Citations

ABSTRACT This study assessed the level of agreement of perceived improvements among pediatric patients with chronic pain and their parents following an interdisciplinary pain management program. This is a retrospective chart review of a heterogeneous group of pediatric patients with chronic pain who completed an interdisciplinary pain management program (IPMP) and their parents ( N = 172 pairs). The IPMP took place in an outpatient pain management center affiliated with an academic rehabilitation hospital. The outcome measures included the Multidimensional Patient Impression of Change (MPIC) and the MPIC parent version were administered post‐treatment. The levels of agreement on the MPIC were analyzed between child and parent using the free‐marginal kappa statistic. The majority of both the parents and the children evaluated the patients to be much or very much improved in six of the eight domains assessed. The levels of agreement in the ratings were fair to moderate among the patient–parent dyads. Parents endorsed significantly higher levels of improved overall pain and mood than their child did, whereas the patients reported greater levels of improved ability to cope with pain than their parents did. Both the patients and their parents reported high levels of perceived improvement following the IPMP. However, there were some differences in their ratings of improvements in overall pain, mood, and ability to cope with pain. Given that some of the perceptions were discrepant, it is recommended that feedback be obtained from the patient and their parent.

Background: Patients with spina bifida are living longer and more productive lives; however, many continue to experience functional limitations in adulthood. This study evaluated long-term functional progression and ambulatory status using the combined Myelomeningocele Functional Classification (MMFC) and Functional Mobility Scale (FMS), and examined factors associated with long-term changes. Methods: A retrospective review at a tertiary care rehabilitation center identified 168 patients with spina bifida. MMFC and FMS classifications were recorded at initial and final visits. A subgroup of ambulatory patients who underwent 3D-gait analysis was analyzed to assess the relationship between MMFC, body mass index (BMI), and functional speed (FS) using multiple linear regression. Results: The average follow-up was 15±10.31 years. The mean age at final follow-up was 20 years (range, 5 to 52), with 52% of patients being male. Fifty-two percent of patients were ≥18 years of age at final follow-up. Within the MMFC1 cohort, 48% used wheelchair mobility (FMS 1,1,1) at initial presentation; this increased to 80% at final follow-up. Eighty percent of the MMFC2 patients were able to complete the 50-yard walk test at initial classification, whereas only 60% were able to complete it at final follow-up. Within the MMFC3 cohort, there was a decline in patients requiring no external support (FMS 6,6,6) from 90% to 78%. All MMFC4 patients maintained an FMS of 6,6,6. A statistically significant relationship was found between functional speed (FS) and MMFC (with MMFC4 faster than MMFC3 and MMFC2) ( P =0.01414). Conclusions: Long-term follow-up demonstrates that functional classification may decline over time in MMFC1 to 3 cohorts, whereas MMFC4 remains stable. In addition, within individual cohorts (MMFC1 to 3), there was also a decline in FMS and functional walk testing. A positive and statistically significant relationship was observed between gait analysis FS and MMFC, and a negative and statistically significant relationship was observed between BMI and MMFC. The combined use of MMFC and FMS provides a structured framework for longitudinal functional assessment in patients with spina bifida. Level of evidence: Level III.

Background: Spasticity after upper motor neuron injury (stroke, spinal cord injury, etc.) alters muscle activity and induces long-term structural remodeling of skeletal muscle [1]. Elbow flexors, including the biceps brachii, are frequently affected, leading to abnormal tone, involuntary co-contraction, and impaired elbow function. Hyper-selective neurectomy (HSN) is a well-established surgical technique that has gained renewed clinical adoption with advances in anatomic understanding and intraoperative nerve mapping [2], yet its effects on muscle properties are poorly defined. Objective: The purpose of this study was to define pre- vs. post-HSN differences in muscle gene expression, sarcomere length, and clinical outcomes of the spastic human biceps. Methods: Individuals with elbow flexor spasticity undergoing a planned two-stage HSN were prospectively enrolled (n=10). Stage 1 released the elbow flexors and provided a pre-biopsy; Stage 2, performed ~3 months later to treat the forearm flexors, provided a second exposure to the biceps and a second biopsy. In both stages, biceps biopsies were obtained with customized clamps [3] at predefined elbow angles (50°, 90°, 135°), fixed, and analyzed for sarcomere length [4]. Total RNA was extracted from pre- and post-HSN biceps samples to characterize transcriptional changes. Clinical spasticity was assessed before Stage 1 and again before Stage 2 using the Modified Ashworth Scale (MAS). Data were compared using repeated-measures models, and single-cell transcriptional changes were analyzed using established analytical pipelines. Results: Sarcomere length (SL) increased significantly after HSN at all joint angles. At 50°, SL increased from 2.45 ± 0.18 µm pre-HSN to 3.05 ± 0.28 µm post-HSN; at 90°, from 2.70 ± 0.29 µm to 2.91 ± 0.16 µm; and at 135°, from 2.72 ± 0.36 µm to 3.24 ± 0.32 µm (all p < 0.05). Clinical spasticity assessment improved significantly as well (p < 0.05), with MAS scores decreasing from 1.89± 0.93 to 0.35 ± 0.53. RNA sequencing revealed changes in key pathways and overall gene expression patterns such as enhanced inflammatory response through increased cytokine production and fibroblast proliferation, leading to elevated collagen synthesis and subsequent fibrosis. We also observed upregulated immune modulation and chemotaxis, while pathways involved in mitochondrial respiration, muscle development, and cellular homeostasis were downregulated. At the transcript level, HSN led to decreased inflammation and adipogenesis, while promoting increased extracellular matrix assembly, and vascular formation. Conclusion: HSN produced coordinated improvements across structural, clinical, and transcriptional levels in the spastic human biceps muscle. Sarcomere lengths increased toward longer resting lengths at all joint angles, clinical spasticity decreased significantly, and RNA sequencing revealed distinct post-operative transcriptional remodeling. The longer sarcomere length and decreased spasticity should contribute to improved patient function after HSN. References: 1. Lieber RL et al. Muscle Nerve. 2002;26:98–105. 2. Leclercq C et al. Hand Clin. 2018;34:537–545. 3. Lieber RL et al. J Neurophysiol. 1994;71:874–881. 4. Ward SR et al. J Biomech. 2009;42:193–196. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

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.

AbstractThe sliding filament theory explains skeletal muscle fibre force change as a function of length based on the overlap of actin and myosin filaments. Although this length‐tension (LT) relationship has been well investigated in animal models, it is not known whether this microscopic sarcomere LT property can be scaled up five orders of magnitude to explain the LT behaviour of a long human muscle such as the gracilis. The goal of this study is to validate the sarcomere LT curve in humans based on human filament length combined with in vivo experimental data. Intraoperative measurements of maximal tetanic force and muscle‐tendon unit length at four different joint configurations (JC) were obtained from 19 patients undergoing free functioning muscle transfer surgery. With physiologically measured fibre length and estimated sarcomere shortening resulting from tendon compliance, we show that 79.7% variance in isometric force data is explained by a simple human sarcomere LT model. This study demonstrates that the human whole muscle LT relationship can be modelled by the sliding filament theory given patient‐specific fibre length, filament length, tendon compliance and sarcomere shortening. imageKey points Whole human gracilis muscle isometric length‐tension relationships were measured in the operating room. Grouped whole muscle raw length‐tension curves showed no obvious form. The width of each experimental length‐tension curve was highly variable across subjects and used to predict fibre length (serial sarcomere number). After whole muscle length‐tension curves were normalized to each patient's serial sarcomere number, the whole human muscle length‐tension curve was well predicted by the sliding filament theory.

The intrinsic force production capability of human muscle can be expressed as “Specific Tension,” or, the maximum force generated per cross-sectional area of muscle fibers. This value can be used to determine, for example, whether muscle quality changes during exercise, atrophy, disease, or hypertrophy. A value of 22.5 N/cm 2 for mammalian muscle has generally become accepted based on detailed studies of small mammals. Determining the specific tension of human muscle is much more challenging as almost all determinations are indirect. Calculation of human muscle specific tension requires an understanding of that muscle’s contribution to joint torque, its activation magnitude, tendon compliance, and joint moment arm. Determining any of these parameters is technically challenging in humans and thus, it is no surprise that human specific tension values reported vary from 2 to 73 N/cm 2 . In this systematic review, we screened 1,506 published papers and identified the 30 studies published between 1983 and 2023 that used appropriate methods and which reported 96 human specific tension values. We weighted each parameter based on whether it was directly measured, estimated, or calculated based on the literature, with decreasing weighting used, the more indirect the methods. Based on this exhaustive review of the relevant human literature, we suggest that the most accurate value that should be used for human muscle specific tension is 26.8 N/cm 2 .

AbstractSkeletal muscle's isometric contractile properties are one of the classic structure–function relationships in all of biology allowing for extrapolation of single fibre mechanical properties to whole muscle properties based on the muscle's optimal fibre length and physiological cross‐sectional area (PCSA). However, this relationship has only been validated in small animals and then extrapolated to human muscles, which are much larger in terms of length and PCSA. The present study aimed to measure directly the in situ properties and function of the human gracilis muscle to validate this relationship. We leveraged a unique surgical technique in which a human gracilis muscle is transferred from the thigh to the arm, restoring elbow flexion after brachial plexus injury. During this surgery, we directly measured subject specific gracilis muscle force–length relationship in situ and properties ex vivo. Each subject's optimal fibre length was calculated from their muscle's length‐tension properties. Each subject's PCSA was calculated from their muscle volume and optimal fibre length. From these experimental data, we established a human muscle fibre‐specific tension of 171 kPa. We also determined that average gracilis optimal fibre length is 12.9 cm. Using this subject‐specific fibre length, we observed an excellent fit between experimental and theorical active length‐tension curves. However, these fibre lengths were about half of the previously reported optimal fascicle lengths of 23 cm. Thus, the long gracilis muscle appears to be composed of relatively short fibres acting in parallel that may not have been appreciated based on traditional anatomical methods. imageKey points Skeletal muscle's isometric contractile properties represent one of the classic structure–function relationships in all of biology and allow scaling single fibre mechanical properties to whole muscle properties based on the muscle's architecture. This physiological relationship has only been validated in small animals but is often extrapolated to human muscles, which are orders of magnitude larger. We leverage a unique surgical technique in which a human gracilis muscle is transplanted from the thigh to the arm to restore elbow flexion after brachial plexus injury, aiming to directly measure muscles properties in situ and test directly the architectural scaling predictions. Using these direct measurements, we establish human muscle fibre‐specific tension of ∼170 kPa. Furthermore, we show that the gracilis muscle actually functions as a muscle with relatively short fibres acting in parallel vs. long fibres as previously assumed based on traditional anatomical models.

Abstract Purpose Breast cancer patients are at risk of losing function during and after treatment. Unfortunately, little is known about the individual and additive effects of specific treatment, disease-related, and demographic factors that may contribute to functional decline. This manuscript reports the results of a multi-center study to evaluate the effects of these factors on function. Methods In this cross-sectional study, women with a history of breast cancer referred to cancer rehabilitation clinics were administered the PROMIS Cancer Function Brief 3D Profile to evaluate function in the domains of physical function, fatigue, and social participation. Clinical and demographic information, including treatment history and disease status, was recorded by clinicians. Patients were analyzed in two groups: those with active disease on antineoplastic treatment, and those with no evidence of disease (NED). A multivariable model was constructed to detect associations between clinical and demographic factors. Results In patients with NED, the presence of chemotherapy-induced peripheral neuropathy (CIPN) was strongly associated with reduced function in all three domains. In those with active disease, having brain metastases was significantly associated with reduced function in all domains and CIPN with reduced physical function. Radiation was associated with improved function in both cohorts. Conclusions Among women seeking rehabilitative care, CIPN and the presence of brain metastases were most strongly associated with a decline in function. The effects of radiation on function were unexpected and may be partially explained by the treatment’s role in symptom management. Clinicians who treat breast cancer should consider a patient’s functional status when providing supportive care.

BackgroundMeasuring function with valid and responsive tools in patients with cancer is essential for driving clinical decision‐making and for the end points of clinical trials. Current patient‐reported outcome measurements of function fall short for many reasons. This study evaluates the responsiveness of the Patient‐Reported Outcomes Measurement Information System (PROMIS) Cancer Function Brief 3D Profile, a novel measure of function across multiple domains.MethodsTwo hundred nine participants across five geographically distinct tertiary care centers completed the assessment and pain rating at two outpatient cancer rehabilitation clinic visits. Patients and providers completed a global rating of change measure at the second visit to indicate whether the patient was improving or worsening in function. Multiple response indices and linear models measured whether the measure was responsive to self‐reported and clinician‐rated changes over time. Correlations between changes in function and changes in anchors (pain rating and performance status) were also calculated.ResultsFunction as measured by the PROMIS Cancer Function Brief 3D Profile changed appropriately as both patients and clinicians rated change. Small to moderate effect sizes supported the tool's responsiveness. Function was moderately correlated with pain and more strongly correlated with performance status, and changes in function corresponded with changes in anchor variables. No floor/ceiling effect was found.ConclusionsThe PROMIS Cancer Function Brief 3D Profile is sensitive to changes over time in patients with cancer. The measure may be useful in clinical practice and as an end point in clinical trials.Lay summary We gave patients a questionnaire by which they told their physicians how well they were functioning, including how fatigued they were. This study tested that questionnaire to see whether the scores would change if patients got better or worse.