Patella Fracture

Topic updated on 06/14/15 5:37pm
  • Patella fractures account for 1% of all skeletal injuries
    • occur either by direct impact injury or indirect eccentric contraction
    • male to female 2:1
    • most fractures occur in 20-50 year olds
  • Patella sleeve fracture
    • seen in pediatric population (8-10 year olds)
    • high index of suspicion required
  • Bipartite patella 
    • may be mistaken for patella fracture 
    • affects 8% of population
    • characteristic superolateral position
    • bilateral in 50% of cases
  • Patella is largest sesamoid bone in body
  • Articular cartilage thickest in body (up to 1cm)
  • Most important blood supply to the patella is located at the inferior pol
  • Can be described based on fracture pattern 
    • nondisplaced
    • transverse
    • pole or sleeve (upper or lower)
    • vertical
    • marginal
    • osteochondral
    • comminuted (stellate)
  • Physical exam
    • palpable patellar defect 
    • significant hemarthrosis
    • unable to perform straight leg raise indicates failure of extensor mechanism 
      • retinaculum disrupted
  • Radiographs
    • patella alta 
    • fracture displacement
      • best evaluated on lateral x-ray
      • degree of fracture displacement correlates with degree of retinacular disruption
  • MRI 
    • obtain MRI if child has normal xrays but is unable to straight leg raise
  • Nonoperative
    • knee immobilized in extension (brace or cylinder cast) and full weight bearing
      • indications
        • intact extensor mechanism (patient able to perform straight leg raise)
        • nondisplaced or minimally displaced fractures
        • vertical fracture patterns
      • early active ROM with hinged knee brace
        • early WBAT in full extension 
        • progress in flexion after 2-3 weeks
  • Operative
    • ORIF with tension band construct
      • indications
        • preserve patella whenever possible 
        • extensor mechanism failure (unable to perform straight leg raise)
        • open fractures
        • fracture articular displacement >2mm
        • displaced patella fracture >3mm
        • patella sleeve fractures in children
      • techniques
        • minifrag lag screw fixation for independent fragments
        • tension bands
          • 0.062 K wires with figure of 8 wire 
          •  longitudinal cannulated screws combined with tension band wires shown to be biomechanically superior 
          • circumferential cerclage wiring 
            • good for comminuted fractures
          • interfragmentary screw compression supplemented by cerclage wiring 
    • partial patellectomy
      • indications
        • comminuted superior or inferior pole fracture measuring <50% patellar height ONLY if ORIF is not possible 
      • techniques
        • quadricep or patellar tendon re-attachment
        • reattachment close to articular surface prevents patellar tilt
        • medial and lateral retinacular repair essential
    • total patellectomy 
      • indications
        • reserved for severe and extensive comminution not amenable to salvage
          • quadriceps torque reduced by 50%
          • medial and lateral retinacular repair essential
  • Weakness and anterior knee pain 
  • Symptomatic hardware
    • most common  
  • Loss of reduction (22%)
    • increased in osteoporotic bone
  • Nonunion (<5%)
    • can consider partial patellectomy
  • Osteonecrosis (proximal fragment)
    • thought to be due to excessive initial fracture displacement
    • can observe these, as most spontaneously revascularize by 2 years
  • Infection
  • Stiffness


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Qbank (6 Questions)

(OBQ12.43) A 36-year-old female sustains a knee injury after falling from a ladder onto her flexed knee. A radiograph is shown in Figure A. Which of the following treatment options has been shown to have the best outcomes with this injury? Topic Review Topic
FIGURES: A          

1. Long leg cast
2. Open reduction and internal fixation of patella
3. Distal patellar resection and patellar tendon advancement
4. Distal patellar resection and allograft reconstruction
5. Placement of a cerclage wire from patella to proximal tibia

(OBQ12.229) A 43-year-old male suffers a knee injury and undergoes the operation seen in Figures A and B. At his one-year follow-up appointment, the patient notes pain in the peri-patellar region that is aggravated by palpation and kneeling. Range-of-motion is from -5 degrees to 130 degrees. A merchant view is performed which shows no significant degenerative changes of the patellofemoral joint. Which of the following treatments would most likely alleviate his pain? Topic Review Topic
FIGURES: A   B        

1. Symptomatic treatment of his patellofemoral arthritis
2. Manipulation under anesthesia
3. Operative treatment of his non-union
4. Knee intrarticular corticosteroid injection
5. Removal of symptomatic hardware

(OBQ07.207) Partial patellectomy is the recommended treatment for which of the following injuries? Topic Review Topic

1. Vertical patella fractures
2. Bipartite patella
3. Severely comminuted inferior pole fracture
4. Stellate patella fracture
5. Chronic quadriceps tendon rupture

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