The bioexpandable prosthesis: a new perspective after resection of malignant bone tumors in children.

Bone reconstruction after resection of malignant bone tumors of the lower extremity in children and adolescents remains a challenge in limb-sparing surgery. Equal limb length at maturity and good functional outcome are the main goals of these surgeries but often are difficult to achieve. Expandable endoprostheses are available but usually require repeated operative interventions for lengthening. Moreover, as the size of the implant increases, the proportion of the implant relative to the remaining bone increases, generating a biomechanical disadvantage to the limb. The authors describe a new concept combining an endoprosthesis with a fully implantable motorized distraction nail that can be activated in gradual steps to lengthen the remaining bone by callus distraction. New high-quality bone is growing and the proportion of prosthesis length compared with leg length develops in favor of the remaining bone.