MR imaging findings of trigger thumb

Area of Science:

• Radiology
• Musculoskeletal Imaging
• Orthopedics

Background:

• Trigger finger/thumb (sclerosing tenosynovitis) is a common condition but infrequently undergoes imaging.
• Radiologists may lack familiarity due to selection bias and misleading clinical indications.
• Magnetic resonance (MR) imaging findings for trigger thumb have not been previously documented.

Observation:

• This review details the anatomy relevant to trigger thumb.
• It describes characteristic MR imaging findings associated with the condition.
• Key findings include flexor pollicis longus tendinosis with nodule formation, A1 pulley thickening, and tenosynovitis.

Findings:

• Flexor pollicis longus tendinosis with a distinct nodule.
• A1 pulley thickening.
• Tenosynovitis; abnormal A1 pulley may be apparent in some cases.

Implications:

• Accurate MR imaging diagnosis of trigger thumb is crucial for timely treatment initiation.
• Recognizing these findings can prevent unnecessary further investigations.
• Enhances radiologist's ability to diagnose this uncommon presentation.