What is crepitus, its clinical significance, and how should it be evaluated and managed in an adult patient?

What is Crepitus?

Crepitus is a crackling, grinding, or popping sound or sensation that occurs with joint movement, most commonly associated with osteoarthritis but also occurring in pain-free individuals and across various musculoskeletal conditions. 1, 2

Definition and Clinical Characteristics

• Crepitus is defined as an audible or palpable grinding, crackling, or popping sound/sensation during joint movement 1, 3
• It can occur with or without pain and represents a common physical examination finding 3
• The sound varies in quality from fine crackling to coarse grinding, with coarse crepitus being more clinically significant 1

Prevalence Across Populations

• In the general population, crepitus occurs in approximately 41% of individuals 2
• Among pain-free persons, the prevalence is 36%, indicating crepitus alone does not necessarily indicate pathology 2
• In patients with established knee osteoarthritis, crepitus is present in 81% of cases 1, 2
• Across other musculoskeletal knee conditions, prevalence ranges from 35% (ligament injury) to 61% (cartilage pathology) 2

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Clinical Significance and Diagnostic Value

Association with Osteoarthritis

The presence of crepitus increases the odds of radiographic osteoarthritis by more than threefold (OR 3.79,95% CI 1.99 to 7.24). 1, 2

• Frequent crepitus predicts incident symptomatic knee OA longitudinally, with greater frequency correlating with higher risk 4
• The odds of developing symptomatic OA increase progressively: rarely (OR 1.5), sometimes (OR 1.8), often (OR 2.2), and always (OR 3.0) 4
• Most incident symptomatic OA cases occur in those with preexisting radiographic OA but without frequent knee pain, making crepitus a useful early warning sign 4

Structural Pathology Associations

• Crepitus is associated with osteophytes at the patellofemoral and lateral tibiofemoral joints 3
• At the medial tibiofemoral compartment, crepitus correlates with osteophytes and medial collateral ligament pathology 3
• Meniscal tears show the strongest association with general knee crepitus in whole-knee analysis 3
• Interestingly, cartilage damage alone may be negatively associated with crepitus at the medial compartment, suggesting the sound originates from other structures 3

Location-Specific Considerations

For sternal crepitus specifically, the differential diagnosis is entirely different and requires urgent evaluation:

• Sternal crepitus most commonly indicates sternal osteomyelitis, fracture, post-sternotomy complications, or gas-forming soft tissue infections 5, 6
• Soft tissue gas in the absence of recent surgery, trauma, or puncture wounds is a reliable indicator of infection requiring immediate intervention 6
• Necrotizing fasciitis involving the chest wall can cause sternal crepitus and represents a surgical emergency 6

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Evaluation Approach

Clinical Assessment

The American College of Rheumatology recommends that knee osteoarthritis can be diagnosed clinically without imaging in patients over 40 years old who present with usage-related pain, short morning stiffness, and characteristic findings including coarse crepitus, joint line tenderness, bony enlargement, and reduced range of motion. 1

Key Physical Examination Findings:

• Assess crepitus in each compartment (medial, lateral, patellofemoral) during passive and active range of motion 3
• Document the quality (fine vs. coarse), frequency (rarely, sometimes, often, always), and associated symptoms 4
• Evaluate for joint line tenderness, particularly over the medial joint line where OA typically predominates 1
• Measure passive arc of motion and compare to the contralateral knee 1
• Palpate for bony enlargement and assess for effusion 1

Red Flags Requiring Further Investigation:

• Mechanical symptoms such as true locking, catching, or giving way suggest meniscal tears or loose bodies 1
• Unexpected rapid progression of symptoms or change in clinical characteristics may indicate inflammatory arthritis 1
• For sternal crepitus: fever, systemic signs of infection, recent cardiac surgery, or trauma 5, 6

Imaging Strategy

For knee crepitus with pain or other symptoms:

• First-line: Standing radiographs (AP, lateral, tunnel, and tangential patellar views) are the initial imaging study 1
• Second-line: MRI without contrast is indicated only if radiographs are normal or non-diagnostic and symptoms persist, or if mechanical symptoms suggest meniscal pathology 1
• Imaging is not required for diagnosis in typical presentations of OA in patients over 40 with characteristic clinical findings 1

For sternal crepitus:

• First-line: Plain radiographs to detect soft tissue gas and bony abnormalities 5, 6
• Second-line: CT without contrast if radiographs show soft tissue gas, offering higher sensitivity for extent and location 5, 6
• For suspected osteomyelitis: MRI with contrast is the preferred modality to determine bone and soft tissue involvement 5, 6
• Blood cultures and tissue/abscess cultures should be obtained to identify causative pathogens 5

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Management Principles

For Knee Crepitus

Management should focus on symptoms and function rather than the presence of crepitus itself, as crepitus alone in the absence of pain or functional limitation does not require treatment. 1

Conservative Management:

• Patient education and reassurance that crepitus is common and does not always indicate progressive disease 7
• Crepitus does not appear to be a major cause for concern among patients who experience it, though it may influence exercise behaviors 7
• Most individuals do not cease exercise due to crepitus but may modify movements; some increase strength training to alleviate it 7

When Functional Limitation Exists:

• If there is a functional element (limitation in movement), consider more aggressive interventions 8
• The least invasive surgical option is arthrocentesis (lavage under local anesthesia), though results are not maintained long-term 8
• Arthroscopy under general anesthesia allows more exploration and may improve functionality, though relapses are common 8

For Sternal Crepitus with Infection

Prompt and aggressive surgical debridement of all necrotic tissue is essential, combined with appropriate antimicrobial therapy. 5

Surgical Management:

• Early and extensive initial surgical debridement improves survival in necrotizing infections 8, 5
• For sternal osteomyelitis, surgical debridement of all necrotic tissue is strongly recommended 5
• Serial imaging (CT or MRI) may be necessary to evaluate treatment response 5

Antimicrobial Therapy:

• For bacterial sternal osteomyelitis: Empiric vancomycin until culture results available 5
• For Candida sternal osteomyelitis: Fluconazole 400 mg daily for at least 6 months OR echinocandin for 2 weeks followed by fluconazole for at least 4 months 5
• For necrotizing soft tissue infections: Broad-spectrum antibiotics covering gram-positive, gram-negative, and anaerobic organisms; vancomycin plus an agent active against gram-negative bacilli for initial empirical therapy 5

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Common Pitfalls and Caveats

Diagnostic Pitfalls:

• Do not assume all crepitus indicates pathology: 36% of pain-free individuals have knee crepitus 2
• Do not over-interpret imaging findings: The majority of people over 70 have asymptomatic meniscal tears that do not correlate with symptoms 1
• For sternal crepitus, never overlook infection: Gas in soft tissues without recent trauma or surgery is a reliable indicator of infection 6
• Distinguish between types of crepitus: Scapulothoracic crepitus (grinding, popping at the shoulder blade) has different causes including bursitis, overuse, or osseous abnormalities 9

Management Pitfalls:

• Avoid treating crepitus in isolation: Focus on pain, function, and quality of life rather than the sound itself 1
• Do not delay surgical intervention for necrotizing infections: Early debridement is critical for survival 8, 5
• For temporomandibular joint crepitus: Education may be more beneficial than splints in the long term 8
• Failure to identify underlying risk factors (diabetes, immunocompromise) may lead to poor outcomes in sternal infections 5

Patient Counseling:

• Reassure patients that crepitus is common and often benign, occurring in over one-third of pain-free individuals 2, 7
• Explain that while frequent crepitus may predict future symptomatic OA, it does not mean they should avoid exercise 4, 7
• Provide guidance on safe exercise modifications if needed, as knowledge deficits about crepitus during exercise are common 7