Flowable Porcine Urinary Bladder Matrix in Wounds Complicated by Tunneling and Undermining: A Multicenter Prospective Study

Objective: This multicenter, prospective, single-arm study evaluated the safety and preliminary clinical performance of a flowable porcine urinary bladder matrix (UBM) particulate for managing tunneling and undermining features in complex wounds. These features are associated with delayed healing, chronic inflammation, and infection risk. Flowable UBM enables targeted delivery into wound tunnels and cavities. Method: Twenty-five subjects from 3 United States (U.S.) sites were enrolled, with 21 meeting protocol criteria for analysis (15 with undermining and 6 with tunneling wounds). Participants received flowable UBM applied directly to tunneling or undermining areas, along with additional UBM particulate or sheet forms applied to the wound surface. The primary endpoint was the percentage reduction in tunneling volume or undermining depth at 12 weeks, with secondary assessment of reduction in overall wound volume. Safety was evaluated through evaluation of device-related adverse events. Results: At 12 weeks, 90.5% of wounds demonstrated positive response, with mean ± standard deviation and median reduction in tunneling or undermining dimensions of 84.6 ± 29.3% and 100.0%, respectively. Complete resolution of these features occurred in 52.4% of wounds (53.3% in undermining and 50.0% in tunneling wounds) with higher closure rates in non-pressure wounds compared to pressure injuries. No device-related adverse events were reported. Conclusions: Overall, flowable UBM was well tolerated and associated with favorable clinical trajectories demonstrated by reduction in tunneling and undermining dimensions; however, comparative effectiveness cannot be inferred from this limited single-arm pilot study. Further controlled studies are needed to confirm comparative effectiveness and optimize clinical use.