The influence of torsion of the spine on techniques of facet joint blocks without help of visualization

Abstract

AIM: The facet joint block is a common procedure in treating and diagnosing facet joint pain usually performed with or without optical guidance. Especially the uncontrolled methods are not well investigated with respect to the precision of the needle’s positioning in patients with scoliosis. METHODS: X-rays from 49 patients with different levels of scoliosis were analyzed retrospectively by measuring the Cobb angle. Subsequently, the patients were arranged in three groups with a rising Cobb angle. Furthermore, the position of the lumbar spine was determined based on computerized tomography (CT) data, aiming for a three dimensional model of the lumbar spine. With this it became possible to calculate the spatial position and rotations around the anatomical axis of specific vertebras. Afterwards, two uncontrolled facet joint block methods using two different definitions of a fingerbreadth (15 mm, 20 mm) were simulated and the point of injection on the skin was identified using vector analysis. The radial distances between a predefined ideal injection point at the lower joint space and the injection points obtained by both methods were measured and correlated with the groups of different Cobb angles. RESULTS: The mean radial distances between the ideal injection points and the injection points for both methods increased with rising Cobb angles. A maximum radial distance of 31.1 mm from the ideal injection point was observed. CONCLUSION: Rising Cobb angle leads to higher risk of incorrect positioning of the needlepoint. This inaccuracy may be responsible for further complications.