In burn patients, the wound healing process may lead to a fibrotic hypertrophic scar, which is raised, inflexible and responsible functional impairments. There are few studies which have investigated the effect of extracorporeal shock wave therapy (ESWT) on hypertrophic scar characteristics using objective measurements. Thus, this study aimed to ascertain the effects of ESWT on burn scars using objective measurements. This double-blinded, randomized, controlled trial involved 36 patients with burns. Patients were randomized into a ESWT (an energy flux density (EFD) of 0.05 to 0.30 mJ/mm2, frequency of 4Hz, and 1000 to 2000 impulses) or a sham stimulation group.

In burn patients, the wound healing process may lead to a fibrotic hypertrophic scar, which is raised, inflexible and responsible functional impairments. There are few studies which have investigated the effect of extracorporeal shock wave therapy (ESWT) on hypertrophic scar characteristics using objective measurements. Thus, this study aimed to ascertain the effects of ESWT on burn scars using objective measurements. This double-blinded, randomized, controlled trial involved 36 patients with burns. Patients were randomized into a ESWT (an energy flux density (EFD) of 0.05 to 0.30 mJ/mm2, frequency of 4Hz, and 1000 to 2000 impulses) or a sham stimulation group. Each intervention was applied to the hypertrophic scars of upper extremities after autologous split-thickness skin grafting (STSG) using Materiderm for 4 weeks once per week. The ESWT group (n=18) received shock waves with low-energy flux density (0.05-0.30 mJ/mm2). The interval between treatments is a 1-week. The ESWT group also received standard treatment. The control group (n=18) received sham stimulation with standard treatment. The investigators compared the skin quality of the ESWT and control groups. Participants were made comfortable and acclimatized to room conditions. Room temperature was maintained at 20-25'C and relative humidity at 40-50 %. In the supine position, skin properties were measured. The thickness was measured with a ultrasonic wave equipment (128 BW1 Medison, Korea). Mexameter® (MX18, Courage-Khazaka Electronics GmbH, Germany) was used to measure melanin levels and the severity of erythema. The higher values indicating a darker and redder skin. TEWL was measured with a Tewameter® (Courage-Khazaka Electronic GmbH, Germany), which is used for evaluating water evaporation. Sebum in the scars was measured with the Sebumeter® (Courage-Khazaka Electronic GmbH, Germany). The measurement is based on the principle of grease-spot photometry using a cassette with its special tape. A microprocessor calculates the result, which is shown on the display in mg/cm2. Elasticity was measured using Cutometer SEM 580® (Courage-Khazaka Electronic GmbH, Cologne, Germany), which applies negative pressure (450 mbar) on the skin. The numeric values (mm) of the skin's distortion is presented as the elasticity. Two seconds of negative pressure of 450 mbar is followed by 2 s of recess, and this consists of a complete cycle. Three measurement cycles were conducted, and the average values were obtained.

Inclusion Criteria:

• aged ≥18 years
• deep partial-thickness (second-degree) burn or a full thickness (third-degree) burn
• less than 6 months since the onset of the burn injury

Exclusion Criteria:

• history of cancer
• fourth-degree burns (involving muscles, tendons, and bone injuries)
• musculoskeletal diseases (fracture, amputation, rheumatoid arthritis, and degenerative joint diseases)
• pregnancy
• if there was potential for additional damage to the skin due to the use of ESWT and conventional occupational therapy

1. The patients didnot know whether it is included in the experimental group and control group
2. Outcome measurements and data analyses were performed by a trained and blinded outcome assessor who was not involved in the intervention.