Does crepitus on the knee suggest osteoarthritis (OA) or other forms of arthritis?

Does Knee Crepitus Suggest Arthritis?

Yes, knee crepitus is strongly associated with osteoarthritis and should raise clinical suspicion for the disease, particularly when accompanied by other symptoms such as pain, though crepitus alone is common even in pain-free individuals. 1, 2

Clinical Significance of Crepitus

Crepitus (crackling, grinding, or popping sounds during knee movement) is highly prevalent in knee osteoarthritis, occurring in approximately 81% of patients with established OA compared to 36% in pain-free individuals. 3 The American College of Radiology specifically identifies articular crepitus as most commonly associated with arthritis. 1

The presence of crepitus increases the odds of radiographic osteoarthritis by more than threefold (OR 3.79,95% CI 1.99 to 7.24). 3 More importantly, frequent crepitus predicts incident symptomatic knee OA longitudinally, with adjusted odds ratios increasing progressively: rarely (OR 1.5), sometimes (OR 1.8), often (OR 2.2), and always (OR 3.0). 4

When Crepitus Indicates Arthritis

Crepitus combined with the following features strongly suggests osteoarthritis: 2

• Age over 40 years - The American College of Rheumatology notes this as a key diagnostic criterion 2
• Usage-related pain - Pain that worsens with activity 2
• Short morning stiffness (typically less than 30 minutes) 2
• Joint line tenderness on examination, particularly medial 2
• Bony enlargement of the joint 2
• Reduced range of motion compared to the contralateral knee 2

The American College of Rheumatology states that clinical diagnosis can be made without imaging when these features are present together. 2

Structural Pathology Associated with Crepitus

Crepitus correlates with specific structural abnormalities on imaging: 5, 3

• Osteophytes - Most strongly associated, particularly at the patellofemoral and lateral tibiofemoral joints 5
• Meniscal tears - Associated with general knee crepitus in whole-knee analysis 5
• Multiple OA-related MRI features including cartilage damage, bone marrow lesions, and synovitis 3

Important Clinical Caveats

Crepitus is NOT specific to arthritis: 3

• 36% of completely pain-free individuals have knee crepitus 3
• Crepitus occurs in 35-61% of other musculoskeletal knee conditions (ligament injuries, cartilage pathology) 3
• The majority of people over 70 years have asymptomatic meniscal tears that may cause crepitus 6

Soft tissue gas must be excluded: The American College of Radiology emphasizes that extremity soft-tissue crepitus could represent soft-tissue gas from recent surgery, trauma, or puncture wounds rather than articular pathology. 1 A history of these events should be sought, and radiographs can detect soft-tissue gas. 1

Diagnostic Approach

When crepitus is present with pain or other symptoms: 1, 2

1. Obtain standing radiographs first (AP, lateral, tunnel, and tangential patellar views) - These are the initial imaging study for chronic knee pain 1
2. Clinical diagnosis is sufficient if the patient is over 40 with usage-related pain, short morning stiffness, and examination findings of joint line tenderness, bony enlargement, and coarse crepitus 2
3. MRI without contrast is indicated only if radiographs are normal or non-diagnostic and symptoms persist, or if mechanical symptoms (locking, catching) suggest meniscal pathology 1, 6

The key distinguishing feature of symptomatic versus incidental pathology is the presence of mechanical symptoms (locking, catching) combined with focal tenderness. 6