Knee Injuries - Patellar Fracture

Authors: Layla Abubshait, MD, Michael Gottlieb, MD, RDMS, Mary Haas, MD
Updated: 11/21/2016

Knee Injuries: Patellar Fracture

Drawing of the types of patellar fractures

X-ray Views

  • AP knee
  • Lateral knee: Best to assess for fracture displacement
  • Patella view: Sunrise or Merchant view

Operative Indications (Outpatient)

  • Knee extensor function disruption
  • >2 mm articular displacement
  • >3 mm fracture fragment separation

Acute Management

  • Knee immobilizer with knee in full extension
  • Weight-bearing instructions as tolerated
  • If non-operative: Early weight bearing to minimize bone loss and muscle atrophy

Follow-Up Timing

Within 1 week

If non-operative:

  • Muscle strengthening education
  • Likely conversion to long leg cast or locking knee brace


  • Nonunion
  • Stiffness
  • Muscle atrophy
  • Osteonecrosis


  • Schwartz A. Patella Fractures Treatment & Management, (June 2016) [Source].
  • Hinton RY, Sharma KM. Acute and recurrent patellar instability in the young athlete. Orthop Clin North Am. 2003 Jul;34(3):385-96. [PubMed]
  • Ji G, et al . Surgical versus Nonsurgical Treatments of Acute Primary Patellar Dislocation with Special Emphasis on the MPFL Injury Patterns. J Knee Surg. 2016 Sep 14. Epub ahead of print. [PubMed]
  • Petri M, et al. Current Concepts for Patellar Dislocation. Arch Trauma Res. 2015 Sep 1;4(3):e29301. [PubMed]
  • Medina O, et al. Vascular and nerve injury after knee dislocation: a systematic review. Clin Orthop Relat Res. 2014 Sep;472(9):2621-9. [PubMed]