A dislocated kneecap (patellar dislocation) occurs when the patella slips out of the trochlear groove, the channel at the end of the thigh bone (femur). This displacement typically forces the kneecap laterally, toward the outside of the leg. Most dislocations are acute injuries, often resulting from a sudden twisting motion of the knee while the foot remains planted, such as during sports. A direct blow to the knee, like a fall or collision, can also push the kneecap out of place.
The Acute Experience: Sensation, Pain, and Visual Signs
The moment a patellar dislocation occurs, it often begins with a “pop” or tearing sensation within the knee joint. This is followed by a feeling that the knee has “given way” or buckled, making it impossible to bear weight on the affected leg. The mechanical displacement causes sudden, severe pain until the kneecap is returned to its proper position.
The pain is compounded by the inability to move the leg; the knee often locks in a slightly bent position. Visually, the dislocation is obvious, as the patella appears as an abnormal bump resting on the side of the knee. Rapid swelling (effusion) develops quickly due to bleeding within the joint caused by the trauma, and bruising may also appear soon after the injury.
Immediate Steps Following Dislocation
Following a suspected kneecap dislocation, seek professional medical attention immediately at an emergency room or urgent care facility. While waiting for help, resist the urge to force or push the kneecap back into place. Attempting a self-reduction can cause further damage to the surrounding ligaments, cartilage, or blood vessels.
The primary goal of first aid is to immobilize and protect the joint in the position it is found. The leg should be supported and kept still to prevent accidental movement. Applying a cold compress or ice pack for 10 to 20 minutes helps control pain and reduce swelling. The leg should also be elevated above the level of the heart to manage fluid accumulation.
Medical Intervention and Rehabilitation
Upon arrival at a medical facility, the injury is confirmed and checked for associated fractures using an X-ray. Once cleared, a healthcare professional performs a closed reduction, manipulating the kneecap back into its groove. This maneuver is often performed with the patient under sedation or pain medication for comfort and muscle relaxation.
Following reduction, the knee is usually immobilized in a brace or splint, often for around four weeks, allowing damaged soft tissues to heal. The subsequent phase involves physical therapy focused on restoring strength and stability to the knee. Strengthening the surrounding muscles, particularly the quadriceps, helps the kneecap track correctly and prevents future dislocations. While non-surgical treatment is the standard initial approach, severe cases may require surgical intervention to stabilize the joint.