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UCT engineers make medical history
12 June 2012
A team of UCT mechanical engineer Dr George Vicatos, his MSc student James Boonzaier and maxillo-facial oral surgeon Dr Rushdi Hendricks offered Mother Nature a helping hand in benchmarking pieces of surgery - probably world firsts.
They harnessed established surgical principles and fine metalwork to rebuild a patient's entire missing palate, or cleft palate.
A cleft palate is a hole where the roof of the mouth should be. This typically occurs when the body's natural structures don't fuse as they should before birth. Usually these clefts are filled by surgery soon after birth or in early childhood.
But the problem also remains common among adults, such as when cancerous palates are removed in later life, for example.
Cleft palates result in a string of medical conditions. Remedies in adults include the use of a prosthetic known as a palatal obturator, which is a souped-up denture. Another option is a bone graft, which involves replacing the palate with bone removed from elsewhere.
But these are unsatisfying, for different reasons. The obturator is still messy, and the bone used in grafting doesn't allow for teeth implants, for example.
For some years, however, Hendricks and surgeons around the world have been applying a technique known as distraction osteogenesis to regenerate bone in the lower jaw.
Distraction osteogenesis was the brainchild of Russian surgeon Gavriil Ilizarov, who in the 1950s developed the technique to grow missing bone. Applying the law of tension-stress, he found that if he carefully severed (or distracted) the bone and pulled it apart a little at a time, new bone and tissue would fill the in-between space.
But the principle works only if the membrane lining the bone, the periosteum, is kept intact. The periosteum contains life-giving progenitor cells that direct the body to grow missing bone and tissue.
In his work with distraction osteogenesis, Hendricks borrowed from the design of a 'plate-guided distractor' developed by American surgeon Alan Herford. While Herford succeeded in growing new bone and soft tissue in the lower jaw or mandible, other surgeons could not do the same for the upper jaw or maxilla because of its peculiar anatomical constraints. When they did, they could work only in a straight line of up to 20mm.
Hendricks has now pushed that boundary to 40 mm and beyond, requiring the plate to negotiate some tricky corners and bends, or a "curvilinear vector", an engineering hiccup.
Vicatos, of UCT's Department of Mechanical Engineering, took up the challenge. Funded by the Medical Research Council, Boonzaier designed the device, now patented by UCT.
Hendricks implanted the team's distractor into two patients in late 2011. In the first they filled a gap of 40mm, in the second, 80mm. The second surgery required a few ergonomic modifications to fit the demands of the patient's missing palate, and to replace three-quarters of the upper jaw.
Further operations are lined up and more design modifications.
They're also confident that both the surgery and the distractor, which is being produced by a local company, will suit the pockets of both medical schemes and state hospitals.
