Sacroiliac joint variation associated with diffuse idiopathic skeletal hyperostosis

Area of Science:

• Rheumatology
• Orthopedic Surgery
• Radiology

Background:

• Diffuse idiopathic skeletal hyperostosis (DISH) is defined by ossification of vertebral bodies and peripheral entheses.
• Sacroiliac (SI) joint changes in DISH patients are not fully understood.
• This study investigates SI joint variations in DISH compared to non-DISH individuals.

Purpose of the Study:

• To evaluate and classify SI joint variations in patients with DISH.
• To compare SI joint changes between DISH-positive and DISH-negative populations.
• To elucidate the role of SI joints in the manifestation of DISH.

Main Methods:

• Computed tomography (CT) examination of 342 SI joints from 171 patients (86 DISH+, 85 DISH-).
• Classification of SI joint variations into four types: normal/minor irregularity, sclerosis/osteophytes, vacuum phenomenon, and bridging osteophyte/bony fusion.
• Assessment of bridging osteophyte type and ossification prevalence across spinal segments.

Main Results:

• Bony fusion (Type 4), specifically anterior paraarticular bridging, was the most common SI joint variation in the DISH+ group (71.6%).
• SI joint vacuum phenomenon (Type 3) was most frequent in the DISH- group (57.1%).
• DISH significantly affected the middle to lower thoracic spine and SI joints, leading to bony ankylosis.

Conclusions:

• Anterior paraarticular bridging is the predominant SI joint alteration in DISH patients undergoing lumbar surgery.
• Understanding these SI joint variations is crucial for comprehending the etiology of DISH.
• The findings highlight specific patterns of sacroiliac joint involvement in diffuse idiopathic skeletal hyperostosis.