Modular prosthesis reconstruction was performed on a male patient of 25 years of age due to closed knee joint resection for synovial sarcoma. Debridement and free phleb repair was tried after early infection. Since the patient, who had phleb failure twice rejected amputation suggestion, first the prosthesis was removed, soft tissue defect was closed with CAV method, and knee arthrodesis with external fixator was provided. Then 15 cm lengthening was provided for the patient with an hybrid external fixator.