Hand Fractures and Dislocations

Hand Anatomy & Fracture Basics - Bone Blueprint

• Hand Skeleton (27 Bones):
  • Carpals (8): Two rows of four.
    • Proximal: Scaphoid, Lunate, Triquetrum, Pisiform. (📌 SLTP: "So Long To Pinky")
    • Distal: Trapezium, Trapezoid, Capitate, Hamate. (📌 TTCH: "Try To Catch Him")
  • Metacarpals (5): Numbered I-V, lateral to medial. Each has base, shaft, neck, head.
  • Phalanges (14): Thumb (proximal, distal); Fingers (proximal, middle, distal).
• Fracture Principles:
  • Description: Location, pattern (transverse, oblique, spiral, comminuted), displacement, angulation, rotation.
  • Open vs. Closed.
  • Children: Salter-Harris classification for physeal injuries (Types I-V).

  ⭐ Scaphoid fractures: Most common carpal bone injury. High risk of avascular necrosis (AVN) and non-union, especially waist/proximal pole fractures.

Phalangeal & Metacarpal Mayhem - Finger Fixes

• Phalangeal Fractures:
  • Tuft (Distal): Crush injury; subungual hematoma (trephinate).
  • Shaft/Intra-articular: Check angulation/rotation.
  • Mallet Finger: Extensor avulsion (DIP). Splint DIP in full extension 6-8 wks.
  • Jersey Finger: FDP avulsion (DIP). 📌 "Sweater finger" sign. Surgical repair.
• Metacarpal Fractures:
  • Boxer's (5th MC neck): Apex dorsal. Acceptable angulation: 5th MC <40°, 4th MC <30°, 3rd MC <20°, 2nd MC <10°.
  • Shaft: Rotational deformity critical.
  • Bennett's: 1st MC base intra-articular # dislocation. Often needs CRPP/ORIF.
  • Rolando's: 1st MC base comminuted (Y/T) intra-articular #. Often needs ORIF.
• General Treatment:
  • Undisplaced/Stable: Buddy tape, splint.
  • Displaced/Unstable/Rotated: CRPP, ORIF.
• Dislocations:
  • PIP (most common): Dorsal (reduce, buddy tape); Volar (often Open Reduction).
  • MCP: Dorsal often irreducible (volar plate interposition).

⭐ Rotational deformity is the most functionally impairing malunion in hand fractures; correct meticulously.

Carpal Chaos & Scaphoid Saga - Wrist Wreckers

• Carpal Bones (Proximal → Distal, Radial → Ulnar):
  • Proximal: Scaphoid, Lunate, Triquetrum, Pisiform
  • Distal: Trapezium, Trapezoid, Capitate, Hamate
  • 📌 Mnemonic: "Some Lovers Try Positions That They Can't Handle"
• Scaphoid Fracture: Most common carpal #. FOOSH.
  • Anatomical snuffbox tenderness.
  • Blood supply: Retrograde; ↑AVN risk (proximal pole).
  • X-ray: Scaphoid views. MRI if occult.
  • Complications: AVN, non-union (SNAC wrist).
  • Tx:
    • Undisplaced: Thumb spica 6-12 wks.
    • Displaced (>1mm)/Proximal pole: ORIF.

⭐ Scaphoid fracture non-union can lead to Scaphoid Nonunion Advanced Collapse (SNAC wrist), a predictable pattern of wrist arthritis.

• Lunate/Perilunate Dislocation: High energy. FOOSH.
  • Lunate dislocation: "Spilled teacup" sign (lateral X-ray).
  • Perilunate: Other carpals dislocate dorsally.
  • Tx: Urgent reduction ± ORIF.

Dislocations & Ligament Drama - Joint Jolts

• PIP Joint Dislocation: Most common finger joint. Dorsal (hyperextension) > Volar.
  • Dorsal: Reduce, extension block splint 0-30° flexion.
  • Volar plate injury: Swan neck deformity risk.
• MCP Joint Dislocation: Thumb (forced hyperextension) most common. Index finger often irreducible (volar plate entrapment).
• DIP Joint Dislocation: Less common, usually dorsal. Easily reducible.
• Skier's/Gamekeeper's Thumb (UCL Tear): Thumb MCPJ. Forced radial deviation/abduction.
  • Valgus stress test: Laxity >30-35° or >15° than contralateral.
  • 📌 Stener Lesion: UCL displaced superficial to adductor aponeurosis.

  ⭐ Stener lesion (UCL displaced over adductor aponeurosis) blocks healing, requires surgery.

• Scapholunate (SL) Dissociation: FOOSH. SL gap >3mm (Terry Thomas sign). Watson scaphoid shift test. Leads to SLAC wrist.

High‑Yield Points - ⚡ Biggest Takeaways

• Boxer's fracture: 5th metacarpal neck fracture; ulnar gutter splint.
• Bennett's fracture: Intra-articular fracture, 1st metacarpal base; requires ORIF.
• Rolando's fracture: Comminuted intra-articular fracture, 1st metacarpal base; T/Y shape.
• Scaphoid fracture: Most common carpal fracture; anatomical snuffbox tenderness; risk of AVN.
• Mallet Finger: Extensor tendon avulsion at DIP joint; splint in extension.
• Gamekeeper's Thumb: UCL injury of thumb MCP joint; instability.