Polyaxial Screws with Thick Rod versus Monoaxial Screws with Thin Rod in Video-Assisted Thoracoscopic Scoliosis Surgery (VATS) / 대한척추외과학회지

ABSTRACT

STUDY DESIGN: Prospective controlled cohort study OBJECTIVE: To analyze the clinical outcome of video-assisted thoracoscopic surgery (VATS) between two different types of implants. SUMMARY OF LITERATURE REVIEW The problem of correction loss has been reported with VATS, and different screws and rods have been developed to overcome this problem. Different implants will have varying effects in correctional outcome after VATS. MATERIALS AND METHODS: A total of 39 cases of idiopathic adolescent scoliosis treated with VATS between June 2001 and January 2005 were included in the study (mono-axial screws and a 4.5 mm rod thin rod group=19 cases; poly-axial reduction screws and a 5.5 mm diameter rod thick rod group=20 cases). All patients were followed for over 2 years postoperatively. For the comparison of surgical outcomes between the two groups, radiographic measurements were performed in the coronal and sagittal planes. RESULTS: Preoperative scoliosis angle (thin rod group 49.8degrees, thick rod group 47.1degrees), age, BMI, Risser stage, union time, operative time, and blood loss showed no statistical difference between the two groups. Postoperative average correction rate of scoliosis angle was 69% (15.8degrees) in the thin rod group and 70% (14.1degrees) in the thick rod group. However, correction rate after 2 years was 51% (24.5degrees) in the thin rod group and 60% (18.7degrees) in the thick rod group, showing statistically significant difference. There was a tendency toward correction loss in the thin rod group (8.7degrees vs. 4.6degrees p=0.0057). CONCLUSION: Postoperative correction rate was satisfactory in both groups. However, the thin rod group showed substantial correction loss. Therefore, poly-axial screws and thick rods are more suitable in VATS correction of scoliosis.