Correction of Scoliosis with Large Thoracic Curves in Marfan Syndrome: Does the High-Density Pedicle Screw Construct Contribute to Better Surgical Outcomes

BACKGROUND The aim of this study was to determine whether higher density screw constructs resulted in better surgical outcomes in patients with scoliosis secondary to Marfan syndrome (MF-S) with large thoracic curves (≥70°). MATERIAL AND METHODS There were 34 MF-S patients who met the inclusion criteria and were evaluated radiographically before surgery, 2 weeks after operation, and at the final follow-up. The mean screw density was taken as the boundary, and patients were categorized as either in the high density (HD) group or the low density (LD) group. Parameters measured included coronal Cobb angle, T5-T12 kyphosis (TK), and T12-S1 lordosis (LL). Additionally, the operation duration, estimated blood loss, screw accuracy, complication rate, and clinical outcomes were compared between the 2 groups. RESULTS The mean screw density of all patients was 1.40±0.15 (range 1.13 to 1.67). Correction rate of the thoracic curve was closely related to the screw density at the concave side (r=0.783, P=0.007). Intergroup comparison showed a significantly higher correction rate of the thoracic coronal curve in HD group (56.59±4.80% versus 44.54±9.61%, P=0.036). At last follow-up, coronal correction loss of >5° occurred in 8 cases (47.1%) in the LD group and 3 cases (17.6%) in the HD group. Both groups demonstrated improvement in each domain of the SRS-22 questionnaire after surgery and no significant intergroup difference was found. CONCLUSIONS The high-density pedicle screw construct contributed to the significantly improved correction rate of thoracic curves in MF-S patients with large thoracic curves (≥70°). Additionally, increasing of pedicle screw number could help to enhance the structural stability and reduce the correction loss during the follow-up period.