The correlation between the diaphragmatic sagittal rotation and pulmonary dysfunction in ankylosing spondylitis kyphosis

English Keywords:Ankylosing spondylitis  Thotacolumbar kyphosis  Pulmonary function  Diaphragm rotation

English Abstract:

  【Abstract】 Objectives: To analyse the correlation between the pulmonary dysfunction patterns and the diaphragmatic sagittal rotation in AS thoracolumbar kyphosis. Methods: From June 2011 to January 2014, 30 patients in our department with thoracolumbar kyphotic deformity secondary to ankylosing spondylitis and undergoing pedicle subtraction osteotomy were reviewed retrospectively. The pulmonary function tests were performed preoperatively including: lung volume capacity(VC), minute ventilation volume(MVV), forced vital capacity(FVC), forced expiratory volume in one second(FEV1), FEV1/FVC, maximum expiratory flow volume(PEF), inspiratory reserve volume(IRV), expiratory reserve volume(ERV). The percentage of all lung function indexes was measured according to the results. All the patients had computed tomographic scan and three dimensional reconstruction, full-length spine radiographs. The diaphragm angle(DA) and T1-S1 Cobb angle on median sagittal plane were measured. The Pearson coefficient was used to evaluate the correlation between DA and pulmonary function and the T1-S1 Cobb angle, respectively. Results: The VC value was (68.26±6.78)％, MVV value was (56.71±6.90)％, FVC value was (69.10±6.34)％, FEV1 value was (43.24±5.67)％, FEV1/FVC value was (46.48±3.81)％, PEF value was (78.07±11.91)％, IRV value was (54.85±6.37)％, ERV value was (63.37±19.73)％; DA was -28.18°±9.67°, T1-S1 Cobb angle was 49.17°±7.43°. The data analysis presented a negative correlation between DA value and the Cobb T1-S1(r=-0.5337, P<0.05). There was also positive correlations between the DA value and VC, FVC, ERV, IRV and PEF(r=0.6184, 0.3893, 0.4966, 0.3732, 0.3633; P<0.05）. There was no significant correlations between the DA value and FEV1, FEV1/FVC and MVV(P>0.05）. Conclusions: Diaphragm rotate more severely with the Cobb T1-S1 increasing; the diaphragmatic sagittal rotation is also a aggravating factor of pulmonary dysfunction in AS patients with kyphosis.