Staged Management of Bone Defects in Chronic Osteomyelitis and Nonunions Using Antibiotic-Loaded Calcium Sulphate-Hydroxyapatite: A Multicenter Retrospective Analysis of 101 Cases.

Purpose: To evaluate the clinical outcomes of an antibiotic-loaded calcium sulphate-hydroxyapatite biocomposite (ALB) used specifically in staged surgical protocols for chronic osteomyelitis and nonunions, including large bone defects resulting from the necessary debridement of necrotic bone. Patients and Methods: This retrospective multicenter study analyzed 101 patients treated between 2013 and 2020. Inclusion criteria comprised adult patients with bone defects resulting from osteomyelitis, septic nonunion, or aseptic nonunion, treated with ALB (gentamicin or vancomycin) in a staged procedure. The primary outcome was treatment success, defined as infection eradication and stable bone consolidation without unplanned surgical revision. Secondary outcomes included revision rates, reinfection rates, and biomaterial-related side effects such as white drainage. Results: Treatment success was achieved in 30.7% of patients. The overall revision rate was 58.4%, and the reinfection rate was 45.5%. The mean defect size was 4.1 cm. Statistical analysis identified larger defect sizes and higher volumes of implanted ALB as significant risk factors for failure. "White drainage" was observed in 13.9% of patients and was significantly associated with the use of larger material volumes. Conclusion: The use of ALB in staged protocols for large bone defects is associated with high revision and reinfection rates. These findings identify the limits of the technique and sharpen its indication spectrum, standing alongside the favorable outcomes reported for single-stage procedures in smaller defects. In large defects, the resorption of the carrier may outpace bone ingrowth, leading to recurrence of infection. Consequently, the use of ALB in large defects cannot be recommended based on these data.