Stretched scars

Stretched, or widened, scars occur when healing wounds are exposed to mechanical stress. They can be the result of the wound physically coming apart - dehiscence - and then healing by secondary intention, or from the early scar deforming in response to the extrinsic forces. Most stretching occurs in the first three months after surgery but the process can continue for up to a year.

There is no age, gender or racial predisposition. However, a stretched scar is more likely when the skin is inherently weak during repair. This can occur with collagen diseases such as Ehlers-Danlos Syndrome, progeria, and with dermal atrophy eg with advanced age or chronic sun exposure. The most significant pathogenetic factor is the inherent tension within the skin. The tension is maximal along discrete lines along the body surface. The skin tends to fold and crease along lines which are generally perpendicular to tension; these are termed 'relaxed skin tension lines' or RSTL's. Incised wounds which are perpendicular to the RSTL's are more likely to be exposed to tension and to stretch.

Usually, stretched scars are flat or depressed, pale and soft with no elevation above the surrounding skin. Typical examples include abdominal striae where the dermal elastic tissue is stretched excessively, and scars across mobile sites such as the knee joint. The limbs and the abdomen are the commonest site of occurrence.

Although generally symptomless, if the patient is concerned by the appearance of a prominent stretched scar, it may be treated by excision and closure with meticulous surgical technique while countering the of stresses across the wound eg by long-term tape dressing support or a permanent, non-absorbable intradermal suture. Such scar revision should only be attempted when the scar has matured to full strength which can typically take 12-18 months. The patient must be made aware that a scar is inevitable again after treatment, and that with further excision, stretching is more likely unless measures are taken to prevent it. Other techniques that have been tried to treat stretched scars surgically include:

• incising the skin around the scar as an ellipse, de-epithelialising the scar and then closing the surrounding skin over the top of the dermis of the previous scar; provides volume to the depressed element of the scar
• revising the scar with realigment of tension eg by placing a z-plasty into the scar
• attempts to increase volume beneath the depressed centre of the scar:
  • injection of fat eg Coleman fat grafting
  • placement of dermal fat grafts composites
  • injection of artificial filler substances like hyaluronic acid