Aim: To assess the kinematic changes that occur within the lumbar spine 2 years following insertion of the Dynesys Spinal stabilisation implant.

Materials and Methods: Twenty patients who were treated with Dynesys surgical stabilisation for dominant lower back pain underwent positional MRI scanning before and two years following surgery.

The patients were divided into two groups, A and B. The first, Group A, in which only Dynesys was used and the second, Group B, in which Dynesys was used adjacent to one or more fused segments.

Results: The results of the pMRI measurements showed that the range of movement (ROM) of the L1/S1 angle in Group A reduced by 11.8o{pre-op=37.9o, postop=26.1o(p=0.085)} while in Group-B reduced by 12.3o {pre-op=37.8o, postop=25.5o(p=0.017)}.

The ROM of the end plate angle at the instrumented segments in Group A reduced from 5.72^o to 1.44^o{difference 4.28^o(p=0.005)} and in Group B reduced from 6.00^o to 2.17^o,{difference 3.83^o(p=0.001)}.

The ROM of the end plate angle at the level above instrumentation in Group A reduced from 8.2^o to 5.1^o {reduction 3.1^o(p=0.085)}, while in group-B increased from 7.3^o to 7.5^o, a difference of 0.2^o (p=0.877).

The mean anterior disc height in Group A reduced by 2.1mm (p< 0.001) from 9.59mm to 7.44mm. The posterior disc height also reduced from 6.56mm to 6.26mm, a difference of 0.3mm, (p=0.434). In Group B, the anterior disc height reduced by 1.98mm (pre-op=9.04mm, post-op= 7.06mm, p=0.001) and the posterior height by 0.35mm (pre-op 6.14mm to post op 5.79mm, p=0.443)

Discussion: This study shows that the Dynesys stabilisation system allows some movement at the operated segment two years following surgery. The study also confirms that the adjacent segment hypermobility often seen following spinal fusion surgery is eliminated.

Aim: To assess the kinematic changes that occur within the lumbar spine 2 years following insertion of the Dynesys Spinal stabilisation implant.

Materials and Methods: Twenty patients who were treated with Dynesys surgical stabilisation for dominant lower back pain underwent positional MRI scanning before and two years following surgery.

The patients were divided into two groups, A and B. The first, Group A, in which only Dynesys was used and the second, Group B, in which Dynesys was used adjacent to one or more fused segments.

Results: The results of the pMRI measurements showed that the range of movement (ROM) of the L1/S1 angle in Group A reduced by 11.8o{pre-op=37.9o, postop=26.1o(p=0.085)} while in Group-B reduced by 12.3o {pre-op=37.8o, postop=25.5o(p=0.017)}.

The ROM of the end plate angle at the instrumented segments in Group A reduced from 5.72^o to 1.44^o{difference 4.28^o(p=0.005)} and in Group B reduced from 6.00^o to 2.17^o,{difference 3.83^o(p=0.001)}.

The ROM of the end plate angle at the level above instrumentation in Group A reduced from 8.2^o to 5.1^o {reduction 3.1^o(p=0.085)}, while in group-B increased from 7.3^o to 7.5^o, a difference of 0.2^o (p=0.877).

The mean anterior disc height in Group A reduced by 2.1mm (p< 0.001) from 9.59mm to 7.44mm. The posterior disc height also reduced from 6.56mm to 6.26mm, a difference of 0.3mm, (p=0.434). In Group B, the anterior disc height reduced by 1.98mm (pre-op=9.04mm, post-op= 7.06mm, p=0.001) and the posterior height by 0.35mm (pre-op 6.14mm to post op 5.79mm, p=0.443)

Discussion: This study shows that the Dynesys stabilisation system allows some movement at the operated segment two years following surgery. The study also confirms that the adjacent segment hypermobility often seen following spinal fusion surgery is eliminated.

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 11.89^o{pre-op=39.26^o,postop=27.37^o(p=0.008)} while in group-B reduced by 13.73^o {preop=36.18^o,po stop=22.45^o(p=0.002)}.

The ROM of the end plate angle at the instrumented segments in group-A reduced from 5.24^o to 2.18^o{difference 3.06^o(p< 0.005)} and in group-B reduced from 6.69^o to 2.46^o,{difference 4.23^o(p=0.008)}. The ROM of the end plate angle at adjacent level in group-A changed from 8.26^o to 7.0^o {reduction 1.26^o(p=0.388)},while in group-B increased from 6.91^o to 8.64^o, {difference 1.73^o(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.

Purpose Of The Study: This study measures the changes in the lumbar spine in different postures, pre- and after insertion of the device.

Material-Method-Results: All the 25 patients, with chronic back pain, had discography preoperatively a positional MRI scans pre-op and nine months postoperatively in different postures.

The patients were divided into two groups. The Group-A with 14 patients in which only Dynesys was used and Group-B with 11 patients in which Dynesys was combined with fused levels.

The operated levels were 51, 13 of which were fused. The results showed that the mean range of movement of the lumbosacral angle reduced by 10.28° (Preop=39.21°, Postop=28.93°) (p=0.016) in group-A. In group-B it reduced by 13.73° (Preop=36.18°, Postop=22.45°) (p=0.02).

The range of movement of the end plate angle at the instrumented segments in group-A reduced by 2.96° (Preop=5.56°, Postop=2.60°) (p=0.016) while in group-Bit reduced by 4.23° (Preop=6.69°, Postop=2.46°)(p=0.008).

The mean range of movement of the end plate angle at adjacent level in group-A reduced by 1.58° (Preop=8.7°, Postop=7.21°)(p=0.427) while in group-B it increased by 1.73° (Preop=6.91°, Postop=8.64°) (p=0.149)

The mean anterior disc height in group-A reduced by 1.18mm (Preop=10.05mm, Postop=8.87mm) (p< 0.005), and the posterior one was increased by 0.6mm (Preop=6.51mm, Postop=8.87mm) (p=0.013). In group-B, the anterior disc height was reduced by 1.11mm (Preop= 10.44mm, Postop=9.33mm) (p=0.049) and the posterior one by 0.16mm (Preop=6.98mm Postop=6.82mm) (p=0.714)

Conclusion: Dynesys stabilizing system allows movement at the instrumented levels, with no significant increased mobility in the adjacent levels. Also the device acted to compress the more the anterior annulus than to distract the posterior.

Introduction The Dynesys device uses transpedicular screws linked by a cord and spacers. It is claimed that the advantage is that it allows some motion, in all directions, in the operative levels. In vitro laboratory biomechanical studies show that the movement permitted is similar to rigid fusions.

This study measures the changes in the lumbar spine in different postures, pre- and after insertion of the device.

Material-method In our study 20 patients with dominant low back pain, with or without leg pain, were treated with Dynesys system. Stress discography was made to evaluate the symptomatic level

All had a positional MRI preoperatively and nine months post-operatively in flexion-extension-lateral bending.

The patients were divided in to two groups:

Group(A) with 8 patients in which Dynesys was used with fusion (disc-height< 40 %)

Group(B) with 12 patients was the Dynesys-only group (disc-height=40–90%).

Results The operated levels were 42, 10 of those were fused levels. The results showed that there was a statistically significant difference in flexion-extension range of movement of the whole lumbar spine (mean= −13.45)(p< 0.005), but it wasn’t significant in the level above (mean=0.056)(p=0.972) and at a single instrumented segment was (mean=−4.06°)(p< 0.05)

The changes in the anterior disc height was (mean= −1.18)(p< 0.05) and to the posterior (mean=0.37)(p=0.134). In bending were (mean=−0.87°)(p=0.18) for left and (mean=−0.24°)(p=0.75) for the right

Discussion 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