A patient must be appropriately undressed; always compare right with left, and with abnormalities of other joints. Note skin, color, rashes, creases, scars, sinuses and contractures.
Erythema may indicate arthritis or infection, while a rash may give important clues to underlying joint disturbances. Abnormal shape of a joint may reflect swelling due to effusions, synovial hypertrophy, inflammation and bony overgrowths.
Deformity may be postural (due to abnormal posture), structural (due to tissue abnormalities), paralytic (due to muscular imbalance) or compensatory (to overcome abnormalities elsewhere). The deformity may be mobile or fixed, i.e. not changeable on passive movement: the deformities may be symmetrical or asymmetrical. The degree of deformity may be mild (e.g. ulnar deviation of the metacarpophalangeal joint in early rheumatoid arthritis) or gross (e.g. destruction of a denervated joint in a neuropathic disorder).
Lateral deviation of the distal portion of a joint in relation to the proximal is termed a valgus, and medial deviation a varus, deformity. Abnormalities of bone alignment are classified as subluxation, when the displaced parts of joint surfaces remain in contact, and dislocation when there is loss of contact between the two adjacent surfaces.
You should note any alteration in the shape or outline of the bone, localised swelling and evidence of tenderness. Bones may be both deformed and enlarged, as in osteitis deformans (Paget’s disease), or there may be alteration of their shape, as in the bowing of the tibia seen in rickets. Tendons and bursae are examined for inflammatory changes.