Knee iSAWE 18

Question

A 23 year old soccer player twists his knee and feels a pop. He has a large effusion within hours.

Knee iSAWE 18, AP radiograph of the knee
AP radiograph of the knee. Image by Ellisbjohns, Wikimedia Commons, Public domain.
  1. What does the radiograph show and what does it signify?
  2. What associated injuries would you expect on MRI?
  3. Outline management.

Answer

Radiograph

  • Small avulsion fragment from the lateral tibial plateau (circled)
  • Segond fracture
  • Avulsion of the anterolateral capsule and anterolateral ligament
  • Internal rotation and varus mechanism

Associated injuries

  • ACL rupture in about 75 to 100%
  • Meniscal tears
  • Bone bruising of the lateral femoral condyle and posterolateral tibia
  • Reverse Segond fracture (medial) implies PCL and medial meniscus injury
  • Arcuate sign (fibular head avulsion) implies posterolateral corner injury

Management

  • MRI to define ligament and meniscal injury
  • Treat as an ACL injured knee
  • ACL reconstruction for active patients with instability
  • Consider lateral extra-articular tenodesis or ALL reconstruction for high grade pivot shift, young athletes or revision
  • STABILITY trial showed lower graft failure when lateral extra-articular tenodesis is added in young high risk patients

Related pages

Author Contributions

Orthofracs team

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.