Late radiographic changes after lumbar intervertebral disc operations involving hemilaminectomy and partial facetectomy.

We carried out a long term clinical and radiographic follow up (seven to twelve years) on seventy-one patients operated on for prolapsed lumbar disc using a hemilaminofacetectomy approach. The following conclusions were drawn: (1) radiographic deterioration at the disc space operated on varies according to its normality or otherwise at the time of operation; (2) late changes were less common at the L4-L5 space than at the L5-S1 space; (3) hemilaminofacetectomy at L4 had a more adverse effect on L5 than hemilaminofacetectomy of L5 had on L4; (4) in 10 per cent of our cases total of partial reconstruction of the remaining hemilamina was demonstrated by tomography.