Use and modifications of cervical and upper thoracic laminar screws in posterior stabilization.

Abstract

Laminar screw technique is used to stabilize C2 and other levels when other techniques cannot be performed. The patients underwent laminar screws at cervical and upper thoracic levels in our clinic during 5 yearswere evaluated retrospectively. In 25 patients, 6 to 82 years old,total 54 laminar screws were used. Most frequent diagnoses were cervical spinal stenosis and craniovertebraljunction anomalies.There were handicaps to perform other type of screwsin 19 out of 25 screws during first 4 years, and 9 out of 29 in the last year (p=0.0009).Two modifications were performed in some cases. In 4 segments with thin lamina, a shorter screw was performed to leave clear the thinnest part, and in 3 C2 levels with almost full length bifid spinous process,shorter screws were inserted from medial sides of the bifid processes with a more vertical orientation. There was ventral cortex penetration in 11 screws without new neurological deficits. One of them was removed because of its full thickness insertion into the spinal canal.Fusion rate was 75% in 16 patients followed radiologically longer than 6 months.In one patient out of 4 without fusion, unilateral screw was loosened, and in others laminar screws were not loosened. Laminar screw technique is easy, safe and effective at C2, C7 and upper thoracic levels. Some modifications may be required due to the anatomical variations.It can be used at other subaxial levels also in theselected cases that other techniques could not be performed.