Dagger sign

Medical sign indicating a specific radiological finding

Dagger sign
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Diagnosis	X-ray
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The dagger sign is a radiological finding observed in certain medical conditions, particularly in the context of ankylosing spondylitis. It is characterized by a single central radiopaque line on an X-ray of the spine, which represents ossification of the supraspinous and interspinous ligaments.

Pathophysiology

The dagger sign is indicative of the ossification process that occurs in ankylosing spondylitis, a type of spondyloarthritis. This condition leads to inflammation of the spinal joints and ligaments, which over time can result in the formation of new bone. The ossification of the ligaments in the midline of the spine gives rise to the appearance of a dagger-like line on the X-ray.

Clinical Significance

The presence of the dagger sign is a useful diagnostic feature for radiologists and clinicians when evaluating patients suspected of having ankylosing spondylitis. It is often seen in conjunction with other radiological signs such as the bamboo spine, which is another classic feature of advanced ankylosing spondylitis.

Diagnosis

The dagger sign is typically identified on a lateral X-ray of the lumbar spine. It is important for radiologists to differentiate this sign from other potential causes of linear radiopaque lines in the spine, such as surgical hardware or other pathological calcifications.

Related Conditions

While the dagger sign is most commonly associated with ankylosing spondylitis, it may also be seen in other conditions that cause similar ossification patterns in the spine. However, these are less common and the dagger sign remains a hallmark of ankylosing spondylitis.

Also see

• Ankylosing spondylitis
• Bamboo spine
• Spondyloarthritis
• Radiology

Rheumatologic diseases

Arthritis is often used to refer to any disorder that affects the joints. Rheumatic diseases usually affect joints, tendons, ligaments, bones, and muscles. Rheumatologic diseases usually affect joints, tendons, ligaments, bones, and muscles.

Connective Tissue Diseases

Rheumatology and	Connective Tissue Diseases
Ankylosing spondylitis	Arthritis
Arthritis and Rheumatic diseases	Autoimmune diseases
Autoinflammatory diseases	Behçet’s disease
Bursitis	Giant cell arteritis
Gout	Juvenile arthritis
Knee problems	Lupus
Osteoarthritis	Polymyalgia rheumatica
Psoriatic arthritis	Reactive arthritis
Rheumatoid arthritis	Scleroderma
Sjögren’s syndrome	Systemic lupus erythematosus (Lupus)
Tendinitis	Rheumatologic diseases