Transverse fractures are most common and may result from blunt trauma or from the pull of the quadriceps muscle (quadriceps avulsion fracture).



Ottawa Knee Rules: Radiograph If One Criterion Is Met:
Patient age >55 y (rules have been validated for children 2–16 y of age)
Tenderness at the head of the fibula
Isolated tenderness of the patella
Inability to flex knee to 90 degrees
Inability to transfer weight for four steps both immediately after the injury and in the ED

Pittsburg Knee XR Rules:



  Initial Treatment
Splint type & position Knee immobilizer
Knee in full extension
Initial follow-up visit 5 to 7 days
Pt instructions Icing and elevation of the knee
Non–weight bearing until follow-up visit
  Follow-up Care
Cast or Splint type & position Cylinder cast above ankle to groin
Knee in full extension, not hyperextension
Knee immobilizer brace for reliable patients
Length of immobilization 4 to 6 weeks
Healing time 8 to 10 weeks
Follow-up visit interval Every 3 to 4 weeks
Repeat radiography interval At 2 weeks to check position
At 4 to 6 weeks to document union
Pt instruction Weight bearing as tolerated and straight-leg raises while in cast or brace
Knee ROM and strengthening exercises after the cast or brace is removed
Physical therapy referral is usually required to restore knee function
Indications for Ortho consult >3 mm of separation of fragments or >2 mm of articular stepoff
Severely comminuted fractures


Mechanism of Knee Injury and Treatment:
Fracture Mechanism Treatment
Patella Direct blow (i.e., fall, motor vehicle crash) or forceful contraction of quadriceps muscle Non-displaced fracture with intact extensor mechanism: knee immobilizer, rest, ice, analgesia
Displaced >3 mm or with disruption of extensor mechanism: above treatment plus early Ortho Consult for ORIF
Severely comminuted fracture: Ortho Consult, surgical debridement of small fragments and suturing of quadriceps and patellar tendons
Open fracture: Ortho Consult, irrigation and antistaphylococcal antibiotics in the ED; debridement and irrigation in the operating room
Femoral condyles Fall with axial load or a blow to the distal femur Incomplete or nondisplaced fractures in any age group or stable impacted fractures in the elderly: long leg splinting and orthopedic referral
Displaced fractures or fractures with any degree of joint incongruity: splinting and Ortho Consult for ORIF
Tibial spines and tuberosity Force directed against flexed proximal tibia in an anterior or posterior direction (i.e., motor vehicle crash, sporting injury) Incomplete or nondisplaced fractures: immobilization in full extension (knee immobilizer) and orthopedic referral in 2-7 d
Complete or displaced fracture: early orthopedic referral, often requires ORIF
Tibial tubercle Sudden force to flexed knee with quadriceps contracted Incomplete or small avulsion fracture: immobilization
Complete avulsion: Ortho Consult for ORIF
Tibial plateau Valgus or varus forces combined with axial load that drives the femoral condyle into the tibia (i.e., fall, leg hit by car bumper)
Nondisplaced, unilateral fracture: knee immobilizer with non-weight-bearing and orthopedic referral in 2-7 d
Depression of articular surface: early Ortho Consult for ORIF

Knee Anatomy:


Types Of Patella Fractures: