The response is likely to be 8cm on femurs exclusively. The level of pain experienced is linked to the rate at which the bone is being lengthened. Personally, the severity of the pain is not a significant factor. If the pain becomes unbearable, you can reduce the speed of the lengthening process. By maintaining a slow yet consistent speed (approximately 0.3mm/day), the risk of premature union can be eliminated. The specific day when satisfactory consolidation is achieved remains relatively constant, with the countdown beginning on the day of the surgical procedure. It is advisable to consider using an internal rod for a more comfortable recovery.