Knee injuries
Unhappy triad is commonly seen following a lateral blow to the knee and consists of damage to the:
- anterior cruciate ligament
- medial collateral ligament
- meniscus (classically the medial meniscus but recent evidence shows that the lateral meniscus is more commonly injured)
| Structure | Notes |
|---|---|
| Anterior cruciate ligament | Damage may result from hyperextension and/or twisting injuries Anterior drawer test and Lachman test may be positive if damaged |
| Posterior cruciate ligament | Damage may occur following dashboard injuries |
| Medial collateral ligament | Damage may commonly result from skiing and following valgus stress Damage typically causes abnormal passive abduction of the knee |
| Lateral collateral ligament | Isolated injury is uncommon |
| Menisci | Damage may result from twisting injuries Locking and giving way are common symptoms |
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