Falls happen, even to the most graceful and coordinated among us. The knee is particularly vulnerable during a fall and is among the most commonly injured joints of the body. Knee pain after a fall might signal any of several types of injuries involving the bones, tendons, cartilage or ligaments of the joint.
A fall directly onto your knee typically leads to a contusion, or bruise. Your knee is likely to feel tender and swell a bit. Some mild discomfort when walking might also occur. If the pain is severe, you likely have a more extensive knee injury.
Four ligaments support and stabilize your knee joint, namely the anterior cruciate, posterior cruciate, medial collateral and lateral collateral ligaments. A fall that involves twisting of your knee can damage one or more of these ligaments resulting in pain and joint instability. Overstretching or a partial or complete tear of a ligament is called a sprain. The anterior cruciate ligament, or ACL, is particularly suceptible to injury. Other knee damage often occurs with an ACL tear. In addition to pain, knee sprain injuries commonly lead to swelling, tenderness, decreased knee range of motion, and difficulty bearing weight or feeling the knee is giving way.
The meniscus is a cartilage cushion that separates the bones of your upper and lower leg at the knee. A fall on a twisted knee can lead to a meniscus tear. Signs and symptoms vary depending on the location and severity of the tear and might include a popping sensation, swelling, stiffness, pain, inability to fully bend or straighten the knee, and knee buckling or catching. Traumatic meniscus tears are often accompanied by knee ligament damage.
A fall sometimes leads to a partial or complete dislocation of the kneecap, or patella. With a partial dislocation, or patellar subluxation, the kneecap usually pops back into place on its own when the knee is straightened. Complete dislocations occur less frequently and typically involve damage to the ligament that normally holds the kneecap in place. Patellar dislocations cause immediate, severe pain until the kneecap is back in place. The pain diminshes but persists after the dislocation is relieved. Other symptoms include swelling and inability to bear weight.
A hard fall can lead to a bone fracture involving the knee joint. Symptoms of a patella fracture include immediate pain, swelling, inability to completely bend or straighten the knee, and inability to walk. A fall that involves hitting the inside or outside of your knee can lead to a fracture of the large bone of the shin at the knee. This injury, known as a tibial plateau fracture, typically causes pain, swelling, limited knee mobility and difficulty or inability to bear weight. The knee might appear deformed with a severe fracture.
Warnings and Precautions
Minor knee pain and bruising not associated with difficulty moving your knee or bearing weight after a fall often responds well to home treatment with periodic application of an ice pack, rest and over-the-counter pain medication. If your pain is moderate to severe, you cannot fully bend or straighten your knee, or you cannot bear weight, seek immediate medical evaluation. Seek emergeny medical care if your knee injury is accompanied a cold or pale foot, or numbness or tingling below the affected knee. These symptoms often signal damage to the blood vessels at the knee, an injury that requires immediate treatment.
- American Family Physician: Evaluation of Patients Presenting with Knee Pain: Part I. History, Physical Examination, Radiographs, and Laboratory Tests
- American Family Physician: Evaluation of Patients Presenting with Knee Pain: Part II. Differential Diagnosis
- BMJ Best Practice: Assessment of Knee Injury
- Journal of the Royal Society of Medicine: The Acute Swollen Knee: Diagnosis and Management
- Family Practice Notebook: Knee Injury Acute History
- Family Practice Notebook: Acute Knee Pain
- British Journal of Sports Medicine: The Menisci: Basic Science and Advances in Treatment