Pulmonary function improvement in patients with ankylosing spondylitis kyphosis following pedicle subtraction osteotomy

English Keywords:Ankylosing spondylitis kyphosis  Pedicle subtractionosteotomy  Pulmonary function

English Abstract:

  【Abstract】 Objectives: To observe postoperative change in pulmonary function in patients with ankylosing spondylitis(AS) kyphosis after pedicle subtraction osteotomy(PSO), and investigate the related factors of pulmonary function changes after operation. Methods: From June 2009 to June 2011, a total of 32(27 males and 5 females) patients with AS kyphosis were eligibly involved. 29(25 males and 4 females) patients with a mean age of 36.4±7.8 years(range, 22-52 years) completed the follow-up and 3(2 males and 1 female) patients lost. Pulmonary function tests, breath-holding time and full-length spine X-ray films in natural standing position were followed postoperatively. The study explored whether there was a change in lung function postoperatively, the relationship of the possible existence of lung function changes with gender, age, course of the disease and the spinal sagittal parameters was investigated. Results: Cobb T1-S1 significantly decreased from 63.0°±20.3° preoperatively to 15.3°±10.3° postoperatively and 17.1°±10.9° at 2-year follow-up. The breath-holding time(BHT) before surgery was 32.5±10.1s, while the postoperative BHT increased to 43.1±8.6s(P<0.05). Two AS patients had normal pulmonary function test before operation, while there were 19 patients at 2-year follow-up. The clinical improvement rate was 85.2%(23/27). The percentage predicted vital capacity(PredVC%) increased from (68.4±9.5)% to (79.4±6.1)% at 2-year follow-up(P<0.05). The percentage predicted forced vital capacity(PredFVC%) before PSO was (75.5±6.4)% and (81.0±6.9)% at 2-year follow-up(P<0.05). The improved PredVC% and PredFVC% had a positive correlation with the correction of Cobb T1-S1(r=0.6328 and 0.8612, P＜0.01, respectively). Conclusions: The postoperative pulmonary function including pulmonary volume and ventilatory function in AS patients with kyphosis is significantly improved at 2-year follow-up. And the improved pulmonary function has a positive correlation with the kyphosis correction.