Extensive Involvement of the Posterior Spinal Region in Ankylosing Spondylitis

A 32-year-old male with axial spondyloarthritis presented with chronic lower back pain for the last 4 years, with concomitant involvement of costovertebral (CV) and costotransverse (CTR) joints, manifesting as restricted spinal movement, eventually progressing to requiring support for sitting and standing. The laboratory parameters revealed elevated inflammatory markers, positive human leukocyte antigen B27, hypercalcemia and low parathyroid hormone level. On computed tomography (CT), there was extensive erosion, sclerosis and ankylosis of CV and CTR joints with concomitant ankylosis of facet and sacroiliac joints and syndesmophyte formation. Magnetic resonance imaging confirmed an ill-defined hyperintense abnormality at the CV and CTR joints, suggesting active inflammatory changes. The patient is undergoing treatment with physiotherapy and supportive medication and has shown improvement. This case report highlights that joint involvement of the CV and CTR contributes to morbidity, as these joints are critical to the mobility of the spine and thoracic cage. This case also highlights challenges in assessing these joints on conventional radiography and the value of CT for assessing changes, thereby improving treatment and supportive care through a better understanding of disease extent and progression.