Musculoskeletal complaints account for >315 million outpatient visits per year and >20% of all outpatient visits in the United States. The Centers for Disease Control and Prevention estimate that 54.4 million, or 1 in 5 adults) of the U.S. population has physician-diagnosed arthritis. While many patients will have self-limited conditions requiring minimal evaluation, reassurance, and symptomatic therapy, specific musculoskeletal presentations or their persistence may herald a more serious condition that requires further evaluation or laboratory testing to establish a diagnosis. The goal of the musculoskeletal evaluation is to formulate a differential diagnosis that leads to an accurate diagnosis and timely therapy, while avoiding excessive diagnostic testing and unnecessary treatment (Table 363-1). There are several urgent conditions that must be diagnosed promptly to avoid significant morbid or mortal sequelae. These “red flag” diagnoses include septic arthritis, acute crystal-induced arthritis (e.g., gout), and fracture. Each may be suspected by its acute onset and monarticular or focal musculoskeletal pain.
TABLE 363-1Evaluation of Patients with Musculoskeletal Complaints |Favorite Table|Download (.pdf) TABLE 363-1 Evaluation of Patients with Musculoskeletal Complaints
| Accurate diagnosis |
| Timely provision of therapy |
| Avoidance of unnecessary diagnostic testing |
| Identification of acute, focal/monarticular “red flag” conditions |
| Determine the chronology (acute vs chronic) |
| Determine the nature of the pathologic process (inflammatory vs noninflammatory) |
| Determine the extent of involvement (monarticular, polyarticular, focal, widespread) |
| Anatomic localization of complaint (articular vs nonarticular) |
| Consider the most common disorders first |
| Consider the need for diagnostic testing |
| Formulate a differential diagnosis |
The majority of individuals with musculoskeletal complaints can be diagnosed with a thorough history and a comprehensive physical and musculoskeletal examination. The initial encounter should determine whether the musculoskeletal complaint signals a red flag condition (septic arthritis, gout, or fracture) or not. The evaluation should ascertain if the complaint is (1) articular or nonarticular in origin, (2) inflammatory or noninflammatory in nature, (3) acute or chronic in duration, and (4) localized (monarticular) or widespread (polyarticular) in distribution.
With this approach, the musculoskeletal presentation can be characterized (e.g., acute inflammatory monarthritis or a chronic noninflammatory, nonarticular widespread pain) to narrow the diagnostic possibilities. However, some patients will not fit immediately into an established diagnostic category. Many musculoskeletal disorders resemble each other at the outset, and some may take weeks or months (but not years) to evolve into a recognizable diagnostic entity. This consideration should temper the desire to establish a definitive diagnosis at the first encounter.
ARTICULAR VERSUS NONARTICULAR
The musculoskeletal evaluation must discriminate the anatomic origin(s) of the patient’s complaint. For example, ankle pain can result from a variety of pathologic conditions involving disparate anatomic structures, including gouty arthritis, calcaneal fracture, Achilles tendinitis, plantar fasciitis, cellulitis, and peripheral or entrapment neuropathy. Distinguishing between articular and nonarticular conditions requires a careful and detailed examination. Articular structures include the synovium, synovial fluid, articular cartilage, ...