9.3 Wrist and Hand Conditions: Carpal Tunnel Syndrome & Tendinopathies

9.3 Wrist and Hand Conditions: Carpal Tunnel Syndrome & Tendinopathies

[!NOTE] DHA Clinical Competency Core: The human hand and wrist possess intricate osseous architecture, tight fibro-osseous tunnels, and delicate neurovascular distributions. On the DHA Physiotherapist Examination, clinicians must demonstrate mastery in diagnosing entrapment neuropathies, recognizing orthopedic fracture emergencies (such as occult scaphoid fractures at risk of osteonecrosis), executing specialized hand biomechanical tests, and prescribing staged multi-modal protocols for Complex Regional Pain Syndrome (CRPS).

Optimal hand function relies on balanced interactions between extrinsic muscular engines in the forearm and intricate intrinsic muscle systems within the carpal framework.

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1. Wrist and Carpal Anatomy & Functional Kinematics

The wrist complex comprises eight carpal bones arranged in two transverse rows:

• Proximal Carpal Row: Scaphoid, Lunate, Triquetrum, and Pisiform (a sesamoid bone within the flexor carpi ulnaris tendon). The proximal row functions as an intercalated segment lacking direct tendon insertions, moving passively in response to forces transmitted from the forearm and distal carpal row.
• Distal Carpal Row: Trapezium, Trapezoid, Capitate (the central rotational keystep), and Hamate (possessing the palpable hook of hamate). Bound firmly to the metacarpal bases by rigid ligaments, forming a stable functional unit.

+---------------------------------------------------------------------------------------------------+
|                         Carpal Architecture & Dart-Thrower's Kinematic Arc                        |
+---------------------------------------------------------------------------------------------------+
| Proximal Row (Mobile Intercalated Segment):  [ Scaphoid ] [ Lunate ] [ Triquetrum ] [ Pisiform ] |
| Distal Row (Rigid Functional Foundation):    [ Trapezium ][Trapezoid][ Capitate  ] [ Hamate   ] |
+---------------------------------------------------------------------------------------------------+
| The Dart-Thrower's Motion (DTM):                                                                  |
| • Functional oblique movement plane combining Wrist Extension + Radial Deviation to Wrist        |
|   Flexion + Ulnar Deviation.                                                                      |
| • Biomechanical Advantage: Maximizes midcarpal movement while rendering the scapholunate joint    |
|   virtually immobile. Crucial for early post-operative rehabilitation of scapholunate ligament   |
|   repairs and scaphoid fracture healing without stressing healing soft-tissue repairs.           |
+---------------------------------------------------------------------------------------------------+

The Triangular Fibrocartilage Complex (TFCC)

The TFCC is a multi-component fibrocartilaginous and ligamentous structure situated on the ulnar side of the wrist, serving as the primary stabilizer of the distal radioulnar joint (DRUJ) and a major shock absorber between the distal ulna and carpus:

• Anatomical Components: The central biconcave articular disc (fibrocartilage), the homologous meniscus, the dorsal and volar radioulnar ligaments, the ulnocarpal collateral ligament, the ulnolunate and ulnotriquetral ligaments, and the subsheath of the extensor carpi ulnaris (ECU).
• Vascular Distribution: The central 80% of the articular disc is completely avascular and aneural, possessing minimal intrinsic healing capacity. The peripheral 15% to 20% adjacent to the ulnar capsule is well-vascularized, rendering peripheral avulsions amenable to surgical repair.
• Load Transmission: Transmits approximately 20% of total axial compressive forces across the wrist joint (the radiocarpal articulation transmits the remaining 80%). In positive ulnar variance (ulna longer than radius), the TFCC absorbs up to 40% of axial loads, predisposing it to degenerative tears (ulnar impaction syndrome).

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2. Carpal Tunnel Syndrome (CTS)

Carpal Tunnel Syndrome is the most common compressive focal neuropathy of the upper extremity, resulting from increased interstitial pressure within the rigid osteofibrous carpal tunnel.

                                  [ CARPAL TUNNEL ARCHITECTURE ]

                     Dorsal / Medial / Lateral Boundaries: Carpal Bones
                     (Scaphoid, Lunate, Capitate, Hamate Carpal Sulcus)
                                               │
                                               ▼
                     [ CONTENTS OF THE TUNNEL: 10 STRUCTURES ]
                     • 4 Tendons: Flexor Digitorum Superficialis (FDS)
                     • 4 Tendons: Flexor Digitorum Profundus (FDP)
                     • 1 Tendon:  Flexor Pollicis Longus (FPL)
                     • 1 NERVE:   MEDIAN NERVE (Volar to superficial flexor tendons)
                                               │
                                               ▼
                     Volar Roof: Transverse Carpal Ligament (Flexor Retinaculum)

Intracarpal Hydrodynamics & Pathophysiology

• Normal physiological intracarpal canal pressure ranges from 2 to 10 mmHg.
• In patients with symptomatic CTS, baseline resting pressures exceed 30 to 50 mmHg.
• During extreme active wrist flexion or extension, intracarpal pressures escalate dramatically to >90 to 110 mmHg, inducing mechanical microvascular collapse, venous stasis, axonal ischemia, endoneurial edema, and progressive myelin breakdown.

Clinical Presentation & Diagnostic Sparing Nuance

• Sensory Symptoms: Intermittent nocturnal numbness, burning, and paresthesias awakening the patient from sleep, requiring them to shake or flick their hands (positive Flick Sign). Sensory loss involves the palmar surface of the thumb, index finger, middle finger, and the radial half of the ring finger, including the dorsal nail beds.
• The Critical Diagnostic Sparing: Thenar Palm Sensation:
  • The palmar cutaneous branch of the median nerve arises approximately 5 cm proximal to the proximal wrist crease and travels superficial (outside) to the transverse carpal ligament.
  • Consequently, sensation over the proximal thenar eminence remains completely intact and normal in idiopathic Carpal Tunnel Syndrome!
  • If sensation over the thenar eminence is diminished or absent, the clinician must suspect a proximal median nerve lesion (such as Pronator Teres Syndrome) or a C6–C7 cervical radiculopathy.
• Motor Impairments: Chronic compression leads to weakness and visible wasting/atrophy of the thenar musculature (the "LOAF" muscles supplied by the recurrent motor branch: Lateral two lumbricals, Opponens pollicis, Abductor pollicis brevis, and Flexor pollicis brevis superficial head). Weakness of the Abductor Pollicis Brevis (APB) is the most sensitive physical indicator of motor denervation in CTS.

+---------------------------------------------------------------------------------------------------+
|                         Diagnostic Special Testing for Carpal Tunnel Syndrome                     |
+---------------------------------------------------------------------------------------------------+
| Test Name               | Execution Technique               | Sensitivity / Specificity          |
+-------------------------+-----------------------------------+------------------------------------+
| **Durkan's Test**       | Examiner applies direct manual    | Sensitivity: **87% to 91%**        |
| (Carpal Compression)    | thumb pressure over median nerve  | Specificity: **90%**               |
|                         | at carpal tunnel for 30 seconds   | (Highest overall clinical accuracy)|
+-------------------------+-----------------------------------+------------------------------------+
| **Phalen's Test**       | Patient rests elbows on table and | Sensitivity: **68% to 75%**        |
|                         | allows wrists to drop into full,  | Specificity: **80% to 88%**        |
|                         | unforced flexion for 60 seconds   |                                    |
+-------------------------+-----------------------------------+------------------------------------+
| **Reverse Phalen's**    | Patient holds wrists in maximum   | Sensitivity: **60% to 70%**        |
| ("Prayer Sign")        | extension with palms pressed      | Specificity: **80%**               |
|                         | together firmly for 60 seconds    |                                    |
+-------------------------+-----------------------------------+------------------------------------+
| **Tinel's Sign**        | Light percussion with reflex      | Sensitivity: **50% to 60%**        |
|                         | hammer over volar wrist crease    | Specificity: **77% to 85%**        |
+-------------------------+-----------------------------------+------------------------------------+

Conservative Physical Therapy Management

1. Neutral Wrist Splinting: Custom or prefabricated thermoplastic orthosis immobilizing the wrist in neutral alignment (0° to 5° of extension), worn primarily at night. Clinical biomechanical studies confirm that intracarpal canal pressures are lowest at neutral wrist angles; cock-up splints positioning the wrist at 20° to 30° of extension significantly elevate canal pressure and are contraindicated.
2. Tendon Gliding Exercises (Totten and Hunter): Five discrete hand positions executed sequentially to optimize differential excursion between the FDS and FDP tendons: (1) Straight Hand, (2) Hook Fist (maximizes differential excursion between FDS and FDP), (3) Straight Fist / Tabletop (promotes maximum FDS glide), (4) Full Fist (promotes maximum FDP excursion), and (5) Intrinsic-Plus / Platform.
3. Median Nerve Neurodynamic Glides: Staged sequencing: (1) wrist neutral with fingers and thumb flexed, (2) wrist neutral with fingers and thumb extended, (3) wrist and fingers extended, (4) thumb extended and abducted, (5) forearm fully supinated, (6) gentle contralateral cervical side-bending.

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3. de Quervain Tenosynovitis & TFCC Pathology

+---------------------------------------------------------------------------------------------------+
|                         First Dorsal Compartment vs. TFCC Pathology                               |
+---------------------------------------------------------------------------------------------------+
| Feature                 | de Quervain Tenosynovitis         | TFCC Tear / Ulnar Impaction        |
+-------------------------+-----------------------------------+------------------------------------+
| Anatomical Site         | 1st dorsal extensor compartment   | Ulnocarpal space / distal ulna     |
| Structures Involved     | **APL** (Abductor Pollicis Longus)| Fibrocartilaginous articular disc, |
|                         | & **EPB** (Extensor Pollicis Brev)| radioulnar ligaments, ECU sheath   |
| Mechanism of Injury     | Repetitive thumb abduction/ext.   | FOOSH with pronated wrist; chronic |
|                         | with ulnar deviation (texting,    | rotational torque (rackets, drills)|
|                         | lifting newborn infants)          | or positive ulnar variance         |
| Location of Tenderness  | Radial styloid process            | Ulnar fovea (between styloid & FCU)|
| Diagnostic Tests        | • **Finkelstein's Test**          | • **Ulnar Fovea Sign**             |
|                         | • **WHAT Test**                   | • **TFCC Grind / Compression Test**|
| Conservative Splinting  | Forearm-based **Thumb Spica**     | Ulnar gutter or wrist cock-up      |
+-------------------------+-----------------------------------+------------------------------------+

de Quervain Tenosynovitis Mechanics and Special Tests

• Pathoanatomy: Stenosing thickening and non-inflammatory myxoid degeneration of the synovial sheath enclosing the Abductor Pollicis Longus (APL) and Extensor Pollicis Brevis (EPB) tendons beneath the extensor retinaculum over the radial styloid process.
• Finkelstein's Test: The examiner grasps the patient's thumb and applies a sharp, passive ulnar traction and deviation of the wrist. Sharp pain reproduced along the radial styloid confirms first compartment tenosynovitis.
• Eichhoff's Test: Often confused with Finkelstein's test: the patient actively places their thumb inside their fist, wraps their four fingers around it, and actively deviates the wrist ulnarly. (Note: Eichhoff's produces a significantly higher false-positive rate due to excessive non-specific mechanical stress).
• WHAT Test (Wrist Hyperflexion and Abduction of the Thumb): Patient holds wrist in hyperflexion while the thumb is actively abducted against manual resistance. Demonstrates superior specificity (94%) with minimal false-positive responses.

TFCC Tear Provocative Testing

• Ulnar Fovea Sign: Examiner palpates the soft depression ("fovea") between the ulnar styloid process, the flexor carpi ulnaris tendon, and the volar pisiform. Intense localized tenderness demonstrates high diagnostic sensitivity (95%) and specificity (86%) for foveal avulsions of the TFCC or ulnolunate/ulnotriquetral ligament tears.
• TFCC Compression / Grind Test: Examiner stabilizes the patient's forearm, places the wrist in full ulnar deviation, and applies an axial compressive force while rotating the wrist into pronation and supination. Reproduction of pain, crepitus, or clicking is positive.
• Piano Key Test: Examiner pushes down on the prominent distal ulna while stabilizing the radius. Pain, excessive laxity, and a spring-back rebound like a piano key confirm distal radioulnar joint (DRUJ) instability.

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4. Fractures of the Wrist: Scaphoid, Colles & Smith

                      [ COMMON WRIST FRACTURE DIFFERENTIATION ]
                                         │
                    ┌────────────────────┼────────────────────┐
                    ▼                    ▼                    ▼
          [ SCAPHOID FRACTURE ]  [ COLLES FRACTURE ]   [ SMITH FRACTURE ]
          • Fall onto outstretched• Extra-articular     • "Reverse Colles"
            hand (FOOSH)           distal radius        • Fall on flexed wrist
          • Snuffbox tenderness  • DORSAL displacement • VOLAR displacement
          • Retrograde arterial    & dorsal angulation    & volar angulation
            supply -> AVN RISK   • "DINNER FORK"       • "GARDENER'S SPADE"

Scaphoid Fracture & Avascular Necrosis (AVN)

• The scaphoid is the most frequently fractured carpal bone, accounting for 70% of all carpal fractures. It typically occurs secondary to a high-energy fall onto an outstretched hand (FOOSH) with the wrist hyperextended >95° and radially deviated.
• Diagnostic Triad:
  1. Point tenderness within the anatomical snuffbox (bordered medially by the extensor pollicis longus tendon, laterally by the abductor pollicis longus and extensor pollicis brevis tendons, with the scaphoid waist forming the floor).
  2. Tenderness over the scaphoid tubercle on the volar radial wrist.
  3. Pain with axial compression of the thumb along the first metacarpal shaft.
• Vascular Anatomy & Osteonecrosis Risk:
  • The scaphoid receives its primary arterial blood supply via a retrograde intraosseous flow originating from dorsal scaphoid branches of the radial artery.
  • Vessels enter the bone at the distal pole and waist, traveling proximally to nourish the proximal pole.
  • Fractures through the waist or proximal third sever this retrograde microvascular supply, resulting in an exceptionally high incidence of non-union and avascular necrosis (AVN / Preiser's disease) of the proximal fragment.
  • DHA Mandatory Radiographic Protocol: Up to 20% of acute scaphoid fractures are radiographically occult (invisible on initial standard radiographs). If the clinical diagnostic triad is positive, the patient must be treated with immediate thumb spica cast immobilization, followed by repeat radiographs or MRI at 10 to 14 days.

Colles Fracture vs. Smith Fracture

• Colles Fracture:
  • Extra-articular metaphyseal fracture of the distal radius occurring within 2.5 cm of the wrist joint.
  • Displacement: The distal radial fragment undergoes dorsal displacement, dorsal angulation, and radial shortening.
  • Deformity: Classic "Dinner Fork" deformity.
  • Mechanism: Fall onto an extended, pronated wrist.
• Smith Fracture ("Reverse Colles"):
  • Fracture of the distal radius with volar (palmar) displacement and volar angulation of the distal fragment.
  • Deformity: Classic "Gardener's Spade" deformity.
  • Mechanism: Fall onto a flexed wrist or direct blow to the dorsum of the hand.

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5. Complex Regional Pain Syndrome (CRPS)

Complex Regional Pain Syndrome is a debilitating, disproportionate neuropathic condition typically emerging in an extremity following trauma, fractures (especially distal radius fractures), or surgery.

• CRPS Type I (Reflex Sympathetic Dystrophy [RSD]): Develops in the absence of an identifiable major peripheral nerve lesion.
• CRPS Type II (Causalgia): Develops secondary to a documented, verifiable injury to a major peripheral nerve trunk (e.g., direct laceration or crush injury to the median, ulnar, or tibial nerve).

+---------------------------------------------------------------------------------------------------+
|                         The Budapest Clinical Diagnostic Criteria for CRPS                        |
+---------------------------------------------------------------------------------------------------+
| 1. Continuing pain that is disproportionate in degree to any inciting event.                      |
| 2. Must report at least ONE symptom in THREE of the FOUR categories:                              |
| 3. Must display at least ONE sign at evaluation in TWO of the FOUR categories:                    |
+---------------------------------------------------------------------------------------------------+
| CATEGORY 1: SENSORY      | Hyperalgesia (to pinprick) and/or Allodynia (pain to light brush touch)|
+--------------------------+------------------------------------------------------------------------+
| CATEGORY 2: VASOMOTOR    | Temperature asymmetry (>1°C) and/or skin color changes / asymmetry     |
+--------------------------+------------------------------------------------------------------------+
| CATEGORY 3: SUDOMOTOR    | Edema and/or sweating changes (hyperhidrosis/hypohidrosis) / asymmetry |
+--------------------------+------------------------------------------------------------------------+
| CATEGORY 4: MOTOR/TROPHIC| Decreased range of motion, motor dysfunction (weakness, tremor,        |
|                          | dystonia), and/or trophic changes (abnormal nail, hair, skin growth)   |
+---------------------------------------------------------------------------------------------------+

Staged Rehabilitation: Graded Motor Imagery (GMI)

Aggressive, painful manual stretching or application of noxious stimuli causes neurogenic flare-ups and sympathetic hyperarousal. Contemporary management centers on Graded Motor Imagery (GMI) developed by Moseley, which systematically reactivates disrupted somatosensory cortical networks:

                            [ GRADED MOTOR IMAGERY (GMI) SEQUENCE ]
                                               │
                                               ▼
       [ Stage 1: Implicit Motor Imagery (Laterality Recognition Training) ]
       • Patient views flashcards/digital images of left vs. right hands
       • Goal: Rapid, accurate identification (<2s per image, >85% accuracy)
       • Activates premotor cortex WITHOUT activating primary motor cortex or provoking pain
                                               │
                                               ▼
       [ Stage 2: Explicit Motor Imagery (Mental Practice / Motor Rehearsal) ]
       • Patient mentally imagines moving the affected hand into various postures
       • NO physical movement occurs; strictly cognitive neural simulation
       • Bridges premotor planning to motor execution pathways
                                               │
                                               ▼
       [ Stage 3: Mirror Visual Feedback (Mirror Therapy) ]
       • Affected hand hidden inside mirror box; unaffected hand placed in front of mirror
       • Patient observes reflection of moving unaffected hand, tricking the visual cortex
       • Resolves cortical sensorimotor incongruence without firing peripheral nociceptors

• Sensory Desensitization Protocol: Non-painful, graded tactile stimulation moving progressively from smooth, non-threatening textures (silk, cotton) to coarser fabrics (velvet, corduroy, wool).
• Watson's Stress-Loading Program: Functional loading program incorporating:
  • Scrubbing: Active closed-chain compression (e.g., patient pushes a bristle brush back and forth across a table in quadruped or seated, bearing weight through the wrist).
  • Carrying: Sustained distraction loading (e.g., carrying a small weighted bag or briefcase throughout daily ambulation).

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6. Clinical Scenarios & DHA Exam Traps

Clinical Scenario: Post-Cast Pain Disproportion

Scenario: A 58-year-old female is referred for physical therapy 7 weeks after sustaining a non-displaced Colles fracture treated with closed reduction and casting. Upon cast removal 3 days ago, she developed burning, throbbing pain (VAS 9/10) over her entire hand and wrist that prevents her from sleeping. On examination, the dorsal hand is diffusely edematous with glossy, stretched skin and excessive hair growth. The skin temperature of the involved hand is 2.5°C warmer than the contralateral limb. Lightly stroking the dorsum of the hand with a cotton swab elicits excruciating pain. The referral requests: "Aggressive joint mobilization and stretching to restore wrist range of motion."

Clinical Decision & Strategy: The patient meets the Budapest Diagnostic Criteria for CRPS Type I (disproportionate pain, sensory allodynia, vasomotor temperature asymmetry, sudomotor edema, and trophic skin/hair changes). Performing aggressive joint mobilizations or forceful stretching is absolutely contraindicated; mechanical trauma will exacerbate local neurogenic inflammation and sympathetic overdrive. The therapist must educate the patient, initiate Stage 1 Graded Motor Imagery (laterality left-right discrimination), implement gentle tactile desensitization, prescribe active pain-free fluid movements within comfort, and coordinate with the physician for medical sympatholytic therapy.

DHA Exam Traps to Master

[!WARNING] DHA Exam Trap 1: Carpal Tunnel Sensation Distribution

• Trap: Assuming that in Carpal Tunnel Syndrome, the entire palm of the hand experiences sensory loss.
• Fact: Sensation over the proximal thenar eminence is spared because the palmar cutaneous branch of the median nerve arises proximal to the carpal tunnel and passes superficial to the transverse carpal ligament.

DHA Exam Trap 2: Splint Positioning for Carpal Tunnel Syndrome

• Trap: Prescribing a wrist cock-up splint at 20° to 30° of wrist extension for CTS.
• Fact: Intracarpal canal pressure is lowest when the wrist is positioned in neutral (0° to 5° extension). Cock-up splints at 20°–30° extension significantly elevate canal pressure, worsening axonal ischemia.

DHA Exam Trap 3: Scaphoid Radiograph Pitfall

• Trap: Discharging or failing to immobilize a patient with severe anatomical snuffbox tenderness after a FOOSH injury because initial radiographs are reported as negative.
• Fact: 10% to 20% of acute scaphoid fractures are radiographically occult at initial injury. The standard of care mandates thumb spica splinting and repeat imaging in 10 to 14 days to avoid non-union and avascular necrosis.