What is the appropriate evaluation and treatment for unilateral elbow swelling?

Evaluation and Treatment of Unilateral Elbow Swelling

Begin with plain radiographs (AP and lateral views) as the initial imaging study to rule out osseous pathology, followed by targeted evaluation based on clinical presentation and radiographic findings. 1, 2, 3

Initial Clinical Assessment

Key Historical and Physical Exam Features to Elicit

Red flag symptoms requiring urgent investigation:

• Night pain or pain at rest suggests inflammatory or neoplastic process 1, 2
• Mechanical symptoms (locking, clicking, catching) indicate intra-articular pathology such as osteochondral lesions or loose bodies 1, 3
• Neurologic symptoms (paresthesias, weakness) require nerve evaluation 1

Location-specific findings:

• Lateral elbow pain with swelling: Test for pain with resisted wrist extension (lateral epicondylitis), assess for mechanical symptoms suggesting osteochondral lesions of capitellum or radial head 2, 3
• Medial elbow pain with swelling: Perform valgus stress testing for UCL injury, assess for medial joint line tenderness (distinct from epicondyle), check for ulnar nerve subluxation with elbow flexion/extension 1, 3
• Diffuse swelling: Unilateral swelling indicates obstructive process at the brachiocephalic, subclavian, or axillary vein level—consider upper extremity DVT 4

Distinguish intra-articular from extra-articular pathology:

• Pain with passive range of motion differentiates intra-articular pathology from tendinopathy 1
• Limited range of motion and effusion may indicate osteochondral lesions 1
• Chronic swelling in adolescent athletes raises suspicion for osteochondral defects requiring immediate investigation 5

Diagnostic Algorithm

Step 1: Plain Radiographs (Always First-Line)

Obtain standard AP and lateral views of the elbow in all patients with unilateral swelling. 1, 2, 3

Plain radiographs identify:

• Intra-articular bodies and heterotopic ossification 2, 3
• Osteochondral lesions of capitellum or medial trochlea 1, 3
• Soft tissue calcification within tendons 1, 3
• Occult fractures and osteoarthritis 2, 3

Consider comparison views of the contralateral elbow for better evaluation. 2, 3

Step 2: Advanced Imaging (When Radiographs Normal or Nonspecific)

For suspected tendon pathology or soft tissue injury:

• MRI elbow without contrast is indicated for suspected tendon tear, nerve entrapment, or soft tissue pathology with normal radiographs 1, 3
• Ultrasound with advanced techniques has 94% sensitivity and 98% specificity for common extensor tendon tears 3

For mechanical symptoms suggesting intra-articular pathology:

• MR arthrography (3T) offers 100% sensitivity for detecting intra-articular bodies and evaluating osteochondral lesion stability 3
• CT arthrography provides 93% sensitivity for loose bodies and excellent assessment of heterotopic ossification 3

For suspected UCL injury in throwing athletes:

• MR arthrography elbow (3T) is most accurate with 81% sensitivity, 91% specificity, and 88% accuracy 1, 3

For suspected nerve entrapment:

• T2-weighted MR neurography is the reference standard for ulnar nerve entrapment, showing high signal intensity and nerve enlargement 1, 3
• EMG and nerve conduction studies when neurologic symptoms suggest cubital tunnel syndrome, pronator syndrome, or posterior interosseous nerve syndrome 1, 2

Step 3: Consider Upper Extremity DVT

If diffuse unilateral arm swelling without clear musculoskeletal etiology:

• US Duplex Doppler of upper extremity is noninvasive first-line test with >80% sensitivity and specificity 4
• Assess for risk factors: indwelling venous devices (catheters, pacemakers), advanced age, cancer, hypercoagulability, recent trauma 4
• Dampening of cardiac pulsatility or respiratory variation on Doppler indicates central venous obstruction 4

Treatment Approach Based on Diagnosis

For Lateral Epicondylitis

• Begin with relative rest, activity modification, and eccentric strengthening exercises (80% recover within 3-6 months) 2
• Cryotherapy for 10-minute periods for acute pain relief 2
• Counterforce bracing may improve function during daily activities 2
• Use corticosteroid injections judiciously for short-term relief only—they are more effective than NSAIDs acutely but do not change long-term outcomes 2

For Medial Epicondylitis

• Similar conservative approach with activity modification and eccentric exercises 1
• Avoid overreliance on corticosteroid injections without addressing underlying biomechanical issues 1

For Inflammatory Arthritis (e.g., Rheumatoid Arthritis)

• Note that clinical assessment of swelling shows only fair agreement (kappa 0.371) with ultrasound-detected effusion 6
• Treatment begins with activity modification, anti-inflammatories, hand therapy, and corticosteroids 7

For Osteochondral Defects

• Surgical repair may be required, particularly in adolescent athletes with chronic swelling 5

Critical Pitfalls to Avoid

• Failing to obtain initial radiographs to rule out osseous pathology before assuming soft tissue injury 1, 2
• Missing osteochondral defects in adolescent athletes—chronic swelling should raise immediate suspicion 5
• Overlooking upper extremity DVT in patients with diffuse unilateral swelling and risk factors 4
• Misinterpreting normal anatomic variants as pathologic on imaging 3
• Assuming MRI without contrast is sufficient for complete evaluation of collateral ligament injuries—MR arthrography provides better accuracy 3
• Missing referred pain from cervical spine pathology or radial tunnel syndrome when initial imaging is negative 3