RADIOGRAPHICAL ANALYSIS OF FLEXIBILITY OF IDIOPATIC SCOLIOSIS IN PRONO AND SUPINO

ABSTRACT Objective To determine if there is a statistically significant difference in the flexibility of the curves in the adolescent idiopathic scoliosis (AIS) by using lateral inclination radiographs in supine or prone decubitus. Methods We evaluated 19 patients with AIS, waiting for surgery. Radiographs of the patients were performed in orthostatic anteroposterior incidences and right and left lateral inclinations in prone and supine decubitus. The comparison between prone and supine decubitus was performed through the flexibility rates of the curves measured in each position. Results The mean flexibility rates measured in lateral inclination radiographs with the patient in the supine position were 54.4% ± 38.8% in the proximal thoracic curve, 45.8% ± 15.6% in the main thoracic curve, and 80.5% ± 20.7% in the thoracolumbar / lumbar curve. When the lateral inclination radiographs were performed with the patient in the prone position, we observed mean flexibility rates of 66.4% ± 34.3% in the proximal thoracic curve, 50.1% ± 12.8% in the main thoracic curve, and 80.6% ± 19.0% in the thoracolumbar / lumbar curve. Conclusion This present study did not find a statistically significant difference between the flexibility rates of the curves in the prone and supine positions, suggesting that the two radiographic methods analyzed are similar in the evaluation of the flexibility of the curves in adolescent idiopathic scoliosis. Level of evidence II; Development of diagnostic criteria in consecutive patients (with “gold” reference standard applied).

Upper instrumented vertebra to the right of the lowest instrumented vertebra as a predictor of an increase in the main thoracic curve after selective posterior fusion for the thoracolumbar/lumbar curve in Lenke type 5C adolescent idiopathic scoliosis: multicenter study on the relationship between fusion area and surgical outcome

OBJECTIVEUnfused main thoracic (MT) curvatures occasionally increase after selective thoracolumbar/lumbar (TL/L) fusion. This study sought to identify the predictors of an unacceptable increase in MT curve (UIMT) after selective posterior fusion (SPF) of the TL/L curve in patients with Lenke type 5C adolescent idiopathic scoliosis (AIS).METHODSForty-eight consecutive patients (44 females and 4 males, mean age 15.7 ± 2.5 years, range 13–24 years) with Lenke type 5C AIS who underwent SPF of the TL/L curve were analyzed. The novel “Shinshu line” (S-line) was defined as a line connecting the centers of the concave-side pedicles of the upper instrumented vertebra (UIV) and lowest instrumented vertebra (LIV) on preoperative radiographs. The authors established an S-line tilt to the right as S-line positive (S-line+, i.e., the UIV being to the right of the LIV) and compared S-line+ and S-line− groups for thoracic apical vertebral translation (T-AVT) and MT Cobb angle preoperatively, early postoperatively, and at final follow-up. The predictors for T-AVT > 20 mm at final follow-up were evaluated as well. T-AVT > 20 mm was defined as a UIMT.RESULTSAmong the 48 consecutively treated patients, 26 were S-line+ and 22 were S-line−. At preoperative, early postoperative, and final follow-up a minimum of 2 years later, the mean T-AVT was 12.8 mm (range −9.3 to 32.8 mm), 19.6 mm (range −13.0 to 41.0 mm), and 22.8 mm (range −1.9 to 68.7 mm) in the S-line+ group, and 10.8 mm (range −5.1 to 27.3 mm), 16.2 mm (range −11.7 to 42.1 mm), and 11.0 mm (range −6.3 to 26.9 mm) in the S-line− group, respectively. T-AVT in S-line+ patients was significantly larger than that in S-line− patients at the final follow-up. Multivariate analysis revealed S-line+ (odds ratio [OR] 23.8, p = 0.003) and preoperative MT Cobb angle (OR 7.9, p = 0.001) to be predictors of a UIMT.CONCLUSIONSS-line+ was defined as the UIV being to the right of the LIV. T-AVT in the S-line+ group was significantly larger than in the S-line− group at the final follow-up. S-line+ status and larger preoperative MT Cobb angle were independent predictors of a UIMT after SPF for the TL/L curve in patients with Lenke type 5C AIS. Surgeons should consider changing the UIV and/or LIV in patients exhibiting S-line+ during preoperative planning to avoid a possible increase in MT curve and revision surgery.