Failure of a modified posterior lumbar interbody fusion technique to produce adequate pain relief in isthmic spondylolytic grade 1 spondylolisthesis patients. A prospective study of 20 patients.

A modified posterior lumber interbody fusion procedure is described: this technique basically uses only two tricortical bone grafts and does not produce a distraction at the interspace while inserting the bone grafts. Twenty patients with intractable back and leg pain due to an isthmic spondylolysis and a grade 1 spondylolisthesis were operated using this technique and a prospective study with a mean follow-up of 41 months was conducted to evaluate the results. The final evaluation involved a questionnaire, a clinical examination, and a lumbar spine radiographic series. Fourty-five percent of the patients had good or excellent results whereas 55% had fair or poor results. The possible reasons for these unfavorable results are discussed.