Can We Predict Dominant Compensatory Curves in Congenital Scoliosis?

Background: A complication in the natural evolution of congenital scoliosis is the development of a compensatory curve. Congenital curves are often focal and rigid, causing patients to develop a compensatory curve cranial and/or caudal to the congenital anomaly to achieve coronal balance. Therefore, surgeons are faced with the difficult choice of waiting for the patient to reach an appropriate age for surgery or correcting the congenital curve before a compensatory curve develops. Methods: By searching the Pediatric Spine Study Group database, we identified 307 pediatric patients (age <18) with congenital scoliosis who had preoperative radiographs taken during at least 2 years of natural growth (without bracing or surgery). Of these patients, 17 (5.5%) had a dominant compensatory curve, and 290 had no compensatory curve or one that was smaller than the congenital curve. Of those 290 patients, we randomly selected 100 to serve as a control group, referred to as the nondominant curve cohort. We extracted data on the type of congenital anomaly and its vertebral level, as well as the Cobb angles of the congenital and compensatory curves at initial and latest follow-up. We compared vertebral level and type of congenital anomaly via chi-squared test between the dominant and nondominant curve group. Results: The congenital anomaly was located at L4 or more caudal in 18% of patients with a dominant and in 0% of the nondominant curve group (p < .001). Similarly, the congenital anomaly was at T5 or more cranial in 47% of patients with a dominant and in 21% of the nondominant curve group (p < .001). At latest follow-up, those in the dominant compensatory curve group had a mean (± standard deviation) congenital curve of 55º ± 19º and compensatory curve of 73º ± 24º. Conclusions: A dominant compensatory curve is an uncommon sequel of congenital scoliosis. We found that it was associated with vertebral anomaly at L4 or caudal or at T5 or cranial. These findings can help clinicians prioritize prophylactic treatment for patients who may be at high risk for developing a dominant compensatory curve.