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.

Introduction and aims: Familial aggregation of low back pain (LBP) symptoms has been described. However, this may be due to genetic factors or common exposure to environmental factors. This study evaluated the relative contribution of genetic and environmental factors to childhood LBP.

Methods: Data was collected from 1995 to 1998 from a national sample of 1790 Finnish twins aged 11-years. A validated pain questionnaire was used to assess LBP pain. Information was also collected on children’s perception of parent-child relationships, parenting behaviours and home environment. In addition, children were asked about various sedentary and active life-style activities. Variance components for genetic and environmental factors were estimated by using biometric structural equation modelling techniques.

Results: The prevalence of LBP at least once a month was 15.7%, and at least once a week was 6.7%. There was small difference in pairwise similarity of LBP between monozygotic and dizygotic pairs, suggesting little genetic influence. LBP was not associated with either sedentary or active lifestyle activities, but was strongly associated with children’s unsatisfactory perception of the following: home environment (p< 0.001), parenting behaviours (Spearman rho = 0.12, 95% CI 0.06–0.18), relationship with mother (p=0.02) and father (p=0.04). Of the total variance in LBP, 41% (95% CI 34 to 48) could be attributed to shared environmental factors within families; and 59% (52 to 66) to unshared environmental factors.

Conclusion: Genetic factors seem to play a very minor role in LBP in 11-year-old twins. Rather than being related to various aspects of lifestyle activities, childhood LBP is best predicted by children’s perception of home environment and family functioning.