Plain radiography of the lumbosacral spine in Marfan syndrome.

Background Context: Marfan syndrome is a connective tissue disorder that results from a defect in the production of fibrillin. These patients tend to have several osseous anomalies of the lumbosacral spine.

Purpose: This study examines the effectiveness of plain radiographic findings in predicting Marfan syndrome.

Study Design/setting: Case-control study.

Patient Sample: Fourteen height-matched controls and 33 patients with Marfan syndrome were obtained from our genetics clinic or through the National Marfan Foundation.

Outcome Measures: Determined using measurements taken on plain radiographs.

Methods: Five measurements were acquired of the lumbosacral spine from the radiographs of both groups: interpedicular distance, scalloping value, sagittal canal diameter, vertebral body width and transverse process width.

Results: The following measurements were significantly larger in patients with Marfan syndrome: interpedicular distance at L1-L5 (p<.0001); sagittal diameters of the vertebral canal at L4-S2 (p<.01); transverse process to vertebral body width ratio at L2-L5 (p<.01). There was no significant difference in the scalloping values from L1-L5 between the patients with Marfan syndrome and the controls. A multivariate regression analysis generated the following criteria for plain film diagnosis of Marfan syndrome (two criteria need to be met for diagnosis): interpedicular distance at L5 greater than or equal to 36.0 mm, sagittal diameter at L5 greater than or equal to 13.5 mm or transverse process to vertebral width ratio at L3 greater than or equal to 2.25.

Conclusion: Based on this criteria, patients can be diagnosed with Marfan syndrome with a high sensitivity (81.8%) but a low specificity (58.3%). Thus, plain radiography can be a useful means of screening patients with Marfan syndrome.