Morphologie des articulations intervertébrales postérieures : Etude réalisée à partir de l'ostéothèque régionale LOMBONICE 2005

Aim of the study: Our anatomical knowledge about lumbar spine is based on few cadaveric dissections with very few specimens of very old. The CT scan is very informative concerning about bony facets morphology. We have first created a database of lumbar CT called « Lombonice 2005 » and then we have made differents measureson 400 subjects. The aim of this study is to obtain a biometric atlas. Then, we wanted to create a new anatomic lumbar facet prosthesis. At least, we would like to determine the age or the sex of a sunject only with anatomic measures. Patients and methods : We have measured 217 men and 183 women of 59 years old on average. The native slices was 1,25 mm thick and goes from L1 to S1. We have created each cutting plan and we have placed many landmarks on them. The coordonates of these landmarks let us calculate differents distances, angles or mechanical circle radius which describe well the shape of the facets. We have compared then the measures obtained and the age, sex, side or level studied. Results : From L1 to S1, on transversal plan, the facets are getting closer to posterior wall but are getting away from each other. The posterior angle like a boat's bow increase from L1 to S1. The mechanical circle radius of each sides are symmetrical just in 50% of cases and unique in less than 10 % of cases. All the measures even in 3 dimensions does'nt let us determine the sex or the age of subjects. Measures on vertebral body seems to be more discriminant. Conclusion: We found that 3D shape of lumbar facets is more complicated than a spere fragment as expected. The side asymmetry makes it difficult to reproduce an anatomical facet's prosthesis.