What is the most likely cause and initial management for sudden isolated left thumb pain in a young healthy male without swelling or redness?

Sudden Onset Left Thumb Pain in Young Male Without Inflammation

Most Likely Diagnosis

The most likely diagnosis is thumb carpometacarpal (CMC) joint osteoarthritis, which can present with sudden pain onset even in younger patients, particularly following repetitive or forceful thumb movements at work or during recreational activities. 1, 2, 3

While CMC osteoarthritis classically affects postmenopausal women (33% prevalence), approximately 20% of all patients with radiographic CMC arthritis require treatment for pain and disability, and the condition can occur in younger individuals with occupational risk factors. 3 The absence of swelling or redness strongly suggests a non-inflammatory mechanical process rather than infection, inflammatory arthritis, or acute trauma. 1, 2

Key Differential Diagnoses to Consider

De Quervain tenosynovitis should be considered, as it presents with sudden wrist/thumb pain, affects younger adults (median onset 40-59 years), and is associated with repetitive thumb movements including frequent mobile phone use. 3 However, this typically presents with visible swelling over the radial wrist, which is absent in this case.

Trigger thumb (stenosing tenosynovitis) can cause sudden pain and affects up to 2% of the general population, with higher rates in those performing repetitive forceful thumb movements. 3, 4 This would typically present with catching or locking sensation during thumb flexion/extension.

Acute ligamentous injury or occult fracture must be excluded through careful history regarding any unrecognized trauma, as even minor injuries can cause significant thumb dysfunction given that the thumb accounts for up to 50% of overall hand use. 4

Initial Management Algorithm

Step 1: First-Line Conservative Treatment

Begin with acetaminophen up to 4g/day as the oral analgesic of first choice, combined with thumb splint immobilization (neoprene or rigid orthosis). 2, 5 The American College of Rheumatology strongly recommends this combination as it provides symptomatic relief while protecting the joint from adverse mechanical factors. 2

• Thumb splinting specifically for CMC joint pathology improves function at long-term follow-up and should be worn during activities that provoke symptoms. 2
• Heat application (paraffin wax or hot packs) before exercise provides symptomatic relief in 77% of patients. 2
• Patient education on joint protection to avoid repetitive or forceful thumb movements is essential for all patients. 2

Step 2: Topical and Oral NSAIDs

If acetaminophen provides inadequate relief after 1-2 weeks:

• Topical NSAIDs are preferred over systemic treatments for mild to moderate pain when only a few joints are affected, as they minimize systemic side effects. 2
• Oral NSAIDs (ibuprofen 400mg every 4-6 hours) should be used at the lowest effective dose for the shortest duration if topical therapy fails. 2

Step 3: Intra-articular Corticosteroid Injection

Consider corticosteroid injection when oral analgesics and topical treatments provide inadequate relief or when pain significantly limits activities of daily living. 2, 5 Intra-articular corticosteroid injection is particularly effective for painful flares in trapeziometacarpal (CMC) joint pathology and provides relief in approximately 72% of patients when combined with immobilization. 2, 3

Step 4: Referral to Occupational/Physical Therapy

Refer to occupational or physical therapy for:

• Splint fabrication and proper fitting 2
• Exercise regimens involving range of motion and strengthening 2
• Self-efficacy training and thermal therapies 2

Step 5: Surgical Referral

Refer to a hand surgeon when:

• Conservative treatments (including corticosteroid injections) have failed 2, 6
• Patient has marked pain and/or disability limiting activities of daily living 2, 6

Critical Diagnostic Workup

Plain radiographs (posteroanterior view of both hands) provide the gold standard for morphological assessment and should be obtained if symptoms persist beyond 2-3 weeks despite conservative management. 1 Classical radiographic features include joint space narrowing, osteophyte formation, subchondral bone sclerosis, and subchondral cysts. 1

Blood tests are not required for diagnosis but may be indicated if inflammatory symptoms develop or atypical sites are involved, to screen for additional inflammatory arthritides such as psoriatic arthritis, rheumatoid arthritis, gout, or hemochromatosis. 1

Important Clinical Pitfalls to Avoid

Do NOT offer platelet-rich plasma (PRP) injections for thumb CMC pathology, as the American College of Rheumatology explicitly recommends against this due to insufficient evidence of benefit. 2, 5

Do NOT proceed directly to surgery without exhausting conservative measures first, as the treatment algorithm requires stepwise progression through non-pharmacological, pharmacological, and invasive non-surgical options. 2, 6

Do NOT assume absence of trauma history rules out fracture or ligamentous injury in a young male, as occupational or recreational activities may cause unrecognized injuries. 4, 7 A 56-year-old man presented with spontaneous painful thumb symptoms 15 years after a work injury, ultimately found to have a pathological fracture. 7

Do NOT overlook occupational risk factors: repetitive and forceful thumb movements can aggravate or cause cumulative trauma disorders including trigger thumb, de Quervain tenosynovitis, and CMC joint arthritis. 4 Ergonomic modifications to decrease thumb motions and forceful pressures at work are essential preventive measures. 4