Imaging of Fractures and Dislocations

Imaging of Fractures and Dislocations

Imaging of Fractures and Dislocations

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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. Types of Fracture Diagram

⭐ 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

ModalityPrimary Use (#/Dislocation)StrengthsLimitations (# Imaging)
X-rayInitial, alignment, most #Available, low cost, quickOccult/stress #, soft tissue
CTComplex/intra-articular #, pre-opExcellent bone detail, multiplanar↑ Radiation, poor soft tissue
MRIOccult/stress #, soft tissue, AVNBest soft tissue/marrow, no radiationCostly, time, contraindications
UltrasoundSuperficial #, peds, dynamicNo radiation, dynamic, bedsideOperator dependent, limited
Bone ScanOccult/stress # (wide), NAIHigh sensitivity (turnover)Low specificity, radiation

⭐ 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. Salter-Harris Fracture Levels I-V Diagram
    • 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.

Practice Questions: Imaging of Fractures and Dislocations

Test your understanding with these related questions

Which of the following is not a differential diagnosis of non-accidental injury?

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Flashcards: Imaging of Fractures and Dislocations

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_____ is the investigation of choice for the diagnosis of avascular necrosis of bone

TAP TO REVEAL ANSWER

_____ is the investigation of choice for the diagnosis of avascular necrosis of bone

MRI

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