The distance between new and previous incisions does not affect skin necrosis in total knee arthroplasty: a parallel-randomized controlled clinical trial

BACKGROUND: To avoid skin necrosis, an 8 cm distance between the new and previous incision is recommended in patients undergoing total knee arthroplasty (TKA). It was hypothesized that making a new incision less than 8 cm of the prior scar does not increase the risk of skin complications, and the new incision can be made anywhere, regardless of the distance from the previous scar. This study investigated how making a new incision, irrespective of the previous scars, affects skin necrosis. METHODS: In this parallel, randomized clinical trial, by simple randomization method using a random number table, 50 patients with single longitudinal knee scars were randomly assigned to two groups with a 1:1 ratio and 25 participants in each group. Patients with a minimum age of 60 and a single longitudinal previous scar on the knee were included. The exclusion criteria were diabetes mellitus, hypertension, morbid obesity, smoking, vascular disorders, cardiopulmonary disorders, immune deficiencies, dementia, and taking steroids and angiogenesis inhibitors. TKA was performed through an anterior midline incision, regardless of the location of the previous scar in the intervention group. TKA was performed with a new incision at least 8 cm distant from the old incision in the control group. Skin necrosis and scar-related complications were evaluated on the first and second days and first, second, and fourth weeks after the surgery. Knee function was assessed using the Knee Society Score (KSS) six months after the surgery. RESULTS: The baseline characteristics of the groups did not differ significantly. The average distance from the previous scar was 4.1 ± 3.2 cm in the intervention group and 10.2 ± 2.1 cm in the control group. Only one patient in the control group developed skin necrosis (P-value = 0.31). Other wound-related complications were not observed in both groups. The mean KSS was 83.2 ± 10.2 and 82.9 ± 11.1 in the intervention and control groups, respectively (P-value = 0.33). CONCLUSIONS: It is possible that in TKA patients, the new incision near a previous scar does not increase the risk of skin necrosis and other complications.