Degloving skin injuries are severe injuries where skin and subcutaneous tissue extensively separate from underlying structures. They are complex and require immediate medical attention due to potential tissue damage and complications. Understanding their nature and mechanisms is important.
Defining Degloving
Degloving is a specific type of avulsion injury where a large section of skin and the fat layer directly beneath it are torn away from deeper muscle, fascia, or bone. This separation occurs across the subcutaneous plane, which is the loose connective tissue layer situated between the dermis and the underlying musculature or bone. The injury effectively “degloves” the affected area, much like removing a glove.
The skin consists of multiple layers: the epidermis (outermost), dermis (middle, containing connective tissue, hair follicles, and sweat glands), and subcutaneous tissue (innermost, primarily composed of fat and loose connective tissue). In a degloving injury, the epidermis and dermis typically remain attached to the subcutaneous tissue, but this unit is detached from the deeper structures, often leading to a compromised blood supply for the avulsed skin segment.
The Mechanics of Injury
Degloving injuries result from mechanical forces that overcome the skin’s tensile strength and its connections to underlying tissues. Shearing forces are a primary mechanism, occurring when tangential forces cause adjacent tissue layers to slide past each other. This tears vascular and connective tissue attachments, initiating degloving.
Crushing forces also contribute to degloving, especially in high-energy trauma. Compressive forces devitalize tissues, leading to separation and detachment as structural integrity is compromised. Crushing against a hard surface causes widespread cellular damage and breakdown of tissue planes.
Tearing or avulsion forces involve direct pulling or tensile stress that rips skin and subcutaneous tissue away from its anatomical position. This happens when a limb or body part is caught and subjected to a strong pulling motion, causing layers to separate violently. Often, a combination of these forces acts simultaneously, exacerbating the extent of the injury.
Common Incidents Leading to Degloving
Motor vehicle accidents frequently cause degloving injuries, especially when limbs are caught between moving parts or a pedestrian is struck and dragged. Impact and friction generate significant shearing and avulsion forces that strip skin from underlying muscle and bone. Motorcycle accidents, in particular, carry a high risk due to the direct exposure of limbs to road surfaces during slides.
Industrial and farming accidents also commonly result in degloving injuries, often involving machinery. Entrapment in conveyor belts, augers, or power take-off (PTO) shafts on farm equipment can exert immense rotational or crushing forces that pull and tear skin. These scenarios often combine crushing and avulsion mechanisms, leading to extensive tissue damage.
Falls from heights or accidents involving heavy objects can also cause degloving, particularly if a limb or body part is pinned and subjected to crushing and shearing forces. While less common, localized degloving can occur from animal attacks, where a bite or clawing action tears skin away from the underlying tissues.
Tissue Damage During Degloving
As degloving unfolds, the separated skin and subcutaneous tissue suffer severe disruption of their blood supply. The intricate network of small blood vessels (arteries, veins, and capillaries) that nourish the skin is torn, leading to significant bleeding and compromised tissue viability. Without adequate blood supply, the avulsed tissue quickly becomes ischemic and can undergo necrosis (tissue death).
Nerve damage is also common, as sensory and motor nerves in the subcutaneous layer are stretched, torn, or crushed during separation. This can result in immediate loss of sensation or function in the affected area, depending on the nerves involved. Lymphatic vessels, responsible for draining fluid, are similarly disrupted, contributing to swelling and fluid accumulation.
The subcutaneous fat and connective tissue, which normally provide cushioning and insulation, are extensively damaged or destroyed. This loss exposes underlying muscles, tendons, and bones, making them vulnerable to infection and further injury. The physical impact on these tissues determines the immediate and long-term consequences for the affected limb or body part.