Advancements in Managing Bone Defects with Limb Length Discrepancies with a Motorized Intramedullary Combined Transport and Lengthening Nail

SUMMARY: Large bone defects that coexist with limb length discrepancy present a challenging problem in limb reconstruction. Historically, management has required complex circular fixation constructs, staged procedures, or separate devices to independently address each problem. However, the development of motorized intramedullary nails capable of performing both bone transport and limb lengthening with a single implant represent a paradigm shift. This review traces the evolution of internal bone transport technology from the initial foundational principles of distraction osteogenesis through first generation motorized lengthening nails and finally to newly available combination transport-lengthening implants. The biologic rational for a single-construct approach is examined, and clinical scenarios where single implant treatment is advantageous are emphasized. The mechanistic design that enables dual functionality is described, along with surgical technique principles including corticotomy, distraction protocols, and docking site management. Finally, recognized challenges specific to a combined approach are discussed and an illustrative case example is provided.