Latetal collateral ligament ( fibular collateral ligament)

• Isolated lesion : rare.

• Most frequently result from MVAs and athletic injuries

  • direct blow or force to weightbearing knee 

  • excessive varus stress, external tibial rotation, and/or hyperextension

• Symptoms : lateral knee pain + varus instability at 30 degrees of knee flexion

• Always check for common peroneal nerve  injury

• Limited immobilization, progressive ROM, and functional rehabilitation for partial tears

• Complete Tears usually needs surgery

• Only 30% of PLC injuries are isolated

• Mechanisms

  • blow to anteromedial knee

  • varus blow to flexed knee

  • contact and noncontact hyperextension injuries

  • external rotation twisting injury

  • knee dislocation

• always search for vascular and nervous injury

• Physical exam

  • Varus laxity in extension (and flexion)

  • Recurvatum in external rotation

  • Dial test: > 10° external rotation asymmetry at 30°and 90° (if only at 30°, think of isolated PCL)

Imaging

• Stress radiographs  

  • bilateral varus stress XR in 20° flexion

  • side-to-side difference 2.7-4 mm = isolated LCL tear

  • side-to-side difference > 4 mm = PLC injury

• Long-leg standing radiographs to evaluate alignment

  • required in cases of chronic PLC injury to distinguish Primary, seocndary and triple varus

• MRI

Treatment :

complete tears of PLC require surgery : reconstruction(+repair), but not repair alone

Generally Treatment is done between 10 and 20 days post op