Primary clinical evaluation of a novel expandable pedicle screw in osteoporotic lumbar spine fixation and fusion.

Objective To evaluate the clinical effect and reliability of a novel expandable pedicle screw (Thunder screw) in osteoporosis lumbar spine fixation and fusion. Methods From August 2006 to December 2007, 42 lumbar disorder patients with severe osteoporosis received expandable pedicle screw fixation with a total of 236 screws implanted. These patients included lumbar degenerative diseases 24 cases, lumbar tuberculosis 8 cases, lumbar compression fractures 6 cases, and revision surgery 4 cases. All patients underwent bone mineral density (BMD) scan. All patients had severe osteoporosis with a mean decrease of 2.6 standard deviations in BMD. The pre-operative and post-operative evaluation of the patients were collect-ed one week, 3 months, 6 months, 12 months and 24 months after surgery. The plain film and three-dimen-sional CT scanning were conducted to evaluate the spinal fusion rate and fixation effectiveness of the ex-pandable pedicle screws. Results The mean follow-up period was 16 months (ranged from 12 to 24 months). There was no loosening, broken or pullout of the expandable pedicle screws. Three, 6, 12 and 24 months after surgery, the score of screw stabilization was 3.0, 3.0, 2.9 and 2.9 respectively. The bone healing was clearly noticed in the area surrounding the screws, intervertebral bodies and posterolaterally. The fusion index was 2.3, 2.5, 3.0 and 3.0 respectively. The clinical symptoms were totally released and the clinical re-sults were satisfactory. Conclusion The expandable pediele screw fixation can achieve excellent screw-bone interface intergration, increase the fixation strength in osteoporosis lumbar spine, thus facilitate spine fusion. The novel expandable pediele screws can be a feasible approach for increasing fixation strength of pedicle screw in osteoporosis and revision spine surgeries. Key words: Osteoporosis;  Bone screw;  Spinal fusion