A shear wound is a type of soft tissue injury that occurs when layers of skin and underlying tissues slide over each other in opposite directions. This movement can stretch and damage blood vessels, reducing blood flow and oxygen to the affected area. Understanding shear wounds is important because they can lead to significant tissue damage that may not be immediately visible on the skin’s surface.
Understanding Shear Wounds
A shear wound is a deeper injury to the skin and underlying tissues, distinct from more superficial skin damage like friction burns or pressure ulcers. Friction injuries involve the top layer of skin (epidermis) separating from the layer beneath it (dermis) due to rubbing against a surface. This damage is typically limited to superficial layers and results in partial thickness wounds.
In contrast, shearing involves both downward pressure and friction, causing deeper tissue layers to shift laterally relative to each other, often when bone and deep tissue move in opposing directions. While friction primarily affects the skin’s surface, shear impacts deeper tissues, causing damage that can be more severe and harder to detect initially.
How Shear Wounds Develop
Shear wounds typically develop when the skin remains stationary on a surface while the underlying bone and deep tissues move. This often occurs when a person slides down in a bed or chair, as the outer skin layer sticks to the surface due to friction, but the deeper tissues attached to the bone continue to move.
Common scenarios include individuals sliding down in bed when the head of the bed is elevated, during transfers from one surface to another, or when a person scoots instead of lifting their body fully. Immobility is a significant risk factor, as individuals who cannot reposition themselves are more susceptible to prolonged shearing forces. Other factors like incontinence can also compromise skin integrity, making it more vulnerable to shear injuries.
Recognizing a Shear Wound
Recognizing a shear wound can be challenging because the damage often begins in the deeper tissue layers and progresses outwards. Unlike pressure injuries that might show early signs like skin reddening, shear-induced wounds may not be visible until they are in an advanced stage.
When a shear wound becomes apparent, it often presents as an asymmetrical, ragged, or unevenly shaped wound, covering a larger surface area than a typical pressure injury. There may be discoloration, similar to a bruise. Signs such as tunneling or undermining, where the wound extends beneath the visible skin surface, are strong indicators of shear forces at play due to deep tissue destruction.
Managing and Preventing Shear Wounds
Effective management of shear wounds involves both immediate care and long-term prevention strategies. For minor shear wounds, initial first aid includes gently cleaning the wound with lukewarm water to remove any dirt or debris, followed by carefully patting the surrounding skin dry. If there is a skin flap, it should be gently repositioned over the wound bed if possible. The wound should then be covered with a non-stick or gentle dressing, secured with a light bandage, avoiding tape on fragile skin.
Professional medical attention is advised if the wound shows signs of infection, continues to bleed, if skin cannot be realigned, or if it appears large, deep, or is not healing. Prevention focuses on reducing the mechanical forces that cause shearing. This includes maintaining the head of a bed at 30 degrees or below to minimize sliding. Proper repositioning techniques, using assistive devices like slide sheets, mechanical lifts, or trapeze bars, can help move individuals without dragging their skin across surfaces.
Using appropriate support surfaces such as specialized mattresses, overlays, or cushions that redistribute pressure and reduce shear is also beneficial. Heel and elbow protectors can shield vulnerable areas. Maintaining good skin hygiene with mild soap and warm water, along with ensuring adequate nutrition and hydration, supports overall skin health.