Sonographic Assessment of Asymptomatic Patellar and Achilles Tendons to Predict Future Pain: A Systematic Review and Meta-analysis.

OBJECTIVE: Patients with clinical tendinopathy often demonstrate significant abnormalities with ultrasound (US) imaging. Tendon abnormalities likely precede pain in these patients. The purpose of this review was to systematically evaluate the available literature regarding the utility of US imaging as a method to predict Achilles and patellar tendon pain. DESIGN: Systematic review and meta-analysis. Inclusion criteria were as follows: prospective studies of Achilles and patellar tendon pain development with baseline US measurements, follow-up clinical measurements, and English-language studies published after 2000. Exclusion criteria were prior rupture or surgery and presence of rheumatologic disorder. SETTING: N/A. PATIENTS: Athletes without Achilles or patellar tendon pain at baseline. INTERVENTIONS: N/A. MAIN OUTCOME MEASURES: Risk ratios (RRs) were identified for the development of pain in those with Achilles or patellar tendon sonographic abnormalities. RESULTS: This review of 16 studies included 810 Achilles and 1156 patellar tendons from a variety of sports and demonstrated that the RR for pain development from abnormal Patellar and Achilles tendons was 6.07 [95% confidence interval (CI), 2.88-12.81; P < 0.001] and 3.96 [95% CI, 2.21-7.09; P < 0.001], respectively. The positive and negative predictive values of an abnormal US finding were 27.2% and 92.0% for the Achilles tendon and 27.2% and 93.5% for the patellar tendon, respectively. CONCLUSIONS: This systematic review and meta-analysis identified that the use of asymptomatic US scanning of the Achilles or patellar tendon has a low positive predictive value but a high negative predictive value for the future development of pain.

Sonographic peripheral nerve cross-sectional area in adults, excluding median and ulnar nerves: A systematic review and meta-analysis.

INTRODUCTION/AIMS: Although electromyography remains the "gold standard" for assessing and diagnosing peripheral nerve disorders, ultrasound has emerged as a useful adjunct, providing valuable anatomic information. The objective of this study was to conduct a systematic review and meta-analysis evaluating the normative sonographic values for adult peripheral nerve cross-sectional area (CSA). METHODS: Medline and Cochrane Library databases were systematically searched for healthy adult peripheral nerve CSA, excluding the median and ulnar nerves. Data were meta-analyzed, using a random-effects model, to calculate the mean nerve CSA and its 95% confidence interval (CI) for each nerve at a specific anatomical location (= group). RESULTS: Thirty groups were identified and meta-analyzed, which comprised 16 from the upper extremity and 15 from the lower extremity. The tibial nerve (n = 2916 nerves) was reported most commonly, followed by the common fibular nerve (n = 2580 nerves) and the radial nerve (n = 2326 nerves). Means and 95% confidence interval (CIs) of nerve CSA for the largest number of combined nerves were: radial nerve assessed at the spiral groove (n = 1810; mean, 5.14 mm2 ; 95% CI, 4.33 to 5.96); common fibular nerve assessed at the fibular head (n = 1460; mean, 10.18 mm2 ; 95% CI, 8.91 to 11.45); and common fibular nerve assessed at the popliteal fossa (n = 1120; mean, 12.90 mm2 ; 95% CI, 9.12 to 16.68). Publication bias was suspected, but its influence on the results was minimal. DISCUSSION: Two hundred thirty mean CSAs from 15 857 adult nerves are included in the meta-analysis. These are further categorized into 30 groups, based on anatomical location, providing a comprehensive reference for the clinician and researcher investigating adult peripheral nerve anatomy.

Prevalence of Sonographic Achilles Tendon, Patellar Tendon, and Plantar Fascia Abnormalities in Division I Collegiate Athletes From a Variety of Sports.

OBJECTIVE: This study aimed to determine the prevalence of ultrasound abnormalities in the Achilles tendon, patellar tendon, and plantar fascia among a large cohort of collegiate student-athletes. DESIGN: Observational cross-sectional study. SETTING: Three Division I institutions. PARTICIPANTS: 243 student-athletes participated in this study. Exclusion criteria included those younger than 18 years or who underwent prior surgery/amputation of structures, including anterior cruciate ligament (ACL) surgeries with patellar tendon grafts. INTERVENTIONS: Ultrasound examination of the Achilles tendon, patellar tendon, and plantar fascia of each leg was performed. An experienced sonographer reviewed each tendon video in a blinded manner, with a separate experienced sonographer separately reviewing to establish inter-rater reliability. MAIN OUTCOME MEASURES: The primary outcome measured was the presence of any sonographic abnormality including hypoechogenicity, thickening, or neovascularity. RESULTS: Ultrasound abnormalities were identified in 10.1%, 37.2%, and 3.9% of all Achilles tendons, patellar tendons, and plantar fasciae, respectively. Abnormalities were significantly associated with the presence of concurrent pain for all structures (P < 0.01). Specifically, athletes with sonographic abnormalities were approximately 4 times [relative risk (RR) = 4.25; 95% confidence interval (CI), 2.05-8.84], 6 times (RR = 5.69; 95% CI, 2.31-14.00), and 5 times (RR = 5.17; 95% CI, 1.76-15.25) more likely to self-report pain in the Achilles tendon, patellar tendon, and plantar fascia, respectively. CONCLUSIONS: This multi-institutional study completed at 3 Division I institutions is the largest study of its kind to identify the prevalence of sonographic abnormalities in the Achilles tendon, patellar tendon, and plantar fascia among collegiate student-athletes of various sports.

Sonographic Screening of Distance Runners for the Development of Future Achilles and Patellar Tendon Pain.

OBJECTIVE: The 2 primary aims of this study were to identify ultrasonographic tendon abnormalities in asymptomatic runners and to examine the likelihood of developing pain in runners with ultrasound abnormalities compared with those without abnormalities. DESIGN: Longitudinal, prospective cohort study. SETTING: 2019 Salt Lake City Marathon. PARTICIPANTS: Recreational half-marathon and full-marathon runners. ASSESSMENT OF RISK FACTORS: The Achilles and patellar tendons of asymptomatic runners were examined with ultrasound imaging before a running event. Runners were monitored for self-reported outcomes of pain in the examined tendons at 1, 3, 6, and 12 months after the event. MAIN OUTCOME MEASURES: Development of pain based on the presence of asymptomatic tendon abnormalities. RESULTS: One hundred thirty-eight runners (36.2 ± 12.0 years, 49.3% men, and 31.2% full-marathon runners) were included. Ultrasound abnormalities of the Achilles and patellar tendons were identified in 24.6% and 39.1% of the runners before the race, respectively. Ultrasound abnormalities were significantly associated with approximately a 3-fold increase [hazard ratio (HR) = 2.55, P = 0.004] in the hazard of developing pain in the Achilles tendon and patellar tendon (HR = 1.67, P = 0.042) over the year after the race. Positive and negative predictive values of developing pain over the year were 34.1% and 87.2%, respectively, for abnormal findings in the Achilles tendon, and 22.9% and 85.0%, respectively, for the patellar tendon. CONCLUSIONS: The presence of ultrasonographic abnormalities is associated with increased development of pain in the Achilles and patellar tendons within 1 year of a marathon or half marathon.

Quantifying passive muscle stiffness in children with and without cerebral palsy using ultrasound shear wave elastography.

AIM: The aim of this study was to compare passive muscle stiffness in children with cerebral palsy (CP) and children with typical development using a novel ultrasound technique: ultrasound shear wave elastography (SWE). METHOD: We conducted a prospective study of 13 children with CP (six females and seven males, median age 5y 1mo [interquartile range 4y 4mo-7y 8mo]) and 13 children with typical development (six females and seven males, median age 5y 3mo [interquartile range 4y 4mo-9y 4mo]). 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, 10° plantar flexion, and 0° plantar flexion using SWE. RESULTS: Children with CP had significantly greater shear modulus measurements at all three foot positions (p<0.050). 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 than in children with typical development when a muscle is at slack and at stretch. When shear modulus was normalized, the results indicate that muscle in children in both groups responds similarly to passive stretch. Further work includes evaluating effect of botulinum toxin on passive muscle properties.

Feasibility and reliability of quantifying passive muscle stiffness in young children by using shear wave ultrasound elastography.

OBJECTIVES: The purpose of this study was to investigate the feasibility and reliability of passive muscle stiffness measurements in children by shear wave ultrasound elastography. METHODS: We conducted a prospective cross-sectional study quantifying the passive stiffness of bilateral lateral gastrocnemius muscles during passive stretching in 20 typically developing children (age range, 2.0-12.6 years). Data collected included passive stiffness of the lateral gastrocnemius muscle (shear modulus in kilopascals) at 4 positions of progressive passive foot dorsiflexion, demographic characteristics of the participants, and comparison of demographic characteristics with the shear modulus. RESULTS: Passive stiffness increased with increasing stretching (mean [SD] range of stiffness, 7.1 [2.0] to 36.2 [22.0] kPa). For all 4 foot positions, no significant difference was found between right and left legs (range, P = .42 to P = .98) or between the sexes (range, P = .28 to P > .99). No correlation of passive muscle stiffness with age, body mass index, or ankle range of motion was found. The reliability of measurements was good to excellent (mean [95% confidence interval] 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 this 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.

Iliac bone grafting of the intact glenoid improves shoulder stability with optimal graft positioning.

BACKGROUND: Bone grafting procedures are increasingly popular for the treatment of anterior shoulder instability. In patients with a high risk of recurrence, open coracoid transplantation is preferred but can be technically demanding. Free bone graft glenoid augmentation may be an alternative strategy for high-risk patients without significant glenoid bone loss. This biomechanical cadaveric study assessed the stabilizing effect of free iliac crest bone grafting of the intact glenoid and the importance of sagittal graft position. METHODS: Eight fresh frozen cadaveric shoulders were tested. The bone graft was fixed on the glenoid neck at 3 sagittal positions (50%, 75%, and 100% below the glenoid equator). Displacement and reaction force were monitored with a custom device while translating the humeral head over the glenoid surface in both anterior and anteroinferior direction. RESULTS: Peak force (PF) increased significantly from the standard labral repair to the grafted conditions in both anterior (14.7 ± 5.5 N vs 27.3 ± 6.9 N) and anteroinferior translation (22.0 ± 5.3 N vs 29.3 ± 6.9 N). PF was significantly higher for the grafts at the 50% and 75% positions compared with the grafts 100% below the equator with anterior translation. Anteroinferior translation resulted in significantly higher values for the 100% and 75% positions compared with the 50% position. CONCLUSIONS: This biomechanical study confirms improved anterior glenohumeral stability after iliac crest bone graft augmentation of the anterior glenoid. The results also demonstrate the importance of bone graft position in the sagittal plane, with the ideal position determined by the direction of dislocation.

Ultrasound elastography: the new frontier in direct measurement of muscle stiffness.

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.

Lower extremity functional electrical stimulation cycling promotes physical and functional recovery in chronic spinal cord injury.

OBJECTIVE: To examine the effect of long-term lower extremity functional electrical stimulation (FES) cycling on the physical integrity and functional recovery in people with chronic spinal cord injury (SCI). DESIGN: Retrospective cohort, mean follow-up 29.1 months, and cross-sectional evaluation. SETTING: Washington University Spinal Cord Injury Neurorehabilitation Center, referral center. PARTICIPANTS: Twenty-five people with chronic SCI who received FES during cycling were matched by age, gender, injury level, and severity, and duration of injury to 20 people with SCI who received range of motion and stretching. INTERVENTION: Lower extremity FES during cycling as part of an activity-based restorative treatment regimen. MAIN OUTCOME MEASURE: Change in neurological function: motor, sensory, and combined motor-sensory scores (CMSS) assessed by the American Spinal Injury Association Impairment scale. Response was defined as ≥ 1 point improvement. RESULTS: FES was associated with an 80% CMSS responder rate compared to 40% in controls. An average 9.6 CMSS point loss among controls was offset by an average 20-point gain among FES subjects. Quadriceps muscle mass was on average 36% higher and intra/inter-muscular fat 44% lower, in the FES group. Hamstring and quadriceps muscle strength was 30 and 35% greater, respectively, in the FES group. Quality of life and daily function measures were significantly higher in FES group. CONCLUSION: FES during cycling in chronic SCI may provide substantial physical integrity benefits, including enhanced neurological and functional performance, increased muscle size and force-generation potential, reduced spasticity, and improved quality of life.

Identification of pre-race ultrasonographic abnormalities of the Achilles tendon and association with future injuries in runners.

OBJECTIVE: To determine if specific morphological changes in ultrasonographic images of Achilles tendons are associated with the development of pain in distance runners. METHODS: This study is a blinded, retrospective analysis of 276 Achilles tendon ultrasound images, which were used to determine if specific morphologic findings could positively or negatively predict future Achilles tendon pain development in distance runners. Pre-race ultrasound scans were performed on 138 asymptomatic half- and full marathon runners (276 tendons in total) who were followed for 12 months after their races. Specific patterns of morphologic abnormality were identified (location, size, and appearance of ultrasound abnormality within the tendon). Sonographic findings were blindly assessed by a medical student, a resident, and a physician who has significant sonographic imaging experience. These specific abnormalities were then compared to those who later did or did not develop tendon pain. RESULTS: Three findings were found to have significant odds of association with the development of pain: 1) focal deep midsubstance intratendinous hypoechogenicity, 2) focal superficial midsubstance intratendinous hypoechogenicity, and 3) linear hyperechogenicity extending into middle of tendon from calcaneus. CONCLUSION: These results suggest that the aforementioned specific morphologic abnormalities in the Achilles tendon may be associated with the future development of pain symptoms in distance runners in this cohort. Looking for these specific abnormalities may increase the specificity of identifying precursors to Achilles tendon pain development.

Ultrasound evaluation of the patellar tendon and Achilles tendon and its association with future pain in distance runners.

Objectives: To examine whether asymptomatic ultrasonographic abnormalities in the Achilles and patellar tendons in runners are associated with an increased risk of pain development.Methods: This is a longitudinal, prospective cohort study with 139 runners recruited at a half and full marathon race. Ultrasound examination of the Achilles and patellar tendons was performed bilaterally the day prior to the race. Self-reported injury data were collected at 1, 3, 6 and 12 months. 104 (74.8%) runners were included in the data analysis.Results: Ultrasonographic tendon abnormalities were found in 24.1% of the Achilles and in 23.1% of the patellar tendons prior to the race. Runners with tendon abnormality were 2-3 times more likely to develop pain within 12 months than those without (relative risk = 3.14, p = 0.010 for Achilles; relative risk = 2.52, p = 0.008 for patellar tendon). After adjusting for gender, age, years of running, average miles per week of running over a year, and pre-race pain, runners with ultrasound abnormality were about 3 times (hazard ratio = 2.89, p = 0.039 for Achilles; hazard ratio = 2.73, p = 0.030 for patellar tendon) more likely to develop pain after the race. Tendon delamination was most strongly associated with pain in both the Achilles (relative risk = 6.00; p = 0.001) and patellar tendons (relative risk = 3.81; p = 0.001).Conclusions: Structural changes in asymptomatic tendons were found in almost 25% of runners. Presence of structural changes was associated with increased development of Achilles and patellar tendon pain within one year.

Design features of a guideline implementation tool designed to increase awareness of a clinical practice guide to HIV rehabilitation: A qualitative process evaluation.

RATIONALE, AIMS, AND OBJECTIVES: A comprehensive electronic guide (e-module) describing an interprofessional, evidence-informed approach to HIV rehabilitation was developed as an education resource for rehabilitation professionals. We developed a guideline implementation tool, consisting of a 10-week, case-based education intervention delivered by email, that was perceived to increase rehabilitation professionals' (occupational therapists (OTs), physical therapists (PTs), and speech language pathologists (SLPs)) knowledge and confidence to apply best practices in HIV rehabilitation. This study aimed to increase understanding of how the design of the guideline implementation tool facilitated increased awareness of and access to the e-module among rehabilitation professionals. METHODS: We conducted a single group intervention study with rehabilitation professionals in Canada and the United Kingdom. Six case studies targeting HIV pathophysiology and associated conditions, an interprofessional approach to rehabilitation assessment and treatment, and psychosocial issues experienced by people living with HIV, were emailed to participants at 2-week intervals. Individual semi-structured interviews were conducted post-intervention. Interview transcripts were analysed using a descriptive qualitative approach. RESULTS: Twenty-six individuals (17 from Canada, and 9 from the UK; 16 PTs, 7 OTs, 3 SLPs) were interviewed. One main theme related to design features of the intervention that facilitated learning and access to the e-module emerged. Subthemes highlighted features of the case-based intervention, including technical feasibility, terminology, formatting and layout, hyperlinks, number and frequency of case studies, and diverse and realistic case scenarios relevant to the learner's practice, that participants described as facilitating access to information and learning. CONCLUSION: Electronically administered case studies were perceived as complementary knowledge tools that increased access to an evidence-informed guide to HIV rehabilitation. Findings provide guidance on using case studies as a guideline implementation tool to facilitate access to information and related resources to optimize learning.

Thoracogenic spinal deformity: a rare cause of early-onset scoliosis.

OBJECTIVESurgery for severe congenital defects, such as congenital diaphragmatic hernia, congenital heart defects, and tracheoesophageal disorders, are life-saving treatments for many infants. However, the incidence of scoliosis following thoracoabdominal surgery has been reported to range from 8% to 50%. Little is known about severe scoliosis that occurs after chest wall procedures in infants. The authors sought to determine the prevalence of thoracogenic scoliosis, disease severity, and need for scoliosis surgery in patients who underwent chest wall procedures in early childhood.METHODSA multicenter database of patients with early-onset scoliosis was queried to identify patients with a history of thoracogenic or acquired iatrogenic scoliosis. Patients with significant congenital spine deformities were excluded. Forty-one patients (1.6%) were noted to have thoracogenic scoliosis. Of these patients, 14 patients were observed; 10 received casts and/or braces; and 17 underwent treatment with rib-based distraction rods, Shilla procedures, or spine-based growing rod devices. Radiographs, complications, and patient characteristics were reviewed.RESULTSThe mean age at scoliosis diagnosis for the 41 patients was 6.0 years. The mean time to follow-up was 2.9 years (4.5 years in the 17 surgical patients). The mean preoperative coronal Cobb angle in the surgical group was 65° and improved to 47° postoperatively (p = 0.01). The mean Cobb angle for the nonoperative group was 31° initially and 32° at follow-up (p = 0.44). Among the 17 patients undergoing surgery for scoliosis, there were 13 complications in 7 patients, including a brachial plexus palsy following rib-based distraction rod placement. This resolved with revision of the rib hooks. There were no known complications in the nonoperative cohort.CONCLUSIONSSevere scoliosis can develop after thoracoabdominal surgeries during infancy. Further work is needed to understand the pathogenesis of scoliosis in this population so as to implement measures for prevention and early diagnosis and to guide appropriate treatment.

Quantifying Effect of Onabotulinum Toxin A on Passive Muscle Stiffness in Children with Cerebral Palsy Using Ultrasound Shear Wave Elastography.

OBJECTIVE: A pilot study was conducted to longitudinally quantify effect of onabotulinum toxin A (BoNT-A) on passive muscle properties in children with cerebral palsy using ultrasound shear wave elastography. DESIGN: This was a prospective longitudinal cohort study. RESULTS: Between 1 and 3 mos post-BoNT-A, a significant improvement in the shear modulus of the lateral gastrocnemius was found at 10-degrees plantar flexion (PF) (-7.57 [-10.98, -5.07], P = 0.02) and 0-degrees PF (-14.74 [-18.21, -9.38], P = 0.03). There was a notable, but nonsignificant, difference in shear modulus at 20-degrees PF, 10-degrees PF, and 0-degrees PF between pre-BoNT-A and 1 mo post-BoNT-A. Pre-BoNT-A shear modulus was not significantly different from 3 mos post-BoNT-A at all foot positions. No significant differences in ankle passive range of motion or spasticity were found. CONCLUSION: Despite no significant change in ankle range of motion or spasticity, shear wave elastography was able to detect a difference in lateral gastrocnemius passive muscle properties in children with cerebral palsy after BoNT-A injections. The difference in passive muscle properties resolved by 3 mos post-BoNT-A.

Quantifying spasticity in individual muscles using shear wave elastography.

Spasticity is common following stroke; however, high subject variability and unreliable measurement techniques limit research and treatment advances. Our objective was to investigate the use of shear wave elastography (SWE) to characterize the spastic reflex in the biceps brachii during passive elbow extension in an individual with spasticity. The patient was a 42-year-old right-hand-dominant male with history of right middle cerebral artery-distribution ischemic infarction causing spastic left hemiparesis. We compared Fugl-Meyer scores (numerical evaluation of motor function, sensation, motion, and pain), Modified Ashworth scores (most commonly used clinical assessment of spasticity), and SWE measures of bilateral biceps brachii during passive elbow extension. We detected a catch that featured markedly increased stiffness of the brachialis muscle during several trials of the contralateral limb, especially at higher extension velocities. SWE was able to detect velocity-related increases in stiffness with extension of the contralateral limb, likely indicative of the spastic reflex. This study offers optimism that SWE can provide a rapid, real-time, quantitative technique that is readily accessible to clinicians for evaluating spasticity.

Quantitative Evaluation of Passive Muscle Stiffness in Chronic Stroke.

OBJECTIVE: The aim of this study was to evaluate the potential for shear wave elastography (SWE) to measure passive biceps brachii individual muscle stiffness as a musculoskeletal manifestation of chronic stroke. DESIGN: This was a cross-sectional study. Nine subjects with stroke were evaluated using the Fugl-Meyer and Modified Ashworth scales. Electromyography, joint torque, and SWE of the biceps brachii were obtained during passive elbow extension in subjects with stroke and four controls. Torque values at the time points corresponding to each SWE measurement during all trials were selected for direct comparison with the respective SWE stiffness using regression analysis. Intraclass correlation coefficients (ICC(1,1)) were used to evaluate the reliability of expressing alterations in material properties. RESULTS: Torque and passive stiffness increased with elbow extension-minimally for the controls and most pronounced in the contralateral limb of those with stroke. In the stroke group, several patterns of shear moduli and torque responses to passive elbow extension were identified, with a subset of several subjects displaying a very strong torque response coupled with minimal stiffness responses (y = 2.712x + 6.676; R = 0.181; P = 0.0310). Values of ICC(1,1) indicate consistent muscle stiffness throughout testing for the dominant side of controls, but largely inconsistent stiffness for other study conditions. CONCLUSIONS: SWE shows promise for enhancing evaluation of skeletal muscle after stroke. The wide variability between subjects with stroke highlights the need for precise, individualized measures.

Shear wave elastography of passive skeletal muscle stiffness: influences of sex and age throughout adulthood.

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 and 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.

Validation of shear wave elastography in skeletal muscle.

Skeletal muscle is a very dynamic tissue, thus accurate quantification of skeletal muscle stiffness throughout its functional range is crucial to improve the physical functioning and independence following pathology. Shear wave elastography (SWE) is an ultrasound-based technique that characterizes tissue mechanical properties based on the propagation of remotely induced shear waves. The objective of this study is to validate SWE throughout the functional range of motion of skeletal muscle for three ultrasound transducer orientations. We hypothesized that combining traditional materials testing (MTS) techniques with SWE measurements will show increased stiffness measures with increasing tensile load, and will correlate well with each other for trials in which the transducer is parallel to underlying muscle fibers. To evaluate this hypothesis, we monitored the deformation throughout tensile loading of four porcine brachialis whole-muscle tissue specimens, while simultaneously making SWE measurements of the same specimen. We used regression to examine the correlation between Young's modulus from MTS and shear modulus from SWE for each of the transducer orientations. We applied a generalized linear model to account for repeated testing. Model parameters were estimated via generalized estimating equations. The regression coefficient was 0.1944, with a 95% confidence interval of (0.1463-0.2425) for parallel transducer trials. Shear waves did not propagate well for both the 45° and perpendicular transducer orientations. Both parallel SWE and MTS showed increased stiffness with increasing tensile load. This study provides the necessary first step for additional studies that can evaluate the distribution of stiffness throughout muscle.

Presumed intramedullary spinal cord sarcoidosis in a healthy young adult woman.

Sarcoidosis is an inflammatory disease of unknown etiology associated with the development of granulomatous nodules in various organs, most commonly the lungs, eyes, and skin. It rarely affects the central nervous system, with the spinal cord being least common area of involvement. However, when sarcoidosis does affect the central nervous system, it is often the first presentation of the disease, making diagnosis more difficult. Physical examination findings are consistent with spinal cord pathology, and imaging often suggests spinal cord tumor. We present a case of an otherwise healthy young woman with a granulomatous mass in her cervico-thoracic spinal cord presumed to be sarcoid and review the clinical findings, diagnosis, treatment, and prognosis associated with this rare disease.