Little-Finger Side Wrist Pain That Snaps When You Turn Your Palm Up
Pain on the little-finger side of the wrist has two usual owners.
- One is the TFCC, the cartilage complex inside the joint.
- The other is the ECU tendon, which runs in a groove on the outside of it.
The distinction is worth making because they’re treated differently, and there’s a fairly clean way to separate them.
TFCC pain is deep, inside the joint, and worst with rotation and load. ECU pain sits on the surface, along a line you can trace with a fingertip, and it’s tender to press directly.
And if there’s a distinct snap or clunk when you turn your palm upwards, that’s the ECU tendon jumping out of its groove, which is a different problem again.
What the ECU is and where it runs
Extensor carpi ulnaris. It runs down the back of the forearm on the little-finger side, sits in a shallow groove in the end of the ulna, and attaches into the base of the little finger’s metacarpal. It cocks the wrist back and bends it towards the little finger.
Where it crosses the wrist it’s held in that groove by a fibrous sleeve of its own, separate from the usual retinaculum. That sleeve is the thing that fails in the second version of this injury.
Trace it yourself: find the knobbly bone at the back of your wrist on the little-finger side, then feel just past it towards your hand. That’s the tendon and its groove.
Version one: tendinopathy
Overload, not injury. An ache along the tendon line, worse after activity, tender to press, sometimes a little swollen and occasionally with mild creaking.
Common in tennis, especially in the non-dominant hand of a two-handed backhand, in golf, in rowing, and in anyone doing repetitive forceful wrist work.
Treatment follows the tendinopathy pattern: relative rest from the aggravating load, a period of splinting, then graded loading to rebuild the tendon rather than pure rest. Injection for stubborn cases, though this tendon is treated with a bit more caution than most. Realistic timeline is 6 to 12 weeks, sometimes longer.
Version two: subluxation, the snapping one
This is the one people describe rather than complain about.
“It snaps.”
The sleeve holding the tendon in its groove tears, usually in a single moment: a fall with the wrist twisted, or a forceful swing where the wrist gets caught. After that, the tendon slides out of its groove during certain movements and snaps back when you reverse them.
The classic trigger is turning the palm upwards with the wrist bent towards the little finger.
You can often reproduce it deliberately, and often see the tendon move.
A wrist that aches is a tendon under load. A wrist that snaps in a repeatable way is a tendon that’s escaped from something.
This one matters because the acute case and the old case get very different treatment.
Caught early, a long cast holding the forearm turned palm-down for around 6 weeks can let the torn sleeve heal, and that avoids surgery entirely. It’s an unglamorous cast in an awkward position and it’s worth it.
Left for months, the sleeve has stretched and scarred, the tendon keeps dislocating, and the fix becomes surgical reconstruction of the sleeve. That works well, and it costs you a few months of recovery you didn’t need to spend.
What to do about it
- Get the snapping version imaged and assessed promptly, ideally with dynamic ultrasound, which can watch the tendon move in real time.
- Stop the movement that reproduces it, particularly forceful supination with the wrist deviated. That’s the serve, the backhand, and the swing.
- Splint or cast per assessment, and for the acute subluxation take the position seriously even though it’s inconvenient.
- Rebuild afterwards. Grip and wrist strengthening through full range, then sport-specific loading. Returning to a racquet before the tendon has capacity is how these recur.
The short version
Little-finger side wrist pain: press along the tendon line at the back. Sore there and it’s ECU. Deep inside the joint with painful rotation and clicking is more likely the TFCC.
And if it snaps when you turn your palm up, say so at your appointment and say when it started. A fresh one can be treated in a cast. An old one needs an operation.
Written by Nigel Chua, hand occupational therapist in practice since 2005. Tens of thousands of hands, wrists and elbows assessed and treated. My credentials are here. This article explains; it doesn’t examine. A wrist that snaps after an injury is worth getting seen sooner rather than later.