The physical examination begins when the physician meets the patient. The physician can assess posture, gait, skin texture, and gross muscle strength by shaking hands, accompanying the patient into the office, and watching him or her move. A comprehensive assessment of the musculoskeletal system includes inspection and palpation of joints and soft tissues as well as evaluation of joint range of motion and neuromuscular function.
Joint swelling, color, and alignment, as well as skin rashes and muscle wasting, are usually obvious in a glance. Comparing similar joints and muscle groups on opposite sides of the body helps detect subtle abnormalities.
The hallmark of inflammation is swelling, which, when present in a joint, indicates that arthralgia has become arthritis. An increase in synovial fluid causes generalized joint swelling unless fluid accumulates in a contiguous synovial pouch (eg, suprapatellar space) or bursa (eg, gastrocnemius-semimembranous popliteal bursa [Baker cyst]). Inflammation of a tendon sheath may cause soft, localized para-articular swelling. Soft tissue edema tends to be more diffuse.
Well-defined swelling over a bony prominence such as the olecranon process or patella may represent an inflamed subcutaneous bursa, a rheumatoid nodule, a gouty tophus, or rarely, a xanthoma or an amyloid deposit. Bony enlargements (osteophytes) adjacent to joints are typical of osteoarthritis and occur as a result of cartilage damage. Occasionally, such overgrowths are a product of chronic inflammation. Osteophytes may be palpable and visible at the distal interphalangeal and proximal interphalangeal (PIP) joints, where they are called Heberden and Bouchard nodes, respectively.
Acute inflammation of a joint may impart an erythematous hue to the overlying skin, reflecting vasodilation of cutaneous vessels. In some cases of crystal-induced disease, such as gout, the joint and surrounding areas have an intense red-violet color mimicking that seen in infectious cellulitis and septic arthritis.
Inflamed joints tend to assume positions that maximize intrasynovial volume, thereby minimizing intrasynovial pressure and reducing pain. In chronic arthritis, when such positions are held for prolonged periods, flexion deformities may ensue. Chronic arthritis can also lead to destruction of supporting structures with consequent malalignment of adjacent bones.
Atrophy of muscles may result from lack of use, neurologic disease, inflammation of an adjacent joint, or myositis associated with an underlying disease. Thus, atrophy of the intrinsic muscles of the hand commonly accompanies inflammation of the fingers or wrists and is visible as depressions between the extensor tendons on the dorsum of the hand. Similarly, synovitis of the knee typically causes atrophy of the quadriceps muscles, resulting in a concavity just above the knee, particularly on the medial aspect.
A “hands on” examination is vital to the detection of inflammation and structural damage in a joint.
Joint tenderness is the most sensitive but the least specific indicator of inflammation. During examination, apply similar pressure to all joint groups and surrounding structures. (Some experts suggest exerting pressure sufficient to blanch the examiner’s fingernail bed.) When indicated, test normal structures to determine the patient’s baseline pain threshold. Remember that the joint capsule and periosteum are pain-sensitive structures, but the articular cartilage and meniscus are not.
A tense synovial effusion has the consistency of a hollow rubber ball, whereas synovial hypertrophy feels more doughy. Inflammation of a tendon sheath results in soft, para-articular swelling in the distribution of the tendon, and the associated subcutaneous edema tends to be more diffuse. Osteophytes produce the bony swelling typical of Heberden and Bouchard nodes. Simultaneous swelling of different joint components can confuse even the most experienced examiner.
An increase in the surface temperature of the joint usually indicates underlying inflammation. By using the dorsum of the hand to palpate the same joint on each side of the body, temperature changes as small as 0.5°C can be detected. Note that surface temperatures of superficial joints such as the knee are normally lower than those of the surrounding tissue (unless there is extra subcutaneous fat overlying the joint). Thus, an equalization of temperatures often indicates joint inflammation.
Joint motion may produce a crackling sound or a crunching sensation on palpation. This phenomenon, called crepitus, occurs when the surfaces of degenerated cartilage rub together or when bone rubs against bone after extensive loss of cartilage. Inflammation of tendon sheaths also can cause crepitus. In normal joints, crepitus usually reflects motion of tendon over bone.
A number of mechanisms can reduce joint motion (Table 1–1). Excessive joint motion may result from destruction of supporting structures or subchondral bone or from joint dislocation. Active range of motion (by the patient) allows rapid assessment of joint mobility, while passive range of motion (by the examiner) permits a more complete evaluation of joint function.
Table 1–1. Factors that Reduce Joint Motion
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Table 1–1. Factors that Reduce Joint Motion
Damage to articular cartilage or bone
Large synovial effusions
Loose bodies within the joint cavity
Fibrous or bony ankylosis
Contracture of the capsule or contiguous tendons
Irritation of pain-sensitive structure in and about the joint
Normal range of joint motion varies according to age and gender. Flexibility tends to diminish with age, and women are typically more flexible than men.
A complete musculoskeletal evaluation includes a neurologic examination with specific attention to the sensorimotor components. Inflammatory myopathies typically cause weakness or wasting of proximal muscles. Immune-mediated diseases tend to affect the central or peripheral nervous systems. Degenerative processes affecting the spine or extremities may lead to impingement on nerve roots or various portions of peripheral nerves.