Ankylosing Spondylitis Osteotomy Biomechanical Study On The Stretching Of The Inferior Vena Cava

Ankylosing spondylitis(AS), a chronic inflammatory disease, involves mainly the axial spinal column. It will ultimately result in the humpbacked malformation. This kind of disease can severely affect the patient's physical and mental health by leading to decrease of pulmonary ventilation, shifting forward of the body center of gravity, and influencing the daily life and appearance. Spinal osteotomy is the best way for the humpbacked malformation of AS.But the abdominal vessel injury is the most serious complication.Someone had an Abdominal Aorta stretching test ,and result showed that the greater is the stretching velocity, the greater is the breakdown load. Stretching rate of the anterior column should be less than the stretching rate of breakage of normal abdominal aorta.No inferior vena cava test has been reported now. Inferior vena cava from the fresh body of normal cadeva were adopted to assess the breakdown load and ratio of stretching .Result of this experiment demonstrated that the breakdown load of the Inferior vena cava is 42.19N;the stretching length of the Inferior vena cava is 30.21mm;the stretching ratio of the Inferior vena cava is 81.72%. If stretching ratio of the anterior column is less than 23.5%, the Inferior vena cava injury can be avoided during operation of spinal asteomy for ankylosing spondylitis patient.