Unilateral spondylolysis

Of 54 vertebrae with spondylolysis, five were found with a unilateral lesion. The unilateral lesion was sometimes associated with hypoplasia of the ipsilateral lamina or by differences in the size and position of the facet joints and by posterior wedging on the affected side. Radiologically there may be sclerosis in the pedicle on the normal side. In one case a healed fracture was noted on the apparently normal side indicating that the lesion originally had been bilateral.