Change and risk factors of cervical alignment after posterior osteotomy correction of congenital cervicothoracic deformity

English Keywords:Congenital scoliosis  Deformity  Cervicothoracic junction  Osteotomy  Cervical alignment

English Abstract:

  【Abstract】 Objectives: To analyze the characteristic and risk factors of sagittal cervical alignment after posterior osteotomy correction of congenital cervicothoracic deformity. Methods: 26 patients with congenital cervicothoracic deformity receiving posterior osteotomy correction between March 2012 and March 2017 in our hospital were analyzed. There were 10 males and 16 females with an average age of 14.2±4.6 years old(9-20 years). The mean follow-up period was 38.0±6.4 months(24-96 months). The pathological classification included hemivertebra in 5 cases, wedge vertebra in 2 cases, butterfly vertebra in 3 cases, hemivertebra with butterfly vertebra in 4 cases, hemivertebra with unilateral unsegment in 7 cases, block vertebra in 5 cases, respectively. The average fusion segments were 7.4±2.3(3-13). Imaging parameters of AP film of standing full spine X ray were collected to compare the coronal [clavicle angle(CA), neck tilt(NT), head shift(HS), coronal balance distance(CBD), main curve Cobb angle, caudal curve and T1 tilt] and sagittal [C2-C7 sagittal vertical axis(C2-C7 SVA), cervical lordosis(CL), cervicothoracic kyphosis(CTK), upper end vertebrae UEV/T1 slope(UEV/T1 slope), thoracic kyphosis(TK), UEV/T1-T12, lumbar lordosis(LL), pelvic incidence(PI), pelvic tilt(PT) and sagittal vertical axis(SVA)] parameters. 26 patients were divided into the lordosis group (8 patients, CL <-5°) and the straight/kyphosis group (18 patients, CL≥-5°) according to CL, and 18 patients in the straight/kyphosis group were subdivided into the deteriorate group(7 patients) and the non-deteriorate group(11 patients). The simplified Chinese version of SRS-22 questionnaire was collected as well. Pearson chi-square test, Fisher exact test, paired sample t-test, independent sample t-test and Pearson correlation coefficient analysis were used for statistical analysis of imaging parameters and SRS-22 questionnaire scores. Results: The average correction rate of primary curve and caudal curve were 67.0% and 47.9% respectively. HS, NT, CBD, T1 tilt and CA significantly improved at final follow-up. There was no significant difference of sagittal parameters among preoperative, postoperative or final follow-up in cervical lordosis group. There was significant difference of UEV/T1 slope(20.2°±0.5° vs 16.4°±4.3°, P<0.05) and UEV/T1-T12 (49.3°±5.2° vs 36.3°±14.3°, P<0.05) between lordosis group and straight/kyphosis group. There were significant differences in the two subgroups of postoperative CTK (2.4°±3.9° vs 12.7°±4.3°, P<0.05), postoperative UEV/T1-T12 (18.7°±3.6° vs 37.8°±7.6°, P<0.05) and CTK(5.2°±4.9° vs 11.7°±6.5°, P<0.05), UEV/T1-T12(20.4°±7.5° vs 38.5°±9.4°, P<0.05), LL(-46.4°±7.9° vs -36.4°±5.2°, P<0.05), SVA(-5.3±1.2cm vs -2.8±2.0cm, P<0.05) at final follow-up. Correlation coefficient tests showed correlations between preoperative cervical kyphosis and preoperative UEV/T1-T12(r=-0.398, P=0.045), postoperative cervical kyphosis and postoperative CTK(r=0.673, P<0.001), postoperative-final follow- up ΔLL(r=0.557, P=0.020) and ΔSVA(r-0.496, P=0.034). The results of SRS-22 questionnaire showed that the patients in the straight/kyphosis group had lower self-image scores and mental scores than those in the lordosis group(P<0.05). And patients in the deteriorate group owned the lowest pain scores and total scores(P<0.05). Conclusions: Congenital cervicothoracic deformity patients have a high cervical kyphosis incidence. Preoperative cervical kyphosis may be related to low preoperative UEV/T1-T12. Low postoperative CTK, increased LL and retrusive SVA may lead to long-term cervical kyphosis deterioration after posterior correction.