Trigger thumb (or flexor pollicis longus stenosing tenosynovitis) is a specific type of trigger finger involving the thumb.
May present as a transient locking of the thumb in flexion, followed by a painful snapping sensation during extension
Ultrasound / MRI
Can show varying degrees of flexor pollicis longus tendinosis (local swelling of the flexor tendons distal to the pulley) with a distinct nodule, A1 pulley thickening, and tenosynovitis. Small cysts may be present at the pulley boundaries due to fluid trapping.
Dynamic scanning during passive flexion and extension could show difficult tendon gliding underneath the abnormal pulley
Doppler imaging may depict hypervascularity in the region of the pulley and surrounding soft tissues
- 1. Shah AS, Bae DS. Management of pediatric trigger thumb and trigger finger. (2012) The Journal of the American Academy of Orthopaedic Surgeons. 20 (4): 206-13. doi:10.5435/JAAOS-20-04-206 - Pubmed
- 2. Chang EY, Chen KC, Chung CB. MR imaging findings of trigger thumb. (2015) Skeletal radiology. 44 (8): 1201-7. doi:10.1007/s00256-015-2172-y - Pubmed
- 3. Boretto J, Alfie V, Donndorff A, Gallucci G, DE Carli P. A prospective clinical study of the A1 pulley in trigger thumbs. (2008) The Journal of hand surgery, European volume. 33 (3): 260-5. doi:10.1177/1753193408087070 - Pubmed