Background: Congenital anomalies of the ribs and chest wall as well as Sprengel deformity of the shoulder are often associated with congenital deformities of the spine. It has been suggested that rib anomalies may adversely affect the progression of the spinal deformity.
Methods: We conducted a retrospective study of the medical records and spine radiographs of 620 consecutive patients with congenital deformities of the spine; 497 patients (80%) had scoliosis; eighty-eight patients (14%), kyphoscoliosis; and thirty-five patients (6%), kyphosis. The rib anomalies were classified into simple and complex, and the presence of a Sprengel deformity of the shoulder was recorded. The rate of scoliosis deterioration without treatment before the age of eleven years, as well as the patient age and curve size at the time of surgery, was compared for different types of vertebral abnormalities in patients with and without rib anomalies.
Results: A total of 119 patients (19.2%) had rib anomalies, which were most commonly associated with congenital scoliosis (111 patients; 93%) and were much less frequently associated with congenital kyphoscoliosis or kyphosis (eight patients). The rib anomalies were simple in ninety-five patients and complex in twenty-four. Eighty-five patients (71%) with rib abnormalities had a scoliosis due to a unilateral failure of vertebral segmentation, and seven patients had mixed or unclassifiable vertebral anomalies. In contrast, only sixteen of 203 patients with a scoliosis due to a hemivertebra alone had rib anomalies. The rib anomalies were most frequently associated with a thoracic or thoracolumbar scoliosis (102 patients; 92%) and occurred on the concavity in eighty-two patients (74%), the convexity in twenty-two patients (20%), and were bilateral in seven patients. The Sprengel deformity occurred in forty-five patients and most frequently in association with a thoracic scoliosis due to a unilateral failure of vertebral segmentation (twenty-seven patients). No significant difference was detected in the rate of curve progression without treatment in patients with and without rib anomalies. The only exception was the mean age at the time of surgery, which was higher for patients with a unilateral unsegmented bar without rib anomalies (p = 0.005). In addition, no significant difference was found with regard to any tethering effect due to the site of the rib fusions on the concavity of the scoliosis, i.e., whether they were in close approximation to the spine or were more lateral (p > 0.05).
Conclusions: Congenital rib anomalies occur most commonly on the concavity of a thoracic or thoracolumbar congenital scoliosis that is due to a unilateral failure of vertebral segmentation, and they do not appear to have an adverse effect on curve size or rate of progression.
Level of Evidence: Prognostic Level II. See Instructions to Authors for a complete description of levels of evidence.
1 Scottish National Spine Deformity Center, Royal Hospital for Sick Children (Level 5), Sciennes Road, Edinburgh EH9 1LF, United Kingdom. E-mail address for M.J. McMaster: email@example.com