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bility to injury. The menisci are mobile, and move posteriorly in flexion, resulting in compression between the posterior por- tion of the tibial plateau.

Clinical history Time spent ascertaining an accurate history is never wasted. The position of the joint at the time of injury determines which structures are damaged. I try to get the patient to demonstrate the mecha- nism and posture at the time of injury with the uninjured leg so that I can understand the position of the knee and resultant forces at the time of injury. In full knee extension, the ACL and PCL fix the knee joint such that little antero- posterior motion occurs between the tibia and femur.

The ACL is often injured during traumatic twisting injuries in which the tibia moves forward on the femur. This may be associ- ated with additional valgus stress. No direct external forces may take place, as the foot is usually planted and the patient may feel a popping sensation. PCL injuries also often occur during twisting with a fixed foot in which the force of the injury is directed posteriorly against the tibia with the knee flexed.

The medial collateral ligament is more commonly injured than the lateral collat- eral ligament, frequently from a valgus force to the knee, often with external rotation, when the knee is extended or slightly flexed. An intact MCL assists the ACL in preventing posterior motion of the femur. Because of this function, together with close proximity and attachments to the medial meniscus, MCL injuries may be associated with injury to the medial meniscus and ACL.

Meniscal injuries usually occur because of the application of traction forces in vari- ous knee positions. During flexion and internal tibial rotation the posterior horn of the medial meniscus is pulled towards the joint centre, resulting in traction forces causing a longitudinal tear of the meniscus.

Meniscal fibrocartilage degenerates with age, making it more susceptible to split- ting, resulting in horizontal cleavage tears. Menisci are important in reducing load on articular cartilage, and reducing the risk of osteoarthritis. Menisci do not

Figure 1: Anterior drawer test

Figure 2: Apley test

Figure 3: Lachmans test with knee.

Figure 4: McMurray's test

Figure 5: Pivot shift test

have any nerve supply and symptoms of pain are usually a secondary feature of tearing and bleeding of the peripheral attachments or traction on the capsule. Magnetic resonance imaging (MRI) fre- quently reports asymptomatic meniscal tears which increases to around 36% for patients over the age of 45 (5).

Meniscal tears can extend anteriorly, cre-

Figure 6: MCL and LCL test

ating a ‘bucket-handle’ tear, which can be unstable, and cause locking of the flexed knee if restoration of anatomical position is not possible. Tears of the posterior horn and lateral meniscus are less likely to cause locking, but the patient may describe a ‘clicking’ sensation. Younger patients tend to have more unstable meniscal tears and are more prone to lock- ing, whilst older patients with degenera-

Summary of history ● Have you had any problems with your knees or joints in the past? ● Where is the knee pain? Can you point to it with one finger? ● How long have you had symptoms? ● Have you changed any activities recently prior to the injury? ● Was there an injury and what were the movements and forces at the time? ● Were you aware of a pop? ● Did the knee become swollen at any stage and if so how long after injury? ● Do you feel the knee may let you down or give way? ● Is the knee locking or catching? ● Is there pain in the hip, thigh or back?

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