De Quervain's tenosynovitis at the first dorsal compartment
Two thumb tendons share one narrow fibro-osseous tunnel at the wrist.
Abductor pollicis longus and extensor pollicis brevis share this compartment.
A thin synovial sheath lets both tendons glide smoothly under the retinaculum.
Up to a third of people even have a septum splitting the tunnel.
The compartment sits directly over the radial styloid, a bony pulley point.
Every thumb movement forces tendons to angle sharply around this bone.
That friction point is exactly where inflammation later concentrates.
A healthy sheath secretes synovial fluid, keeping friction near zero.
Tendons slide several millimeters with each thumb motion, unimpeded.
Named for Fritz de Quervain, who first described this condition in 1895.
Repeated gripping, texting, and lifting overload the tendon-sheath interface.
Repeated ulnar-radial thumb motion grinds tendons against the retinaculum.
Microtears accumulate faster than the sheath can repair them.
Texting thumbs, racquet sports, knitting, and lifting a baby all contribute.
New parents get this so often it is nicknamed "mommy thumb".
A dull ache at the wrist base appears first, worsened by grip.
Swelling is often still too subtle to see.
Occupations with repetitive grasping show markedly higher De Quervain incidence.
Chronic irritation thickens the sheath, squeezing both tendons inside.
Chronic friction triggers fibroblast proliferation and collagen deposition.
The sheath wall thickens, and the tunnel effectively shrinks around the tendons.
The condition is technically a stenosing process, not true infection or tear.
Tendons themselves stay intact but glide with visible resistance.
A firm, tender swelling becomes palpable directly over the styloid.
Grip strength and thumb range of motion both decline.
Swelling can be visible as a firm bump before any test is performed.
Tucking the thumb into a fist and deviating ulnarly reproduces sharp pain.
The patient makes a fist around the tucked thumb, then bends the wrist toward the pinky.
This stretches the inflamed tendons tightly across the swollen sheath.
Ulnar deviation maximizes tension exactly where the sheath is thickest.
Compressed, inflamed tissue fires nociceptors, producing sharp radial-side pain.
Sharp pain at the radial styloid confirms the clinical diagnosis.
Imaging is rarely needed when the test is clearly positive.
A positive Finkelstein test alone is usually enough to diagnose De Quervain's.
A thumb spica splint rests the tendons; injection targets inflammation directly.
Immobilizing the thumb and wrist rests the tendons and lets swelling settle.
Worn several weeks, it is the first-line conservative treatment.
A steroid injected into the sheath directly suppresses local inflammation.
Most patients feel significant relief within one to two weeks.
Release of the compartment roof is reserved for refractory cases.
Most patients never need to escalate beyond splint and injection.
Combining splint and injection outperforms either treatment used alone.