A popping sound after an injury may be indication that the patient may have a torn issue or a torn meniscus. This injury is associated with increased swelling and pain immediately after the injury. For conditions like tear in the ligament- a medial collateral ligament, lateral collateral ligament, anterior cruciate, ligament or posterior cruciate ligament, there will be associated instability.
In addition, the neurovascular structures around the joint have to be evaluated very closely to ensure there’s no damage there after the injury. Crackling sounds in the joint may indicate arthritis or the start of arthritis. Arthritis in the joint, especially associated with pain, has to be evaluated further by an orthopedic surgeon.