Knee fractures

Background

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

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
• If suspicion high but x-ray negative consider MRI or CT

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