denervation-induced contractures rather than drug pharmacodynamics, given the sex-independent effects of MSTN inhibition on normally innervated muscle. Future studies must rigorously interrogate the contributions of sex in contracture pathophysiology. Significance: Our discovery identifies MSTN as a signaling target for modulating contractures in females and highlights the overlooked role of sex in the pathophysiology of acquired neuromuscular disorders. Level of Evidence: Not Applicable FDA: The FDA has not cleared the following pharmaceuticals and/or medical devices for the use described in this presentation.