Instrumented Fusion of Same-Level Lamina and Transverse Process for the Treatment of Lumbar Spondylolysis: A Preliminary Report

Lim, Jae Hyeon; Park, Jeong Hyun; Ha, Seong Il; Kim, Young Keun; Yang, Joong Won; Jang, Il Tae

Abstract

OBJECTIVE
There were many instruments introduced for direct repair of spondylolysis. But those instruments were not designed for direct repair of spondylolysis originally. Dynesys implants consist of pedicle screws and cords or laminar hooks that were designed for lumbar dynamic stabilization. We used pedicle screws and cord or laminar hook of Dynesys spinal system for repairment of spondylolysis.
METHODS
July 2005 to March 2009, Six patients with lumbar spondylolysis were treated with a new technique using a pedicle screw with a u-shaped rod or laminar hook combined with bone grafting of the transverse process and lamina of the same level, bypassing the spondylolytic defect. There were 5 males and 1 female. Ages ranged from 18-48 years(average of 34.5 years). A total of 8 vertebral levels were fused(one patient had spondylolytic defects at 3 levels). Five defects were at L5, two at L4, and one at L3. The patients had low back pain that was unimproved after 3-6 months of conservative management. None demonstrated spondylolisthesis or instability, disc degeneration on MRI, nor radiculopathy. All symptoms resolved after isthmus block. The patients were followed-up for a period of 3-27 months(average of 14.8 months). The authors compared pre-operative and post-operative clinical symptoms and radiographic findings retrospectively. Success of the procedure was determined by the following criteria: impro- vement of clinical symptoms(VAS score), absence of isthmic motion on plain radiographs, and evaluation for the presence of a bone mass bridging the transverse processes and laminae using plain radiographs and reconstruction CT scan.
RESULTS
All patients demonstrated improvement in pain scores(average of 8.3 to an average of 3.2). A fusion rate of 87.5% was achieved(7 out 8 levels). No complications were noted. The authors were able to demonstrate a potential benefit in using this new technique for the treatment of lumbar spondylolysis.
CONCLUSION
Direct repair of spondylolysis with Dynesys spinal system is technically easy and fixes strongly biome- chanically.