Limited revision for extramedullary stem fracture of the custom articular prostheses / 中华骨科杂志

ABSTRACT

Objective To introduce a new method of limited revision for the extramedullary stem fracture of the custommade tumor prostheses and evaluate its clinical effect.Methods There were 3 patients with extramedullary stem fracture after custom-made tumor prostheses replacement,2 male and 1 female.The age was 25,51 and 52 years old respectively.The pathological diagnosis and involved locations were osteosarcoma of distal femur,recurrent giant cell tumor of distal femur,and chondrosarcoma of proximal femur.The interval between replacement operation and extramedullary stem fracture were 11 months,34 months and 28 months respectively.The fracture occurred when they were walking without obvious history of trauma.The fracture sites located at the conjunction of the extramedullary stems in distal femoral prostheses and femoral neck basis in proximal femoral prosthesis.According to the firm fixation of the intramedullary stem and the enough length of the residual extramedullary stem,the revision prosthesis for limited revision operation was designed in order to avoid removing the firmly fixed intramedullary stem and bone cement which is very difficult.The revision prosthesis consists of sleeve part and joint part with the same material as former prosthesis,which is sleeved to the residual extramedullary stem and fixed by bone cement and interference screws in limited revision operation.The wearing fittings were replaced at the same time.Patients took regularly functional exercises postoperatively.The stability of revision prosthesis and the function of the involved limbs were observed in follow-up.Results The reasons of prosthesis fracture were fatigue fractures at the conjunction of extramedullary stem in one distal femur prosthesis,at the basis of femoral neck in one proximal femur prosthesis and conjunction loosening and locked screw breakage in the other distal femur prosthesis.The follow-up times were 1 month,103 months and 1 10 months respectively.One patient with giant cell tumor underwent tumor resection due to tumor recurrence in soft tissue.The revision prostheses were fixed firmly without loosening.According the MSTS scoring system,the scores of involved extremities function were 66.7％、86.7％ and 83.3％ respectively.Conclusion The fracture of custom-made tumor prosthesis could occur due to metal fatigue and conjunction failure.The newly designed revision prosthesis allows a limited revision operation with preserving the firmly fixed intramedullary stem,which reduces the difficulty of operation and makes the recovery of the limb function as soon as possible.