Prospective Radiographic and Clinical Outcomes of Dual Rod Instrumented Anterior Spinal Fusion in Adolescent Idiopathic Scoliosis: Comparison with Single Rod Constructs

Summary: Prospective radiographic and clinical data were evaluated in 57 consecutive AIS patients treated with dual rod instrumented anterior spinal fusion for major thoracic (n=18) or thoracolumbar/lumbar (n=39) curves. Adequate deformity correction was maintained with dual rod constructs. No pseudarthroses were identified. SRS outcome scores showed significant improvement in self-image and function. Compared to a previous series of single rod constructs, patients treated with dual rod instrumentation trended towards a lower pseudarthrosis rate.

Introduction: Several reports have described the use of anterior single rod instrumentation for the treatment of AIS curves with acceptable correction rates, but with pseudarthroses/implant failures of up to 31%.

Objectives: To compare the results of anterior dual rod instrumentation in single major AIS curves with our previous experience using single rod constructs.

Methods: 57 consecutive AIS patients (12M, 45F; average age 15.4 yrs.) with major thoracic (n=18) or thoracolumbar/lumbar (n=39) curves were treated with dual rod instrumented ASF. Follow-up was 2-5 years. Patients were evaluated prospectively with SRS questionnaires.

Results: Major thoracic curves were corrected from a mean of 55 degrees preoperative to 27 degrees at latest follow-up (51% correction), while major thoracolumbar/lumbar curves were corrected from an average of 51 degrees to 17 degrees (67% correction). No pseudarthroses were identified. With the use of single rod constructs, a similar amount of coronal correction was obtained for both thoracic (47%) and thoacolumbar/lumbar curves (70%). However, the pseudarthrosis rate for single rod constructs was 5.5%. The obvious trend towards a lower pseudarthrosis rate in dual rod (0/57) versus single rod (5/90) constructs did not reach statistical significance (p=0.08). Follow-up SRS questionnaire data in dual rod patients showed that 95% were satisfied, and 93% would have the same treatment again. SRS domain scores were improved at a significant level.

Conclusion: In this largest single center report of dual rod constructs for AIS patients, a similar amount of radiographic deformity correction was obtained when compared to single rod implants. However, the absence of any pseudarthroses in the 57 dual rod patients is a distinct advantage.