Study protocol and statistical analysis plan for a randomized controlled trial evaluating the safety and feasibility of the recombinant human platelet-derived growth factor B (rhPDGF-BB)-enhanced collagen plug for complex perianal fistula healing. - Kuo MC; Younan SA; Lempicki MD; Hawkins AT; Smith J; Shirey-Rice JK; Pulley JM; Lynch SE; Ueland TE; Khan A; Clark CR; Blette BS (MedRxiv : the preprint server for health sciences, 2026)