Abstract
Hypertrophic scars are painful and unsightly scars frequently resulting from dermal trauma and characterised by excessive collagen. The application of silicone gel sheeting is an effective treatment for these scars. Proton Induced X-Ray Emission, Elastic (Non-Rutherford) Backscattering and Instrumental Neutron Activation were used to determine the compositional changes in the silicone gel sheeting and the skin resulting from contact of the gel with scarred and unscarred skin, and found that although in vitro tests on split skin and in vivo tests using unscarred tissue causes the skin to absorb Si (an essential constituent of collagen) from the silicone gel sheeting; in vivo tests on hypertrophic scar and control tissue show the reverse: silicone gel sheeting absorbs Si from hypertrophic scars against the concentration gradient. It is believed that this is an important factor in the success of the treatment of hypertrophic scars by silicone gel sheeting. The major, minor and trace element composition was determined for a total of 35 skin samples including breast, abdominal and hypertrophic scar tissue, comparing dermis and epidermis for these samples. Some split skin samples were also included. The hypertrophic scar tissue is characterised by enhanced Si content, with 3wt% compared with an average of 2wt% for the unscarred tissue. A pilot clinical trial was then conducted on 20 unscarred volunteers as controls over a week, and 9 volunteers with hypertrophic scars (clinical gel) over a three month period with silicone gel sheeting nominally used according to a strict protocol. Two subjects did not complete the trial, and there was evidence of non-compliance for at least three others. However, without excluding any data, we have observed a significant increase (10+/-1%) in Si content of the silicone gel sheeting in contact with hypertrophic scar over the controls. Significant composition differences between the dermis and the epidermis were observed as expected. Differences between the composition of scarred and unscarred tissue were not large. Significant increases in the average elemental composition were seen between the clinical gel compared to the unused gel for the elements: Cl, K, Ca, Fe and Ag providing further evidence that the gel absorbs elements from the scar tissue.