What is the likely cause of chronic throbbing pain on the edge of the right thumb, present for 2 years, especially when picking things up, with no history of trauma?

Chronic Thumb Pain: Likely Diagnosis and Management

This is most likely De Quervain's tenosynovitis or chronic tendinopathy of the thumb, given the 2-year history of localized throbbing pain at the thumb edge that worsens with gripping activities, minimal erythema, and no trauma history. 1

Clinical Reasoning

The presentation strongly suggests a chronic degenerative tendon condition (tendinosis/tendinopathy) rather than an inflammatory process, despite the patient describing "throbbing pain." 1 Key features supporting this:

• Duration over 2 years indicates chronic degenerative changes, not acute inflammation 1
• Pain with functional loading (picking things up) is the hallmark of overuse tendinopathy 1
• Absence of swelling, discharge, or fever makes infection unlikely 1
• Failure of salt soaks suggests this is not a simple inflammatory condition 1
• Localized to thumb edge points to specific tendon involvement, likely abductor pollicis longus or extensor pollicis brevis 1

Initial Diagnostic Approach

Start with plain radiographs of the thumb/hand as the most appropriate initial imaging study to rule out other causes including arthritis, fracture, or bone pathology. 1

If Radiographs Are Normal or Nonspecific:

Ultrasound of the affected area is the next most appropriate study for suspected tendon pathology, as it can directly visualize: 1

• Tendinopathy and tendon tears 1
• Tenosynovitis (fluid around tendons) 1
• Tendon thickening or degeneration 1
• Dynamic assessment during movement 1

MRI without IV contrast is an alternative if ultrasound is unavailable or inconclusive, though it provides similar information for superficial tendons. 1

Treatment Recommendations

Approximately 80% of patients with overuse tendinopathies recover fully within 3-6 months with conservative treatment. 1, 2

First-Line Conservative Management:

• Relative rest and activity modification to reduce repetitive strain 1, 2
• Ice application for 10 minutes for acute pain relief 2
• NSAIDs for short-term pain relief, though they don't affect long-term outcomes 1, 2
• Counterforce bracing/thumb spica splint to reduce tendon tension 2
• Eccentric strengthening exercises once acute pain subsides, as these promote tendon healing 1, 2
• Stretching exercises for thumb extensors/abductors 2

Important Caveats:

The term "tendonitis" is a misnomer - most chronic cases are degenerative (tendinosis), not inflammatory, which explains why anti-inflammatory treatments alone often fail. 1 This patient's 2-year duration and failed conservative measures (salt soaks) confirm this is a degenerative process requiring mechanical treatment strategies, not just anti-inflammatory approaches. 1

Corticosteroid injection may provide pain relief but should be used cautiously in tendon pathology due to potential weakening effects. 1

If conservative treatment fails after 3-6 months, surgical referral may be appropriate, though this should not be first-line given good outcomes with conservative care. 2