Following brachymet surgery with distraction, how long should the external fixator remain after the desired length is achieved?

• A. 2-4 weeks
• B. 3-6 months
• C. 2-4 times the lengthening time
• D. Until radiographic evidence of consolidation

Answer: (C)

After distraction-lengthening in brachymet surgery, the new bone that forms during lengthening is immature and mechanically weak. Keeping the external fixator in place during a consolidation period allows this regenerate to mineralize and remodel safely, reducing the risk of relapse or deformity as tissues adapt to the new length.

The practical guideline is to maintain the fixator for about two to four times the actual lengthening time. This multiplier accounts for the fact that longer or more extensive lengthening requires more time for adequate consolidation, while avoiding keeping hardware on far longer than necessary, which can raise the risk of pin problems or stiffness. Radiographic signs of consolidation can help assess progress, but relying solely on radiographs can lag behind true mechanical stability, so the time-based rule provides a reliable, table-friendly benchmark.

In short, once the desired length is achieved, the fixator is left on for a period proportional to the lengthening duration—roughly two to four times that period—to ensure solid bone healing before hardware removal.