Major Effusion Test (aka Ballottable Patella)

Purpose:
Usually performed after an injury to assess for a major increase in the synovial fluid or blood within the knee joint capsule

Procedure:

• Patient is supine, the affected knee is extended as much as possible (with effusion, patient may not be able to extend their knee fully)
• Therapist gently extends the knee further, then compresses the patella down on to the condyles then release

Positive Sign:
Patella clicks onto the femur and then rebounds to the floating position. This could be caused by torn cruciate ligaments, meniscal tearing, or fracture and is considered a Medical Emergency. (Joint effusion within two hours of injury might be caused by blood in the joint, and joint effusion with synovial fluid usually develops 8 hours after injury.