Evaluation of Sacroiliac Joint Shape in Women with Ankylosing Spondylitis According to Mode of Birth Delivery: A Retrospective Study

<i>Background and Objectives</i>: Ankylosing spondylitis (AS) is a chronic progressive inflammatory process of the axial skeleton and sacroiliac joints (SIJ). Symptoms typically appear between the ages of 20 and 40, although there are also cases of juvenile-onset AS. This suggests that most patients with AS are of reproductive age at the time of diagnosis. The study aimed to identify differences in the shape of the sacroiliac joint depending on the type of birth (vaginal delivery (V/D) and the cesarean section(C/S) in patients with ankylosing spondylitis. <i>Materials and Methods</i>: On pelvis X-ray images of women n = 36 with AS and n = 34 in the control group, 12 landmarks were marked, and differences in SIJ shape between the study groups were assessed using generalized Procrustes Analysis. <i>Results</i>: The results showed that the anterior point of the SIJ had an enlarged shape in the V/D group compared with the C/S group, even in the control group. There was a difference between the mean right and left SIJ shapes of the AS group patients with V/D and the controls with C/S (<i>p</i> = 0.007 and <i>p</i> < 0.001). The superior part of the right SIJ tended to be enlarged in V/D-delivered AS patients, compared to the C/S control group. On the left side, the middle region of the SIJ was statistically enlarged in AS patients with V/D compared to the healthy C/S group. <i>Conclusions</i>: This study demonstrates that vaginal delivery is associated with increased sacroiliac joint (SIJ) enlargement in both healthy individuals and those with ankylosing spondylitis (AS). Our findings suggest that delivery type independently influences SIJ morphology, and cesarean section (C/S) may serve as a protective procedure for preserving SIJ shape in AS patients. These results underline the importance of individualized obstetric planning for AS patients to mitigate potential risks to SIJ morphology.