Finger Pulley Injury on MRI & ultrasound: Imaging Findings
The finger pulley system keeps the flexor tendons close to the phalanges. A2 pulley injuries are well known in climbers because crimp positions create high force across the proximal phalanx. Ultrasound can dynamically show tendon bowstringing, while MRI can show pulley discontinuity, tendon separation from bone, edema, and associated tenosynovitis.
Common Symptoms
- Sudden pop or sharp pain in the finger during crimp grip or climbing
- Pain along the palm side of the finger over the A2 or A4 pulley region
- Visible or palpable bowstringing when actively flexing the finger
- Swelling, stiffness, and loss of grip strength after loading the flexor tendons
What We Look For on Imaging
- A2 or A4 pulley thickening, discontinuity, or edema
- Increased tendon-to-bone distance indicating bowstringing
- Flexor tendon sheath fluid or tenosynovitis around the injured pulley
- Partial versus complete pulley tear and single versus multiple pulley involvement
- Associated bone stress reaction, collateral ligament injury, or tendon tear
Frequently Asked Questions
Is MRI or ultrasound better for a pulley injury?
Both can help. Dynamic ultrasound can show bowstringing during active motion and is often excellent when performed by an experienced operator. MRI provides a broader view of soft tissue edema, tendon sheath fluid, and associated bone or ligament injury.
Why do climbers talk about the A2 pulley so much?
The A2 pulley is a major restraint over the proximal phalanx and takes high load in crimp grip. A complete A2 tear can allow bowstringing, reducing finger flexion efficiency and changing return-to-climbing planning.
Sources
- Schöffl V, Hochholzer T, Winkelmann HP, Strecker W. Pulley injuries in rock climbers. Wilderness Environ Med. 2003;14(2):94-100.
- Klauser A, Frauscher F, Bodner G, et al. Finger pulley injuries in extreme rock climbers: depiction with dynamic US. Radiology. 2002;222(3):755-761.
- Hauger O, Chung CB, Lektrakul N, et al. Pulley system in the fingers: normal anatomy and simulated lesions in cadavers at MR imaging, CT, and US with and without contrast material distention of the tendon sheath. Radiology. 2000;217(1):201-212.
- Bollen SR. Injury to the A2 pulley in rock climbers. J Hand Surg Br. 1990;15(2):268-270.
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