Kaufman, Kenton R

Objectives: To examine the effects of anterior load carriage on dynamic sagittal spinal alignment during the gait cycle in younger (<65 y) and older (≥65 y) adults. Design: Cross-sectional study of 47 participants aged 20–80 years categorized as young and older adults. Participants walked at self-selected speeds with and without a 4.5 kg anterior chest load. Whole-body kinematics were recorded using a 19-camera infrared motion capture system. Outcome measures included lumbar lordosis (LL), thoracic kyphosis (TK), trunk inclination (TI), sagittal trunk shift (STS), and pelvic tilt (PT). Gait-cycle–dependent differences were analyzed using statistical parametric mapping. Results: The mean age was 41 years in young adults (n=28) and 70 years in older adults (n=19). Anterior load carriage increased LL during portions of the gait cycle and reduced TI throughout the entire gait cycle. Younger adults demonstrated greater LL and lower TI than older adults. A significant age-by-load interaction for TI was observed during portions of the gait cycle. Conclusions: Anterior load carriage alters spinal alignment by increasing LL and reducing TI during walking, with distinct age-related patterns. These results provide valuable reference data and a foundation for future studies on load management and ergonomic interventions across the adult lifespan.

Wearable inertial measurement units (IMUs) offer an accessible alternative to optical motion capture (MoCap) gait analysis, but their performance in Progressive Supranuclear Palsy (PSP) requires validation. We assessed the concurrent validity of IMU-derived versus MoCap-derived gait metrics and static postural sway in 30 patients with PSP using Bland–Altman analysis, Intraclass Correlation Coefficients (ICC), and Spearman rank correlations. Finally, we assessed equivalence using the Two one-sided tests (TOST) procedure. Multivariable linear regression was used to determine whether clinical severity, as measured by the PSP Rating Scale (PSPRS), independently predicted absolute IMU measurement error while controlling for patient age and gait velocity. IMUs demonstrated excellent between-system agreement for parameters such as cadence (100.76 ± 11.42 vs. 100.52 ± 11.59) and cycle time (1.21 ± 0.15 vs. 1.22 ± 0.15; ICC > 0.98), despite a systematic underestimation of gait velocity (p < 0.05). Agreement significantly diminished for micro-phases (e.g., single/double support times) and spatial asymmetry. Interestingly, the TOST procedure revealed that only sagittal and transverse trunk kinematics were equivalent between systems, with all other measures failing to find equivalency. For static sway, the IMU demonstrated strong rank-order correspondence for tracking relative postural instability (ρ = 0.82, p < 0.05). Multivariable analysis revealed that higher PSPRS scores are independently associated with greater between-system discrepancies in support phases and pelvic and trunk kinematics (p < 0.05), irrespective of reduced gait speed. These findings highlight the need to develop disease-specific algorithms, rather than relying on normative commercial models, to establish reliable digital biomarkers for monitoring progressive motor decline.

Wearable sensors are increasingly used to monitor physical activity, yet low-power devices often rely on data aggregation to conserve battery life, potentially impacting measurement accuracy. This study evaluates the performance of a new low-power wearable (LPW), designed for monitoring steps across multiple months in a free-living environment, compared to a research-grade sensor (RGS) that collects raw acceleration data, with a focus on how different aggregation intervals impact step count accuracy. Thirty-two participants wore both sensors over two days, with LPW data collected in 10 min, 1 min, or 10 s aggregation periods (APs). Sensitivity and specificity of wear time detection were high across all APs (0.96 and 0.98, respectively). While total daily step count error did not differ significantly between APs, the 10 min AP exhibited greater undercounting and wider limits of agreement, especially in APs containing more than 40 steps. These findings suggest that although AP does not affect total daily step count, it influences the accuracy and variability of more granular data windows. Aggregating step counts over longer intervals may obscure short, fragmented bouts common in daily activity, leading to underestimation of steps. Optimizing APs and sensor settings is critical for improving accuracy in low-power wearables used outside laboratory settings.

This study presents the first in vivo intraoperative measurement of the kinetic properties of spastic human muscle. Despite slower relaxation in spastic biceps, the force-frequency relationship was similar to that of the healthy gracilis muscle. This suggests that spasticity does not substantially alter frequency-dependent force summation, possibly due to similar fiber-type compositions and limited changes in calcium handling or myosin isoforms in human spastic muscle.

There is an increased clinical use of elbow orthoses. It is important to consider patient experiences in their use. Patient-reported outcome measures (PROMs) serve as essential tools for gathering patient perspectives. This review provides a comprehensive list of PROMs used in clinical trials of elbow orthoses, and documents their properties, uses, and quality. A systematic literature search across PubMed, Scopus, Embase, Cumulative Index to Nursing and Allied Health Literature, and Web of Science identified 31 clinical trials of elbow orthoses that used PROMs as outcome measures. Subsequently, manual searches were conducted to report on each PROM's characteristics. A total of 15 different PROMs were used as outcome measurements in clinical trials that used an elbow orthosis as an intervention for 11 different conditions. Researchers can use this review to aid in making informed decisions about which PROMs to use for future clinical trials.

Case: We present a 55-year-old woman with a very short transfemoral amputation who underwent osseointegration. We compared gait analyses before and following osseointegration, demonstrating improvements in kinematics. At follow-up, the patient wore the prosthetic for 16 hours and averaged 10,000 steps daily. She achieved her goal of walking the beach with her prosthetic limb and often traveled without an assistive device. Conclusion: This case study of a patient with a very short transfemoral amputation demonstrated continued improvements in gait and significantly increased prosthetic use over time.

Background/Objectives: Traditional fusion leads to a loss of spine mobility across the fused vertebrae. Vertebral body tethering (VBT) was developed with the goal of increasing flexibility and maintaining some spinal mobility. However, it is not known if the additional mobility leads to significant functional improvement. This prospective motion analysis study evaluates functional outcomes, specifically gait stability, in pre-operative, post-fusion, and post-VBT patients by using postural perturbations on a treadmill. Methods: Overall, 79 subjects underwent a computer-controlled treadmill study with postural perturbations, which simulated trips and slips. The subjects were harnessed for safety. Overall, 21 subjects were healthy controls, 18 patients were at least one-year post-VBT, 15 patients were at least one-year post-fusion, and 25 were pre-operative scoliosis patients. Subject weight, height, and treadmill acceleration were recorded and used to determine anteroposterior single (ASSTs, PSSTs) and multiple (AMSTs, PMSTs) stepping thresholds to describe the maximum torque a patient could withstand before failing to recover from the simulated trip. Independent t-tests were run to compare groups under the advice of a master statistician with expertise in orthopedic surgery. Results: Pre-operative scoliosis patients had lower PSSTs than healthy controls (uncorrected p = 0.036). No significant differences were observed between pre-operative and post-operative groups for both fusion and VBT. There was no significant difference in ASST, AMST, or PMST between any of the groups. Conclusions: The lower PSST in pre-operative scoliosis patients compared to healthy controls may reflect impaired reactive balance and potentially increased fall risk. Interestingly, there was no significant difference in reactive balance measures between pre-operative and post-operative scoliosis patients or between post-fusion and post-VBT patients.

Six patients treated by hyperselective neurectomy were assessed using preoperative dynamic electromyography and intraoperative force measurements. Patients with lower preoperative biceps dynamic electromyography activation had significantly reduced force production at operation, suggesting that these findings could guide and improve procedure selection. Level of evidence: IV

Background/Objectives: Limited spinal range of motion (ROM) is linked to low back disorders, emphasizing the need to maintain mobility in the elderly. This study measured maximum spinal ROM, asymmetrical patterns, and the effects of age and muscle activation on spinal mobility. Methods: Forty healthy participants aged 50 and older were recruited. An optical motion capture system recorded three-dimensional coordinates of reflective markers placed on spinal landmarks. Asymmetry was analyzed in sidebending and axial rotation. Electromyography (EMG) data were collected bilaterally from paraspinal muscles at L3 during flexion, extension, sidebending, and axial rotation. Results: Trunk ROM averaged 111° in flexion, 38° in extension, 46° in sidebending, and 87° in axial rotation. Kinematic asymmetry was observed in sidebending and axial rotation. ROM decreased with age in flexion motion (p ≤ 0.04). EMG activity was significantly correlated with ROM data for all combined motions (p = 0.0002). The strongest EMG signal was recorded during flexion, whereas the weakest signal was observed during extension. EMG activity also correlated with kinematic asymmetry (p ≤ 0.03). Conclusions: Age and muscle activation significantly influence spinal ROM in the elderly. Lumbar kinematic asymmetry can be partially attributed to paraspinal muscle activation, underscoring the importance of analyzing asymmetrical motions in conjunction with EMG activity.

ABSTRACT Introduction Recovering from neuromuscular injuries or conditions can be a challenging journey that involves complex surgeries and extensive physical rehabilitation. During this process, individuals often rely on orthotic devices to support and enable movement of the affected limb. However, users have criticized current commercially available powered orthotic devices for their bulky and heavy design. To address these limitations, we developed a novel powered myoelectric elbow orthosis. Materials and Methods The orthosis incorporates 3 mechanisms: a solenoid brake, a Bowden cable-powered constant torque elbow mechanism, and an extension limiter. The device controller and battery are in a backpack to reduce the weight on the affected arm. We performed extensive calculations and testing to ensure that the orthosis could withstand at least 15 Nm of elbow torque. We developed a custom software effectively control the orthosis, enhancing its usability and functionality. A certified orthotist fitted a subject who had undergone a gracilis free functioning muscle transfer surgery with the device. We studied the subject under Mayo clinic IRB no. 20-006849 and obtained objective measurements to assess the orthosis’s impact on upper extremity functionality during daily activities. Results The results are promising since the orthosis significantly improved elbow flexion range of motion by 40° and reduced compensatory movements at the shoulder (humerothoracic joint) by 50°. Additionally, the subject was able to perform tasks which were not possible before, such as carrying a basket with weights, highlighting the enhanced functionality provided by the orthosis. Conclusion In brief, by addressing the limitations of existing devices, this novel powered myoelectric elbow orthosis offers individuals with neuromuscular injuries/conditions improved quality of life. Further research will expand the patient population and control mechanisms.