To detect the oncological and functional result of segmental reconstruction for the diaphyseal defect after the femur tumor resection under navigation.

Between September 2008 and May 2017, 28 patients with bone sarcomas underwent surgical resection and diaphyseal segmental reconstruction under computer-assisted navigation in Department of Orthopaedic Oncology Surgery, Beijing Jishuitan Hospital, Capital Medical University. The cohort comprised 18 males and ten females with a median age of 20 years (range: 8-60 years). The tumors were osteosarcoma (n=20), chondrosarcoma (n=4), Ewing sarcoma (n=2), undifferentiated pleomorphic sarcoma (n=1), spindle cell sarcoma (n=1). This study made a pre-operative plan for each patient using navigation system software and performed navigation-aided resection. The reconstruction included custom-made prosthesis (n=22) and allograft (n=6). The average reconstruction length was 181 mm (85-275 mm). The average follow-up was 86.5 months (6-166 months). The oncological and functional results were detected.

Of the 28 patients, 22 remain disease free, one is alive with disease, and five died of the disease. The 5-years survival rate was 80.8%. Six patients developed lung metastasis. Three patients developed local recurrence and the LR rate was 10.7%(3/28). The custom-made prosthesis fracture occurred in 1 patient and the revision for distal femur tumor prosthesis performed. In another patient the prosthesis failed mechanically and revision needed. Two allograft fractures and one deep infection occurred in the allograft reconstruction group. The distal femur tumor prosthesis reconstruction in one fracture patient, plate removal and intramedullary fixation in another patient and debridement performed for deep infection patient. The mean Musculoskeletal Tumor Society score at the final follow-up was 91%(80%-100%). The 5-year survival rates for prosthesis and allograft were 92.3% and 75%, respectively.

The oncological results are good for the resection of femur sarcoma under computer-assisted navigation. The MSTS function are good for both custom-made prosthesis and allograft reconstruction although the complication occurred. The salvage for the failure of reconstruction is conventional tumor implant reconstruction.