[Direct screw repair of spondylolysis with the hooked screw]

The majority of patients with symptomatic spondylolysis can be treated conservatively. Only when symptoms persist in spite of conservative treatment surgery may be indicated. In young patients, however, fusion of a mobile segment should be avoided, but a direct repair of the pars defect can be attempted. This procedure allows complete healing and possibly avoids degeneration of the intervertebral disk. For this purpose Morscher developed the hook screw, which connects the arch with the anterior articular process. It allows compression of the defect without crossing the defect with the screw. A follow-up study of the first 33 patients with a follow-up time of 3.5 years on average showed a good subjective result in 79% of the patients. In patients younger than 20 years of age, however, the result was good in 87.5% of cases. The reason for the better results in young patients is that in older patients the origin of the pain is often not the pars defect, but the degeneration of the intervertebral disk. Direct repair of spondylolysis is therefore indicated when pain persists after 6 months of conservative treatment or there is a progressive olisthesis of not more than 10 mm. After the end of growth an MRI study of the intervertebral discs should show whether there is degeneration or not. Direct repair is indicated only in the absence of disc degeneration. After the age of 25 years this procedure should not be carried out.