Abstract-A growing number of clinical trials and case reports support qualitative claims that use of an elevated vacuum suspension (EVS) prosthesis improves residual-limb health on the basis of self-reported questionnaires, clinical outcomes scales, and wound closure studies. Here, we report first efforts to quantitatively assess residual-limb circulation in response to EVS. Residual-limb skin health and perfusion of people with lower-limb amputation (N = 10) were assessed during a randomized crossover study comparing EVS with nonelevated vacuum suspension (control) over a 32 wk period using noninvasive probes (transepidermal water loss, laser speckle imaging, transcutaneous oxygen measurement) and functional hyperspectral imaging approaches. Regardless of the suspension system, prosthesis donning decreased perfusion in the residual limb under resting conditions. After 16 wk of use, EVS improved residual-limb oxygenation during treadmill walking. Likewise, prosthesis-induced reactive hyperemia was attenuated with EVS following 16 wk of use. Skin barrier function was preserved with EVS but disrupted after control socket use. Taken together, outcomes suggest chronic EVS use improves perfusion and preserves skin barrier function in people with lower-limb amputation.Clinical Trial Registration: ClinicalTrials.gov; "Evaluation of limb health associated with a prosthetic vacuum socket system": NCT01839123; https://clinicaltrials.gov/ct2/show/ NCT01839123?term=NCT01839123&rank=1

Scar research is challenging because rodents do not naturally form excessive scars, and burn depth, size, and location cannot be controlled in human longitudinal studies. The female, red Duroc pig model has been shown to form robust scars with biological and anatomical similarities to human hypertrophic scars. To more closely mimic the mode of injury, recreate the complex chemical milieu of the burn wound environment and enhance scar development, an animal model of excessive burn-induced scarring was developed and compared with the more commonly used model, which involves excisional wounds created via dermatome. Standardized, full-thickness thermal wounds were created on the dorsum of female, red Duroc pigs. Wounds for the dermatome model were recreated using two different total dermatome settings: ~1.5 mm and > 1.9 mm. Results from analysis over 150 days showed that burn wounds healed at much slower rate and contracted more significantly than dermatome wounds of both settings. The burn scars were hairless, had mixed pigmentation, and displayed four-fold and two-fold greater excess erythema values, respectively, compared with ~1.5 mm and > 1.9 mm deep dermatome injuries. Burn scars were less elastic, less pliably and weaker than scars resulting from excisional injuries. Decorin and versican gene expression levels were elevated in the burn group at day 150 compared with both dermatome groups. In addition, transforming growth factor-beta 1 was significantly up-regulated in the burn group versus the ~1.5 mm deep dermatome group at all time points, and expression remained significantly elevated versus both dermatome groups at day 150. Compared with scars from dermatome wounds, the burn scar model described here demonstrates greater similarity to human hypertrophic scar. Thus, this burn scar model may provide an improved platform for studying the pathophysiology of burn-related hypertrophic scarring, investigating current anti-scar therapies, and development of new strategies with greater clinical benefit.

Background The current standard of care for the prevention and treatment of scarring following burn injury is pressure garment therapy (PGT). Although this therapy has been used clinically for many years, controversy remains regarding its efficacy. The purpose of this study was to evaluate the efficacy of PGT in a female Red Duroc pig (fRDP) burn model where wound depth could be tightly controlled. Methods Full-thickness burn wounds were generated on fRDPs. At day 28 post-burn, PGT was applied to half of the wounds (10 mmHg), with control wounds covered with garments exerting no compression. Scar area, perfusion, hardness, and elasticity were quantified at days 0, 28, 42, 56, and 72 using computerized planimetry, Laser Doppler and torsional ballistometry. Scar morphology was assessed at days 28, 56 and 76 using histology, immunohistochemistry and transmission electron microscopy. Results Pressure garment therapy significantly hindered scar contraction with control scars contracting to 64.6 + 13.9% original area at day 72 while PGT scars contracted to 82.7 + 17.9% original area. PGT significantly reduced skin hardness and increased skin strength by 1.3X. No difference in perfusion or blood vessel density was observed. Average collagen fiber diameter was greater in control burns than PGT. Conclusions PGT was effective at reducing scar contraction and improving biomechanics compared to control scars. These results confirm the efficacy of pressure garments and highlight the need to further investigate the role of pressure magnitude and time of therapy application to enhance their efficacy for optimal biomechanics and patient mobility.

Objective: (1) Develop a standardized approach to quantitatively measure residual limb skin health. (2) Report reference residual limb skin health values in people with transtibial and transfemoral amputation. Approach: Residual limb health outcomes in individuals with transtibial (n = 5) and transfemoral (n = 5) amputation were compared to able-limb controls (n = 4) using noninvasive imaging (hyperspectral imaging and laser speckle flowmetry) and probe-based approaches (laser doppler flowmetry, transcutaneous oxygen, transepidermal water loss, surface electrical capacitance). Results: A standardized methodology that employs noninvasive imaging and probebased approaches to measure residual limb skin health are described. Compared to able-limb controls, individuals with transtibial and transfemoral amputation have significantly lower transcutaneous oxygen tension, higher transepidermal water loss, and higher surface electrical capacitance in the residual limb. Innovation: Residual limb health as a critical component of prosthesis rehabilitation for individuals with lower limb amputation is understudied in part due to a lack of clinical measures. Here, we present a standardized approach to measure residual limb health in people with transtibial and transfemoral amputation. Conclusion: Technology advances in noninvasive imaging and probe-based measures are leveraged to develop a standardized approach to quantitatively measure residual limb health in individuals with lower limb loss. Compared to able-limb controls, resting residual limb physiology in people that have had transfemoral or transtibial amputation is characterized by lower transcutaneous oxygen tension and poorer skin barrier function.