Biomechanical adaptations after transhumeral amputation

/ ABSTRACT Our long-term goal is to improve the health, care, and well-being of individuals with transhumeral limb loss by uncovering the biomechanical origins of functional deficits and long-term musculoskeletal complications that disproportionately affect them. Trauma is the most common cause of transhumeral limb loss, and while socket- based prosthetics are standard of care, more than half of affected individuals wear their devices infrequently or abandon them altogether. This negatively affects quality of life and results in overuse injuries and pathologies in the intact contralateral limb. Prior research has examined prosthetic devices/interfaces, outcomes of treatment, and percutaneous osseointegrated devices (PODs) to skeletally attach prostheses since they may mitigate socket issues and restore normal shoulder function. Yet there are virtually no data on three-dimensional (3D) shoulder kinematics and morphology after unilateral transhumeral amputation. Given the paucity of data on these understudied and underserved individuals, we will collect high precision, bilateral, 3D form-function data to quantify local (e.g., bone) and global (e.g., joint level) 1) kinematic compensations and 2) morphologic variations in the shoulders of patients who use socket suspension. We will then 3) analyze the form-function relationships that arise from these data. This cross-sectional observational study will recruit unilateral transhumeral amputees and a healthy control cohort. A medical history and medical imaging of both shoulders will be collected. Dynamic 3D motion of the thorax, scapulothoracic and glenohumeral joints in the shoulders, and the arm/prosthesis, will be captured using optical motion analysis and dynamic stereoradiography. Anatomy will be quantified on medical imaging using established 2D/3D clinical measures, and 3D anatomic models will be used to create statistical shape models that uncover previously unseen modes of morphologic variation. Analyses will examine bilateral (a)symmetry within and between groups to quantify biomechanics related to functional deficit and musculoskeletal complications, controlling for age, sex, residual limb length, and time since amputation. The results of these studies will provide clinicians, device designers, and researchers with the first accurate subject- specific in vivo 3D form-function measurements in transhumeral amputees. These extremely rare, yet highly valuable data will facilitate discovery of morphologic and kinematic biomarkers related to pathology and functional deficiency in shoulders after transhumeral amputation. Research into prosthetics and implanted device design, bone-limb-prosthesis interfaces, musculoskeletal function and rehabilitation, and surgical planning will all benefit. Techniques like finite element analyses and musculoskeletal modelling can then also query joint contact patterns and load/deformation of tissues using subject-specific data to drive studies. These data will also motivate and benchmark FDA evaluation of PODs for safe and effective widespread clinical use for limb loss. Project Number: 1R01HD117342-01 | Fiscal Year: 2025 | NIH Institute/Center: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) | Principal Investigator: Heath Henninger | Institution: UTAH STATE HIGHER EDUCATION SYSTEM--UNIVERSITY OF UTAH, SALT LAKE CITY, UT | Award Amount: $634,234 | Activity Code: R01 | Study Section: Musculoskeletal Rehabilitation Sciences Study Section[MRS] View on NIH RePORTER: https://reporter.nih.gov/project-details/1R01HD11734201