PURPOSE: It is estimated that 13 to 29% of patients in hospitals and nursing homes have pressure sores. Surgical principles underlying the management of pressure sores have been excision of the scar, soft tissue debridement, removal of the underlying infected bone and filling the dead space with fasciocutaneous or musculocutaneous flaps. Antibiotic-impregnated polymethylmethacrylate (PMMA) beads have been used in chronic osteomyelitis to deliver antibiotics locally in concentrations that exceed the minimal inhibitory concentrations. However once the antibiotic has leached out of the bead, it acts as a nidus for infection and requires removal. OsteoSet (Wright Medical Group, Inc. Arlington, TN), a bioabsorbable medical grade calcium sulfate bone graft substitute, can be impregnated with antibiotics and used to fill the bony cavity. Since it obliterates dead space and acts as a scaffold for new bone formation, a flap procedure is not required and can be preserved for future recurrences. Although commonly used in orthopedics, its use has not been described in pressure sore associated osteomyelitis. We describe our experience using this technique in three patients.

METHOD: A Preoperative MRI confirmed osteomyelitis. After soft tissue debridement, the outer cortex of the infected bone was opened with a dental burr to allow complete debridement of the infected cancellous bone in the entire medullary cavity. The remaining cortex was kept intact to provide housing for the bone graft substitute. After thorough irrigation, the bony defect was packed with antibiotic impregnated PMMA beads and the wound temporarily closed in a single layer using a nonabsorbable monofilament suture. Multiple débridements may be required till the wound is clean. Typically, at a second debridement, the methacrylate beads were removed. The OsteoSet-antibiotic mixture was then molded into the bony defect. Layered closure of the wound was then done over a suction drain. Intravenous antibiotics were continued for 6 weeks.

RESULTS: We retrospectively identified 3 patients with ischial pressure sore associated osteomyelitis secondary to spinal cord injury, who underwent debridement and OsteoSet placement. Two of them had recurrences, three years after the operation. At reoperation, healthy viable bone was present at the sites where OsteoSet had been placed at the initial operation. The new area of osteomyelitis was débrided and OsteoSet was placed in the bony cavity followed by layered closure. There was no recurrence at 6 month follow up. The third patient had pressure sore associated left ischial osteomyelitis that was treated utilizing the above technique. Subsequently, he developed a right ischial pressure sore that was treated at a different hospital. He failed multiple débridements, partial ischiectomy, hamstring advancement flap and re-advancement of the flap on the right side within two years. The left side continues to remain healed at 3 year follow up.

CONCLUSION: The use of antibiotic impregnated bone graft substitutes is a simple and effective technique for pressure sore associated osteomyelitis that provides a high local concentration of the antibiotic. It also obliterates bony dead space and acts as construct for bone formation thus preserving local tissue to salvage future recurrences that are inevitable in this patient population.