Background: In children with osteosarcoma around the knee joint without epiphysis involvement, joint-sparing surgery seems to be an ideal way to retain knee joint function. However, there are two points of debate with regard to the technique: How to accurately achieve a safe surgical margin, and how to achieve intercalary reconstruction of the massive bone defect following resection of the tumor.
Case summary: We present the case of an 8-year-old girl with osteosarcoma of the distal femur without involvement of the epiphysis. Epiphyseal distraction was applied to separate the epiphysis and metaphysis, and this provided a safe surgical margin. The massive bone defect was reconstructed with a custom-made antibiotic-loaded polymethyl methacrylate (PMMA) construct combined with a free non-vascularized fibular graft. Six months after surgery, bone union between the autograft and host bone was confirmed in both the proximal and distal femur by computer tomography (CT) examination. Moreover, considerable callus formation was found around the PMMA construct. After 28 mo of follow-up, there was no sign of recurrence or metastasis. The patient could walk without any aid and carry out her daily life activities satisfactorily.
Conclusion: In cases of osteosarcoma without epiphysis involvement, epiphyseal distraction can be easily applied to obtain a safe margin. Hybrid reconstruction with an antibiotic-loaded PMMA construct combined with a free non-vascularized fibular graft has the advantages of being easy to manufacture, less time-consuming to place, and less likely to get infected, while also ensuring bone union. Our case provides an alternative technique for biological reconstruction after joint-sparing surgery in patients with osteosarcoma around the knee without epiphyseal involvement.
Keywords: Case report; Custom-made polymethyl methacrylate construct; Epiphyseal distraction; Non-vascularized fibular graft; Osteosarcoma.
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