[Pars interarticularis reconstruction of spondylolysis using plates and screws with grafting without arthrodesis. Apropos of 78 cases].

Between 1978 and 1985, 78 reconstructions of the pars interarticularis were performed for painful spondylolysis in which there had been failure to respond to conservative methods and the subjacent disc was not degenerate. Sixty-five patients were reviewed with a follow-up greater than 2 years and a mean of 4.4 years. The concept of pars interarticularis reconstruction can be attributed to Kimura (1968), Buck (1970) and Nicol and Scott (1986). It consists of a posterior approach with freshening of the margins of the defect, the insertion of cancellous chips taken from the spinous processes, resection of the tips of the articular processes above the partes interarticulares and fixation with a butterfly plate and screws which was devised for this purpose. The plate was removed after 6 months. The rate of union after this procedure was 93.5 per cent and rose to 95.7 per cent after a secondary bone graft. Two bilateral non-unions required a lumbosacral arthrodesis. The results were excellent or good as regards pain in 86 per cent of cases. A return to heavy work and intensive sporting activity was possible in 88 per cent of cases. Movement of the lumbosacral spine was reduced by a mean of 41 per cent.