An accurate diagnosis of a lateral knee ligament sprain is important in order to prescribe an effective knee rehab program.
We look at the assessment procedure a sports therapy practitioner may use to diagnose a lateral knee ligament sprain. This will include observation, palpation or feeling, range of movement as well as specific tests which stress the injured ligament.
The therapist will observe the joint for swelling, bruising and deformity and then proceed to palpate around the joint for areas of tenderness, warmth, swelling etc. In cases of lateral collateral ligament (LCL) injury palpating over the ligament will range from mild tenderness in grade one sprains, to acute pain in more serious injuries.
Range of motion
The therapist will check the range of motion at the knee. They will usually ask you to bend and straighten the knee yourself (active) and will then ask you to relax as they do it for you (passive). Ligament injuries are usually painful on both active and passive motion, whereas muscle injuries are less painful on passive movements. In LCL injuries, range of motion is often affected in more severe injuries and is usually only limited by pain or swelling.
Resisted muscle tests
The therapist will usually ask you to try to bend and straighten your knee against resistance. Doing this causes the muscles to contract. Pain on contraction suggests a muscular injury rather than a ligament, although does not rule out an LCL injury.
Varus stress test
This test is used in cases of suspected LCL injuries. The therapist takes hold of the limb, ensuring the knee is slightly bent (approx 30 degrees). They stabilise the thigh whilst applying an inward pressure on the lower leg. This stretches the lateral ligament. Pain on the outside of the knee indicates a positive test. The degree of damage can be determined by how much movement / instability is present.