Tenosynovitis

Populations and Risk Factors

• Repetitive hand and thumb movements: Computer users (keyboard, mouse), texters ("texting thumb"), painters, mechanics, musicians (guitarists, pianists), assembly line workers — cumulative friction between the tendon and sheath exceeds the sheath's capacity to maintain lubrication
• Pregnant and postpartum women: Hormonal changes (relaxin, estrogen fluctuations) alter connective tissue properties; fluid retention increases sheath volume and pressure; repetitive lifting and gripping of the newborn (particularly the thumb-abducted position for cradling) — de Quervain's is colloquially called "new mother's thumb" or "baby wrist"
• Inflammatory conditions: Rheumatoid arthritis produces synovitis that directly involves the tendon sheaths (RA-associated tenosynovitis); gout produces crystal deposition within the sheath; psoriatic arthritis affects extensor tendon sheaths (dactylitis — "sausage digit")
• Age: Incidence increases after age 40 as the synovial sheath's capacity for self-repair and lubrication decreases; trigger finger peaks at 55–60 years
• Sex: De Quervain's is 6–10 times more common in women than men; trigger finger is 2–4 times more common in women
• Diabetes mellitus: 10–20% of diabetic patients develop trigger finger — glycation of collagen fibers thickens the tendon and the A1 pulley, increasing friction; diabetic patients often have multiple affected digits
• Workers in repetitive manual occupations: Butchers, gardeners, chefs, assembly line workers — any occupation requiring sustained gripping, twisting, or repetitive finger movements
• Penetrating wound near tendon sheath: Puncture wounds (thorn, nail, knife) can introduce bacteria into the closed sheath space — infectious tenosynovitis is a surgical emergency

Causes and Pathophysiology

• Synovial sheath anatomy: The synovial sheath is a double-walled tube that encloses tendons where they pass through tight fascial tunnels or over bony prominences — the wrist, hand, ankle, and foot are the primary locations. The inner (visceral) layer is attached to the tendon surface; the outer (parietal) layer lines the fibrous tunnel. Between the two layers, synovial fluid provides lubrication that reduces friction during tendon excursion. The sheath is a closed system — inflammation within it produces elevated pressure and reduced volume for tendon movement.
• Repetitive friction mechanism (primary): Each tendon excursion produces friction between the tendon surface and the inner sheath wall. Under normal conditions, the synovial fluid maintains lubrication and the friction is negligible. When the cumulative friction exceeds the sheath's capacity to maintain lubrication (from excessive repetition, sustained awkward postures, or pre-existing inflammation), the inner sheath surface becomes irritated and inflamed. Inflammatory exudate enters the sheath space, increasing pressure and reducing the volume available for tendon gliding. The inflamed, roughened sheath surfaces produce MORE friction with each tendon excursion, creating a self-perpetuating cycle of irritation.
• De Quervain's tenosynovitis (first dorsal compartment): The first dorsal compartment of the wrist contains the APL and EPB tendons, which pass through a fibro-osseous tunnel over the radial styloid. These tendons control thumb abduction and extension — movements that are repetitive in gripping, pinching, wringing, and lifting with the thumb abducted. De Quervain's develops when the friction between these tendons and their shared sheath exceeds the lubrication capacity. A septum dividing the compartment into separate APL and EPB channels is present in approximately 30% of individuals — this anatomical variant reduces the available space and increases susceptibility. The condition produces pain at the radial styloid that is aggravated by thumb use and reproduced by Finkelstein's test (fist closed over the thumb, followed by ulnar wrist deviation — this forces the APL and EPB tendons to glide through the inflamed sheath under maximum stretch).
• Stenosing tenosynovitis (trigger finger/thumb): In the fingers, the flexor tendons pass through a series of annular pulleys (A1–A5) that hold the tendon close to the bone, preventing bowstringing during flexion. Stenosing tenosynovitis occurs when either the flexor tendon develops a nodular thickening (usually at the metacarpophalangeal joint level) or the A1 pulley thickens and narrows. The nodule or thickened pulley creates a mechanical mismatch — the tendon can enter the pulley during flexion (with increasing force) but catches when trying to exit during extension. This produces the characteristic "triggering" — the finger locks in flexion and then snaps straight with a painful click as the nodule forces past the constriction. In advanced cases, the finger cannot extend at all (locked trigger finger). The ring finger and thumb are most commonly affected.
• Crepitus mechanism: When the tendon surface or the inner sheath surface becomes roughened (from inflammation, fibrosis, or crystal deposition), tendon excursion produces a palpable or audible grating, squeaking, or crackling — crepitus. The examiner can feel this by placing fingertips over the tendon sheath while the patient actively moves the tendon. Crepitus is the hallmark palpation finding for tenosynovitis and indicates that the smooth gliding surface has been disrupted.
• Adhesion formation (chronic complication): If the inflammation is not resolved, fibroblasts invade the inflamed sheath space and produce collagen adhesions between the visceral and parietal layers of the sheath. These adhesions permanently restrict tendon gliding — the tendon becomes "stuck" within its sheath. Chronic adhesive tenosynovitis produces a progressive loss of ROM that does not respond to muscle stretching (the restriction is at the tendon-sheath interface, not in the muscle). This complication makes early treatment critical — adhesion prevention is easier than adhesion treatment.
• Infectious tenosynovitis (emergency): A penetrating wound can introduce bacteria (most commonly Staphylococcus aureus) into the closed synovial sheath space. The sheath provides an ideal environment for bacterial proliferation — warm, moist, enclosed, with limited immune cell access. Kanavel's signs are the diagnostic criteria: (1) fusiform (sausage-like) swelling of the entire digit; (2) flexed posture of the digit; (3) tenderness along the entire tendon sheath; (4) pain with passive extension of the digit. Infectious tenosynovitis is a surgical emergency — the infection can destroy the tendon within 24–48 hours and can spread through the sheath to communicate between the thumb and little finger via the radial and ulnar bursae (the "horseshoe abscess"). Any patient presenting with these signs requires immediate medical referral. Do not treat.

Signs and Symptoms

By Type

General Findings

• Localized pain over the tendon sheath that worsens with tendon excursion — movement of the affected tendon through the inflamed sheath reproduces the pain
• "Sausage-like" swelling over the tendon sheath — the closed sheath space distends with inflammatory fluid; the swelling is fusiform (elongated) following the sheath contour
• Crepitus — palpable or audible grating, squeaking, or crackling during tendon movement; felt with fingertips placed over the sheath; indicates roughened tendon-sheath surfaces
• Reduced ROM and weakness — movement feels "sticky" or restricted; the tendon cannot glide freely through the constricted or adhered sheath
• Sharp pain during tendon excursion; dull ache at rest — the pain is mechanical (friction-dependent) and increases with the speed and range of tendon movement
• Visible redness in acute cases — the skin over the inflamed sheath may be erythematous
• Morning stiffness — the sheath fluid thickens overnight, and initial movement is stiff and painful until the tendon "warms up"

Assessment Profile

Subjective Presentation

• Chief complaint: Pain at the wrist or finger that worsens with gripping, pinching, or repetitive hand use — de Quervain's: "it hurts right here on the side of my wrist when I pick up my baby" or "my wrist hurts when I text or use the mouse"; trigger finger: "my finger catches and locks when I try to open my hand and then snaps straight" or "I wake up with my finger stuck in a bent position"
• Pain quality: Sharp during tendon excursion (active movement through the inflamed sheath); dull, aching at rest; may describe a "squeaking" or "grinding" sensation; trigger finger: the catching/locking is more distressing than the pain itself
• Onset: Gradual — develops over days to weeks with repetitive use; de Quervain's in postpartum women may develop rapidly within weeks of delivery due to the combination of hormonal changes and new repetitive lifting; trigger finger develops insidiously over weeks to months
• Aggravating factors: De Quervain's: gripping, pinching, thumb opposition, wringing, lifting (especially with thumb abducted — the baby-cradling position); trigger finger: gripping (especially sustained grip), making a fist, morning (worst after nocturnal immobility); general: cold environments, forceful repetitive hand use
• Easing factors: Rest from the provocative activity; splinting (de Quervain's: thumb spica splint immobilizing the thumb and wrist; trigger finger: buddy splint limiting MCP flexion); warmth (morning stiffness improves with warm water immersion); NSAIDs for acute inflammation
• Red flags: Puncture wound near the affected tendon with progressive swelling, redness, fever, and pain with passive extension → suspect infectious tenosynovitis; emergency referral; do not treat; finger locked in flexion that cannot be passively extended → advanced stenosing tenosynovitis requiring medical referral; rapid progression of multiple digit involvement with systemic symptoms → consider inflammatory arthritis

Observation

• Local inspection: De Quervain's: swelling over the radial styloid; the first dorsal compartment may appear full or distended compared to the contralateral side; trigger finger: may see the finger in a flexed position (locked trigger); palpable nodule at the MCP joint; fusiform swelling of the digit; general: redness overlying the affected sheath in acute cases
• Posture: Hand and wrist posture may be guarded — the patient holds the hand in a position that minimizes tendon excursion (wrist neutral, fingers slightly flexed); de Quervain's: the patient avoids thumb abduction and may splint the wrist against the body
• Gait: Not applicable for hand/wrist conditions

Palpation

• Tone: Hypertonic forearm extensors and flexors — the muscles proximal to the affected sheath compensate by increasing their resting contraction; for de Quervain's: APL and EPB muscle bellies in the dorsal forearm are hypertonic; for trigger finger: flexor digitorum superficialis and profundus muscle bellies in the volar forearm are hypertonic; trigger points commonly develop in the overloaded forearm muscles
• Tenderness: De Quervain's: marked tenderness directly over the radial styloid at the first dorsal compartment; the tenderness follows the sheath and is reproduced by palpation with thumb movement; trigger finger: tenderness at the A1 pulley (MCP joint level on the volar surface); the tendon nodule may be palpable as a firm, mobile lump that moves with the tendon during flexion-extension; general: tenderness follows the line of the sheath, not a single focal point
• Temperature: Warm over the inflamed sheath — the inflammatory response produces local vasodilation; more pronounced warmth suggests more active inflammation; compare bilaterally; dramatic warmth with spreading redness suggests infection
• Tissue quality: Crepitus is the hallmark — place fingertips over the sheath and have the patient actively move the tendon; a palpable grating, squeaking, or crackling indicates roughened tendon-sheath surfaces; for trigger finger: the triggering itself is palpable — the examiner can feel the tendon nodule catch and release as it passes through the A1 pulley; chronic cases: the sheath feels thickened and inelastic with reduced tendon excursion amplitude; adhesions between tendon and sheath feel like a "tethering" that limits smooth gliding

Motion Assessment

• AROM: Pain with active movement in the direction that requires the affected tendon to glide through the inflamed sheath — de Quervain's: pain with active thumb abduction and extension; trigger finger: catching or locking during active finger flexion-extension, often with a painful snap as the nodule passes through the A1 pulley; ROM may be mechanically restricted by the thickened sheath or adhesions; the restriction is at the tendon level, not the joint level
• PROM / end-feel: Pain when the tendon is passively placed on stretch — de Quervain's: pain with passive ulnar deviation combined with thumb flexion and adduction (the Finkelstein's maneuver is essentially a passive stretch test); trigger finger: pain with passive extension of the affected digit that forces the tendon through the constricted pulley; end-feel varies: muscle stretch in early cases; firm in chronic adhesive cases
• Resisted testing: Pain at the sheath site during resisted contraction of the affected tendon — de Quervain's: pain with resisted thumb abduction and extension; trigger finger: pain with resisted finger flexion; strength may be mildly reduced due to pain inhibition; "strong and painful" or mildly "weak and painful" depending on severity; the pain localizes to the sheath (not the MTJ or muscle belly)

Special Test Cluster

Intersection syndrome distinction: Pain and crepitus at 4–6 cm proximal to the Lister's tubercle (where the APL/EPB cross over the ECRL/ECRB) is intersection syndrome, NOT de Quervain's. The location of tenderness (proximal forearm vs. radial styloid) distinguishes the two conditions.

Differential Assessment