[An unknown after surgical lengthening of the femur in children: spontaneous postoperative parasitic lengthening].

The authors have studied overgrowth or diminished growth seen in 54 femora lengthened surgically by a one-stage procedure between 1963 and 1979. Thirty six cases were of poliomyelitis. An overgrowth was regularly seen of the order of 2.5 p. 100- that is 11 mm on average. This stimulation of growth by lengthening was not related to age. It was more marked where there was severe involvement. In contrast, in 13 cases of congenital femoral abnormalities and 5 cases of miscellaneous diseases (Ollier's disease, neurofibromatosis, sequelae of septic arthritis) overgrowth or diminished growth have been observed. This phenomenon was not constant and could not be predicted.