RESUMEN

Objective To explore the early clinical efficacy of 3D printing technology-assisted customized prosthesis with preservation of femoral condyles for the reconstruction of bone defects after resection of distal femoral malignancies.Methods From June 2019 to September 2021,our department determined the lesion range of 12 cases of malignant tumors in the distal femur through CT and MRI before surgery.We used computer-aided production of osteotomy guide plates and customized prostheses that preserved the femoral condyle.After the prostheses were customized,the tumor segment was removed and a reconstruction was performed by using the customized prosthesis with preservation of femoral condyles.The knee function was evaluated by the American Musculoskeletal Tumor Society(MSTS)functional evaluation criteria.Results The operative time was 180-270 min,with a mean of 200 min.The intraoperative bleeding was 300-800 ml,with a mean of 450 ml.A total of 12 cases were followed up for 12-50 months(average,21.9 months).Two patients died of lung metastasis at 12 and 16 months after surgery,one patient survived with lung metastasis at 3 months after surgery,and one patient(8.3%)developed periprosthetic infection at 1 year after surgery.In 10 patients,imaging showed that the prosthesis and plate were in a good position without signs of loosening or bone resorption,the proximal femur was fixed in place with the 3D printed collar,and continuous bone scab formation was found in 4 cases.At the final follow-up,the functional status of the affected limb was good,with the knee flexion of 105°-135°(mean,115°)and no limitation of extension.The MSTS score was 22-28 points[mean,(24.3±1.8)points].Conclusion Application of 3D printing-assisted customized prosthetic replacement technology with preservation of the femoral condyles allows for precise resection of malignant distal femoral tumors and effective anatomical reconstruction without increasing surgical trauma and risk,significantly improving postoperative limb function and potentially reducing long-term complications.