Changes of the Abdomen in Patients With Ankylosing Spondylitis Kyphosis

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Study Design.

A retrospective clinical study.


To investigate changes of the abdomen in patients with ankylosing spondylitis kyphosis.

Summary of Background Data.

Since 1945, many authors had reported the good clinical and radiographical outcomes and higher patient satisfaction rates of spinal osteotomy techniques. However, to our knowledge, whether the visceral and diaphragmatic compression that results from the inferior edge of the thoracic cage is relieved by the surgery has not yet been reported.

Materials and Methods.

From July 2010 to July 2013, 26 patients (24 males, and 2 females) with severe ankylosing spondylitis kyphosis, who underwent pedicle subtraction osteotomy in the Department of Orthopaedics at Chinese People's Liberation Army General Hospital were studied. Preoperative and postoperative computed tomographic scan, 3-dimensional reconstruction, and preoperative pulmonary function test were performed. Via those tests, the minimum distance on the median sagittal plane of the abdomen (MD), the acreage of the abdominal median sagittal plane (AMSPA), the diaphragm angle on median sagittal plane can be gained. A paired sample t test was performed to determine the differences between the preoperative and postoperative AMSPA and MD and diaphragm angle on median sagittal plane, respectively. Postoperative MD/preoperative MD and postoperative AMSPA/preoperative AMSPA and global kyphosis were also analyzed by performing independent sample t test for the 2 groups.


The diaphragm angle on median sagittal plane has changed significantly in all the patients. There was significant change of both MD and AMSPA in patients whose abdominal wall was folded into abdomen, whereas neither MD nor AMSPA in patients without the factor.


To a certain degree, the diaphragmatic compression and the visceral compression could be compensated for by turning to flattening or even developing into kyphosis of the lumbar lordosis before surgery, which could be corrected by a spinal osteotomy. Sagittal rotation of diaphragm in ankylosing spondylitis kyphosis could also be improved by a spinal osteotomy.


Level of Evidence: 4

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