Yeah tough to tell since humans are so much bigger than rabbits. you can't definitively make that conclusion as the research pointed out. "It is not possible to compare absolute values between patients and experimental models." If you were to compare absolutes, then it would be a bad idea to lengthen more than 2cm (the amount of lengthening on the rabbits).
Their main conclusion does support the idea that slower distraction is better (as long as you don't risk pre consolidation like TRS said).
Agreed, and I actually find the rabbit study very encouraging after making a rough comparison between rabbit and human lengthening.
For the sake of the argument, assume that human and rabbit muscle cells are the same size and have the same tolerance for stretching. Also, the human tibia is roughly 4 times the length of the rabbit tibia lengthened in the study.
The study says the rabbit muscles on the lengthened limb weren't damaged when lengthened at 0.4 mm per day. Given the assumptions above, you could lengthen 1.6 mm (since the human tibia is 4 x longer) safely.
Think of it this way, if the rabbit muscle is composed of 10 cells, then lengthening 0.4 mm per day would stretch each individual cell 0.04 mm. If stretching each cell that much is safe, then a human muscle containing four times as many cells (40) could be lengthened 1.6 mm per day, which would stretch each cell the same 0.04 mm as the rabbit.
Obviously, it's not that simple since the assumptions made don't perfectly reflect reality, but it's a good indication that lengthening 1 mm per day or less in humans is safe. The rabbit study also examined the muscles right after lengthening, which does not consider the body's ability to repair the damage over time.
The main takeaway is that the less you stress your muscles during lengthening, the less they will be damaged. To accomplish that:
1. Stretch and improve flexibility as much as possible before surgery (you're basically pre-lengthening your muscles to give them a head start)
2. Distract lower total daily amounts
3. Distract in multiple small increments per day instead of all at once