We have conducted various studies during tibial lengthening in dogs and patients. Histological, histochemical, and microautoradiographical studies in dogs indicated that if lengthening after tube-like elevation of the periosteum without tearing of the tube was limited to an amount equivalent to 10 per cent of the bone's length union progressed in a manner quite similar to that seen after fracture. It was also noted that the bone particles produced by the osteotomy participated actively in the new-bone formation. Biochemical studies on the enzymes in the elongated muscles showed that slow lengthening in several stages was far more advantageous than speedy lengthening. Electromyography suggested that 10 per cent lengthening was the limit of safe lengthening. The blood flow in the fore part of the foot during lengthening was studied by venous occlusions plethysmography. The flow decreased markedly in rapidly elongated limbs, and bone union was impaired. Intravenous thiopental sodium anesthesia and diazepam given by mouth at the time of lengthening increased blood flow. Limb-lengthening operations in patients consisted of the smallest possible skin incision, circumferential detachment of the periosteum to keep it as a tube, and oblique osteotomy. The lengthenings were carried out slowly in several stages during two weeks or more, the first lengthening being limited to about 3 per cent of the initial tibial length. Each lengthening was performed under the thiopental sodium anesthesia, occasionally combined with the administration of diazepam.

The clinical results in terms of bone union and the complications of seventy-four patients who had leg lengthenings were analyzed. The results in sixty-three patients operated on with the technique recommended were highly satisfactory.