Knee fractures

Background

  • Most pts with severe ligamentous or meniscal injury have normal radiographs
  • Lipohemarthrosis suggests occult fx
    • Lateral view: Fat-fluid level indicates intra-articular fracture

Differential Diagnosis

Knee diagnoses

Acute knee injury

Nontraumatic/Subacute

Patella fracture

Background

  • Occurs via direct blow or forceful contraction of quadriceps muscle
  • Do not confuse a bipartite patella with a fx

Clinical Features

  • Focal patellar tenderness, swelling, effusion
  • Check integrity of knee extensor mechanism by having pt perform straight-leg raise

Imaging

  • AP and lateral
    • Lateral view: Distance from tibial tubercle:lower pole of patella ~ length of patella +/- 20%
      • If greater than this suspect patellar ligament rupture
  • Consider skyline (sunset) view if suspect fx of articular surface

Management

  • Nondisplaced w/ intact extensor mechanism: knee immobilizer, rest, ice
  • Displaced >3mm or disruption of extensor mechanism: above + early referral for ORIF

Tibial plateau fracture

Background

  • Occurs via axial load that drives femoral condyle into tibia
  • ACL and MCL injuries assoc w/ lateral plateau fx
  • PCL and LCL assoc w/ medial plateau fx
  • Compartment syndrome may occur
  • Segond Fracture
    • Avulsion fx of margin of lateral tibial plateau just below joint line
    • Associated w/ tear of ACL and meniscal ligaments

Imaging

  • AP, lateral, oblique views (internal for lateral plateau, external for medial plateau)
    • AP - line drawn at lateral margin of femur should not have >5mm of tibia beyond it
  • CT or MRI should be considered if plain film negative but high clinical suspicion

Schatzker Classification

  • Schatzker I Lateral split
  • Schatzker II Split with depression
  • Schatzker III Pure lateral depression
  • Schatzker IV Pure medial depression
  • Schatzker V Bicondylar
  • Schatzker VI Split extends to metadiaphysis
Schatzker Classification of Tibial Plateau Fractures

Management

  • Knee immobilizer w/ non-weightbearing and ortho referral in 2-7d

Disposition

  • Indications for referral within 48hr:
    • Significant displacement or depression
    • Suspected or documented ligamentous injury

See Also

Source

  • Tintinalli