Induced membrane technique combined with antibiotic-loaded calcium sulfate-calcium phosphate composite as bone graft expander for the treatment of large infected bone defects: preliminary results of 12 cases.

Background: Management of large infected bone defects is a major clinical and socioeconomic problem. The induced membrane technique has been widely used as a solution. However, it has apparent disadvantages such as limited autologous bone graft supply and lack of continuous infection control. Meanwhile, calcium sulfate/calcium phosphate composites have efficacious osteogenesis and antibiotic delivery capacity. For the first time, we analyzed the efficiency of calcium sulfate/calcium phosphate composites as a bone graft expander in the induced membrane technique to treat large infected bone defects.

Methods: We retrospectively analyzed the clinical data of 12 patients with large infected bone defects of 6.1-17.2 cm treated with the induced membrane technique from November 2016 to July 2019. In the second reconstruction stage, the bone defect was filled with a mixture of the autogenous iliac bone and vancomycin-impregnated calcium sulfate/calcium phosphate composites at a ratio of 3:1. We assessed the bony union by Samantha X-ray score and recorded infection recurrence and complications. Paley scale and SF-36 score were used to evaluate the function of adjacent joint and quality of life pre and postoperatively. Pearson's correlation coefficients were calculated for union time and other clinical scores.

Results: The mean follow-up was 69 weeks (ranging from 30 to 142) after the second stage of the operation. The mean Samantha X-ray score was 5.1 [3-6], preoperative and postoperative SF-36 scores showed that there were statistical differences in all the nine aspects, and the excellent rate of adjacent joint function was 75% (Paley). All cases were radiologically healed, and none of the 12 patients had infection recurrence or failure of fixation at the last follow-up. Two cases had delayed wound healing and were cured after dress changing. There was a significant correlation between union time and Samantha X-ray score (r =‒0.887; P=0.000), while there was no correlation between filling dose, size of the defect, and other outcomes.

Conclusions: This study provided evidence supporting calcium sulfate/calcium phosphate composites as an effective and safe bone graft expander in the induced membrane technique to treat large infected bone defect. This technique may help decrease the use of autologous bone graft and enhance the anti-infection effect of the induced membrane technique.