Risk factors of coronal decompensation following posterior hemivertebra resection in patients with thoracic hemivertebra

English Keywords:Congenital scoliosis  Thoracic hemivertebra  Coronal decompensation  Hemivertebra resection  Risk factors

English Abstract:

  【Abstract】 Objectives: To analyze the risk factors of coronal decompensation after posterior thoracic hemivertebra resection, pedicle screw fixation and fusion. Methods: Data of 57 patients with single thoracic hemivertebra who received posterior hemivertebra resection and pedicle screw fixation and fusion in our department from January 2011 to January 2019, were retrospectively analyzed. Among them, 7 patients occurred coronal decompensation after surgery were included in the decompensation group, while 50 patients without any secondary deformity were included in the control group. Both clinical data and radiographic parameters before surgery and at the last follow-up were collected in this study. The age, Risser sign, main curve Cobb angle, upper instrument vertebra(UIV) tilt angle, UIV translation, lower instrument vertebra(LIV) tilt angle, LIV translation, and LIV disc wedge angle were compared between decompensation and control groups. And the correlation between the above parameters and postoperative decompensation was analyzed by multivariate analysis. The cut-off value was calculated by ROC curve. Results: Decompensation group included 4 males and 3 females, averaged 10.2±3.6 years(4 to 14 years old) with 1 patient <10 years old and 6 patients between 10 to 14 years old. Control group included 27 males and 23 females, averaged 10.2±3.6 years(4 to 17 years old)with 26 patients <10 years old, 17 patients between 10 to 14 years old and 7 patients between 14 to 18 years old. There was no difference in gender distribution(P=0.697) but significant difference in age distribution between the two groups(P=0.032). The decompensation group had more patients between 10－14 years old. Decompensation group included 6 patients of Risser sign grade 0 to 2 and 1 patient of grade 3 to 5, while control group had 20 patients of Risser sign grade 0 to 2 and 30 patients of grade 3 to 5. The ratio of grade 0－2 patients were significant higher in decompensation group(P=0.029). The preoperative UIV tilt angle and LIV tilt angle in the decompensation group were 29.5°±10.4° and 22.1°±11.8° respectively, which were significantly larger than those in the control group(13.2°±6.4° and 14.9°±7.5°, P<0.05). Multivariate analysis showed age (OR=1.401), Risser sign (OR=0.357), preoperative UIV(OR=1.230), preoperative LIV(OR=1.309) were the risk factors for postoperative coronal decompensation(P<0.05). The cut-off value of preoperative UIV tile angle was 19.2° while the preoperative LIV tilt angle was 17.6°. Conclusions: The thoracic hemivertebra patients aged 10 to 14 years old with Risser sign between grade 0 to 2 have a very high risk for coronal decompensation; and the preoperative UIV tilt angle ≥19.2° or LIV tilt angle ≥17.6° may be the risk factor for coronal decompensation after operation.