Abstract
Purposes Of The Study-Background Data: Dynesys is claimed that allows motion in the operative levels. This study measures the changes in the lumbar spine in different postures, pre- and after insertion of the device.
Thirty patients with were treated with Dynesys system. All had discography and positional MRI preoperatively and nine months post-operatively.
The patients were divided in to two groups. The first in which only Dynesys was used and the second in which Dynesys was used with fusion.
Results: The operated levels were 63. The results of the pMRI measurements showed that the range of movement(ROM) of the L1/S1 angle in group-A reduced by 11.89o{pre-op=39.26o,postop=27.37o(p=0.008)} while in group-B reduced by 13.73o {preop=36.18o,po stop=22.45o(p=0.002)}.
The ROM of the end plate angle at the instrumented segments in group-A reduced from 5.24o to 2.18o{difference 3.06o(p< 0.005)} and in group-B reduced from 6.69o to 2.46o,{difference 4.23o(p=0.008)}. The ROM of the end plate angle at adjacent level in group-A changed from 8.26o to 7.0o {reduction 1.26o(p=0.388)},while in group-B increased from 6.91o to 8.64o, {difference 1.73o(p=0.149)}
The mean anterior disc height in-group A reduced by 1.43mm (p< 0.005) from 9.75mm to 8.32mm, and the posterior one was increased from 6.27mm to 6.77mm {difference of 0.5mm,(p=0.008)}. In group-B the anterior disc height reduced by 1.11mm (pre-op=10.44mm,post-op= 9.33mm,p=0.049) and the posterior one by 0.16mm (pre-op 6.98mm to post-op 6.82mm,p=0.714).
Conclusion: This study shows that in the Dynesys stabilizing system allows small range of movement at the instrumented levels, with no significant increased mobility in the adjacent levels. Also the device acted to compress the anterior annulus.
Correspondence should be addressed to Ms Alison McGregor, c/o BOA, SBPR at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.
