What are mechanical symptoms of intra-articular (within the joint) pathology?

Mechanical Symptoms of Intra-Articular Pathology

Mechanical symptoms of intra-articular pathology refer to specific physical manifestations that occur when structural abnormalities within a joint physically interfere with normal joint motion, most commonly presenting as locking, clicking, catching, snapping, or limited range of motion. 1

Core Mechanical Symptoms

The defining mechanical symptoms that indicate intra-articular pathology include:

• Locking: A sensation where the joint becomes stuck or "catches" in a particular position, preventing full range of motion 1, 2
• Clicking or popping: Audible or palpable sounds during joint movement, particularly when accompanied by pain or other symptoms 1
• Catching: A sensation of something physically obstructing smooth joint motion 1, 2
• Limited range of motion: Restricted movement compared to the contralateral joint, often with a mechanical endpoint rather than pain-limited motion 1
• Snapping: A sensation of structures moving abnormally within or around the joint 3

Clinical Significance and Underlying Pathology

When mechanical symptoms are present with chronic joint pain, they strongly suggest specific intra-articular structural abnormalities that require advanced imaging evaluation. 1

The most common intra-articular pathologies causing mechanical symptoms include:

• Labral tears: Tears of the fibrocartilaginous labrum can cause catching and clicking, with prevalence of 62% in symptomatic hips 4
• Osteochondral lesions: Fragments of cartilage or bone (loose bodies) that physically obstruct joint motion 1
• Chondral defects: Articular cartilage damage with prevalence of 64% in symptomatic individuals 4
• Meniscal tears (in the knee): Torn meniscal tissue can cause locking and catching, though the majority of people over 70 have asymptomatic tears 5
• Synovial abnormalities: Including synovial chondromatosis or other proliferative processes 1

Diagnostic Approach

The presence of mechanical symptoms with chronic joint pain warrants progression beyond plain radiographs to advanced imaging, even when radiographs are normal or show only mild changes. 1

Initial Evaluation

• Plain radiographs should be obtained first to screen for obvious bony abnormalities, joint space narrowing, or loose bodies 1
• Physical examination should specifically assess for reproducible locking, clicking with specific maneuvers, and mechanical blocks to range of motion 1

Advanced Imaging Indications

• MRI or MR arthrography is usually appropriate when mechanical symptoms are present with normal or nonspecific radiographs to evaluate for osteocartilaginous bodies, osteochondral lesions, labral tears, or synovial abnormalities 1
• CT arthrography is an equivalent alternative to MR arthrography for detecting intra-articular pathology causing mechanical symptoms 1

Critical Distinction from Non-Mechanical Pain

A key clinical distinction exists between mechanical symptoms and simple pain without mechanical features. 1

Non-mechanical symptoms that do NOT indicate intra-articular structural pathology include:

• Pain alone without locking, catching, or clicking 1
• Stiffness that improves with warm-up rather than mechanical blocking 1
• Diffuse joint tenderness without focal mechanical symptoms 1
• Pain that is worse at night or at rest (suggests inflammatory or neoplastic processes) 1

Common Clinical Pitfalls

The most important pitfall is assuming that all clicking or popping represents pathology requiring intervention. 2, 6

• Crepitus alone without pain or other mechanical symptoms may represent normal joint sounds or early osteoarthritis that does not require surgical intervention 6
• Asymptomatic labral tears are found in 54% of individuals without pain, so imaging findings must correlate with mechanical symptoms 4
• In patients over 70, asymptomatic meniscal tears are present in the majority, making the presence of true mechanical symptoms (locking with focal tenderness) the key distinguishing feature of a symptomatic tear 5

Joint effusions are uncommon with pure tendinopathy and their presence should raise suspicion for intra-articular pathology rather than extra-articular causes of pain. 1