Citations

Background: Individuals with brachial plexus injuries (BPIs) can be prescribed assistive devices, including myoelectric elbow orthoses (MEOs), for rehabilitation or functional use after failed treatment for elbow flexion restoration. Although recent case studies indicate potential for clinical improvements after using an MEO after BPI, the patients' perspectives on such use are still unknown. Objective: To explore patient perspectives on the use of an MEO after surgical treatment for a traumatic BPI. Study design: Qualitative using both a focus group and semistructured interviews. Methods: Patients with BPI that used an MEO were recruited. Five patients participated in an in-person focus group, whereas three patients participated in individual phone interviews. Themes that emerged from the focus group were compared against those that emerged from the personal interviews. Results: Feedback was grouped into three themes: device usage, hardware performance, and device design. Within each theme, positive elements, areas for improvement, and additional considerations emerged. Patients indicated a positive attitude toward using an MEO as a rehabilitation tool. They desired a streamlined, stronger device to support them and assist during activities of daily living. Conclusions: For patients with BPI, a well-designed MEO that meets their needs could assist with rehabilitation and increase independence in daily activities. Continued patient engagement in the evaluation and development of both medical devices and treatment plans offers the best opportunity for improved outcomes that are important to the patient.

Background: Adult traumatic brachial plexus injuries (BPIs) can result in severe impairment following penetrating wounds, falls, and motor vehicle accidents or other high-energy trauma. Objective: Quantify functional outcomes of adult patients with a BPI using a myoelectric orthosis to restore elbow flexion. Study design: Retrospective review. Methods: A clinic specializing in the BPI treatment at a large academic medical center tested nineteen adult patients with BPI. These patients had failed to achieve antigravity elbow flexion following their injury and observation or surgical reconstruction. They were provided a myoelectric elbow orthosis (MEO) if they had detectable electromyography signals. Results: There was significant improvement in strength and significant reductions in function and pain when using an MEO. Following initiation of the MEO, 12 of the 19 patients had clinical improvements in muscle strength, 15 patients showed improvement in their DASH, and 13 patients reported improvements in their Visual Analog Scale. Conclusion: The use of an MEO improves elbow flexion strength, increases function, and reduces pain in the majority of patients with BPI and inadequate elbow flexion following observation or surgical reconstruction.

ABSTRACT We measured the passive mechanical properties of intact, living human gracilis muscles (n=11 individuals, 10 male and 1 female, age: 33±12 years, mass: 89±23 kg, height: 177±8 cm). Measurements were performed in patients undergoing surgery for free-functioning myocutaneous tissue transfer of the gracilis muscle to restore elbow flexion after brachial plexus injury. Whole-muscle force of the gracilis tendon was measured in four joint configurations (JC1–JC4) with a buckle force transducer placed at the distal tendon. Sarcomere length was also measured by biopsy from the proximal gracilis muscle. After the muscle was removed, a three-dimensional volumetric reconstruction of the muscle was created via photogrammetry. Muscle length from JC1 to JC4 increased by 3.3±1.0, 7.7±1.2, 10.5±1.3 and 13.4±1.2 cm, respectively, corresponding to 15%, 34%, 46% and 59% muscle fiber strain, respectively. Muscle volume and an average optimal fiber length of 23.1±0.7 cm yielded an average muscle physiological cross-sectional area of 6.8±0.7 cm2 which is approximately 3 times that measured previously from cadaveric specimens. Absolute passive tension increased from 0.90±0.21 N in JC1 to 16.50±2.64 N in JC4. As expected, sarcomere length also increased from 3.24±0.08 µm at JC1 to 3.63±0.07 µm at JC4, which are on the descending limb of the human sarcomere length–tension curve. Peak passive muscle stress was 27.8±5.5 kPa in JC4 and muscle modulus ranged from 44.8 MPa in JC1 to 125.7 MPa in JC4. Comparison with other mammalian species indicates that human muscle passive mechanical properties are more similar to rodent muscle than to rabbit muscle. These data provide direct measurements of whole-human muscle passive mechanical properties that can be used in modeling studies and for understanding comparative passive mechanical properties among mammalian muscles.

Background: In recent years, the prevalence of medial ulnar collateral ligament injuries has increased in throwers of all ages and skill levels. The motusBASEBALL sensor possesses an inertial measurement unit (IMU) that has been developed and applied to the throwing arm to allow for measurements of several objective parameters, which may prove beneficial for monitoring, rehabilitation, and injury prevention in the throwing athlete. However, the reliability, consistency, and validity of the IMU have not been independently assessed. Purpose: To evaluate the reliability, consistency, and validity of the motusBASEBALL sensor compared with the historic gold standard of marker-based motion capture. Study Design: Controlled laboratory study. Methods: A total of 10 healthy male baseball athletes with varsity-level high school experience volunteered to participate in this study. Participants were fitted with 37 retroreflective markers for motion capture and the motusBASEBALL IMU sensor. Participants threw 5 fastballs at maximum effort, with measurements recorded simultaneously by motion capture and the IMU. Arm slot, arm speed, arm stress, and shoulder rotation were measured and compared. Results: Of the 4 metrics generated by the IMU, significant differences were found for 3 of the throwing metrics compared with motion capture including arm slot (5.0°± 6.1°; P = .037), elbow varus torque (9.4 ± 12.0 N·m; P = .037), and shoulder rotation (6.3°± 6.1°; P = .014). Arm speed did not demonstrate a statistically significant difference (29.2 ± 96.8 rpm; P = .375). The IMU consistently underreported pitching performance values. Shoulder rotation exhibited excellent reliability with <5° of error, and arm slot demonstrated good reliability with <10° of error. Arm stress and arm speed were less reliable. Conclusion: The IMU was not accurate or valid for arm slot, arm stress, and shoulder rotation compared with marker-based motion capture. It was relatively accurate for arm speed. Despite its lack of validity, it was consistent and reliable for arm speed and shoulder rotation and relatively reliable for arm slot and arm stress. Caution should be used when comparing values provided by this IMU to the gold standard of marker-based motion capture. Clinical Relevance: IMU technology has potential to be used in monitoring, rehabilitation, and injury prevention in throwing athletes if valid. This study demonstrates that the values provided by the IMU should not be considered equivalent to those generated by the gold standard of marker-based motion capture; however, there may still be a role for this technology when relying on its internal consistency for intrathrower comparisons and tracking.

The force within a muscle may be assessed using intramuscular pressure measurements (IMP). However, a limiting factor in implementing this technology in the clinic is the observed variability of IMP measurements. The variability may be due in part to the flow of interstitial fluid. The objective of this study was to develop a technique for tracking interstitial fluid flow during muscle lengthening using fluorescent microspheres. Additionally, the effect of microsphere diameter on dispersion was evaluated. Fluorescent microspheres were injected into the rat tibialis anterior (TA) either before (right limb) or after (left limb) lengthening to 10% strain (n = 5). To help discriminate the effects of microsphere size, 10 µl of microspheres (0.25% by volume) were injected simultaneously: 0.1 µm in sky blue and 0.2 µm in yellow green. Once frozen, 20 µm muscle cross‐sections were stained and imaged using confocal microscopy to evaluate the microsphere's axial dispersion as a percent of muscle length. The microsphere dispersion was normalized to the muscle length. The fluorescent microspheres flowed with the interstitial fluid and did not penetrate the muscle fiber. There was significantly greater microsphere dispersion with passive strain (p‐value > 0.01) for lengthened samples (31±7%) compared to static samples (17±9%). Dispersion did not differ for the two bead sizes. In conclusion, this illustrates the microspheres track the interstitial fluid and passive lengthening results in additional dispersion. Supported by NIH under award number R01HD31476 and T32HL105355.

Abstract Background How significant asymmetries in otolith organ function in the presence of symmetrical and asymmetrical semicircular canal function influence skull vibration-induced nystagmus testing (SVINT) has not been well described. Purpose The aim of the study is to examine the agreement between SVINT and caloric testing, ocular vestibular-evoked myogenic potentials (oVEMP), and cervical vestibular-evoked myogenic potentials (cVEMP) for detecting asymmetric vestibular function. Research Design This is a retrospective study of patients presenting with the chief complaint of vertigo, dizziness, or imbalance. Study Sample A total of 812 patients were studied with a median age at testing of 59 years (interquartile range 46‐70; range 18‐93) and included 475 (59%) women. Intervention Either the monothermal warm caloric test or alternate binaural bithermal caloric test, oVEMP, and cVEMP tests were administered to all patients. All patients underwent the SVINT prior to vestibular laboratory testing. Data Collection and Analysis Agreement between tests categorized as normal versus abnormal was summarized using percent concordance (PC). Sensitivity and specificity values were calculated for SVINT compared with other tests of vestibular function. Results There was higher agreement between ipsilateral and contralateral SVINT with the caloric test (PC = 80% and 81%, respectively) compared with oVEMP (PC = 63% and 64%, respectively) and cVEMP (PC = 76% and 78%, respectively). Ipsilateral and contralateral SVINT showed higher sensitivity for the caloric test (sensitivity = 47% and 36%, respectively) compared with oVEMP (sensitivity = 26% and 21%, respectively), or cVEMP (sensitivity = 33% vs. 27%, respectively). Specificity of SVINT was high (>80%) for all assessments of vestibular function. Conclusion The presence of SVIN is a useful indicator of the asymmetry of vestibular function between the two ears when making judgments about semicircular canal asymmetry but is less sensitive to asymmetries in otolith organ function.

Background Low back pain (LBP) is common among individuals with transfemoral amputation (TFA) and has a negative impact on quality of life. Little is known about health care utilization for LBP in this population and whether utilization varies by amputation etiology. Objective To determine if individuals with TFA have an increased likelihood of seeking care or reporting symptoms of acute or chronic LBP during physician visits after amputation compared with matched individuals without amputation. Design Retrospective cohort. Setting Olmsted County, Minnesota (2010 population: 144 248). Participants All individuals with incident TFA (N = 96), knee disarticulation, and transfemoral amputation residing in Olmsted County between 1987 and 2014. Each was matched (1:10 ratio) with non‐TFA adults on age, sex, and duration of residency. Individuals were divided by etiology of amputation: dysvascular and trauma/cancer. Interventions Not applicable. Main Outcome Measurements Death and presentation for evaluation of LBP (LBP event) while residing in Olmsted County. LBP events were identified using validated International Classification of Diseases, Ninth Revision (ICD‐9) codes and corresponding Berkson, Hospital International Classification of Diseases Adapted (HICDA), and ICD‐10 diagnostic codes. Hurdle and competing‐risk Cox proportional hazard models were used. Results Having a TFA of either etiology did appear to correlate with increased frequency of LBP events, although this association was only statistically significant within the dysvascular TFA cohort (dysvascular TFA cohort: relative risk [RR] 1.80, 95% confidence interval [CI] 1.07‐3.03, median follow‐up 0.78 years; trauma/cancer TFA cohort: RR 1.14, 95% CI 0.58‐2.22, median follow‐up 7.95 years). In time to event analysis, dysvascular TFA had an increased risk of death and event. Obesity did not significantly correlate with increased frequency of LBP events or time to event for either cohort. At any given point in time, individuals with TFA of either etiology who had phantom limb pain were 90% more likely to have an LBP event (hazard ratio [HR] 1.91, 95% CI 1.11‐3.31). Conditional on not dying and no LBP event within the first 2.5 years, individuals with prosthesis had a decreased risk of LBP events in subsequent years. Conclusions Risk of LBP events appears to vary by TFA etiology. Obesity did not correlate significantly with increased frequency of LBP event or time to event. Phantom limb pain correlated with decreased time to LBP event after amputation. The association between prosthesis receipt and LBP events is ambiguous. Level of Evidence III.