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Direct Repair of Spondylolysis Using a New Pedicle Screw Hook Fixation: Clinical and CT-Assessed Study: An Analysis of 19 Patients

Objective: A prospective analysis of 19 consecutive cases of spondylolysis repair using a new hook screw device is presented. The objective of the study was to assess the clinical, radiologic, and computed tomography (CT) scan outcomes to establish the indications of isthmic repair in the treatment of spondylolysis. Methods: Nineteen patients treated with a new segmental pedicle screw hook fixation were followed up for a minimum of 2 years (mean 30 months, range 24-48 months). Mean age was 20.5 years (range 13-29 years). All lytic defects were bilateral and located at L5, except for one at L3. CT scans were obtained at 6 months and 1 year postoperatively. CT scans were performed using both traditional and reverse gantry angled cuts to assess the healing of the defect. Fusion was considered to be present when trabeculae passed across the lytic defect. CT scan images were not considered conclusive until 1 year after surgery, because in two cases, trabecular pass across the pars was observed on only one side after 6 months, becoming bilateral 1 year postoperatively. Conclusions: Twelve of 13 patients who were 20 years or younger at the time of the study (average age 17.2 years) had fusion (92%), whereas in the group of 6 patients age 21 and older (average age 27.5 years), no cases of fusion were observed. Clinical outcome was excellent to good in 15 patients, fair in 3 cases, and poor in 1. The group of patients age 20 or younger had significantly better clinical results (84% excellent or good) (P = 0.00097) than those obtained in the group of patients age 21 and older (66% excellent or good) (P = 0.016). According to the current findings, the authors believe that segmental pedicle screw hook fixation is a useful alternative in the treatment of spondylolysis in adolescents but do not recommend this procedure in patients over age 20.