Synopsis
Localise medial and lateral ligament injury, detect multiligament, peroneal-nerve and vascular threats, use stress examination and MRI coherently, protect healing without stiffness, and identify patterns needing repair or reconstruction.
- Identify mechanism and exact tenderness: MCL spans medial femur to tibia; LCL runs lateral femur to fibular head and lateral injury demands peroneal-nerve examination.
- Apply valgus and varus stress at about 30 degrees to isolate collaterals and in extension to screen capsule and cruciates, but do not stress a possible fracture or unreduced dislocation.
- Grade laxity by endpoint and opening, compare the other knee and repeat when guarding settles; pain without opening differs from complete functional disruption.
Key red flags
Gross laxity in more than one plane, high-energy mechanism or transient deformity requires knee-dislocation vascular surveillance even with present pulses.
Investigation priorities
Detect arterial and common peroneal injury.
Identify fracture, avulsion and alignment.
Management branches
High-energy mechanism, gross laxity, deformity, neurological change or perfusion concern is present.
- Reduce deformity, immobilise and document vascular and nerve function before and after intervention.
- Measure perfusion and obtain urgent CT angiography and vascular input when abnormal or equivocal.
Key medicines
Topical or short oral NSAIDUse a licensed topical NSAID at the product frequency or one oral NSAID at the lowest effective adult dose for the shortest period that enables motion, adding gastroprotection when an oral regimen and individual risk require it.
Thromboprophylaxis for selected immobilised patientsUse the current local lower-limb immobilisation regimen only after formal venous-thromboembolism and bleeding assessment, prescribing the exact agent, dose, start and stop dates if risk outweighs harm.