Keystone Flap, a Versatile Option for Salvaging Infected Spinal Instrumentation Associated to Soft-tissue Defects: A Novel Option.

Keystone design perforator island flaps (KDPIFs) are fasciocutaneous flaps based on multiple perforators that provide reliable perfusion to large tissue segments. Their design incorporates elements of advancement, rotation, interpolation, and transposition, allowing recruitment of surrounding lax tissue to achieve durable coverage with minimal tension. These characteristics make them particularly useful for reconstruction of complex posterior trunk defects. We present the case of a 23-year-old man with severe neuromuscular scoliosis who underwent posterior spinal instrumentation from T3 to L5 and subsequently developed vertebral osteomyelitis caused by multidrug-resistant organisms. Following serial debridements, negative pressure wound therapy, and targeted antibiotic therapy, a 40 × 15 cm dorsal midline defect with exposed spinal instrumentation remained. Given the substantial mechanical and deformity-related risks associated with hardware removal, a strategy focused on implant preservation was pursued. Reconstruction was performed using a subtype IIA KDPIF, achieving tension-free closure, effective dead-space obliteration, and stable soft-tissue coverage over the instrumentation. At 2-year follow-up, there was no evidence of recurrent infection or hardware exposure, with preservation of implant stability and satisfactory functional and aesthetic outcomes. In this case, hardware salvage combined with KDPIF reconstruction provided durable soft-tissue coverage while avoiding the mechanical instability and deformity risks associated with implant removal. KDPIFs may represent a useful reconstructive option for selected patients with complex spinal defects and exposed instrumentation.