Swelling is always a sign that something is wrong. It is your bodies way of communicating an injury or problem and should not be ignored. whether the swelling comes instantly or after a while, your joint should be seen by a physio.
The most common joint that swelling occurs at after injury is the knee.
A knee that swells within a few hours after an injury is the most common type of swollen knee.
These cases often involve non-contact injuries caused by things like stopping suddenly, changing direction very quickly, twisting, turning or slipping.
High-energy injuries caused by, for example, falling off a motorbike are often very major injuries to the ligaments or fractures and you should seek immediate medical attention. In the case of elderly patients with thin bones (osteoporosis), simply tripping over can cause fractures.
The vast majority of patients who present with a knee that has swollen very rapidly have injured a ligament.
The most common such injuries are to the Anterior Cruciate Ligament or ACL (to the front of the knee), the Medial Collateral Ligament or MCL (inner knee) and, more rarely, the patella (kneecap).
Classically, a torn (ruptured) ACL is a non-contact injury that may be accompanied by a snap, pop or tearing sensation and may feel unstable.