Effect And Prognosis Of Tumor-type Knee Prosthesis Replacement For The Treatment Of Malignant Bone Tumors Around The Knee

Objective:To investigate the effects,complications and patient survival of tumor-type knee prosthesis replacement for the treatment of malignant bone tumors around the knee.Methods:A retrospective analysis was made on the data,which included patient survival,prosthesis survival and complications,limb function,tumor recurrence,lung metastasis of47 patients,undergoing tumor-type knee prosthesis replacement in the Second Affiliated Hospital of Shanxi Medical University from January 2010 to April 2018.There were 21 males and 26 females aged from 7 to 70 years.The pathologic diagnosis included 39 osteosarcomas,3 chondrosarcomas,2 malignant fibrous histiocytomas,2 malignant giant cell bone tumors,1 fibrosarcoma.18 patients were staged as ?A and 29 as ?B according to the Enneking staging system.The involved locations were the distal femur in 35 cases and proximal tibia in 12 cases.Patients with osteosarcoma and malignant fibrous histiocytoma received 2 courses of chemotherapy before surgery and 4 to 6 courses of chemotherapy after surgery.Results:All patients were followed-up for 5-102 months,with a median of 25 months.The 1year survival rate was 95.74%,the 3 year survival rate was 71.29%,and the 5 year survival rate was 58.06%.The 1 year disease-free survival rate was 86.42%,the 3 yeardisease-free survival rate was 55.49%,and the 5 year disease-free survival rate was50.86%.There was a higher 5 year survival rate in osteosarcoma patients staged as?A(83.08%)than those staged as ?B(40.21%),and the difference was significant(P=0.021).Local recurrence developed in 10 patients within 3 years after operation.Of the 10 patients,8 had a recurrence of the soft tissue tumor for which the resection was performed;the other 2 patients underwent amputation of the diseased limb.15 patients developed pulmonary metastasis.The 5 year survival rate of prosthesis was82.33%.Periprosthetic infection occurred in 3 patients.Of the 3 patients,1 underwent debridement;the other 2 patients underwent two-stage revision.Aseptic loosening occurred in 1 patient who underwent revision.Prosthesis breakage occurred in 1 patient who underwent revision.The MSTS score is 21(15,24).There was a higher incidence of extensor lag in patients with tumor in the proximal tibia(33.33%)than those with tumor in the distal femur(2.86%),and the difference was significant(P = 0.016).Conclusion:Tumor-type knee prosthesis replacement can effectively treat malignant bone tumors around the knee and maintain satisfactory limb function and patient survival rate.However,the occurrence of postoperative complications may lead to limb salvage failure.It is necessary to reduce the occurrence of complications through standardized chemoradiotherapy,extensive and strict tumor resection and appropriate rehabilitation exercise.