https://upload.orthobullets.com/topic/4120/images/patella sleeve fracture.jpg
  • Overview
    • patellar sleeve fractures are a rare injury seen in children between 8 and 12 years of age characterized by separation of the cartilage "sleeve" from the ossified patella
      • most fractures are displaced and require treatment with open reduction and internal fixation
  • Epidemiology
    • incidence
      • <1% of pediatric fractures
      • accounts for >50% of patella fractures in children
    • demographics
      • more common in males (5:1)
      • occurs in children 8-12 years old
        • when patellar ossification is nearly complete
  • Pathophysiology
    • mechanism of injury
      • indirect injury caused by powerful contraction of the quadriceps muscle applied to a flexed knee
    • pathoanatomy
      • separation between the cartilage "sleeve" and main part of the patella and ossific nucleus 
  • Prognosis
    • higher risk of complications associated with greater degree of
      • comminution
      • displacement
  • Osteology
    • patella is largest sesamoid bone in body
      • ossification begins at 3-5 years old
    • superior 3/4 of posterior surface covered by articular cartilage
      • articular cartilage thickest in body (up to 1cm)
    • posterior articular surface comprised of medial and lateral facets
      • lateral facet is larger
      • facets separated by vertical ridge
  • Soft tissue attachments
    • quadriceps tendon and fascia lata attach to anterosuperior margin
      • quadriceps tendon comprised of 3 layers
        • superficial layer formed from rectus femoris tendon
        • middle layer formed by vastus medialis and vastus lateralis tendons
        • deep layer formed by vastus intermedius tendon
    • patellar tendon attaches to inferior margin
  • Blood Supply
    • derived from anastomotic ring originating from geniculate arteries
    • most important blood supply to the patella is located at the inferior pol
  • Anatomic
    • superior pole
      • least common
    • inferior pole
      • most common
  • History 
    • indirect injury
      • not associated with a direct blow to the knee
  • Symptoms
    • severe knee pain
    • inability to bear weight
  • Physical exam
    • inspection
      • soft tissue swelling
      • diffuse tenderness
      • hemarthrosis of the knee joint is often present
      • high-riding patella or palpable gap at the distal end of the patella
        • indicates disruption of the extensor mechanism
    • motion
      • difficulty with active extension of the knee, especially against resistance
  • Radiographs
    • recommended views
      • AP
      • lateral
      • tangential
    • findings
      • small flecks of bone adjacent to superior or inferior pole
        • diagnosis may be missed because the distal bony fragment is not readily discernible on radiographs
      • slight anterior tilt of superior pole
        • seen with proximal fractures
      • patella alta
        • seen with distal fractures
      • patella baja
        • seen with proximal fractures
  • MRI or ultrasound
    • indications
      • may be useful for identifying a sleeve fracture when the diagnosis is not clear from the clinical and radiographic findings
  • Nonoperative
    • cylinder cast for 6 weeks
      • indications
        • nondisplaced fractures with intact extensor mechanism
          • rare (most require ORIF)
  • Operative
    • open reduction and internal fixation 
      • indications
        • > 2-3mm displacement
        • > 2-3mm articular step-off
        • disrupted extensor mechanism
  • Open reduction and internal fixation
    • approach open reduction - periosteal sleeve (white arrow) and inferior pole cartilage (asterisk) opposite cancellous bone of the main patella (black arrow).
      • medial parapatellar approach to knee 
    • soft tissue
      • repair torn medial/lateral retinaculum and/or quadricept/patellar tendon
    • instrumentation
      • stabilize fracture using
        • transosseous sutures
        • modified tension band wiring (A) Patellar “sleeve” fracture. (B) and (C) demonstrate AP and lateral x-ray of the knee after reduction and fixation with Kirschner wires and tension band wiring
        • intraosseous suture anchors
        • interfragmentary screws
    • post-operative care
      • cylinder cast in extension for 2-3 weeks
  • Patella alta
  • Extensor lag
  • Quadriceps atrophy
  • Malunion
  • Nonunion
  • Painful hardware

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(OBQ09.77) A 10-year-old female presents to the emergency department complaining of anterior knee pain after a fall from her bicycle. Exam reveals ecchymosis and swelling over the patella and an extensor lag. Radiographs are shown in Figures A and B. What is the most appropriate next step in treatment? Review Topic

QID: 2890

Open reduction and suture fixation




Open reduction and internal fixation with plating and wire cerclage technique




Cylinder cast




Partial patellectomy and advancement of patellar tendon




Patellar tendon midsubstance rupture repair with nonabsorbable suture



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