The knee is a large, hinge joint comprised of the lower end of the thigh bone (femur), upper end of the shin bone (tibia), and kneecap. Four strong ligaments stabilize the bones of the joint. A sprain or tear in one or more knee ligaments is a common sports injury.
The medial collateral ligament and lateral collateral ligament sit on the inside and outside of the knee respectively. They control sideways motion and protect the knee against any unusual movement. The anterior cruciate ligament and posterior cruciate ligament cross inside the knee joint and control back and forth movement of the knee as well as some rotational stability.
Injury to a knee ligament can occur from direct blow to the knee, a fall, or any traumatic event. Pain, knee swelling, and feeling that the knee will buckle or “give out” are common symptoms.
You doctor will discuss your symptoms and how the injury occurred. Often times, the doctor will be able to feel laxity in the ligament that is injured during examination of the knee. X-rays are ordered to rule out any fractures or other bone abnormalities. An MRI of the knee may be ordered to evaluate the soft tissue structures and confirm the diagnosis of a ligament sprain.
Ligaments injuries are graded on severity.
- Grade 1: mild sprain or stretching of the ligament
- Grade 2: partial tear of the ligament
- Grade 3: complete tear of the ligament
Treatment for ligament sprains depends on how many ligaments are affected and the severity of injury. Grade 1 and most Grade 2 ligament sprains will heal with a period of rest, bracing, and physical therapy. Some Grade 3 ligament injuries will heal with nonsurgical treatment as well. Grade 3 ligament injuries to the ACL (anterior cruciate ligament) most often require surgery to reconstruct the ligament.
Read about Complex Knee Ligament Reconstruction.