Schilaty, Nathan D.

Background: Rapidly reversible weakness with neck flexion (McArdle sign) is common in patients with multiple sclerosis (MS). The pathophysiology is unknown. Objective: To evaluate changes in central motor conduction time (CMCT) in patients with and without McArdle sign. Methods: We measured McArdle sign with a torque cell and CMCT with neck flexed and extended in patients with MS, other causes of myelopathy, and healthy controls. Results: CMCT was prolonged with neck flexion disproportionately in those with MS-associated myelopathy (MSAM) with prominent McArdle sign compared to MS patients with lesser degrees of McArdle sign, and to controls. Conclusion: McArdle sign may result from stretch-induced slowing of conduction due to demyelination.

Context: Epidemiological studies have shown an increased risk of musculoskeletal injury after concussion. The purpose of this study was to determine whether the reverse relationship exists, specifically whether there is an increased risk of concussion after an anterior cruciate ligament (ACL) injury in a population-based cohort. Design: Retrospective cohort. Methods: The Rochester Epidemiology Project was searched between 2000 and 2017 for International Classification of Diseases, 9th and 10th Revision codes relevant to the diagnosis and treatment of concussion and ACL tear. A total of 1294 unique patients with acute, isolated ACL tears and no previous history of concussion were identified. Medical records for cases were reviewed to confirm ACL tear diagnosis and to determine history of concussion after the ACL injury. Cases were matched by age, sex, and Rochester Epidemiology Project availability to patients without an ACL tear (1:3 match), resulting in 3882 controls. Medical records of matched control patients were reviewed to rule out history of ACL injury. The hazard ratio of concussion injury following an ACL injury was determined. Results: Nine patients with an ACL injury suffered concussion up to 3 years after the ACL injury. The rate of concussion was no different between ACL-injured cases (0.7%) compared with matched controls with no ACL injury (1.2%), which corresponded to a hazard ratio of 0.55 (95% confidence interval, 0.3–1.1; P = .10). Conclusions: Based on the current evidence, there does not appear to be a significant association between ACL injury and subsequent concussion, which suggests that a concussion uniquely affects the risk of future subsequent musculoskeletal injury.

Purpose To report the rate of anterior cruciate ligament (ACL) graft failure by physis status (open, closing, closed) and to analyze which factors were associated with higher risk of ACL graft failure. Methods Patients younger than 18 years who underwent transphyseal ACL reconstruction (ACLR) between 2000 and 2018 at a single institution were reviewed at minimum 2 years after ACLR. Patient records were reviewed for anthropometrics, surgical techniques, and ACL graft failure. Patients were subsequently stratified based on physis status (open, closing, closed) and analyzed. Results A total of 272 patients (mean age of 15.4 ± 1.3 years) were assessed. The transtibial technique was used in 63.6% of cases. A hamstring autograft was used exclusively in the open physis group. A patellar tendon autograft was used in 65.9% of patients with a closing physis and 80.9% of patients with a closed physis. The overall graft failure rate was 13.2%, with a contralateral ACL injury rate of 11.0%. Kaplan‐Maier analysis by physis status showed different injury free from ACL reinjury ( P < .001). An open physis was associated with increased risk of ACL reinjury (hazard ratio, 5.2; P < .001) when compared to a closed physis. A closing physis presented a higher hazard ratio but was not statistically significant (hazard ratio, 2.6; P = .08). Hamstring graft type ( P = .03) and lower graft diameter ( P = .04) were significantly related to higher ACL reinjury after adjusting for physis status. Conclusions Transphyseal ACLR is a safe procedure in pediatric patients. The rate of reinjury was 13.2%. This rate decreases with skeletal maturity, use of patellar tendon autograft, and a larger graft diameter. Level of Evidence Level III, retrospective cohort study.

Background Following anterior cruciate ligament (ACL) injury, many athletes that undergo surgery and 6–9 months of rehabilitation struggle to return to sport. Evidence suggests that psychological factors contribute to this failure to return-to-sport. Objective Determine the motor control relationship between thigh musculature motor unit characteristics and psychological readiness to return to sport between ACL-injured and healthy controls. Study design A longitudinal cohort study. Methods Athletes longitudinally completed the ACL Return to Sport after Injury (ACL-RSI) survey and isometric strength measures with a measurement of electromyography (EMG) of the vastus lateralis, vastus medialis, biceps femoris, and semitendinosus. A score cut-off of 61 on the ACL-RSI was used to divide ACL-injured groups. EMG was decomposed to provide each identified motor unit’s characteristics (amplitude, average firing rate, etc). Results Data demonstrated increased average firing rate for hamstrings (p<0.001), decreased average firing rate for vastus lateralis (p<0.001) and decreased motor unit size for both the quadriceps and hamstrings at return-to-sport post-ACL reconstruction compared with sex-matched and age-matched healthy controls (p<0.001). Furthermore, there were marked differences in disparate ACL-RSI scores between ACL-injured athletes. Conclusions At return to sport, ACL-injured athletes have major alterations of thigh musculature motor control, with smaller motor units used by those with low ACL-RSI scores. This study uniquely demonstrates objective thigh muscle motor unit characteristics that coincide with subjective reports of psychological readiness. This information will be important to address psychomotor complexes of injury for future rehabilitation protocols.

Introduction: Physical activity is protective against cardiovascular (CV) disease and mortality, yet more than 25% of adults do not perform any regular exercise. Whole body electronic muscle stimulation (WB-EMS) is a novel FDA-approved device used for physical training that simultaneously stimulates all major muscle groups using percutaneous electrical impulse transmission during exercise. Preliminary studies demonstrated increased muscle mass, reduced fat mass, and improved functional capacity in elderly individuals who trained with WB-EMS. We evaluated the effects of training with WB-EMS on measures of CV health. Methods: Healthy adults were randomized to physical training with versus without WB-EMS for one 20-minute session each week for 16 weeks. Participants wore a specifically designed vest and arm and leg straps connected to the WB-EMS device (Miha Bodytec, Germany). Biphasic electrical stimulation was delivered through the vest and straps (4 sec on, 4 sec off) at a frequency that elicited a score of 5-6 on the Borg perceived exertion scale when each major muscle group was stimulated. Individuals randomized to no WB-EMS wore the same equipment but received no stimulation. Sessions were provided by trainers certified in WB-EMS training and consisted of a fixed protocol of simple exercises such as squats and lunges. Temporal changes in measures of CV health were compared between groups. Results: Forty-one individuals were recruited between 02/2021 and 02/2022 (n=24 WB-EMS, n=17 no WB-EMS; mean age 35.9±11.2 yrs; 61.3% females; median BMI 24.3 (21.8, 28.1) kg/m 2 . After 16 weeks there were significant and favorable differences in the intervention group compared to controls in waist: hip ratio (-1.2 cm vs. 0.9, p=0.05); total cholesterol (-1.1 mg/kg vs. 14.2 mg/kg, p=0.02); anaerobic threshold (68.2% vs. 30.8%, p=0.03); breathing efficiency (VE/VCO2: -10.36 vs -7.38, p=0.01); and peripheral endothelial function, measured with reactive hyperemia peripheral arterial tonometry (-0.009 vs. -0.29, p=0.06). Conclusions: Once weekly training with WB-EMS yielded more favorable changes in CV biomarkers compared to conventional training alone in healthy adults, and thus may offer an effective and time-efficient method of physical training.