The radiologic, clinical results and digestive function improvement in patients with ankylosing spondylitis kyphosis after pedicle subtraction osteotomy

Abstract

Background contextAlthough there have been several reports describing the radiologic and clinical outcomes of pedicle subtraction osteotomy (PSO) in ankylosing spondylitis (AS) with spinal kyphotic deformity, little is known about the digestive function improvement in AS kyphosis after PSO. PurposeThe aim was to assess radiologic and clinical results and digestive function improvement in patients with AS kyphosis after PSO. Study design/settingThis was a retrospective clinical study. Patient sampleFrom January 2009 to July 2013, 53 patients in our department with AS kyphotic deformity who underwent PSO were reviewed. Outcome measuresThe globe kyphosis (GK) was measured. A health-related quality of life included Oswestry Disability Index (ODI) and Scoliosis Research Society outcomes instrument-22 (SRS-22). The acreage of the abdominal median sagittal plane (AMSPA) and the minimum distance (MD) between the xiphoid process and the spine or between the abdominal wall and the spine when the abdominal wall was folded into abdomen were measured on the three-dimensional computed tomography scans. The positional changes of abdominal viscera, such as the liver, spleen, and kidney, were also measured. Digestive function assessment included weight and the food intake (FI), and the change of the defecate frequency was recorded. MethodsA paired sample t test was performed to determine the differences between the preoperative and postoperative MD, AMSPA, and weight, respectively. A paired sample t test was also performed to determine the differences between preoperative and postoperative Cobb angles and Oswestry Disability Index (ODI), SRS-22 for all the patients, respectively. A paired sample t test was also performed to determine the positional changes of abdominal viscera. Description date was presented as mean±standard deviation. Additionally, an independent sample t test was performed to determine the differences between the patients (Group 1) who had defecate frequency change and the remaining patients (Group 2) for preoperative GK, age, and disease duration, respectively. An independent sample t test was also performed to determine the differences between the patients (Group A) who had obviously increased FI and the remaining patients (Group B) for preoperative GK, age, and disease duration, respectively. ResultsAll the patients had good radiologic and clinical results, postoperatively. The postoperative positions of the abdominal viscera were changed significantly. The weight, the mass of FI, and the defecate frequency were also changed significantly, postoperatively. The preoperative GK, age, and disease duration were not significantly statistical different between the patients who had defecate frequency change and the remaining patients, respectively. There were also not significantly statistical differences between the patients who had obviously increased FI and the remaining patients in preoperative age and disease duration. There was a significantly statistical difference between the patients who had obviously increased FI and the remaining patients for preoperative GK. ConclusionsThe single-level or two-level PSO is an effective and safe technique to correct AS kyphosis. And the conditions of extrusion of viscera by trunk flexion decreased volume of the abdominal cavity, and abnormal visceral positions were improved by the osteotomy, followed with digestive function improvement.