Progress in and from Limb Lengthening 5

I 1988, soon after I started my career as a limb lengthening surgeon, my first article on limb lengthening entitled Current Techniques in Limb Lengthening was published in the Journal of Pediatric Orthopedics.1 At that time I did not imagine that this would go on to become number 19 of the 25 most cited articles in pediatric orthopedics.2 Twenty-five years later, I find myself sitting down to write the sequel “Progress in and from Limb Lengthening”. Surgical limb lengthening dates back to the turn of the 20th century with the publication by Codivilla3 in 1905. Over the first half of the 20th century, the lengthening devices ranged from the traction Thomas splint device of Codivilla, to various bed-mounted and semi-portable external fixation devices. The early limb lengtheners4–10 employed distraction osteogenesis to fill the distraction gap produced by their fixators. It was not however until the 1950s and 1960s that the biology of distraction osteogenesis became understood. This was largely due to Ilizarov and his group in Kurgan, USSR. His pioneering basic science and clinical work demonstrated that distraction osteogenesis was primarily an intramembranous bone formation technique, in which a pluripotential fibrous interzone which forms in the middle of the distraction gap between two bone ends that are gradually distracted apart. Longitudinal bony trabeculae-looking like opposing stalactites and stalagmites meet at this interzone and are parallel to the direction of distraction. The trabeculae are lined with osteoblastic cells that take their origin in the pluripotential cells of the “fibrous interzone”. In between these trabeculae run longitudinally oriented vascular channels, making this “regenerate” mass a very vascular tissue. Ilizarov showed that under ideal, stability, rate, and rhythm of distraction, and preservation of the vascularity of the bone and its surrounding tissues, the regenerate bone would “directly” form as