Mansher Singh

The external microenvironment of healing skin wounds.

The skin wound microenvironment can be divided into two main components that influence healing: the external wound microenvironment, which is outside the wound surface; and the internal wound microenvironment, underneath the surface, to which the cells within the wound are exposed. Treatment methods that directly alter the features of the external wound microenvironment indirectly affect the internal wound microenvironment due to the exchange between the two compartments. In this review, we focus on the effects of temperature, pressure (positive and negative), hydration, gases (oxygen and carbon dioxide), pH, and anti‐microbial treatment on the wound. These factors are well described in the literature and can be modified with treatment methods available in the clinic. Understanding the roles of these factors in wound pathophysiology is of central importance in wound treatment.

Challenging the Conventional Therapy: Emerging Skin Graft Techniques for Wound Healing.

Background: Split-thickness skin grafting is the current gold standard for treatment of major traumatic skin loss. However, split-thickness skin grafting is limited by donor-skin availability, especially in large burns. In addition, the donor-site wound is associated with pain and scarring. Multiple techniques have been developed in the past to overcome these limitations but have been unable to achieve clinical relevance. In this study, the authors examine the novel emerging skin grafting techniques, aiming to improve the utility of split-thickness skin grafting. Methods: An extensive literature review was conducted on PubMed, MEDLINE, and Google Scholar to look for new skin grafting techniques. Special focus was given to techniques with potential for large expansion ratio and decreased donor-site pain. Results: The new modalities of modified skin grafting technique, discussed in this article, include (1) Xpansion Micrografting System, (2) fractional skin harvesting, (3) epidermal suction blister grafting, and (4) ReCell technology. These techniques are able to achieve significantly increased expansion ratios compared with conventional split-thickness skin grafting and also have decreased donor-site morbidity. Conclusions: These techniques can be used separately or in conjunction with split-thickness skin grafting to overcome the associated pitfalls. Further studies and clinical trials are needed to define the utility of these procedures and where they fit into routine clinical practice.

The effect of pH on cell viability, cell migration, cell proliferation, wound closure, and wound reepithelialization: In vitro and in vivo study

Wound microenvironment plays a major role in the process of wound healing. It contains various external and internal factors that participate in wound pathophysiology. The pH is an important factor that influences wound healing by changing throughout the healing process. Several previous studies have investigated the role of pH in relation to pathogens but studies concentrating on the effects of pH on wound healing itself are inconclusive. The purpose of this study was to comprehensively and in a controlled fashion investigate the effect of pH on wound healing by studying its effect on human primary keratinocyte and fibroblast function in vitro and on wound healing in vivo. In vitro, primary human keratinocytes and fibroblasts were cultured in different levels of pH (5.5–12.5) and the effect on cell viability, proliferation, and migration was studied. A rat full‐thickness wound model was used to investigate the effect of pH (5.5–9.5) on wound healing in vivo. The effect of pH on inflammation was monitored by measuring IL‐1 α concentrations from wounds and cell cultures exposed to different pH environments. Our results showed that both skin cell types tolerated wide range of pH very well. They further demonstrated that both acidic and alkaline environments decelerated cell migration in comparison to neutral environments and interestingly alkaline conditions significantly enhanced cell proliferation. Results from the in vivo experiments indicated that a prolonged, strongly acidic wound environment prevents both wound closure and reepithelialization while a prolonged alkaline environment did not have any negative impact on wound closure or reepithelialization. Separately, both in vitro and in vivo studies showed that prolonged acidic conditions significantly increased the expression of IL‐1 α in fibroblast cultures and in wound fluid, whereas prolonged alkaline conditions did not result in elevated amounts of IL‐1 α .

Functional Outcomes after Bilateral Hand Transplantation: A 3.5-Year Comprehensive Follow-Up.

Background: Since the first successful hand transplantation in 1998, 72 patients have been operated on for unilateral/bilateral hand transplantation across 13 countries. There have been multiple studies evaluating the outcomes of hand transplantation; however, there is considerable variability among the outcome measures evaluated in these studies. Methods: This article reports functional outcomes in a patient with bilateral hand transplants at a mid-forearm level with serial follow-ups over 3.5 years. Different parameters used to study the functional outcomes include the Disabilities of the Arm, Shoulder, and Hand score, the Carroll test, the Hand Transplant Score System, the Short Form-36 Health Survey, and routine occupational therapy measures. Various task-oriented outcomes were also assigned to provide milestones to the recovery. Results: The patient had a Disabilities of the Arm, Shoulder, and Hand score of 40, a Carroll test score of 48 (right) and 49 (left), and a Hand Transplant Score System score of 58 (right) and 57.5 (left) at 3.5-year follow-up. Interestingly, his objective scores did not change significantly during the follow-up, but he continued to function quite independently and is subjectively pleased with his outcomes. Conclusions: Multiple functional outcome measures provide an objective way to follow patients who have undergone hand transplantation. The authors propose a series of measures to elucidate subtleties in functional gains. However, use of this series in isolation may belie subjectively good results. They also propose a series of milestones in the recovery to give a better real-world explanation of progress. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Inequalities in Specialist Hand Surgeon Distribution across the United States.

Background: Unequal access to hospital specialists for emergency care is an issue in the United States. The authors sought to describe the geographic distribution of specialist hand surgeons and associated factors in the United States. Methods: Geographic distributions of surgeons holding a Subspecialty Certificate in Surgery of the Hand and hand surgery fellowship positions were identified from the American Board of Medical Specialties Database and the literature (2013), respectively. State-level population and per capita income were ascertained using U.S. Census data. Variations in hand trauma admissions were determined using Healthcare Cost and Utilization Project national/state inpatient databases. Risk-adjusted generalized linear models were used to assess independent association between hand surgeon density and hand trauma admission density, fellowship position density, and per capita income. Results: Among 2019 specialist hand surgeons identified, 72.1 percent were orthopedic surgeons, 18.3 percent were plastic surgeons, and 9.6 percent were general surgeons. There were 157 hand surgery fellowship positions nationwide. There were 149,295 annual hand trauma admissions. The national density of specialist hand surgeons and density of trauma admission were 0.6 and 47.6, respectively. The density of specialist hand surgeons varied significantly between states. State-level variations in density of surgeons were independent and significantly associated with median per capita income (p < 0.001) and with density of fellowships (p = 0.014). Conclusions: Specialist hand surgeons are distributed unevenly across the United States. State-level analyses suggest that states with lower per capita incomes may be particularly underserved, which may contribute to regional disparities in access to emergency hand trauma care.

Pixel Grafting: An Evolution of Mincing for Transplantation of Full-Thickness Wounds.

Background: Split-thickness skin grafting is the gold standard for treatment of major skin loss. This technique is limited by donor-site availability in large burn injuries. With micrografting, a technique where split-thickness skin graft is minced into 0.8 × 0.8-mm pieces, the authors have demonstrated an expansion ratio of 1:100 and healing comparable to that achieved with split-thickness skin grafting. Methods: In this study, the authors explore the regenerative potential of a skin graft by cutting split-thickness skin grafts to pixel size (0.3 × 0.3 mm) grafts. Wound healing was studied in full-thickness wounds in a porcine model by creating an incubator-like microenvironment using polyurethane wound chambers. Multiple wound healing parameters were used to study the outcome of pixel grafting and compare it to micrografting and nontransplanted wounds. Results: The authors’ results show that 0.3 × 0.3-mm pixel grafts remain viable and contribute to skin regeneration. The pixel graft–transplanted wounds demonstrated a faster reepithelialization rate, decreased wound contraction, and increased mechanical stability compared with nontransplanted wounds. The reepithelialization rates of the wounds were significantly increased with pixel grafting at day 6 after wounding compared with micrografting. Among the other wound healing parameters, there were no significant differences between wounds transplanted with pixel grafts and micrografts. Conclusions: Pixel grafting technique would address the most commonly encountered limitations of the split-thickness skin graft with the possibility of an even larger expansion ratio than micrografting. This technique is simple and fast and can be conducted in the operating room or in the clinic.

The medial femoral condyle free osteocutaneous flap for osteomyelitis in pilon fractures

BACKGROUND High energy tibial plafond (pilon) fractures are known to have a high rate of complication, particularly wound dehiscence and infection. Wound infection, requiring debridement of both soft tissue and bone can be especially challenging to reconstruct due to the combination of high load-bearing requirements within a thin soft tissue envelope. METHOD We present a case of a pilon fracture with a post-operative complication of wound dehiscence and infection necessitating bone debridement, ultimately resulting in chronic osteomyelitis. We used a medial femoral osteocutaneous free flap to provide vascularised structure to the defect. Included is a comprehensive literature review for the use of the MFC osteocutaneous free flaps in lower extremities. RESULTS This flap provided restoration of the medial column of the ankle. The use of vascularised bone resulted in rapid post-operative bony union. The vascularised bone flap was press fit into the defect ruling out the potential for further hardware related infections. We report follow up of over one year. CONCLUSION The MFC free osteocutaneous flap is a good option for small bone and soft tissue defects of lower extremities, especially in setting of chronic osteomyelitis. It can be custom fabricated and either fixated or press fit into a chronic pilon fracture cavity to obliterate dead space with vascularised bone. LEVEL OF EVIDENCE Level IV, retrospective case study.

Psychosocial Outcomes after Bilateral Hand Transplantation

Background: Since the first successful hand transplantation in 1998, there have been multiple reports about surgical technique, transplant survival, and immunosuppression. However, very limited published data exist on psychosocial outcomes following hand transplantation. Methods: We report psychosocial outcomes in a patient with bilateral hand transplants at the midforearm level with serial follow-ups over 3.5 years. Different metrics used to study psychosocial outcomes included the following: SF-12, CES-D, Dyadic Adjustment Scale, Rosenberg SE, and EQ-5D. Result: Preoperatively, our patient did not have any evidence of depression (CES-D = 3), had a nonstressful relationship with his spouse (Dyadic Adjustment Scale = 100), and self-esteem was in the normal range (Rosenberg SE = 21). These metrics and his additional scales (SF-12 MCS, EQ-5D, and EQ-VAS) did not change appreciably and were within the normal range for the entire duration of 3.5-year follow-up at all different time points. Conclusion: With the increasing popularity of hand transplantation and the increasing awareness of the importance of psychosocial parameters in overall success, appropriate, comprehensive, and standardized measurements are important. These should be an integral part of patients’ screening and follow-up.

Evolution of skin grafting for treatment of burns: Reverdin pinch grafting to Tanner mesh grafting and beyond

BACKGROUND Skin grafting is the current standard care in the treatment of full thickness burns. It was first described around 1500 BC but the vast majority of advancements have been achieved over the past 200 years. METHODS An extensive literature review was conducted on Pubmed, Medline and Google Scholar researching the evolution of skin grafting techniques. The authors concentrated on the major landmarks of skin grafting and also provide an overview of ongoing research efforts in this field. RESULTS The major innovations of skin grafting include Reverdin pinch grafting, Ollier grafting, Thiersch grafting, Wolfe grafting, Padgett dermatome and modifications, Meek-wall microdermatome and Tanner mesh grafting. A brief description of the usage, advantages and limitations of each technique is included in the manuscript. CONCLUSIONS Skin grafting technique have evolved significantly over past 200 years from Reverdin pinch grafting to modern day meshed skin grafts using powered dermatome. Increasing the expansion ratio and improving the cosmetic and functional outcome are the main focus of ongoing skin grafting research and emerging techniques (such as Integra®, Recell®, Xpansion®) are showing promise.

Development of a precise experimental burn model

BACKGROUND Porcine wounds closely mimic human wounds and are often used experimentally in burn studies. Multiple burn devices have been reported but they rarely described precise amount of heat transfer and the burn devices generally have low and varying heat capacity resulting in significant and varying temperature drop. METHODS The authors developed a customized aluminum burn device with cork insulation and high heat capacity. A thermistor probe was embedded in the device to accurately measure the temperature of the aluminum. The burn injury was inflicted by preheating the burn device to 100°C and pressing on the dorsum of pig skin for different time points ranging from 5 to 30s using standardized force of 10N on the device. With the knowledge of the heat capacity of the aluminum block and the temperature drop, the amount of heat transferred can be calculated. RESULT The temperature drop was 0°C, 1°C, 2°C, 3°C and 5°C for a wound-device contact time of 5, 10, 15, 20 and 30s, respectively. The depths of injury at 72h after burn were 0.46mm, 0.82mm, 1.21mm, 1.61mm and 1.91mm at 5, 10, 15, 20 and 30s respectively. 3.1mm represented a full thickness burn. The depth of the burn wounds significantly correlated with the heat transferred per cm2 (correlation coefficient=0.96, p-value=0.03). CONCLUSION The authors describe a simple, standardized and reproducible animal burn model using a customized burn device. The high heat capacity ensures minimal temperature drop which minimizes the variability of heat transferred with a large temperature drop. The correlation between the heat transfer and the depth of injury can facilitate standardization of burn depths in future studies.