40.3 Wrist & Hand Soft-Tissue Injuries: De Quervain, TFCC & Finger Sprains

De Quervain Tenosynovitis

De Quervain tenosynovitis is a painful, stenosing condition affecting the first dorsal extensor compartment of the wrist. It is one of the most common entrapment tendinopathies in primary care, with a strong female predominance (female-to-male ratio approximately 6:1).

Functional Anatomy & Pathophysiology

• Tendons Involved: The first dorsal compartment is an osteofibrous canal located directly over the radial styloid process through which two tendons pass:
  1. Abductor Pollicis Longus (APL): Abducts the thumb carpometacarpal joint.
  2. Extensor Pollicis Brevis (EPB): Extends the thumb metacarpophalangeal (MCP) joint. (Clinical Mnemonic: "All Police Love Eating Peanut Butter").
• Pathophysiology: Not an acute inflammatory synovitis, but a non-inflammatory fibrocartilaginous thickening and myxoid degeneration of the overlying extensor retinaculum pulley and tendon sheaths. This leads to progressive canal stenosis, high mechanical friction, and impaired glide of the APL and EPB tendons during thumb movement.
• Anatomical Variations: Up to 30% to 50% of individuals possess a complete bony or fibrous subcompartment septum separating the APL and EPB within the first compartment, and the APL frequently has multiple tendon slips (duplications). These anatomical variations increase susceptibility to entrapment and explain why blind corticosteroid injections occasionally fail.
• Risk Factors & Mechanisms: Repetitive thumb abduction combined with rapid ulnar deviation of the wrist:
  • Postpartum Mothers ("Baby Wrist"): Lifting a newborn out of a crib or carrying an infant by scooping under the axillae with hyperabducted thumbs and ulnarly deviated wrists (hormonal laxity and fluid shifts during pregnancy/lactation further predispose);
  • Racket sports players, golfers, carpenters, knitters, assembly line workers;
  • Smartphone users performing excessive one-handed thumb texting ("text thumb").

Physical Examination & Provocative Maneuvers

• Clinical Signs: Localized tenderness, warmth, and firm fusiform swelling directly over the radial styloid process. Crepitus may be palpable during thumb flexion and extension.
• Provocative Tests:
  1. Finkelstein Test (Classic Maneuver): The examiner grasps the patient's thumb and performs passive, gentle, sharp ulnar deviation of the wrist while applying longitudinal traction to the thumb. Severe lancinating pain along the radial styloid process confirms a positive test.
  2. Eichhoff Maneuver (Often Conflated with Finkelstein): The patient actively places the thumb across the palm, tightly clenches the remaining four fingers over the thumb to make a fist, and then deviates the wrist toward the ulnar side. Elicits severe pain over the radial styloid. Highly sensitive, though has a higher false-positive rate than the passive Finkelstein test.
  3. WHAT Test (Wrist Hyperflexion and Abduction of the Thumb): The patient fully flexes the wrist and forcefully abducts the thumb against examiner resistance. High sensitivity and specificity (>90%).

Management Strategy

• First-Line Conservative Therapy:
  • Thumb Spica Splint: A rigid splint that immobilizes both the wrist and the first metacarpophalangeal (MCP) joint (leaving the thumb interphalangeal [IP] joint free), resting the APL and EPB tendons. Worn continuously or during aggravating activities for 4 to 6 weeks.
  • Activity modification: Instruct postpartum mothers to lift infants using their forearms and palms scooping under the torso, keeping wrists neutral and thumbs adducted.
  • Oral NSAIDs for short-term symptom relief.
• Second-Line / Definitive Intervention: Corticosteroid Injection:
  • Injection of 10 to 20 mg of triamcinolone acetonide (or methylprednisolone) mixed with 1 mL of 1% lidocaine into the first dorsal extensor compartment sheath.
  • Efficacy: Produces complete symptom resolution / cure in 70% to 80% of patients after a single injection, and up to 90% after a second injection.
  • Ultrasound Guidance: Recommended when available to ensure delivery into both the APL and EPB subcompartments if a septum is present.
  • Complications to Counsel: Skin hypopigmentation (depigmentation) and subcutaneous fat atrophy (dermal depression/thinning), which are particularly noticeable and potentially permanent in darkly pigmented individuals. Clinicians must avoid injecting into the superficial dermis.
• Surgical Decompression: Longitudinal incision and surgical release of the first dorsal compartment retinaculum. Reserved for patients with intractable symptoms persisting >3 to 6 months despite splinting and 2 corticosteroid injections. Clinicians must identify and release any separate EPB subcompartment and carefully protect the superficial branch of the radial nerve (sensory neuroma avoidance).

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Triangular Fibrocartilage Complex (TFCC) Tears

The Triangular Fibrocartilage Complex (TFCC) is a load-bearing, biconcave fibrocartilage disc and surrounding ligamentous structure situated on the ulnar side of the wrist between the distal ulna, lunate, and triquetrum.

Functional Anatomy & Vascular Zones

• Components: The TFC articular disc (meniscus homologue), dorsal and volar radioulnar ligaments, ulnolunate and ulnotriquetral ligaments, and the extensor carpi ulnaris (ECU) tendon subsheath.
• Functions:
  1. Primary Stabilizer of the Distal Radioulnar Joint (DRUJ);
  2. Cushions & Transmits Load: Transmits approximately 20% of axial compressive carpal load from the hand to the distal ulna (the remaining 80% is transmitted across the radiocarpal joint to the radius);
  3. Facilitates smooth, stable forearm pronation and supination.
• Vascularity (Palmer Classification):
  • Central Zone: Avascular and aneural (analogous to the central meniscus of the knee); tears in this region cannot heal spontaneously and require arthroscopic debridement.
  • Peripheral Zone (Outer 10-20%): Highly vascularized via branches of the ulnar and anterior interosseous arteries; tears in this zone possess robust healing potential and are amenable to direct surgical repair.

Mechanisms of Injury & Clinical Presentation

• Traumatic Mechanism: Fall onto an outstretched hand (FOOSH) with the wrist hyperextended and pronated; sudden violent forearm twisting or traction loading (e.g., using a high-torque rotary power drill, swinging a baseball bat).
• Degenerative Mechanism: Chronic wear associated with positive ulnar variance (the distal articular surface of the ulna projects >2 mm distal to the articular surface of the radius), causing repetitive ulnocarpal impaction syndrome.
• Clinical Presentation: Ulnar-sided wrist pain aggravated by forearm pronation/supination, gripping, and ulnar deviation; sensations of painful clicking, popping, or catching; subjective feeling of wrist instability and weakened grip strength.

Provocative Examination Maneuvers

1. TFCC Fovea Sign: The examiner applies deep manual pressure into the soft depression ("fovea") located between the ulnar styloid process, the pisiform, and the flexor carpi ulnaris tendon. Exquisite tenderness confirms a positive test (sensitivity 95%, specificity 87% for foveal avulsions of the TFCC).
2. TFCC Grind / Compression Test: The examiner stabilizes the distal forearm with one hand, places the patient's wrist in ulnar deviation, and applies an axial compressive load while rotating the carpus back and forth across the distal ulna. Elicitation of sharp pain, clicking, or mechanical crepitus indicates a tear.
3. Piano Key Test (DRUJ Instability): With the patient's forearm resting in pronation on an examination table, the clinician applies downward manual pressure onto the distal ulnar head. Exaggerated dorsal displacement and painful spring-back (like a piano key) indicates disruption of the radioulnar ligaments and DRUJ instability.

Diagnostic Imaging & Management

• Imaging: Standard wrist radiographs assess for positive ulnar variance, ulnar styloid non-union fractures, and DRUJ arthritis. Magnetic Resonance Imaging (MRI) or MR Arthrography of the wrist is the non-invasive gold standard for confirming tear location (Palmer Type I traumatic vs. Type II degenerative) and vascular zone.
• Management:
  • Conservative: Immobilization in a neutral wrist splint, Munster splint, or sugar-tong splint (preventing forearm pronation/supination) for 4 to 6 weeks, paired with oral NSAIDs and occupational therapy.
  • Operative: Indicated for persistent mechanical catching, instability, or failed conservative therapy. Central tears undergo arthroscopic debridement; peripheral vascular tears undergo arthroscopic or open suture repair; patients with positive ulnar variance and impaction may require an ulnar shortening osteotomy.

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Ganglion Cysts

Ganglion cysts are the most common soft-tissue mass of the hand and wrist, accounting for 60% to 70% of all presentations. They are benign, non-neoplastic, mucin-filled cystic lesions arising from joint capsules, tendon sheaths, or ligaments.

                     COMMON GANGLION CYST LOCATIONS

   1. Dorsal Wrist Ganglion (60-70% of all wrist ganglions)
      • Arises from the Scapholunate Interosseous Ligament
      • Appears on dorsum of wrist between EPL and EDC tendons
      • Prominent with wrist flexion

   2. Volar Wrist Ganglion (18-20% of wrist ganglions)
      • Arises from Radiocarpal Joint or Scaphotrapezial Joint
      • Located on radial-volar wrist, adjacent to Radial Artery
      • Aspiration carries risk of radial artery injury

   3. Retinacular / Flexor Sheath Ganglion (10%)
      • Arises from the A1 Pulley of the flexor tendon sheath
      • Small (2-4 mm), firm, tender "BB-like" nodule at base of digit

Clinical Presentation & Physical Examination

• Presentation: Smooth, well-demarcated, mobile, rubbery or firm mass. May fluctuate in size over time (enlarging with vigorous hand activity and shrinking with rest). Typically painless, though large cysts can cause a dull ache, mechanical restriction of wrist extension, or paresthesias from peripheral nerve compression (median or ulnar nerve branches).
• Physical Examination Hallmark: Transillumination:
  • In a darkened room, a penlight or otoscope is placed directly against the side of the mass.
  • Ganglion cysts transilluminate brightly because they are filled with clear, viscous, gelatinous mucin (rich in hyaluronic acid and glucosamine).
  • Solid soft-tissue neoplasms (giant cell tumor of the tendon sheath, schwannoma, lipoma, or sarcoma) do not transilluminate.

Management Protocol

1. First-Line: Observation & Reassurance: Up to 50% of ganglion cysts resolve spontaneously without any medical or surgical intervention. In asymptomatic patients, reassurance of benignity is all that is required.
2. Obsolete Practice: "Bible Therapy": Smashing the cyst with a heavy book or hard object is strictly contraindicated; it produces severe localized contusion, ligamentous rupture, joint damage, and high recurrence.
3. Needle Aspiration:
   • Indicated for painful cysts, functional limitation, or cosmetic distress.
   • Technique: Sterile prep; an 18-gauge large-bore needle is used (mucin is too viscous for fine needles) to aspirate thick, clear jelly-like fluid. May be combined with a puncture-puncture technique.
   • Critical Counseling Point: Needle aspiration carries a 50% recurrence rate, because the cyst capsule, stalk, and connection to the underlying joint remain intact.
   • Safety Rule for Volar Cysts: Always palpate and mark the radial artery prior to attempting aspiration of a volar ganglion, or perform under ultrasound guidance.
4. Surgical Excision: Indicated for recurrent cysts, severe pain, joint limitation, or nerve compression. Requires complete excision of the cyst, its stalk, and a 2- to 3-mm cuff of adjacent joint capsule/scapholunate ligament to prevent recurrence (recurrence rate <5% to 10%).

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Traumatic Finger Injuries & Deformities

                 TRAUMATIC FINGER DEFORMITIES & MECHANISMS

     [MALLET FINGER] ───────────> Terminal Extensor Avulsion at DIP Base
                                 • Axial blow to extended fingertip
                                 • 'Drop finger' deformity (DIP flexed, cannot extend)
                                 • CONTINUOUS DIP EXTENSION SPLINTING x 6-8 WEEKS
                                 • If DIP flexes ONCE -> RESET CLOCK TO DAY 1!

     [BOUTONNIÈRE] ─────────────> Central Slip Rupture at Middle Phalanx
                                 • Lateral bands slip volarward
                                 • PIP FLEXION + DIP HYPEREXTENSION
                                 • Splint PIP in full extension x 6 weeks; DIP free

     [SWAN-NECK] ───────────────> Volar Plate Attenuation at PIP
                                 • Terminal tendon stretching
                                 • PIP HYPEREXTENSION + DIP FLEXION
                                 • Rheumatoid arthritis association; Silver rings

     [SKIER / GAMEKEEPER] ──────> Ulnar Collateral Ligament (UCL) of 1st MCP
                                 • Forced hyperabduction of thumb
                                 • Laxity >30-35° or >15° side-to-side = COMPLETE TEAR
                                 • Stener Lesion: Adductor aponeurosis interposition
                                 • Complete tear / Stener -> SURGERY <2-3 WEEKS

1. Mallet Finger ("Drop Finger")

• Mechanism: Sudden, violent, forced hyperflexion applied to an actively extended distal interphalangeal (DIP) joint—most commonly when a ball (baseball, basketball, football) strikes the tip of an outstretched finger axially.
• Pathophysiology: Disruption, stretching, or avulsion of the terminal extensor tendon at its insertion on the dorsal base of the distal phalanx. May be pure tendon rupture (soft-tissue mallet) or involve a bony avulsion fragment (bony mallet).
• Physical Examination: The patient holds the DIP joint in flexion (typically 15° to 45° of flexion, "droop deformity"). The patient is completely unable to actively extend the DIP joint, although passive extension is completely normal and painless.
• Diagnostic Radiographs: 3-view finger radiographs (AP, lateral, oblique) are mandatory to assess for articular surface involvement and subluxation.
• Management: The 6- to 8-Week Uninterrupted Rule:
  • First-Line: Rigid DIP extension splinting (Stack splint, malleable aluminum-foam splint, or custom thermoplastic splint) holding the DIP joint in continuous, uninterrupted neutral to slight hyperextension (0° to 5°) for 6 to 8 weeks.
  • The PIP joint is left completely free to maintain motion and prevent proximal joint stiffness.

  • [!CAUTION] STRICT COMPLIANCE MANDATE: THE ZERO-FLEXION RULE The patient must be explicitly and forcefully warned: The splint must NEVER be removed, allowing the DIP joint to flex even a single degree during the entire 6-to-8-week period! If the DIP joint flexes even momentarily (such as during hand washing or splint cleaning), the fragile, healing collagen bridge tears apart, and the entire 6-to-8-week splinting clock immediately restarts from Day 1! During splint changes, the patient must keep the finger flat against a tabletop in full extension.

  • Following the initial 6 to 8 weeks, weaning begins with night splinting for an additional 4 to 6 weeks.
  • Indications for Surgery: Bony avulsion involving >30% of the DIP articular surface, volar subluxation of the distal phalanx, or failed conservative splinting.

2. Boutonnière Deformity

• Pathophysiology: Rupture or avulsion of the central slip of the extensor digitorum tendon at its insertion onto the dorsal base of the middle phalanx. Over the subsequent 1 to 3 weeks, the lateral bands of the extensor hood migrate volarward (anteriorly), falling below the axis of rotation of the PIP joint. The lateral bands now function paradoxically as flexors of the PIP joint while exerting excessive extensor tension across the DIP joint.
• Anatomical Deformity: Flexion of the Proximal Interphalangeal (PIP) joint combined with Hyperextension of the Distal Interphalangeal (DIP) joint.
• Etiology: Direct blunt impact or laceration over the dorsum of the PIP joint, acute volar PIP dislocation, or chronic rheumatoid synovitis attenuating the central slip.
• Management: Splinting the PIP joint in continuous, rigid full extension (0°) for 6 weeks, while deliberately leaving the DIP joint completely free to perform active flexion and extension exercises (which stretches the oblique retinacular ligaments and draws the lateral bands back dorsally).

3. Swan-Neck Deformity

• Pathophysiology: Hyperextension laxity or rupture of the volar plate at the PIP joint, combined with secondary stretching or rupture of the terminal extensor tendon at the DIP joint.
• Anatomical Deformity: Hyperextension of the Proximal Interphalangeal (PIP) joint combined with Flexion of the Distal Interphalangeal (DIP) joint.
• Etiology: Severe rheumatoid arthritis (synovitis destroying the volar plate), untreated mallet finger, spastic cerebral palsy, or traumatic volar plate rupture.
• Management: Figure-of-eight splints (Silver Ring splints) that mechanically block PIP hyperextension while allowing functional PIP flexion.

4. Gamekeeper's / Skier's Thumb (UCL Injury of 1st MCP)

• Terminology: "Gamekeeper's thumb" refers to chronic repetitive attenuation of the ulnar collateral ligament (historic British gamekeepers breaking rabbits' necks); "Skier's thumb" refers to acute traumatic rupture.
• Mechanism: Forced hyperabduction and hyperextension of the thumb metacarpophalangeal (MCP) joint—classically when a skier falls while holding a ski pole, forcing the web space against the grip.
• Physical Examination:
  • Swelling, ecchymosis, and exquisite point tenderness over the ulnar aspect of the 1st MCP joint; weak pincer grip.
  • Valgus Stress Testing: Performed in both full extension (0°) (tests accessory collateral ligament and volar plate) and 30° of MCP flexion (isolates the proper UCL):
    • Complete Tear Criteria: Valgus laxity >30° to 35°, or asymmetric laxity >15° greater than the uninjured contralateral thumb, or the complete absence of a firm end-point.
  • Precaution: Always obtain plain radiographs before applying valgus stress to rule out a non-displaced avulsion fracture; applying stress to an avulsion fragment can displace the fracture!
• The Stener Lesion (Crucial Board Concept):
  • Occurs in up to 50% to 80% of complete UCL ruptures.
  • The distal torn end of the proper UCL avulses from the base of the proximal phalanx, retracts proximally, and flips superficial to the adductor pollicis aponeurosis.
  • Clinical Significance: Because the broad, fibrous adductor aponeurosis is now physically interposed between the torn ligament ends, spontaneous contact, scar formation, and ligament healing are anatomically impossible! Non-operative cast immobilization of a Stener lesion guarantees persistent instability, chronic pain, and early joint osteoarthritis.
• Management:
  • Partial Tear (Grade I-II, stable, firm endpoint): Immobilization in a thumb spica cast or rigid splint for 4 to 6 weeks.
  • Complete Tear (Grade III) or Stener Lesion: Prompt orthopedic surgical repair within 2 to 3 weeks of injury (direct suture anchor re-fixation of the UCL to the proximal phalanx).

5. Trigger Finger (Stenosing Flexor Tenosynovitis)

• Pathophysiology: Size mismatch between the flexor tendons (flexor digitorum profundus and superficialis) and the first annular (A1) pulley at the level of the metacarpal head. Repetitive friction produces localized nodular thickening of the tendon and fibrous stenosis of the A1 pulley.
• Presentation: Painful snapping, clicking, popping, or "catching" during active finger flexion and extension. In advanced stages, the finger locks rigidly in full flexion, requiring passive manual extension with the other hand.
• Exam: Palpable, tender nodule over the A1 pulley in the distal palmar crease that moves synchronously with finger flexion.
• Management:
  • Conservative: Splinting the MCP joint in neutral extension at night, oral NSAIDs, activity modification.
  • Corticosteroid Injection into Flexor Tendon Sheath: Injection of triamcinolone 10 to 20 mg into the flexor tendon sheath at the A1 pulley achieves a 60% to 80% cure rate (lower in patients with diabetes).
  • Surgical Release: Open or percutaneous release of the A1 pulley for refractory locking.