Ligaments connect bones together at joints; a sprain is a ligament injury. Commonly resulting from falls and sports injuries, ligament injuries can cause swelling, bruising, and pain.
The most commonly injured ligament in the wrist is the scapholunate ligament, which, as you might expect, attaches the scaphoid bone to the lunate bone. This often occurs from a fall onto your outstretched hand.
Your doctor can diagnose this by history, examination, X-rays, and possibly MRI or CT- arthrogram. Ligament injuries can be treated by different methods ranging from immobilization to reconstructive surgery.
Untreated injuries can result in severe wrist arthritis which can be treated symptomatically or by reconstructive "salvage" surgery.
Even if treated well, these can result in long-term pain, swelling, and stiffness. We still haven’t figured out the best way to treat this, but investigations are underway.