Differences in Curve Behavior After Fusion in Adolescent Idiopathic Scoliosis Patients With Open Triradiate Cartilages

Abstract

Retrospective review. To compare the results of spinal fusion in patients with open triradiate cartilages (OTRC) and closed triradiate cartilages (CTRC). Patients with OTRC at the time of spinal fusion may be at increased risk of developing postoperative changes related to growth. From a database of patients with adolescent idiopathic scoliosis, we identified 44 patients with OTRC (mean age, 11.6 years) and 450 patients with CTRC (mean age, 15.6 years) and a minimum follow-up of 2 years. Patients in both groups were treated with anterior-only, posterior-only, or combined anterior and posterior spinal fusion; none had all-pedicle screw posterior instrumentation. In the OTRC group, anterior or posterior instrumentation, but not the combined approach, resulted in a significant mean late increase in the main curve (4.4 degrees and 7.3 degrees vs. 0 degrees , respectively; P = 0.002), an approach-related difference not seen in the CTRC group. Significantly more OTRC patients had proximal levels added on after surgery than did CTRC patients (18% vs. 8%, respectively; P = 0.02), and there was a trend toward this phenomenon distally (29% vs. 19%, respectively; P = 0.10). Proximal and distal junctional kyphosis was not significantly different between the 2 groups. Reoperation rate was 11% and 7% for OTRC and CTRC patients, respectively. For the selectively fused Lenke 1C curves in OTRC and CTRC patients, there was a trend in the uninstrumented lumbar curve toward a smaller lumbar curve before surgery (36 degrees and 41 degrees , respectively; P = 0.07) and a larger curve after surgery (27 degrees and 24 degrees , respectively; P = 0.07). Patients with scoliosis and OTRC have a greater risk of adding-on proximally and of loss of correction with anterior-only instrumentation; they may also have less predictable lumbar correction from selective thoracic fusion. However, after combined surgery, they have results similar to those of more skeletally mature patients.