Background Numerous structural and compositional changes – related not only to age, but also activity level and sex – may affect skeletal muscle stiffness across the adult age-span. Measurement techniques available thus far have largely limited passive stiffness evaluations to those of entire joints and muscle-tendon units. Shear wave elastography is an increasingly popular ultrasound technique for evaluating the mechanical properties of skeletal muscle tissue. The purpose of this study was to quantify the passive stiffness, or shear modulus, of the biceps brachii throughout adulthood in flexed and extended elbow positions. We hypothesized that shear modulus would be higher in males relative to females, and with advanced age in both sexes. Methods Shear wave elastography quantified biceps brachii stiffness at 90° elbow flexion and full extension in a large sample of adults between 21–94 years old (n=133; 47 males). Findings Regression analysis found sex and age were significant parameters for older adults (>60 years) in full extension. As expected, shear modulus values increased with advancing age; however, shear modulus values for females tended to be higher than those for males. Interpretation This study begins to establish normative trends for skeletal muscle shear modulus throughout adulthood. Specifically, this work establishes for the first time that the higher passive joint torque often found in males relative to females likely relates to parameters other than muscle shear modulus. Indeed, perhaps increases in skeletal muscle passive stiffness, though potentially altering the length-tension curve, serve a protective role – maintaining the tendon-muscle-tendon length-tension curve within a functional range.

The use of brightness-mode ultrasound and Doppler ultrasound in physical medicine and rehabilitation has increased dramatically. The continuing evolution of ultrasound technology has also produced ultrasound elastography, a cutting-edge technology that can directly measure the mechanical properties of tissue, including muscle stiffness. Its real-time and direct measurements of muscle stiffness can aid the diagnosis and rehabilitation of acute musculoskeletal injuries and chronic myofascial pain. It can also help monitor outcomes of interventions affecting muscle in neuromuscular and musculoskeletal diseases, and it can better inform the functional prognosis. This technology has implications for even broader use of ultrasound in physical medicine and rehabilitation practice, but more knowledge about its uses and limitations is essential to its appropriate clinical implementation. In this review, we describe different ultrasound elastography techniques for studying muscle stiffness, including strain elastography, acoustic radiation force impulse imaging, and shear-wave elastography. We discuss the basic principles of these techniques, including the strengths and limitations of their measurement capabilities. We review the current muscle research, discuss physiatric clinical applications of these techniques, and note directions for future research.

Aim The aim of this study was to compare passive muscle stiffness in children with cerebral palsy (CP) and typically developing (TD) children using a novel ultrasound technique – ultrasound shear wave elastography (SWE). Method We conducted a prospective study of 13 children with CP (6 females and 7 males, ages 68.7 (28.3) months) and 13 TD children (6 females and 7 males, ages 67.3 (35.0)). Demographic information and physical exam measurements were obtained in addition to shear modulus measurements (passive muscle stiffness) of the lateral gastrocnemius muscle at 20° plantar flexion (PF), 10° PF, and 0° PF using SWE. Results Children with CP had significantly greater shear modulus measurements at all three foot positions (P<0.05). When the shear modulus values were normalized to the baseline value for each child, there was no significant difference between the two groups. Interpretation Passive muscle stiffness, measured without the influence of spasticity, is greater in children with CP as compared to TD children when a muscle is at slack and at stretch. When shear modulus was normalized, the results indicate that muscle in children in both groups respond similarly to passive stretch. Further work includes evaluating effect of botulinum toxin on passive muscle properties.

Chronic pain in children and adolescents can be difficult for a single provider to manage in a busy clinical setting. Part of this difficulty is that pediatric chronic pain not only impacts the child but also the families of these children. In this review article, we discuss etiology and pathophysiology of chronic pain, along with variables that impact the severity of chronic pain and functional loss. We review diagnosis and management of selected chronic pain conditions in pediatric patients, including headache, low back pain, hypermobility, chronic fatigue, postural orthostatic tachycardia syndrome, abdominal pain, fibromyalgia, and complex regional pain syndrome. For each condition, we create a road map that contains therapy prescriptions, exercise recommendations, and variables that may influence pain severity. Potential medications for these pain conditions and associated symptoms are reviewed. A multidisciplinary approach for managing children with these conditions, including pediatric pain rehabilitation programs, is emphasized. Lastly, we discuss psychological factors and interventions for pediatric chronic pain and potential complementary and alternative natural products and interventions.

The COVID-19 pandemic has accelerated many changes in medicine including the transition from providing care in person to providing care via technology enabled telemedicine. The benefits of telemedicine visits with a Pediatric Rehabilitation Medicine (PRM) provider, also known as telerehabilitation medicine visits, are numerous. Telerehabilitation medicine provides an opportunity to deliver timely, patient and family-centric rehabilitation care while maintaining physical distance and reducing potential COVID-19 exposure for our patients, their caregivers and medical providers. Telerehabilitation medicine also allows for access to PRM care in rural areas or areas without medical specialty, virtual in-home equipment evaluation, and reduced travel burden. Because of these and many other benefits, telerehabilitation medicine will likely become part of our ongoing model of care if barriers to telemedicine continue to be lowered or removed. This paper is intended to establish a foundation for pediatric telerehabilitation medicine visit efficiency and effectiveness in our current environment and into the future.

This is the first comprehensive Common Data Elements (CDEs) for children and young people with CP for clinical research. The CDEs for children and young people with CP include common definitions, the standardization of case report forms, and measures. The CDE guides the standardization for data collection and outcome evaluation in all types of studies with children and young people with CP. The CDE ultimately improves data quality and data sharing.

Objective To investigate the feasibility and reliability of passive muscle stiffness measurements in children through use of shear wave ultrasound elastography. Methods This is a prospective cross -sectional study quantifying the passive stiffness of bilateral lateral gastrocnemii muscles during passive stretch in twenty typically developing children (age range, 2.0–12.6 years). Data collected included passive stiffness of the lateral gastrocnemius muscle (shear modulus in kilopascal [kPa]) at four positions of progressive passive foot dorsiflexion; demographic characteristics of the child participants; and comparison of demographic characteristics with the shear modulus. Results Passive stiffness increased with increasing stretch (mean [SD] range of stretch, 7.1 [2.0]–36.2 [22.0] kPa). For all four foot positions, no significant difference was found between right and left legs (range P=0.42 to P=0.98) or between the sexes (range P=0.28 to P> 0.99). No correlation of passive muscle stiffness to age, body mass index, or ankle range of motion was found. Reliability of measurements was good to excellent (mean [95% CI] range of reliability 0.67 [0.44–0.83] to 0.80 [0.63–0.90]). Conclusions Measurements of passive stiffness of the lateral gastrocnemius muscle are feasible and reliable in children as young as 2 years. Because the present study found no significant difference between sex and the side tested in this age-group, future studies involving children of this age range may not need to be stratified on the basis of these parameters. Defining normal passive muscle stiffness in children is critical for identifying and understanding the implications of abnormal passive muscle stiffness in children with neuromuscular disorders.

Spastic cerebral palsy (CP), despite the name, is not consistently identifiable by specific brain lesions. CP animal models focus on risk factors for development of CP, yet few reproduce the diagnostic symptoms. Animal models of CP must advance beyond risk factors to etiologies, including both the brain and spinal cord.