I asked Dr Parihar for his thoughts on cross-lateral lengthening when I sent in my latest x-rays, because I remembered him telling me before that he wouldn't want to perform it. Here was his reply.
Dr Parihar: The advantage of doing cross lengthening is that you are putting less lengthening strain on the leg. i.e. if you are doing the same side femur and tibia, even if you distract at 1 mm per day, the limb overall is lengthening at 2 mm per day. 2 mm per day in the limb may not be good for the other soft tissues like nerves etc. Therefore one would probably need to go at about .5 mm or .75 per day at each lengthening site, making up a total of 1 or 1.5 mm lengthening per day for the limb. The disadvantage of cross lengthening, is that for any reason if lengthening had to be abandoned during or after the first phase, (infection, patient not able to continue due to pain or other reasons, cost issues etc), then the patient would be left with the same overall leg length while standing (presuming equal lengthening in tibia and femur) but while sitting one knee would be higher than the other (longer tibia side), and the other knee would be pushing forward (femur longer side). It's realistically doable only with internal methods. With external methods, having a frame on the tibia as well as femur at the same time, risks knee stiffness. If i ever had a patient who was insistent on cross lengthening, i would probably need to do a very detailed consent, outlining the above. Given the cost of the nails, I don’t see myself needing to do one of those anytime soon.