Hx

• Significant valgus force
• Significant twisting injury
• Immediate pain +- "pop"
• Immediate swelling with haemarthrosis

LOOK

• True knee joint swelling

FEEL

• Tenderness of the anteromedial corner

MOVE

• Reduced active movement due to pain
• AP force test the ACL ("Lachman's test", "Anterior draw test")

• Normal laxity is 0
• Grade 1: 0-0.5 cm of translation with an end point

(There may be no detectable opening in a Grade 1 injury)

• Grade 2: 0.5-1.0 cm of translation with an end point
• Grade 3: >1.0 cm of translation, usually there is no end point

• IR subluxation/reduction tests ACL ("Pivot shift test")

Exclude combined ACL+ Meniscal Detachment

• Joint line tenderness

Exclude combined ACL + MCL

• Valgus force tests the MCL

Exclude combined ACL + PCL

• ER subluxation/reduction tests PCL ("Reverse pivot shift test")
• PA force test the PCL ("Posterior sag sign", "Posterior draw test")

Exclude combined ACL + PLC

• ER instability tests the PLC and PCL ("ER Recurvatum Test", "Dial Test")
• Varus force tests to LCL / Proximal Tibiofibular Joint / ITB

XRAYS

AP and Lateral views

• Usually reassuringly normal
• Segond Fractures

Exclude combination injuries

• MCL: Joint Opening, Avulsion fractures
• PCL: Joint Subluxation, Avulsion ractures
• PLC: Joint Opening, Avlusions "Arcuate sign"
• Osteohondral fracture: Lipo-haemarthrosis

MRI

• For all multiple ligament injuries
• Whenever a meniscal avulsion is suspected
• For osteochondral fractures (lipo-haemarthrosis)