import { HighYieldBox, ExamCheatSheet, Tabs, Tab, ComparisonTable, VivaScenario, ContentSection, SpecialTestCard , MedicalImage} from '@/components/content' # Finger Examination Finger examination requires systematic assessment of tendons, joints, and ligaments. Examiners expect you to test flexor and extensor tendons in isolation, understand the cascade and posture of the hand, and recognize common injury patterns like mallet finger and jersey finger. ## Quick Reference One-Pager ## Anatomy **Flexor System:** - **FDS (Flexor Digitorum Superficialis)**: Inserts on middle phalanx, flexes PIP - **FDP (Flexor Digitorum Profundus)**: Inserts on distal phalanx, flexes DIP - **Vincula**: Blood supply to tendons - **Pulleys**: A1-A5 annular, C1-C3 cruciate (A2 and A4 most important) **Extensor System:** - **EDC (Extensor Digitorum Communis)**: Extends MCP - **Central slip**: Extends PIP - **Terminal tendon (lateral bands)**: Extends DIP - **Sagittal bands**: Center EDC over MCP - **Intrinsics**: Lumbricals and interossei (flex MCP, extend IP) **Joints:** - **MCP**: Condyloid, collaterals tight in flexion - **PIP**: Hinge joint, most prone to stiffness - **DIP**: Hinge joint **Normal Finger Cascade:** When hand is relaxed: - Fingers progressively more flexed from index to little - Index least flexed, little most flexed - Loss of cascade suggests tendon injury **Tenodesis Effect:** - Wrist extension → fingers flex passively - Wrist flexion → fingers extend passively - Confirms tendon continuity ## Flexor Tendon Examination **FDS Test - Key Points:** - MUST hold other fingers extended (blocks FDP) - Index and little finger may have independent FDP (test may be false positive) - Absent FDS to little finger is normal variant (15% population) **Mechanism:** - Forced extension against active flexion - Common in rugby/American football (grabbing jersey) - Ring finger most commonly affected (60%) **Examination:** - Finger held in extension at DIP - Cannot actively flex DIP - Palpable mass may be felt where tendon retracts - Tenodesis: DIP doesn't flex with wrist extension **Classification (Leddy-Packer):** | Type | Retraction Level | Treatment Urgency | |------|------------------|-------------------| | I | Palm | Urgent (7-10 days) - no vincular blood supply | | II | PIP level | Less urgent (6 weeks) - vinculum intact | | III | Bony avulsion at A4 | Less urgent - bone prevents retraction | ## Extensor Tendon Examination **Mechanism:** - Forced flexion against extended DIP - Ball striking fingertip - May be bony (avulsion fracture) or tendinous **Examination:** - Extensor lag at DIP (cannot actively extend) - Passive extension full - Resting position: DIP in flexion **Classification:** | Type | Description | |------|-------------| | I | Tendinous (no fracture) | | II | Small avulsion fracture | | III | Large avulsion (greater than 1/3 articular surface) | | IV | Epiphyseal injury (pediatric) | **Mechanism:** - Forced flexion against extended PIP - Penetrating injury to dorsal PIP - RA destruction of central slip **Examination:** - PIP flexion deformity - DIP hyperextension (lateral bands displaced volar) - Elson test positive (rigid DIP) **Stages:** 1. Mild: Passively correctable, tendon healing potential 2. Moderate: Fixed but reducible with anesthesia 3. Severe: Fixed with joint changes ## Intrinsic Muscle Testing ## Collateral Ligament Testing **Collateral Ligament Testing:** **Why 30° Flexion?** - MCP collaterals are cam-shaped: tight in flexion, lax in extension - PIP collaterals more uniform but still test in 30° for accuracy - At 30°, stress isolates collateral from volar plate **Compare with contralateral:** Essential for detecting subtle laxity ## Trigger Finger Assessment **Examination:** - Nodule palpable at A1 pulley (volar MCP crease) - Active triggering with flexion/extension - May be locked in flexion or extension **Classification (Quinnell):** | Grade | Description | |-------|-------------| | 0 | Normal | | I | Uneven movement | | II | Actively correctable locking | | III | Passively correctable locking | | IV | Fixed locked position | **Differential:** Locked PIP may also be trigger or volar plate injury ## Pulley Assessment **Relevant Anatomy:** - A2 (proximal phalanx) and A4 (middle phalanx) most critical - Rupture allows bowstringing - Common in rock climbers **Examination:** - Bowstringing: Flexor tendons palpable with finger flexion (not constrained by pulley) - Pain over pulley during resisted flexion - Swelling at pulley site **Forced Flexion Test:** - Apply resistance during active flexion - Observe for bowstringing ## Common Finger Deformities ## Summary Presentation ## Examination Sequence 1. **Observation**: Cascade, swelling, deformity, posture 2. **Tenodesis**: Wrist extension (fingers flex), wrist flexion (fingers extend) 3. **FDS Test**: Each finger with others extended 4. **FDP Test**: DIP flexion with PIP held extended 5. **Terminal Tendon**: DIP extension against resistance 6. **Central Slip**: Elson test 7. **Collaterals**: Stress at 0° and 30° flexion 8. **Intrinsic Tightness**: Bunnell test 9. **Trigger**: Palpate A1 pulley, active flexion/extension 10. **Neurovascular**: Two-point discrimination, capillary refill ## Examiner Tips