Approach to the adult with unspecified knee pain
- Carlton J Covey, MD
Carlton J Covey, MD
- Assistant Professor of Family Medicine
- Uniformed Services University of the Health Sciences
- Robert H Shmerling, MD
Robert H Shmerling, MD
- Section Editor — Diagnostic Issues in Rheumatology
- Associate Professor of Medicine
- Harvard Medical School
- Section Editor
- Karl B Fields, MD
Karl B Fields, MD
- Editor-in-Chief — Primary Care Sports Medicine (Adolescents and Adults)
- Section Editor — Biomechanics, Rehabilitation, and Recovery; Sports-Related Injuries; Symptom Assessment and Physical Examination
- Professor of Family Medicine and Sports Medicine
- University of North Carolina at Chapel Hill
The knee has the largest articulating surface of any joint. Depending on the activity, this weight-bearing joint can support two to five times a person's body weight. Chronic knee pain affects 25 percent of adults and has a deleterious effect on daily function and quality of life [1,2].
The general evaluation of the adult presenting with undifferentiated knee pain is discussed here, including details about differentiating among the causes of knee pain based upon the history and examination findings. For cases where knee pain develops following acute, low-energy trauma or chronic overuse, often in athletes or active adults, and is most likely musculoskeletal in origin, a separate in-depth discussion of how to approach such patients is provided. (See "Approach to the adult with knee pain likely of musculoskeletal origin".)
BASIC KNEE ANATOMY AND BIOMECHANICS
The anatomy and basic biomechanics of the knee are reviewed separately. (See "Physical examination of the knee", section on 'Anatomy'.)
HISTORY OVERVIEW AND DIAGNOSTIC CATEGORIES
History-taking for the active adult presenting with knee pain is discussed in detail separately, but several aspects of the history warrant emphasis. (See "Approach to the adult with knee pain likely of musculoskeletal origin", section on 'History'.)
First, the differential diagnosis for knee pain is complex and obtaining a clear history remains essential for diagnosis. The following flow chart provides an overview of how to approach the diagnosis of knee pain in the adult (algorithm 1). Information from the history helps the clinician to distinguish among four diagnostic categories:
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- BASIC KNEE ANATOMY AND BIOMECHANICS
- HISTORY OVERVIEW AND DIAGNOSTIC CATEGORIES
- PHYSICAL EXAMINATION OF THE KNEE
- INITIAL STEPS TO CATEGORIZING KNEE PAIN
- Step one: Distinguish acute versus chronic pain
- Step two: Distinguish traumatic versus non-traumatic pain
- Step three: Determine whether an effusion is present
- Step four: Determine pain location
- ACUTE KNEE PAIN ASSOCIATED WITH TRAUMA
- CONDITIONS NOT INVOLVING ACUTE TRAUMA
- Non-traumatic conditions associated WITH a joint effusion
- - Conditions made worse by activity
- - Conditions NOT related to activity
- Non-traumatic conditions NOT associated with joint effusion
- - Anterior knee pain
- - Medial knee pain
- - Lateral knee pain
- - Posterior knee pain
- BONE TUMORS
- REFERRED PAIN
- OTHER INFREQUENT CAUSES OF KNEE PAIN
- Systemic conditions
- Medication side effects
- Additional ultrasound resources
- SUMMARY AND RECOMMENDATIONS