External fixation and lengthening over nail

The lengthening methods described in this guide, and internal lengthening nails, share the same underlying principle. The surgeon cuts the bone, and the two segments are then gradually drawn apart so that new bone forms in the gap. The orthopaedic literature calls this distraction osteogenesis and describes it in three stages: a latency phase after the operation, a distraction phase during which lengthening takes place, and a consolidation phase during which the new bone hardens.

What differs between methods is mainly how the bone is held and lengthened — with a frame outside the limb, a device inside the bone, or a combination of the two.

An external fixator is a frame that sits outside the limb and is connected to the bone with wires, pins, or both. During the lengthening phase the frame is adjusted, which gradually separates the bone segments; AAOS patient information describes this as adjusting the frame several times daily, with the exact schedule set by the treating team. Most of the device stays outside the body for the whole period it is in place.

Monolateral (also called unilateral) fixators are attached along one side of the limb. A published review of limb lengthening describes the unilateral fixator as the standard method of fixation for a long time, with later designs placing pins in more than one plane.

Circular (ring) fixators surround the limb with rings connected to the bone by wires or pins. They spread widely following the work of Gavriil Ilizarov, whose method is still referred to by his name. The same review describes hexapod frames, including computer-assisted designs, as allowing lengthening and deformity correction to be managed with the same frame. These are descriptions of how the devices are built, not a comparison of results.

Hybrid techniques combine an external fixator with an internal implant. According to the published review, they were developed with the aim of shortening the time the external frame has to stay on. In lengthening over nail (LON), as described in a 1997 clinical study, a nail is placed inside the bone and an external fixator is applied at the same operation; after gradual lengthening, the nail is locked in place and the external fixator is removed.

A related approach, lengthening and then nailing (LATN), uses an external fixator for the lengthening and places the internal nail at a later stage. The guide LON and LATN: two combined techniques sets the two sequences side by side. Providers may use these terms in slightly different ways, so it is worth asking a specific provider how they define and apply them.

Because pins or wires pass through the skin, external fixation involves regular care of the pin sites. Cleveland Clinic patient information describes cleaning the pin sites every day to help prevent infection, and notes that the frame can make some clothing difficult to wear. The published review describes pin-site infection as the most commonly reported complication of external fixation, with a reported frequency that varies widely between studies.

This is a description of what the method involves, not a comment on comfort, difficulty or suitability for any individual.

This guide does not state or imply that external fixation, LON, or any hybrid method is better or worse than internal lengthening nails, or than each other. The published review notes that internal nails avoid many of the drawbacks of external fixation but have complications of their own, and that results are significantly affected by the surgeon's clinical experience. A 2025 systematic review of aesthetic (cosmetic) lower limb lengthening concluded that further research with more rigorous study designs is needed.

Method selection depends on clinical factors specific to each patient and should be discussed directly with a qualified orthopaedic surgeon.

If you are researching providers that list external fixation or hybrid techniques among their methods, the questions below can help make their answers comparable. They are prompts for your own research, not a checklist of correct answers.