CLINICAL AND RADIOLOGICAL OUTCOME OF C1 LATERAL MASS AND C2 PEDICLE SCREW INSERTION-A PROSPECTIVE STUDY

Abstract

BACKGROUND: The craniovertebral junction (CVJ) is a complex transition between the skull and the upper cervical spine, the brain and spinal cord respectively. Thus any bony abnormality at the CVJ involves not only the bony structures but also the encompassed nervous system. The atlantoaxial joint (C1-C2 joint) is characterized by a high degree of mobility and little intrinsic stability. Atlantoaxial instability can occur when any part of the components are damaged by trauma, inflammation, neoplasm or congenital defects. The clinical presentation of atlantoaxial instability (C1-C2 instability) varies from mild symptoms such as high posterior cervical pain to severe presentation as different grades of myelopathy.
MATERIALS AND METHODS: This prospective study was carried out at the Department of Neurosurgery, Manipal Hospital, Old Airport Road, Bangalore over a period of 4 years (from April 2016 to April 2020).The sample size was 30. All patients admitted were between 18-78 years of age with atlantoaxial instability and underwent posterior C 1 lateral mass and C 2 pedicle screws fixation.The patients were clinically and radiologically assessed post-operatively at 3 months, 6 months and 1 year. Chi-square test or Fischer’s exact test was used as test of significance for qualitative data. Mc Nemar’s test was used as test of significance for paired qualitative data. Continuous data was represented as mean and standard deviation. Paired t test was the test of significance for paired data such as pre op vs postop for quantitative data.
RESULTS: In our study a clinically significant improvement was noted in terms of neck pain and myelopathy according to the Modified Japanese orthopaedic association score (MJOA-score), Nurick’s grading and visual analogue scale (VAS) on interval follow up of 3 months, 6 months and 1 year with a significant p value < 0.01 as well as significant bony fusion was noted radiologically according to the X ray and CT fusion criteria used in our study.
CONCLUSION: This is one of the few studies where both clinical and radiological outcomes of posterior C1 lateral mass and C2 pedicle screw fixation have been assessed.The fusion rates of this study are comparable to transarticular technique of C1 C2 screw fixation by the CT and X ray fusion criteria where 100 % fusion rates have been reported.