Bifocal Lengthening with Monorail External Frame for Severe Shortening of the Femur: A Case Report.

Aim and background: Femoral lengthening using a monorail external frame often involves creating two simultaneous distraction sites. This approach allows for a better distribution of the osteogenesis process and can reduce the overall treatment duration, particularly in cases of severe shortening. However, the literature on bifocal femoral lengthening is limited, with reported cases rarely exceeding 10 cm of lengthening. This case report aims to describe the treatment and outcome of a patient who underwent bifocal lengthening with a monorail external frame for severe femoral shortening. Case description: A 26-year-old female presented with a 23 cm shortening of the left lower limb resulting from previous surgeries for infection. She underwent bifocal femoral lengthening using a monorail external frame, achieving 20 cm of lengthening. Following the removal of the external fixator, a fracture occurred in the regenerated bone, necessitating intramedullary nailing. Conclusion: For severe femoral shortening, various lengthening techniques can be considered. Bifocal lengthening with a monorail external frame offers specific advantages and disadvantages that should be evaluated based on factors such as required treatment duration, expected patient compliance, and infection risks. Clinical significance: This case demonstrates that substantial femoral lengthening may be achievable with a monorail external frame, especially when two simultaneous osteotomies are utilised. For large bone regenerates, even with radiographic evidence of callus maturation, internal stabilisation may be advisable, despite the peculiar technical challenges involved.