Knee Injuries - Knee Dislocation

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

Knee Injuries: Knee Dislocation

Posterior vs anterior knee dislocation drawing

X-ray Views

AP view

  • Look especially for small avulsions, such as a Segond fracture, which is a lateral tibial condyle avulsion fracture

Lateral view

  • Look for symmetric or irregular joint space

Acute Management

Orthopedic vascular emergency!

  • Reduce knee and re-examine neurovascular status
  • Consult vascular surgery for hard signs of vascular injury

Measure the Ankle-Brachial index(ABIs):

  • ABI ≥ 0.9: Monitor by serial exam
  • ABI < 0.9: Obtain CT angiography

Splint knee in 20-30 degrees of flexion

Follow-Up Timing

Hospital admission required for serial neurovascular exams and consideration for surgical stabilization


Dimple sign

  • Buttonholing of medial femoral condyle through medial capsule
  • Suggests irreducible posterolateral dislocation

Associated findings with knee dislocations

  • Popliteal artery injury (18%)
  • Common peroneal nerve injury (25%) – check for foot dorsiflexion weakness and numbness to dorsal foot
  • Ligament tears


  • 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]