But don't take my word for it.
http://www.archives-pmr.org/article/S0003-9993(09)00967-8/fulltextsummary:
*11 patients underwent FEMUR LENGTHENING ONLY and 5 underwent femur AND tibia lengthening using the Ilizarov technique.
*The amounts lengthened total varied from between 2.5 cm and 8.5 cm, with an average of 4.4 cm. The largest gain for a femurs only patient was 6.6 cm with most doing 3.0-5.0 cm. It doesn't say specifically how much each person lengthened each segment by for the patients who did two lengthenings, but it's probably safe to assume no particular leg segment was lengthened more than 6.6 cm given ones who did over 6.6cm total were all patients who did femurs and tibias.
*Using a few exercises (sprinting up stairs in a given time, squats performed in a given time, etc), they tested muscle strength among other things.
*Patients at 6 months post op, 1 year post op, and 2 years post op were tested with these tests, and the patients on average by the 2 year mark were within 3% of their pre-operative strength and ability.
*No significant correlations were found between recovery and age or between recovery and amount lengthened. But given what I know about statistics, you cannot reliably discern a significant relation given each subgroup if you look at them by age ranges or lengthening ranges would be only a few people. Still, 16 is a decent size for a total sample, and based on the measures they used to test their patients, a 97+% total recovery on average is what I call excellent.
There is way too much emphasis naysayers who say you will never make a good recovery put on things as unreliable as internet diaries (single cases, ESPECIALLY popular diaries of atypical cases, people who did completely ridiculous amounts, or with crazy foreign doctors, which of course tend to be read WAY more often) or their own faulty intuition (YOU BREAK YOUR LEGS AND GROW = YOU WILL NEVER BE ABLE TO RUN AGAIN BECAUSE YOU HAVE TO PAY FOR IT SOMEHOW").