Scars are the body’s natural method of repairing damaged tissue. A contracture scar is a distinct and severe category of scar characterized by the pathological tightening and shortening of the skin and underlying tissues. This type of scarring is concerning because it is not merely a cosmetic issue; it physically restricts movement and function. Contracture scars represent a significant health challenge due to their profound effect on physical abilities and overall quality of life.
The Biological Mechanism of Contracture Scar Formation
The formation of a contracture scar begins with a deep tissue injury, such as a third-degree burn or severe trauma, that extends beyond the superficial layers of the skin. This deep injury triggers an excessive and prolonged response from specialized cells called myofibroblasts. Myofibroblasts are modified fibroblasts that possess contractile properties, similar to smooth muscle cells, allowing them to pull the edges of a wound together during normal healing.
These cells express alpha-smooth muscle actin (\(\alpha\)-SMA), which enables them to generate strong, sustained mechanical forces on the surrounding tissue matrix. Myofibroblasts also secrete large amounts of new extracellular matrix (ECM), particularly collagen. This collagen is deposited in a disorganized, dense fashion, creating the core structure of the scar.
The persistent activation and mechanical action of the myofibroblasts on the collagen matrix physically shorten the wound bed, a process known as wound contraction. While beneficial for closing a minor wound, this process becomes pathological when it continues excessively, pulling the adjacent healthy skin inward. Unlike hypertrophic or keloid scars, which involve tissue overgrowth, a contracture scar is defined by this mechanical retraction and physical shortening.
Identifying the Functional Limitations Caused by Contractures
The primary consequence of contracture scar formation is a profound restriction in the range of motion (ROM) of a joint. When the skin and underlying tissue shorten, they act like a tight band, preventing the full extension or flexion of a limb. This limitation can vary from moderate stiffness to a complete inability to move the affected joint.
The most susceptible areas for contractures are those with high mobility, including:
- The neck
- Hands
- Armpits (axilla)
- Elbows
- Knees
For example, a contracture on the neck can impair the ability to turn the head or look up, limiting the horizontal plane of vision. Contractures across the joints of the hand can lead to severe deformities that compromise the ability to grip or perform fine motor tasks.
In severe cases, the deep scar tissue can embed underlying structures, including tendons, blood vessels, and nerves. This deep involvement can lead to nerve entrapment, causing chronic pain, numbness, tingling, or muscle weakness in the affected limb. Tissue deficits can range from 2 to 10 centimeters in the most affected areas. This functional restriction, rather than the scar’s appearance, is the main measure of the contracture’s severity and impact.
Current Treatment and Management Options
Management of contracture scars requires a multidisciplinary approach, often beginning with non-surgical interventions aimed at prevention and maintenance. Physical and occupational therapy are initiated early to maintain the existing range of motion through active and passive stretching exercises. Constant stretching helps to elongate the developing scar tissue, which is particularly malleable in the first few months after the injury.
Pressure therapy, using custom-fitted pressure garments, is a standard non-surgical technique. This therapy applies continuous, uniform pressure to the scar, which reduces blood flow and discourages excessive collagen production, leading to a flatter, softer texture. Silicone sheets or gels are also applied to the scar surface to improve hydration and flexibility, encouraging pliable scar maturation.
If non-surgical methods are insufficient to restore function, surgical intervention becomes necessary to release the tension caused by the scar. The goal of surgery is to excise the tight scar tissue and replace the resulting skin deficit to allow for full range of movement.
Surgical Techniques
For linear contractures, a procedure called Z-plasty is commonly used, involving making a Z-shaped incision to rearrange the tissue flaps and lengthen the scar line.
In cases of larger or more severe planar contractures, the defect must be covered with healthy tissue using a skin graft or a flap. A skin graft involves transplanting a thin layer of skin from a healthy donor site. A skin flap includes the underlying blood vessels, fat, and sometimes muscle, and is preferred for deeper defects or areas with poor blood supply.
Tissue expansion involves surgically inserting a balloon-like expander under healthy skin adjacent to the contracture, slowly stretching the skin over time to generate extra tissue for reconstruction. Post-operatively, patients must immediately return to aggressive physical therapy and splinting to prevent the repaired site from re-contracting.