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

Jonas Armbruster,1 Nick Mattern,1 Felix Lamadé-Dootz,1 Eva Simone Steinhausen,2,3 Gregor Reiter,1 Marcel Dudda,2,3 Paul Alfred Grützner,1 Holger Freischmidt1 1Department for Orthopaedic and Trauma Surgery at Heidelberg University, BG Klinik Ludwigshafen, Ludwigshafen, Germany; 2Department of Orthopaedic and Trauma Surgery, BG Klinikum Duisburg, University of Duisburg-Essen, Duisburg, Germany; 3Department of Trauma, Hand and Reconstructive Surgery, University Hospital Essen, University of Duisburg-Essen, Essen, GermanyCorrespondence: Holger Freischmidt, Department for Orthopaedic and Trauma Surgery at Heidelberg University, BG Klinik Ludwigshafen, Ludwigshafen, Germany, Tel +49 621 6810 0, Email Holger.Freischmidt@bgu-ludwigshafen.dePurpose: 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.Plain Language Summary: Bone infections (osteomyelitis) and non-healing fractures are challenging conditions that often require complex surgery. Surgeons typically treat these by removing infected tissue and stabilizing the bone. Recently, doctors have utilized a special biodegradable material that fills gaps in the bone and releases antibiotics directly to the affected area. This study aimed to evaluate how well this material works when used in a “staged” procedure, where surgeons clean the bone first and implant the material in a second surgery weeks later. The team analyzed the recovery of 101 patients treated at two specialized trauma centers in Germany. These patients had significant bone loss due to infection and received the antibiotic-loaded filler to help their bones heal. The study found that the success of this treatment depends heavily on the size of the bone gap. For smaller injuries, the material can be effective. For large bone gaps (larger than 5 cm), the results were challenging. Over half of the patients needed additional surgeries, and infection returned in nearly 45% of cases.The results suggest that in large gaps, the material dissolves faster than the patient’s new bone can grow. This creates a fluid-filled space where bacteria can survive. Consequently, the study recommends to use alternative methods for patients with large bone defects, reserving this specific antibiotic-loaded material for smaller injuries. This insight helps ensure patients receive the most effective treatment strategy for their specific condition.Keywords: synthetic bone graft, fracture related infection, bone infection, calcium sulphate-hydroxyapatite, staged surgery