Radiographic assessment of congenital C2-3 synostosis.

PURPOSE To evaluate the morphologies of congenital C2-3 synostosis in 25 patients. METHODS Radiographs of 11 males and 14 females aged 5 to 74 years with congenital C2-3 synostosis were reviewed. All cases were found incidentally on radiographs when presenting with neck/shoulder discomfort/pain. RESULTS 13 of the patients had spondylosis in 21 segments: C1-2 (n=1) and C3-4 (n=1), C4-5 (n=7), C5-6 (n=9), and C6-7 (n=3). Of whom 12 had normal sagittal alignment and one had kyphotic synostosis (who developed compensatory hyperlordosis of the caudal mobile segments and subsequent spondylosis at C3-4 and C5 retrolisthesis). The remaining 12 patients had no spondylosis and had normal sagittal alignment, but had other associated pathologies including disc herniation at C3-4, C1 ring hypoplasia, and calcification of the nuchal ligament. CONCLUSION Normally aligned congenital synostosis of C2-3 is rarely associated with a junctional problem, whereas a kyphotic synostosis is associated with a caudal junctional problem. Spondylosis developing after age 40 years is not associated with C2-3 synostosis.