Due to advances in neoadjuvant therapies and preoperative imaging modalities, joint-sparing resections have become appealing in bone tumor surgery. However, the intercalary reconstruction of metadiaphyseal bone defects of the femur and the tibia after juxta-articular tumor resection remains challenging. Both biological and prosthetic reconstructions have been used for joint-sparing resections, but little is known about the long-term outcome of these procedures. The authors reviewed a consecutive series of 64 patients treated with joint-sparing intercalary resection and reconstruction with bone grafts. Inclusion criteria were an osteotomy line within 5 cm from the knee and ankle joint surface and an osteotomy line proximal to 1 cm below the lesser trochanter at the hip level. Intra-epiphyseal resection was performed in 25 patients (39%)and intercalary resection was performed in 39 (61%). Reconstruction included 49 allograft + vascularized fibular graft (VFG), 10 allografts, and 5 VFG + structural allogenic grafts. At a mean follow-up of 117 months (range 12-305), 51 patients (80%) were continuously disease-free, and 6 showed no evidence of disease after treatment of local recurrence or metastatic lesion. One patient was alive with lung metastases at 26 months of follow-up and six patients died of disease. In the entire series of 64 patients, 26 had a non-oncological complication that required surgical revision (40.6%). Overall survival (OS) of reconstruction was 92% at 5 years and 90% at 10 and 15 years. Limb salvage survival (LSS) was 94% at 5, 10 and 15 years. Twenty-two fractures occurred in 17 patients (26.5%). There were a total of nine non-unions (14%). Six patients (9.3%) presented early wound dehiscence (average 1.8 months, range 0-6). A deep infection occurred in 3 cases (4.7 %). In 12 patients treated with VGF reconstruction (12/54:22%), a donor-site complication was observed. The overall Musculoskeletal Tumor Society (MSTS) functional score in 54 evaluable patients, who were alive with reconstruction in situ, was 27 points (range 18-30). Biologic intercalary reconstructions with bone grafts resulted in effective joint-sparing resections of the lower limb, allowing joint preservation in all but one case who required a total knee replacement for varus osteoarthritis. Despite the high rate of complications requiring surgical revision, at 15 years, overall survival of the reconstruction was 90% and limb salvage survival was 94%. In our experience, revision-free survival was better with VFG reconstruction than with allograft alone and the combination of VFG and allogenic graft seems to favor spontaneous fracture-healing and to decrease the non-union rate.