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Patellar Pole Avulsion Fracture

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Other Names

  • Patellar Sleeve Fracture
  • Patellar Sleeve Avulsion Fracture
  • Patellar Sleeve Avulsion (PSA)
  • Pediatric Patellar Avulsion Fracture
  • Sleeve fracture of the patella

Background

  • This page refers to patellar pole avulsion or sleeve fractures
    • Defined as an avulsion of the chondral or osteochondral "sleeve" from the inferior pole of the Patella
    • Very rarely, this can occur on the superior pole
  • This should not be confused with Patellar Apophysitis (Sinding-Larsen-Johansson Syndrome)
    • Although occurring along the inferior patellar pole, it is a chronic overuse injury

History

Epidemiology

  • Demographics (need citation)
    • Occur in pediatrics between age 8 and 16
    • Mean age is 12.7 years
    • Occurs in males at a ratio of 3:1[1]
  • Represent less than 1% of all pediatric fractures[2]
  • Represents between 42% and 72% of patella fractures in children[3]

Pathophysiology

Illustration of patella sleeve avulsion fracture[4]
  • Patellar sleeve fracture
    • Defined as avulsion of a small fragment of bone and/or periosteum, retinaculum, and cartilage
    • Typically occurs at the inferior pole of the patella (rarely at the superior pole)
    • Articular cartilage is pulled from the deep side, periosteum and cartilage from the superficial side[5]
  • Patella is hypermobile
    • More susceptible due to rapid growth, increased sports activity, and relative patella instability
    • High cartilage-bone ratio at transformation zone
    • Increases vulnerability to acute, chronic eccentric loads and shearing forces
  • Mechanism (most common)
    • Indirect, acute forceful muscle contraction of quadriceps
    • Eccentric contraction of the quadriceps on a flexed knee
    • Examples: jumping sports, soccer, fall from elevation onto feet, bicycle accident

Pathoanatomy

Risk Factors

  • Sports
    • Jumping
    • Running
    • Skateboarding

Differential Diagnosis

Clinical Features

  • History
    • Patients will have an acute injury
    • Typically a sudden, forceful contraction of the quadriceps muscle
    • No direct contact or blow to knee
    • They will endorse tenderness at the bottom of the knee cap
    • Pain or difficulty with knee extension
    • Inability to bear weight
  • Physical Exam: Physical Exam Knee
    • Antalgic Gait
    • Soft tissue swelling
    • Hemarthrosis/ joint effusion
    • On palpation, they will be tender at the the inferior pole of the patalla
    • High riding patella may be present
    • A gap or defect may be palpable
    • Patella may be high-riding
  • Special Tests

Evaluation

Lateral knee XR demonstrating patella alta and a 1.3cm ossific fragment representing an avulsion with partial rupture of the patellar sleeve.[6]

Radiographs

Knee US of the suprapatellar region shows a crescent-shaped echogenic fragment at the upper pole of the patella consistent with proximal pole avulsion fracture.[7]

Ultrasound

  • Findings[8]
    • Disruption of cartilage
    • Measure degree of seperation
  • Secondary findings
    • Soft tissue edema and swelling
    • Joint effusion
    • Hyperemia

MRI

  • Indicated to best evaluate the degree of chondral injury

Classification

  • Based on direction of force acting on patella
    • Common: Inferior Pole Avulsion
    • Rare: Superior, Medial or Lateral Pole Avulsion

Management

Nonoperative

  • Goal
    • Achieve functional extensor mechanism
  • Indications
    • Nondisplaced or minimally displaced (< 2 mm) fractures
  • Recommend surgical consultation with pediatric specialist
  • Cylinder Cast with knee in extension
    • For 6 weeks

Operative

  • Indications
    • >2 mm displacement of the chondral- or osteochondral fragment
    • >2 mm articular step-off
    • Loss of extensor mechanism
  • Technique
    • Open reduction, internal fixation

Rehab and Return to Play

Rehabilitation

  • Needs to be updated

Return to Play

  • Needs to be updated

Complications and Prognosis

Prognosis

  • Risk of complications increases with greater degree of
    • Comminution
    • Displacement

Complications

See Also

References

  1. ↑ Gupta, Rishi R., et al. "Patellar sleeve fractures in children: a case report and review of the literature." American journal of orthopedics (Belle Mead, NJ) 35.7 (2006): 336-338.
  2. ↑ Bates DG, Hresko MT, Jaramillo D. Patellar sleeve fracture: demonstration with MR imaging. Radiology. 1994;193:825–7.
  3. ↑ Gao GX1, Mahadev A, Lee EH. Sleeve fracture of the patella in children. J Orthop Surg (Hong Kong). 2008 Apr;16(1):43-6
  4. ↑ https://radiopaedia.org/cases/69752
  5. ↑ Hunt, David M., and Naresh Somashekar. "A review of sleeve fractures of the patella in children." The knee 12.1 (2005): 3-7.
  6. ↑ Sullivan, Scott, Kevin Maskell, and Tristan Knutson. "Patellar sleeve fracture." Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health 15.7 (2014).
  7. ↑ Hemeleers, Wouter, and Wim Siemons. "Superior sleeve avulsion of the patella." Journal of the Belgian Society of Radiology 102.1 (2018).
  8. ↑ Kimball MJ, Kumar NS1, Jakoi AM, Tom JA. Subacute superior patellar pole sleeve fracture. Am J Orthop (Belle Mead NJ). 2014 Jan;43(1):29-32.
Created by:
John Kiel on 7 July 2019 05:24:20
Authors:
Last edited:
4 October 2022 15:57:13
Categories:
Knee | Lower Extremity | Trauma | Pediatrics | Acute

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