Can imaging show tophi causing bone erosions with overhanging edges of cortical bone in Gout (Gouty Arthropathy)?

From the Guidelines

Imaging can indeed show tophi causing bone erosions with overhanging edges of cortical bone in Gout (Gouty Arthropathy), as evidenced by the latest guidelines and research in the field 1.

Key Points to Consider

• The 2023 EULAR recommendations on imaging in diagnosis and management of crystal-induced arthropathies suggest that ultrasound and DECT can be used to monitor crystal deposition and inflammation in gout 1.
• The recommendations also state that plain radiographs can be used to assess structural damage due to gout, particularly in long-standing disease, and can show characteristic bone erosions with overhanging edges of cortical bone 1.
• The presence of tophi and bone erosions can be detected using high-resolution ultrasound, CT, or dual energy CT, and plain radiographic findings consistent with tophi, such as characteristic bone erosion, can be used to evaluate disease burden and guide clinical decision making 1.
• The "double contour sign" on ultrasound can be consistent with non-tophaceous urate crystal deposition on the surface of articular cartilage, but is not universally detectable and should not be used as a sole indication for initiating or increasing the intensity of urate-lowering therapy 1.

Imaging Modalities for Gout

• Ultrasound: can detect tophi, double contour sign, and aggregates, and is sensitive to change over time 1.
• DECT: can detect crystal deposition and is useful for monitoring disease activity, but has limited utility in early gout and is not capable of visualizing synovitis 1.
• Plain radiographs: can assess structural damage due to gout, particularly in long-standing disease, and can show characteristic bone erosions with overhanging edges of cortical bone 1.

Clinical Implications

• Imaging can play a crucial role in the diagnosis and management of gout, particularly in advanced disease where tophi and bone erosions are present 1.
• The choice of imaging modality depends on the clinical circumstances and the availability of resources, but ultrasound and DECT are recommended for monitoring crystal deposition and inflammation in gout 1.

From the Research

Imaging of Tophi and Bone Erosions in Gout

• Imaging can be used to assess the complications of gout, including bony erosions 2
• The characteristic radiographic hallmarks of chronic gouty arthritis are the presence of macroscopic tophi and erosions with overhanging edges and relative preservation of the joint space 3
• Tophi can erode the underlying bone, leading to the development of bone erosions in gouty arthritis 3
• Dual-energy computed tomography can be used to measure the urate volume within tophus and bone erosion volume in patients with tophaceous gout 4
• The relationship between urate within tophus and bone erosion can be analyzed according to the anatomic location of urate deposition, with intraosseous tophi contributing the most to bone erosions 4

Bone Erosions in Gouty Arthropathy

• Bone erosion is a central feature of gouty arthritis and is associated with disease severity and poor functional outcome 5
• The pathogenesis of bone erosions in gouty arthritis involves mechanical, pathological, cellular, and immunological factors, including the role of osteoclasts and the receptor for activation of nuclear factor κ B (RANK) and RANK ligand (RANK-RANKL) pathway 3
• Interleukin 1β (IL-1β) has been implicated in bone destruction and erosions in gouty arthritis, and future IL-1 inhibitors may prevent and treat erosion formation due to tophaceous gouty arthritis 3
• Imaging modalities, including ultrasonography and dual-energy computed tomography, can be used to detect and quantify bone erosions in gouty arthritis 3, 4

Tophi and Bone Erosions

• Tophi are stone-like deposits of monosodium urate in the soft tissues, synovial tissues, or in bones near the joints, and are pathognomonic for gout 2
• Tophi can be found anywhere in the body, especially in areas of friction or trauma, and are usually painless and rarely present as the initial manifestation of gout 2
• The presence of tophi visible on examination or imaging is an indication for urate-lowering therapy, according to the American College of Rheumatology (ACR) guidelines 2
• Tophi can cause bone erosion and destruction, resulting in gait disturbance and other complications, especially in patients with early-onset gout and obesity 6