The evaluation of a knee dislocation begins with a history and physical examination.

Physical findings in someone with a kneecap dislocation include:

• Difficulty walking
• Difficulty moving the knee
• Knee deformity at the kneecap
• Tenderness over the kneecap
• Knee swelling

The diagnosis of a kneecap dislocation is made during physical exam. Tests are rarely necessary.

Physical findings in someone with a knee joint dislocation include:

• Inability to move the knee
• Severe knee swelling
• Severe knee pain:
• Worse with movement
• Foot weakness
• Leg numbness (unilateral):
• Below the knee
• Leg weakness (unilateral):
• Below the knee

Tests are necessary to confirm the diagnosis of a knee joint dislocation.

Tests that may be used to evaluate a knee joint dislocation include:

• Knee x-ray
• Arthroscopy
• Bone scan
• MRI scan of the knee

Additional tests that may be used to evaluate severe knee joint dislocations include:

• Angiography:
• A dye test to study the blood vessels that travel behind the knee joint
• MRI angiography
• Doppler ultrasound