LATN effective in lower extremity limb lengthening
By Mary Ann Porucznik
A new technique—lengthening and then nailing (LATN)—is effective in correcting leg length discrepancy (LLD) for a variety of conditions, according to the researchers for poster exhibit P459. In addition to addressing the deformity correction, the LATN technique also minimizes the time needed in external fixation.
In 24 patients treated with LATN, LLD improved from 6.3 cm (range: 2.5 cm to 12.9 cm) to 1.0 cm (range: 0 cm to 5.5 cm). Full weight bearing was tolerated 7 weeks (range:
6 weeks to 11 weeks) after nailing and was considered the time of bony healing. Patients spent an average of 13 weeks (range: 3 weeks to 27 weeks) in an external fixator frame, resulting in an external fixation index (EFI) of just 0.5 months/cm (range: 0.3 months/cm to 0.7months/cm). In comparison, the classic Ilizarov method often requires an EFI of 1.5 months/cm to 2 months/cm in adults.
The LATN technique uses monolateral frames (such as the Ilizarov/Taylor Spatial or EBI frames) for the distraction phase. Pins and wires are placed to allow subsequent intramedullary nailing. At the end of the distraction phase, reamed large-diameter, full-length, statically locked intramedullary nails are inserted and the frames are removed. Contact between external fixation pins and wires and internal fixation must be carefully avoided.
Advantages of LATN
Although alternatives such as lengthening over a nail (LON) and using internal lengthening nails exist, they have limitations, many of which are addressed by the LATN technique.
Both LON and LATN allow frame removal after the distraction phase of lengthening. However, potential advantages of the LATN technique include the following:
Physicians used LATN to treat 24 patients with LLD (36 limbs—33 tibiae and 3 femora). The patients had developed LLD due to a variety of causes: malunion (6), fibrous dysplasia (2), nonunion (2), polio (1), and congenital (1). In 12 patients, the procedure was used for stature lengthening.
For this retrospective, IRB-approved study of consecutive patients treated by a single surgeon, researchers recorded both clinical and radiographic data and compared the results with historical controls.
The average patient age was 35 years old (range: 22 years to 55 years old). The average follow-up was 36 months (range: 7 months to 64 months). LATN was successful in lengthening the legs an average of 5.7 cm (range: 2.5 cm to 10 cm), reducing LLD from an average of 6.3 cm to an average of 1.0 cm. In addition to the reduced time in frame, researchers also noted the following:
One patient experienced skin breakdown over a prominent interlocking screw and a deep infection, which was treated successfully by removing the nail and administering a six-week course of intravenous antibiotics. At that point, the regenerate was fully healed and no other hardware was needed.
One patient with spina bifida developed temporary bilateral sciatic nerve palsy, but this eventually resolved. There were no nonunions, fractures or loss of position.
Several additional procedures were performed, including 14 gastrocnemius recessions, 9 intramedullary nail removals, 2 ankle fusions, 1 gradual correction of a knee contracture and 1 gradual correction of ankle contracture.
Based on this study, LATN seems to be a safe and effective procedure for limb lengthening and deformity correction, and researchers conclude that further study of LATN is warranted. The lead researcher is S. Robert Rozbruch, MD, of New York City. Additional researchers include: Dawn Kleinman, BA; Austin Fragomen, MD; and Svetlana Ilizarov, MD, all of New York City. Drs. Rozbruch, Fragomen and Ilizarov receive research funding from Smith + Nephew and EBI.