A thorough knowledge of musculoskeletal anatomy is essential to the performance of an accurate and meaningful examination. As a quick reference, an atlas should be near at hand (or only a few computer strokes away). Manifestations that are elicited objectively, eg, swelling, warmth, effusions, or clearly limited range of motion, must be distinguished from more subjective findings such as tenderness and pain on motion.

The musculoskeletal system constitutes a demanding part of the physical examination in terms of both knowledge and time. The skillful examiner focuses this critical task through information obtained in a careful history.

The clinician may begin the patient interview by asking the following two questions: (1) Are the patient’s symptoms articular in nature? and (2) Do they derive from a musculotendinous location? If the answer to either of these questions is yes, then the examiner can begin to focus his or her efforts on the specific anatomic parts referred to by the patient in the history, bearing in mind two points:

• Referred pain and an incomplete understanding of the anatomy may affect the patient’s localization of the complaint. For example, “hip pain” perceived over the lateral side while rolling over in bed at night is more likely to be trochanteric bursitis than pathology of the true hip joint.
  
• Musculoskeletal complaints are sometimes part of overarching, systemic disorders that affect the joints, muscles, bones, and tendons.

Pain present at rest usually indicates an acute inflammatory, neurologic, or neoplastic process. In addition to determining which musculoskeletal structures are the source of the patient’s symptoms, the overall objectives of the examination, which are outlined in Table 1–1, should be kept in mind.

Observation

The examiner should take the opportunity to observe the patient’s posture and mobility when he or she first enters the examination room. Alternatively, if the patient is already in the examining room or on the examination table when first encountered, the examiner should request at some point during the assessment that the patient stand, walk a few yards, and sit again. Gait analysis (for limp) can help separate primary from antalgic or extra-articular manifestations of musculoskeletal disease, such as weakness. This exercise also facilitates the identification of certain deformities. Genu varum or pes planus, for example, become more evident with weight bearing.

Palpation

A bilateral comparison may be helpful in evaluating a swollen area. The anatomic extent of swelling should be verified by palpation, keeping in mind the anatomy of the part. The presence of free fluid is determined by ballottement alternatively at two positions over the swollen area. Joint effusions are most easily detected over their extensor surfaces, where they are not covered by a flexor retinaculum, nerves, and blood vessels. The bony margins of the normal joint can usually be felt on the extensor surface. The inability to feel the joint margins is evidence of synovial swelling or joint effusion. Comparing metacarpophalangeal (MCP) or metatarsophalangeal (MTP) joints in this way is a sensitive test for rheumatoid arthritis.

The presence of local warmth or erythema as signs of inflammation should be noted. The knee, ankle, and wrist joints should all be cooler than the skin over their adjoining long bones. This is gauged most effectively by placing the dorsum of the examiner’s hand over the portion of the limb adjacent to the joint in question and then placing the dorsum of the hand over the joint itself. A warmer temperature over these joints strongly suggests the presence of inflammation.

Pain on Motion

Almost all causes of joint pain, including rheumatoid arthritis, permit some relatively painless passive range of motion. Pain elicited by the slightest movement suggests a septic joint, gout, rheumatic fever, intra-articular hemorrhage, tumor, or joint fracture. Both passive and active range of motion should be tested. Pain caused by active but not passive motion often implicates an extra-articular source of the problem, such as a tenosynovitis.

Range of Motion

Measuring the range of motion in joints is useful for documenting the course of arthritis and the degree of disability. Several measurements systems are in use. A simple one is to use a positive sign before the measurement in degrees for flexion, abduction, internal rotation, or pronation, and a negative sign for the opposite motion, all measured from the “anatomic position.” For example: Shoulder flexion -45 + 160, abduction -30 + 90. A prepared form or template saves time.

Hands

Observe for full finger joint extension. The volar surfaces of the palms and fingers should make full contact when placed together. In making a fist, each fingertip should touch the MCP crease.

Synovial swelling of the proximal interphalangeal (PIP) and MCP joints can be detected readily by the presence of soft tissue swelling on either side of the dorsal aspects. The examiner supports the palm in individual fingers with both hands and palpates the joint margins using the thumbs. When synovial fluid swelling is present, the joint margins will be less distinct compared to the same joint on the opposite hand. Inflammation of the distal interphalangeal (DIP) joints has a limited differential diagnosis that includes osteoarthritis (typically characterized by Heberden nodes), gout (with tophi often occurring at sites of Heberden nodes), and psoriatic arthritis. Septic arthritis, trauma, sarcoidosis, and syphilis are also in the differential diagnosis. Classic rheumatoid arthritis rarely involves the PIP joint alone. Psoriatic arthritis of the PIP joints commonly stimulates the juxta-articular periosteum, giving them a fusiform, erythematous appearance called a sausage digit. Pain caused by lateral compression of the MCP joints as a group is a good screening test for small joint polyarthritis.