A 72-year-old man presented with a 9-cm painless mass in the right knee just lateral to the distal end of patellar tendon. The tumor was located subcutaneously and intra-muscularly but partially invaded into the lateral cortex of the proximal tibia (Fig. 3a). Core needle biopsy confirmed the diagnosis of synovial cell sarcoma. After pre-operative radiotherapy, wide resection included the lower one-third of the patella, the whole patellar tendon, infrapatellar fat pad, anterior lateral knee joint capsule, and one anterior-lateral third in axial section of the proximal tibia extending more distal than the previous cases. After resection, BPTB allograft was fixed to the residual patella and proximal tibia with screws. A lateral proximal tibial plate and screws were added but no cable wire was added because the suitable hole site for cable wiring, just distal to the tibial tuberosity, was resected (Fig. 3b). Post-operatively, we managed this patient similar to the previous patients, maintaining the operated knee straight in splint for the first 8 weeks. Five months post-operatively, an increasingly painful stress fracture of the proximal tibia was diagnosed (Fig. 3c). The fracture was fixed with another plate. Bone union between the implanted allograft and host bones was completed 1 year after surgery. At 18 months after the initial surgery, the fracture site was united, FWB was tolerated, but the knee ROM was restricted with -10  of extension and 115  of flexion. MSTS score was 28/30 (93 %).