Your doctor will likely ask how you injured your knee, how it has been feeling since the injury and if you've injured your knee before. He or she will check for pain or tenderness along the inside of the knee. In addition, your doctor will approximate the cause of the injury by exerting pressure on the outside of your knee while your leg is both bent and straight.
Depending on the degree of pain or looseness of your knee joint, the injury will be classified as one of three grades:
- Grade 1: There is some tenderness and minor pain at the point of the injury.
- Grade 2: There is noticeable looseness in the knee ("opening up" approximately five millimeters) when manipulated by hand, major pain and tenderness at the inside of the knee, and in some cases swelling.
- Grade 3: There is considerable pain and tenderness at the inside of the knee along with some swelling and marked joint instability (the knee opens up approximately one centimeter when manipulated). A grade three MCL tear often occurs in conjunction with an ACL tear or, more rarely, with a PCL tear.
In some cases, the immediate pain and swelling may make it too difficult for your doctor to accurately gauge the severity of the injury. If this occurs, you may be asked to wear a light splint and ice and elevate your knee until the swelling and pain lessen, so that an accurate diagnosis can be made.
In addition, your doctor may order the following tests:
- X-ray: To assess for other damage and bone injury
- Magnetic Resonance Imaging (MRI: This test is 90 percent accurate in diagnosing MCL injuries and may be ordered if the physical examination is unclear or if your doctor suspects that you have other injuries.
- Stress X-ray: This also may be used to look for ligament tears. Although this test is similar to a normal X-ray, the doctor or technician will hold the knee open from the side so that any widening of the joint space will be evident on the X-ray.
Reviewed by health care specialists at UCSF Medical Center.