Surgical treatment of spondylolysis and spondylolisthesis with a hook screw.

Seventeen patients with spondylolysis and minimal spondylolisthesis were treated with a Morscher hook screw and bone grafting. At follow up, 82% had no symptoms and radiographs confirmed fusion of the isthmic defect. One patient had occasional pain, and two had an unsatisfactory result. They were both over 25 years of age and had a moderate displacement of 3–4 mm.