Reconstruction of the proximal part of the tibia in children with use of an unconstrained tibial component cemented in an allograft-prosthetic composite after proximal tibial resection spares the distal femoral physis and articular cartilage, maintains the bone stock of the tibia, and allows the allograft to be adapted to the small tibial dimension in very young patients. Make a longitudinal incision medially or laterally, depending on the side of the biopsy (usually medial), encompassing and encircling the biopsy site. A parapatellar arthrotomy is performed, and the cruciate ligaments are cut close to the femoral attachment. Retract the medial gastrocnemius muscle and then isolate and protect the popliteal and posterior tibial vessels. Perform an osteotomy of the tibiofibular joint and the tibial shaft at the appropriate level as determined on the basis of the preoperative imaging, and then complete the resection. Cut and prepare the allograft according to the specimen dimensions. Cement the tibial component of an unconstrained total knee prosthesis in the allograft and place the trial device. Place the trial composite device and then fix the composite device to the host tibia and suture the capsule and ligaments. Immobilize the knee with an above-the-knee plaster cast, which is worn for six weeks, and then have the patient perform progressive functional rehabilitation. The rate of postoperative infection after proximal tibial reconstruction with a resurfaced allograft composite in children has been found to be no higher than that with other reconstructive techniques for the proximal part of the tibia; our series had a 5% rate of deep infection.IndicationsContraindicationsPitfalls & Challenges.