Introduction: In this study, we report interobserver reliability of X-ray for the interpretation of pedicle screw osteointegration based on the diagnosis of “Halo zone” surrounding the screw.

Dynamic stabilisation system for the spine relies on titanium screw purchase within the pedicle. Decision on osteointegration is important especially when the patient becomes symptomatic following initial good outcome. From our cohort of 420 Dynesys patients, over all incidence of screw loosening was 17%. Only 35% were symptomatic.

Method: Lumbar spine X-ray images of 50 patients in two views (AP and lateral) randomly selected from our cohort of 420 Dynesys patients. The images were deployed in a CD-ROM. The authors were asked to review the images and state whether or not each pedicle screw is loose (total of 258 pedicle screws).

Seven observers composed of two expert orthopaedic spine consultant surgeons and one spine expert consultant radiologist and four Specialist Registrars in orthopaedics and radiology.

Data gathered were distributed and presented in tables in the form of descriptive statistics. The evaluation of interobserver agreement was performed by obtaining a Kappa (K) index. For continuous variables comparison, the t test was employed, with a significance level of 0.05.

Results: Kappa Index among three experts was 0.2198 at 95% CI (−0.0520, 0.4916) while for all 7 assessors (3 Experts & 4 SpR), KI was 0.1462 at 95% CI (0.0332, 0.2592)

Discussion & Conclusion: Kappa Index among expert assessors was 0.2 which means X-ray is unreliable for the assessment of pedicle screw osteointegration. Validity of X-ray is not applicable as it is unreliable.

We are planning to evaluate a 3D computer reconstruction model based on 2 X-ray views at 45 degree angle to each other which might be sensitive to detect screw loosening.

Introduction: In this study, we report interobserver reliability of X-ray for the interpretation of pedicle screw osteointegration based on the diagnosis of “Halo zone” surrounding the screw.

Dynamic stabilisation system for the spine relies on titanium screw purchase within the pedicle. Decision on osteointegration is important especially when the patient becomes symptomatic following initial good outcome. From our cohort of 420 Dynesys patients, over all incidence of screw loosening was 17%. Only 35% were symptomatic.

Method: Lumbar spine X-ray images of 50 patients in two views (AP and lateral) randomly selected from our cohort of 420 Dynesys patients. The images were deployed in a CD-ROM. The authors were asked to review the images and state whether or not each pedicle screw is loose (total of 258 pedicle screws).

Seven observers composed of two expert orthopaedic spine consultant surgeons and one spine expert consultant radiologist and four Specialist Registrars in orthopaedics and radiology.

Data gathered were distributed and presented in tables in the form of descriptive statistics. The evaluation of interobserver agreement was performed by obtaining a Kappa (K) index. For continuous variables comparison, the t test was employed, with a significance level of 0.05.

Results: Kappa Index among three experts was 0.2198 at 95% CI (−0.0520, 0.4916) while for all 7 assessors (3 Experts & 4 SpR), KI was 0.1462 at 95% CI (0.0332, 0.2592)

Discussion & Conclusion: Kappa Index among expert assessors was 0.2 which means X-ray is unreliable for the assessment of pedicle screw osteointegration. Validity of X-ray is not applicable as it is unreliable.

We are planning to evaluate a 3D computer reconstruction model based on 2 X-ray views at 45 degree angle to each other which might be sensitive to detect screw loosening.

Background: Spinal fusion for degenerative disc disease remains a controversial issue due to adjacent segment disease. Several alternatives have been evaluated; including Dynamic Neutralisation System for Spine and artificial disc arthroplasty. In our cohort study, we are highlighting advantages of DYNESYS over TDA and fusion as being a simple and reversible procedure if removal of implants is necessary.

Materials and Methods: Prospective cohort study on 415 patients underwent DYNESYS. The implant has to be removed in 43 patients. Patients were evaluated preoperatively using Oswestry Disability Index, SF 36 and Visual Analogue Scores together with plain imaging and MRI scanning. Preoperative discography was performed in 81% of patients. Questionnaires were evaluated on subsequent follow up at 3 & 6 months, 1 year then at annual intervals.

Results: Average treatment period was 26 months with a range from 3/12 to 60/12. The main reason for DYNE-SYS removal was screws’ failure or loosening followed by infections. The implant was used to treat single disc space in 20.9%, two spaces in 67.4% and three disc spaces in 9.3%. 81% of the screws were not Hydroxy-appetite coated. No loosening was detected among HA coated screws.

Outcome assessment revealed significant improvement in SF36 even after removal of stabilising system while no worsening of ODI or VAS in comparison with preoperative status.

Conclusions: DYNESYS can maintain disc height and restricts movements exceeding physiological limits. HA coated screws have superior biomechanical characteristics in preventing screw loosening and subsequent spinal spasms. If necessary, removal of implants is a simple procedure.

Background: Spinal fusion for degenerative disc disease remains a controversial issue due to adjacent segment disease. Several alternatives have been evaluated; including Dynamic Neutralisation System for Spine and artificial disc arthroplasty. In our cohort study, we are highlighting advantages of DYNESYS over TDA and fusion as being a simple and reversible procedure if removal of implants is necessary.

Material & Methods: Prospective cohort study on 415 patients underwent DYNESYS. The implant has to be removed in 43 patients. Patients were evaluated preoperatively using Oswestry Disability Index, SF 36 and Visual Analogue Scores together with plain imaging and MRI scanning. Preoperative discography was performed in 81% of patients. Questionnaires were evaluated on subsequent follow up at 3/12, 6/12 then at annual intervals.

Results: Average treatment period was 26 months with a range from 3/12 to 60/12. The main reason for DYNE-SYS removal was screws’ failure or loosening followed by infections. The implant was used to treat single disc space in 20.9%, two spaces in 67.4% and three disc spaces in 9.3%. 81% of the screws were not Hydroxy Appetite coated. No loosening was detected among HA coated screws.

Outcome assessment revealed significant improvement in SF36 even after removal of stabilising system while no worsening of ODI or VAS in comparison with preoperative status.

Conclusions: DYNESYS can maintain disc height and restricts movements exceeding physiological limits. HA coated screws have superior biomechanical characteristics in preventing screw loosening and subsequent spinal spasms. If necessary, removal of implants is a simple procedure.