Clinical And Radiographic Study Of Dynamic Neutralization System( Dynesys ) For The Treatment Of Lumbar Degenerative Disease

Objective :To observe the early effect of dynamic neutralization system( Dynesys) for the treatment of lumbar degenerative disease. To analyze radiographic changes of lumbar segments and intervertebral disc rehydration after Dynesys dynamic fixation. Methods :89 cases of lumbar degenerative disease who received operation in our hospital between December 2011 and October 2013 were retrospectively analyzed. The cases were divided into two groups according to the operation method : group Dynesys comprised 27 males and 11 females( average age, 37.66±9.58 years) who had received Dynesys dynamic fixation, and group PLIF comprised 35 males and 16 females( average age, 40.53±11.72 years) who had undergone posterior lumbar interbody fusion. The VAS score and ODI score of two groups were assessed at pre-operation and the last follow-up. The height of anterior and posterior intervertebral space, lumbar lordosis and flexion-extension range of motion( ROM) were measured by X-ray of lumbar spine. The average calibrated disc signal( CDS) of surgical level was calculated by lumbar MRI. Results :89 cases were evaluated with a mean follow-up of 25.11 months. All the patients received X-ray re-check and 23 cases of group Dynesys received MRI re-check. At the last follow-up, the VAS scores of back and leg pain and ODI scores of two groups were improved signi?cantly than those of pre-operation. Compared with pre-operation, the anterior and posterior intervertebral space height of the stabilized segment in group Dynesys had a statistically significant decrease( P<0.05). At the upper adjacent segment, the anterior intervertebral space height in two groups has no signi?cant change( P>0.05), but the posterior height has a signi?cant loss( P<0.05). There was no significant difference in the height of anterior and posterior intervertebral space of the lower adjacent segment and lumbar lordosis in two groups. The flexion-extension ROM of the operated segment in group Dynesys, which was( 5.31±2.60)° preoperatively and( 2.90±1.72)° at the last follow-up, was limited significantly( P<0.05), but it still keep 64.11 percents of preoperative level. It has no significant change at the adjacent level and total lumbar segments. However, the ROM of the upper adjacent level in group PLIF, which was( 5.64±2.79)° preoperatively and( 7.76±3.15)° at the last follow-up, was significantly increased( P<0.05), and it has no statistically significant difference at the lower adjacent segment and total lumbar segments( P>0.05). In group Dynesys, 23 cases received lumbar MRI reexamination. Their average CDS significantly improved from 42.74±13.15 percents to 47.69±14.38 percents( P=0.004). Conclusion :Compared with lumbar fusion operation, Dynesys is also an effective and alternative surgical procedure for lumbar degenerative disease. Dynesys is able to reserve segmental ROM of the stabilized segments and avoid hypermobility at the adjacent segments. Meanwhile, intervertebral disc rehydration emerges, which may indicate that Dynesys can accelerate repair of disc tissue. However, there also has some problems after Dynesys non-fusion operation, such as the obvious losses of intervertebral space height at the operated segments and compensatory segmental lordosis of the upper adjacent level. The further long-term observation is still recommended.