Scarring is a natural product of the repair of trauma to human tissue and is the result of the proliferation of fibrous tissue at the site of healing injury. The formation of keloid scars often results in unsightly appearance and functional impairment. They are classified according to their histological and morphological distinctions: superficial keloid scars, proliferative keloid scars, atrophic keloid scars, and keloid scars. The treatment of keloid scars is tricky, so prevention of keloid scars is more important than treatment, and many non-surgical treatment modalities for keloid scars are also preventive means.
Keloids often extend beyond the edges of the original injury, usually do not resolve on their own, often recur after excision, and are collectively referred to as pathologic keloid scars along with hyperplastic keloids. Non-surgical treatment of keloid scars and large hyperplastic scars in non-functional areas is mainly used, and non-surgical methods are also needed to prevent re-growth of the scar contracture after surgical excision or release. There is a wide variety of these methods with varying efficacy, and it can be said that no one treatment is the most effective for all patients, and a combination of treatment modalities is often needed to pursue the best results.
1.Silicone products
In 1983, Perkins et al. first reported the use of silicone film for the treatment of scarring in burn patients. Since then, scholars have been practicing and researching the use of silicone gel film for the treatment and prevention of scar growth for nearly 30 years now. Currently, silicone products are available in various forms, including creams, gels, silicone films, sprays, and silicone orthopedic garments. The mechanism of the therapeutic action of silicone is not yet fully understood. Silicone products have the advantage of being easy to use and non-invasive, flattening the scar, increasing its malleability and softening it, without side effects. Some scholars believe that wearing them for 12-24 hours a day for 2-3 months is more effective.
2.Compression therapy
The use of compression therapy for keloid scars dates back to 1835 and was widely used in the 1970s when some doctors found that applying compression stockings to the lower extremities after burns would accelerate the maturation of the scar and reduce its redness and thickness. The method is mainly used for recurrence prevention after surgery for proliferative or hyperplastic keloids or keloid scars with large scar areas.
The application method is roughly the same, with some suggesting a pressure of 20-40 mmHg, worn for 24 hours and removed for no more than 30 minutes a day for 6 months or more. Some studies have also found that elastic garments releasing more than 15 mmHg of pressure can accelerate the maturation of the scar. The main adverse effects of this method are moist heat, rash, restricted motion, and frictional damage.
3.Local drug injection
(1) Intra-scar corticosteroid injection
This is the most commonly used modality, and tretinoin is the most commonly used of the steroids. The concentration of trimethoprim depends on the location and size of the lesion and the age of the patient. The mechanism is to inhibit inflammatory mediators by inhibiting fibroblast proliferation, collagen synthesis, and glycosaminoglycan synthesis, promoting scar vasoconstriction and scar atrophy. Generally, concentrations of 10-20 mg/ml are used, up to 40 mg/ml when injected within larger and harder scars.
The injection may be repeated once every 2-4 weeks depending on the size of the scar and the response to treatment. The total dose depends on the effect of the injection and its systemic and local side effects. Pain during injection is an important limiting factor for the long-term use of this therapy, but with the availability of new needle-free injection systems, this problem should soon be resolved. Studies have shown that trimethoprim injection alone is effective in reducing scar volume in most patients. Intra-focal steroid injections are widely used clinically with proven efficacy and have long been considered a first-line treatment for keloids and hyperplastic scars.
(2) Intra-focal fluorouracil (5-FU) injection
This treatment method is becoming increasingly popular. It acts on rapidly proliferating skin fibroblasts that produce excessive collagen. 5-FU alone has been shown to be effective in the treatment of keloids. The concentration and frequency of use is 50 mg/ml, 1-3 times/week. The main side effects of 5-FU are pain, wound ulceration, purpura at the injection site, local depression, and hyperpigmentation.
(3) Intra-scar injections of Pingyangmycin
Pingyangmycin is a traditional antitumor drug with cytotoxic properties. Some studies have shown that pinyamycin is superior to cryotherapy combined with intra-scar hormone injections for the treatment of larger keloids or hyperplastic scars (>100 mm2). It has been documented that up to 53.8%C73.3% of patients with complete flattening of the skin without recurrence after intra-scar injections. Skin toxicity usually occurs after a cumulative total of 200-300 U, with pulmonary fibrosis occurring after a total of more than 400 U. The main adverse effects are local hyperpigmentation as well as ulceration. More rarely, serious complications in the lungs, liver and other organs due to Pingyangmycin have been found.
(4) Topical injections of other drugs
Local injections of botulinum toxin type A, collagenase, hyaluronic acid, etc. Local injection of botulinum toxin is more effective and has now started to be commonly used.
4.Radiotherapy
Radiation therapy has been used for many years as a monotherapy for keloids or as an adjunct to surgical excision. Surgery combined with radiotherapy is considered to be the most effective method. Its effectiveness rate is 67-98%. The scar is surgically removed and radiotherapy is administered within 24-48 hours. The growth inhibition and potential carcinogenicity of this method in young children are the main limiting factors. Most scholars recommend immediate postoperative radiotherapy with multiple small doses, and the total dose should be 15-20 Gy. E-beam irradiation is usually considered the most effective, and strontium 90 brachytherapy also has good efficacy. In recent years, brachytherapy with 32P dressing has made this method more convenient and effective.
Most radiation therapists consider keloids to be an indication for radiation therapy, and the benefits outweigh the risks. Adverse effects include skin redness, peeling, capillary dilation and permanent skin color changes, hypopigmentation, all of which are acceptable.
5.Laser
Lasers are now becoming increasingly important in scar treatment. In recent years, pulsed dye laser (PDL) has been used to treat keloid scars with good results. once every 4-8 weeks, a total of 1-6 treatments can achieve better results. pDL can be used to reduce hyperplastic keloid scars after surgery or after burns. It is effective in reducing redness, thickness, itching, and restoring skin texture. The main side effects are transient purpura and hyperpigmentation or depigmentation. However, laser treatment is not effective for keloids.
The treatment of keloid scars is still a medical challenge, and once a scar is created, it cannot be completely eliminated. There are many current treatments for hyperplastic keloid scars and keloids, but none of them can achieve fully satisfactory results. Silicone, pressure, hormonal injections, radiation therapy after surgical excision, and laser are all relatively effective and can be used alone or in combination with each other to achieve certain therapeutic results. In general, the combination of two or more treatment methods is more effective than one treatment method alone.