Unexpected wound occurring following negative pressure wound therapy

Dear Editors, A 67-year-old man with type 2 diabetes mellitus of 2 years duration was presented 4 weeks after amputation of a gangrenous and infected toe, with a large non-healing wound at the surgical site (Figure 1). Pedal pulses were non-palpable and he had severe loss of foot sensation. The patient had a poor diabetes control with a haemoglobin A1c level of 8·4% (normal 3·3–6·4%). Apart from hypertension, he did not have any other known comorbidities. Infection markers at admission were as follows: white blood count = 13500 (mm3/L), erythrocyte sedimentation rate = 105 mm/hour, C-reactive protein = 57 mg/l. The patient received comprehensive wound management including daily wound care, culture-driven antimicrobial treatment, hyperbaric oxygen therapy and negative pressure wound therapy (NPWT). The NPWT system, which has been shown to promote wound healing, consists of a vacuum pump and a canister connected to each other and to the wound site with several tubes. The system drains excess fluid from the wound base and thereby sustains an optimum moist milieu, helps control bacterial burden and restores microcirculation by decreasing interstitial pressure. In the current case, we had fixed the drainage tube, one of the pieces of the NPWT system, over the dorsal aspect of the patient’s foot. On opening the dressing 3 days after its application, to our great surprise we