Imaging of Fractures and Dislocations

Fracture Basics - Bone Break Intro

• Definitions:
  • Fracture: Break in bone continuity.
  • Dislocation: Complete loss of articular contact between joint surfaces.
  • Subluxation: Partial loss of articular contact.
• Classification based on skin integrity:
  • Closed (Simple): Skin overlying fracture is intact.
  • Open (Compound): Fracture site communicates with the external environment.
• Basic Fracture Patterns:
  • Transverse: Perpendicular to bone's long axis.
  • Oblique: Angled to long axis.
  • Spiral: Rotational force; multiplanar.
  • Comminuted: ≥3 bone fragments.
  • Segmental: Two distinct fracture lines isolating a segment of bone.
  • Avulsion: Tendon/ligament pulls off bone fragment.
  • Impaction: Bone fragments driven into each other.
  • Greenstick (Pediatric): Incomplete fracture; one cortex broken, other bent.
  • Torus/Buckle (Pediatric): Buckling of cortex.

⭐ The "Rule of Twos" in fracture imaging: obtain at least two views (usually orthogonal), image two joints (above and below the suspected fracture), consider two occasions (repeat X-rays for occult fractures), and if needed, image two limbs (for comparison, especially in children).

Imaging Modalities - Pixel Peeping Pics

⭐ Suspect scaphoid #, neg X-ray? MRI if 3-5 days. Else, repeat X-ray 10-14 days or CT.

Describing & Classifying - Damage Report Decoded

• Use LADDERS for systematic fracture description: Location, Articular involvement, Displacement/Deformity, Angulation, Rotation, Shortening, Soft tissues.

• Key Classifications:
  • Salter-Harris (Physeal Injuries): Types I-V. 📌 SALTR: Slipped - Type I, Above (metaphysis) - Type II, Lower (epiphysis) - Type III, Through/Transverse (physis, epiphysis & metaphysis) - Type IV, cRush/Ruined (physis) - Type V.
  • Gustilo-Anderson (Open Fractures):
    • Type I: Wound <1 cm, clean.
    • Type II: Wound >1 cm, no extensive soft tissue damage.
    • Type IIIA: Extensive soft tissue damage; adequate bone coverage.
    • Type IIIB: Periosteal stripping, bone exposure, significant contamination.
    • Type IIIC: Arterial injury requiring repair.
  • Garden Classification (Femoral Neck Fractures): Types I-IV (evaluates displacement).

⭐ Salter-Harris Type II fractures, involving the physis and metaphysis, are the most common type of physeal injury and typically have a good prognosis with appropriate management.

Complications & Healing - Healing Hiccups & Hazards

• Fracture Healing Stages (Briefly): Inflammation → Soft Callus → Hard Callus → Remodeling.
• Complications:
  • Early:
    • Neurovascular Injury: Clinical; imaging for sequelae (hematoma).
    • Compartment Syndrome: Clinical; imaging: ↑soft tissue swelling.
  • Late:

    • Malunion: Healed, non-anatomical position.

    • Delayed Union: Slow healing (e.g., 3-6 months).

    • Nonunion: No healing by 6-9 months; Hypertrophic ("elephant foot", good biology, poor stability) vs. Atrophic ("pencil point", poor biology).

    • Avascular Necrosis (AVN): Ischemic bone death. 📌 Sites: Femoral head, Scaphoid (proximal), Talus (body). X-ray: Sclerosis, cysts, crescent sign, collapse. MRI: Most sensitive.

      ⭐ The "crescent sign" on an X-ray of the femoral head is an early indicator of Avascular Necrosis, representing subchondral collapse.

    • Osteomyelitis: Bone infection (sequestrum, involucrum).

    • Post-traumatic Osteoarthritis: Secondary joint degeneration.

High‑Yield Points - ⚡ Biggest Takeaways

• Two orthogonal views (e.g., AP, Lateral) are mandatory for fracture assessment.
• Master Salter-Harris classifications (Types I-V) for diagnosing pediatric physeal injuries.
• MRI is gold standard for occult fractures (scaphoid, femoral neck) and evaluating ligamentous injuries.
• Dislocation is complete loss of articular contact; Subluxation is partial loss.
• Recognize key eponymous fractures: Colles', Smith's, Jones', Monteggia, Galeazzi.
• Fat pad signs (elbow) and lipohaemarthrosis (knee) strongly suggest occult intra-articular fractures.