Knee injuries
unhappy triad
- anterior cruciate ligament
- medial collateral ligament
- meniscus (classically the medial meniscus but recent evidence shows that the lateral meniscus is more commonly injured)
specific injuries
| Anterior cruciate ligament rupture | |
|---|---|
| Mechanism | twisting with foot planted on the ground. |
| Clinical presentation | - “pop” with immediate swelling, unable to weight-bear immediately afterward ⇒ loss of anterior translation of tibia - Lachman (similar to drawer test); pivot shift (sublux knee under anaesthesia) |
| Imaging | XR: exclude Segond # (pathognomonic for ACL, suggests high-stress tears). MRI after 2 weeks when ↓ inflammation. |
| Associated injuries | Segond fracture Avulsion # of intercondylar region |
| Management | ➥ Physical therapy – to build stability by muscles ➥ Surgical: reconstruction |
| F/up and discharge advice |
| Patellar dislocation | |
|---|---|
| Mechanism | valgus stress + flexion + ext rotation, or direct trauma Most common = lateral dislocation; superior is less comon |
| Clinical presentation | - A popping sound/sensation - Significant knee pain/tenderness - Inability to straighten the knee affected - Swelling of the knee - Inability to walk/bear weight |
| Associated injuries | Patellar tendon |
| Management | Extend knee Guide patella back into anatomical position |
| F/up and discharge advice | Splint? Crutches |
ottawa knee rule = do they need imaging?
- age >55
- isolated tenderness of patella
- fibular head tenderness
- unable to flex knee to 90 deg
- unable to weight bear in ED AND immediately after