Assessment and Management of Knee Pain with Popping Sound

Clinical Assessment

• The American College of Rheumatology recommends a systematic physical examination focusing on weight-bearing ability, range of motion to 90 degrees, and presence of effusion, then obtain plain radiographs if the pain is chronic (>6 weeks) or meets acute trauma criteria, and initiate conservative treatment with acetaminophen up to 4g/day combined with exercise and patient education 1, 2
• Documenting weight-bearing status, by having the patient take at least 4 steps, is crucial as it directly influences management decisions 2
• Range of motion should be documented, specifically whether the patient can flex the knee to at least 90 degrees 2
• Inspection findings, including deformity, swelling, ecchymosis, and erythema, should be assessed to evaluate injury severity 2
• Joint effusion should be palpated for, as it may indicate inflammatory processes or structural damage 1, 2

Diagnostic Imaging Strategy

• Plain radiographs (AP, lateral, Merchant/sunrise, and tunnel views) should be obtained if pain has been present for more than 6 weeks, or if acute trauma meets evidence-based criteria for imaging, or if physical examination reveals effusion, suspected fracture, or signs of degenerative changes 1, 2, 3
• MRI should be reserved for specific situations, such as when surgery is being considered, pain persists despite adequate conservative treatment, initial radiographs are normal but symptoms continue, or when evaluating meniscal pathology, cartilage lesions, or bone marrow edema 1, 3
• Ultrasound can be useful for detecting synovial pathology and evaluating superficial structures 3

Management Algorithm

• The European League Against Rheumatism recommends initiating a combination approach of acetaminophen up to 4g/day, exercise therapy, and patient education for all patients without urgent indications 1, 4
• Acetaminophen should be started with up to 4g/day in adults as the first-line oral analgesic, due to its safer profile for long-term use compared to NSAIDs 1, 4
• Exercise therapy, including regular, progressive exercise, is essential for long-term improvement, with load progression individualized based on patient tolerance 4
• Patient education should explain the nature of the condition and pain management strategies, addressing pain beliefs and behaviors that may affect recovery 4
• Weight reduction is recommended if the patient is obese, as it addresses a key risk factor for knee osteoarthritis 4
• Topical NSAIDs or capsaicin can be considered as second-line pharmacological options if acetaminophen is ineffective, due to their clinical efficacy and excellent safety profiles 4
• Oral NSAIDs can be considered in patients unresponsive to acetaminophen, with gastroprotection if gastrointestinal risk factors exist 4
• Intra-articular corticosteroid injection is indicated specifically for pain flares accompanied by effusion 4
• Surgical referral is indicated when there is radiographic evidence of osteoarthritis with refractory pain and disability despite conservative treatment, or when specific mechanical pathology is identified, or when persistent symptoms despite 6+ weeks of adequate conservative treatment with concerning MRI findings 3, 4

Management of Knee Pain and Popping

Initial Assessment and Diagnostic Workup

• The American College of Radiology recommends reserving MRI for persistent symptoms despite adequate conservative treatment, normal radiographs with ongoing symptoms, or when surgery is being considered 5

Initial Conservative Management

• The American Academy of Orthopaedic Surgeons suggests using oral NSAIDsogle with gastroprotection if gastrointestinal risk factors are present 6
• The British Journal of Sports Medicine recommends initiating eccentric strengthening as pain allows, progressing based on tissue tolerance to load, and incorporating balance, agility, and coordination exercises to improve performance-based function 7
• The British Journal of Sports Medicine also suggests adding hip strengthening if the patient demonstrates poor tolerance to loaded knee flexion 7, 8
• The Annals of the Rheumatic Diseases propose incorporating the "pacing principle" of "small amounts often" linked to daily activities to establish routine, and promoting autonomy and self-management skills 9, 10

Supporting Interventions

• The American Academy of Orthopaedic Surgeons recommends using manual therapy in addition to exercise, which may improve pain and function when symptoms are severe 6
• The British Journal of Sports Medicine suggests prescribing prefabricated foot orthoses when the patient responds favorably to treatment direction tests, and customizing the density and geometry for comfort 7, 8

Reassessment Timeline

• The British Journal of Sports Medicine recommends reassessing at 6 weeks if no favorable outcomes are observed, and considering MRI if not yet obtained and symptoms persist 8
• The Journal of the American College of Radiology suggests considering MRI if not yet obtained and symptoms persist 5