Vertebral Morphology of Loeys-Dietz Spine

Introduction: Understanding pedicle and laminar anatomy is crucial for secure fixation of spinal instrumentation and to ultimately prevent complications such as pseudoarthrosis. This study explores the spinal morphology in the LD vertebrae and compares it to vertebrae of TDP. Methods: The morphology of 36 vertebrae from T1 to L5 were measured in 4 LD syndrome patients, using MRI and CT scans. The morphology of 140 vertebrae from T1 to L5 were measured in non-connective tissue disorder patients, using MRI, CT, and X-rays. These values were then compared to each other. Comparisons via paired Student’s t-test were made between the concave and convex side of the curve in LD patients with scoliosis. Results: On average, pedicle widths in LD vertebrae were significantly thinner than pedicles in non-connective tissue disorder vertebrae (p=0.002). As the vertebral level approached the apex of the spinal curvature, the pedicle widths decreased by 1.13 mm and 1.17 mm per level on the concave and convex side, respectively. Starting from L5, the pedicle widths decreased as the vertebral levels went up the lumbar spine. The average width of concave lamina was 6.5 ± 2.5 mm while the average width of convex lamina was 5.8 ± 2.2 mm (p=0.021). Pedicle width and laminar thickness measurements from CT and MRI were not significantly different. X-ray pedicle width measurements correlated moderately well to both MRI and CT pedicle width measurements (R2=0.52 and 0.59, respectively). Conclusion: LD spines are associated with vertebral asymmetry that is most pronounced at the apex of the curve. Pedicles on the convex side of the curve were significantly thicker than those on the concave side. Pedicles were much thinner in LD patients than in non-connective tissue disorder patients. Such unique vertebral morphology finding supports obtaining preoperative routine MRI or CTs when operating on LD spine with pedicle screws and lamina hooks. X-rays can be useful in characterizing pedicle morphology as well. Our findings can help surgeons understand and plan for secure fixation in the LD population.