The most typical symptom that alarms patients is pain (gonalgia). The seat of pain depends on the structure affected by the pathology and the compartment involved. In older patients pain is typically medial, the compartment most frequently affected in the initial stages of arthrosis.
The manner of onset varies with the pathology that causes it. A slow beginning of pain with gradual worsening in an elderly patient suggests the onset of gonarthrosis, while acute pain in a young patient following a distortive trauma or strain suggests the onset of a meniscal lesion. Pain caused by the knee joint may be solicited by loading (ambulation) or passive mobilization by the examiner through full excursion of the joint.
Knee pain may often be accompanied by limping caused by the patient’s efforts to minimize the stepping momentum of a leg with a painful knee. Such effort produces asymmetry of gait because the foot of the “sick” leg is in contact with the ground for less time than that of the healthy leg.
Pain may just as often be accompanied by swelling. Swelling of the joint (sometimes evident on simple observation) is caused by an increase in the quantity of intra-articular liquid. When the excess liquid is synovial liquid, as in the case of inflammation of the inner wall of the capsule (synovitis), the swelling is called hydrarthrosis. The presence of hydrarthrosis is typical in the case of severe arthrosis. When the excess liquid contains blood (caused by a fracture or an intra-articular ligament lesion following a trauma), it is called haemarthrosis.
Less common is rigidity, often due to severe consumption of the articular surface and the onset of calcification diminishing articular excursion.
Knee locking, on the other hand, is when joint movement is limited to a few degrees of excursion, often accompanied by acute pain. Such locking always has a mechanical cause and is most frequently caused by a fragment of ruptured meniscus between the two articular surfaces preventing them from sliding against one another.
Knee instability is the sensation of the joint giving out under load. In elderly patients this may be caused by degeneration of the collateral ligaments and consumption of the femur or tibia, and in young patients to lesion of the anterior cruciate ligament.