Regardless of whether knee pain is acute or chronic in presentation, the primary care physician must be confident and practiced in his or her musculoskeletal examination skills to perform a thorough assessment. Keeping in mind the types of problems that tend to occur in different age groups and in certain patient populations with particular risk factors, a preconceived differential diagnosis list should be present in the physician's mind. In most cases, the history and physical examination findings are sufficient to formulate a definitive diagnosis. Plain radiography (multiple views) and laboratory studies if indicated may narrow the differential. Advanced imaging studies will affirm the clinical findings. Referral may be necessary for surgical management, particularly in pediatric and unstable orthopedic cases (eg, suspected growth plate injury, compartment syndromes, displaced or intra-articular fractures). Consultation should always be readily available if questions arise on preliminary clinical work-up and management.