A filled chocolates technique to seal negative-pressure wound therapy around external fixation devices: a randomized controlled trial

BACKGROUND: In complex injuries, external fixation device represents a challenge to maintain negative-pressure wound therapy (NPWT). In this trial, we compared a combination of bone wax and colostomy paste versus bone wax alone to seal NPWT around external fixation devices. METHODS: Debridement surgeries of limbs with open fracture and large soft tissue defect need NPWT to be applied around the external fixation devices were randomized into two groups. The seal between external fixation devices and the drape was established using either bone wax first and then reinforced with colostomy paste or bone wax alone. The primary outcome was seal failure within 3 days of debridement. Secondary outcomes included the number of seal failure per debridement surgery and the time spent in repairing the seal within 3 days. RESULTS: A total of 56 debridement surgeries were enrolled: 28 to the bone wax/colostomy paste group versus 28 to the bone wax control group. One patient in the control group died 1 day after the first debridement surgery. One patient in the bone wax/colostomy paste group was transferred to other hospitals within 3 days. The final analysis included 27 debridement surgeries in the bone wax/colostomy paste group and 27 debridement surgeries in the control group. The rate of seal failure (defined by loss of negative pressure at anytime within 3 days) was 81.5% (22/27) in the control group versus 11.1% (3/27) in the bone wax/colostomy paste group (p < 0.001; χ(2) test). The bone wax/colostomy paste group also had significantly lower number of seal failures per debridement (median of 0 vs. 2; p = 0.004), and shorter time spent in repairing the seal (median of 0 vs. 18 min; p < 0.001). CONCLUSIONS: Using bone wax followed by colostomy paste to seal NPWT around external fixation devices reduces seal failure.