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[Bone graft repair of adolescence spondylolysis with lag screw and tension band fixation].

OBJECTIVE
To investigate direct bone graft repair with lag screw and tension band fixation technique and its value for the treatment of adolescence spondylolysis.


METHODS
Lysis was prepared and the fibrous tissue within the gap was removed in 12 patients from 12 to 26 years (average 18.4). 1 - 2 mm extra bony element was resected on both sides with fresh interface with the bone graft harvested from the iliac crest. From the entry point 8 mm away from the midline at the inferior margin of the lamina, titanium lag screws of 35 - 45 mm long and 3.5 mm in diameter were placed at 300 upward and outward and tighted through the lysis, bone graft and the superior and lateral aspect of the pedicle. Extra match bone graft was placed around the surface of defect, an high intensity Nilon wire tension band between the cap of the screw and the basis of transverse process was constructed before wound closure and suction drainage. The patients were immobilized with plaster brace of Paris for 2 months.


RESULTS
Average operation time was (10 +/- 55) minutes, and average blood loss was 170 ml. Follow-up ranged from 12 to 36 months (mean 17 months), and cases of 22 lysis healed within 3 months.


CONCLUSIONS
Technique of direct bone graft repair with lag screw and tension band fixation for the treatment of adolescence spondylolysis is simple, safe and reliable. Combined biomechanical and biological processes, it is less invasive but advantageous in preserving the motion in the affected segment.