It is important to establish the nature of the patient’s complaint before any examination. The history should include information about the complaint, the signs and symptoms, and the patient’s lifestyle (level of activity). This history may give a significant clue to the type of injury and the likely findings on clinical examination, for example, if the patient was kicked around the medial aspect of the knee, a valgus deformity injury to the tibial collateral ligament might be suspected.
The examination should include assessment in the erect position, while walking, and on the couch. The affected side must be compared with the unaffected side.
There are many tests and techniques for examining the knee joint, including the following.
Lachman’s test—the patient lies on the couch. The examiner places one hand around the distal femur and the other around the proximal tibia and then elevates the knee, producing 20° of flexion. The patient’s heel rests on the couch. The examiner’s thumb must be on the tibial tuberosity. The hand on the tibia applies a brisk anteriorly directed force. If the movement of the tibia on the femur comes to a sudden stop, it is a firm endpoint. If it does not come to a sudden stop, the endpoint is described as soft and is associated with a tear of the anterior cruciate ligament.
Anterior drawer test—a positive anterior drawer test is when the proximal head of a patient’s tibia can be pulled anteriorly on the femur. The patient lies supine on the couch. The knee is flexed to 90° and the heel and sole of the foot are placed on the couch. The examiner sits gently on the patient’s foot, which has been placed in a neutral position. The index fingers are used to check that the hamstrings are relaxed while the other fingers encircle the upper end of the tibia and pull the tibia. If the tibia moves forward, the anterior cruciate ligament is torn. Other peripheral structures, such as the medial meniscus or meniscotibial ligaments, must also be damaged to elicit this sign.
Pivot shift test—there are many variations of this test. The patient’s foot is wedged between the examiner’s body and elbow. The examiner places one hand flat under the tibia pushing it forward with the knee in extension. The other hand is placed against the patient’s thigh pushing it the other way. The lower limb is taken into slight abduction by the examiner’s elbow with the examiner’s body acting as a fulcrum to produce the valgus. The examiner maintains the anterior tibial translation and the valgus and initiates flexion of the patient’s knee. At about 20°–30° the pivot shift will occur as the lateral tibial plateau reduces. This test demonstrates damage to the posterolateral corner of the knee joint and the anterior cruciate ligament.
Posterior drawer test—a positive posterior drawer test occurs when the proximal head of a patient’s tibia can be pushed posteriorly on the femur. The patient is placed in a supine position and the knee is flexed to approximately 90° with the foot in the neutral position. The examiner sits gently on the patient’s foot placing both thumbs on the tibial tuberosity and pushing the tibia backward. If the tibial plateau moves, the posterior cruciate ligament is torn.
Assessment of other structures of the knee
Assessment of the tibial collateral ligament can be performed by placing a valgus stress on the knee.
Assessment of lateral and posterolateral knee structures requires more complex clinical testing.
The knee will also be assessed for: joint line tenderness, patellofemoral movement and instability, presence of an effusion, muscle injury, and popliteal fossa masses.
After the clinical examination has been carried out, further investigations usually include plain radiography and possibly magnetic resonance imaging, which allows the radiologist to assess the menisci, cruciate ligaments, collateral ligaments, bony and cartilaginous surfaces, and soft tissues.