[Dynamic neutralization using the Dynesys system for treatment of degenerative disc disease of the lumbar spine].
OBJECTIVE
Degenerative disc disease (DDD) is a spinal condition resulting from degeneration of the intervertebral discs. It is associated with symptoms of sciatica, back pain and leg weakness and also with degenerative instability of the spine. To arrest the degenerative cascade of disc disease, and taking into consideration stress placed on the adjacent discs managed by decompression and stabilisation by instrumented fusion, the lumbar spine was treated by dynamic posterior stabilisation of the segments affected. Based on the classification described by Dubois et al., the Dynesys system was used. The aim of this study was to evaluate the mid-term results of this method in DDD patients.


METHODS
In the 2002-2007 period, 102 patients (65 men and 37 women; average age, 54 years) underwent surgery for problems due to DDD manifested by pain, neurological findings and radiographic evidence of degenerative changes in the spine. The classification of age-related changes, as described by Dubois et al. and Kirkaldy-Willis, showed that type 4 and type 6 of DDD (64% disc degeneration with spinal canal stenosis) were most common. After surgery using the Dynesys system, the patients were followed up for an average of 36 months. Patient examination included: pre- and post-operative medical history, clinical, radiographic (including magnetic resonance imaging/MRI) and neurological examination, and the pain and functional status assessment using the visual analog scale (VAS) and Oswestry disability index (ODI), respectively. A total of 146 lumbar spine segments were surgically treated in 102 patients, the L4-L5 segment being treated most frequently, with a total of 61 interventions at this level. Radicular pain before surgery was reported by 40 patients. The average operative blood loss was 1013.8 ml and patients stayed in the hospital for an average of 13.8 days. There were 15 post-operative complications treated. After surgery, the patients participated in a. special rehabilitation programme and were allowed full weight-bearing after 3 months.


RESULTS
At 36 months of follow-up, the improvement as against the pre-operative condition included a drop in the average VAS value from 7.3 to 4.7 and that in the average ODI from 54.5 to 39.9. The results were statistically analysed using ANOVA software and the t-test and Bartlet test (level of significance set at 0.05). The improvement in the patients' health status was statistically significant during all 3-year post-operative period. As shown by the MRI findings obtained from repeated examination in 26 patients, the use of the Dynesys system resulted in the post-operative disappearance of disc bulging and the restoration of the posterior longitudinal ligament and space in the lumbar spinal canal. The surgery had no positive effect on disc regeneration, but improved peridiscal marrow oedema of that lumbar segment in the way described by Modic et al.


CONCLUSIONS
In patients with DDD, stabilisation of the lumbar spine by instrumented rigid fusion often results in increased biomechanical stress and damage to the segments adjacent to the area of fusion. The use of dynamic stabilisation devices, including the Dynesys system, reduces this potential risk. The Dynesys system is also effective in the treatment of DDD combined with spinal stenosis in elderly patients, as reported by other authors. A certain risk associated with Dynesys use may lie in disc height reduction in the anterior segment by up to 0.7 mm, thus producing a fulcrum pin effect. Despite this risk factor, dynamic stabilisation in DDD patients will considerably improve the quality of their lives.


CONCLUSIONS
The results of 102 patients, with 146 segments treated by posterior dynamic neutralisation using the Dynesys system, show that this method improved subjective feelings, morphological findings and pain and functional status in the patients with DDD in the three-year post-operative period. This had a good effect on the quality of life in these patients.
Cienciala
J
J
Ortopedická klinika FN Brno.
Chaloupka
R
R
Repko
M
M
Krbec
M
M
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D016268:Internal Fixators; D055959:Intervertebral Disc Degeneration / Q000000981:diagnostic imaging / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011859:Radiography