What are the possible causes and treatments for thumb pain when bending in a frequent hand user with no prior medical history?

Thumb Pain with Bending in a Frequent Hand User

For a frequent hand user with thumb pain on bending and no prior medical history, the most likely diagnoses are thumb base (carpometacarpal) osteoarthritis or de Quervain tenosynovitis, and you should immediately initiate a custom-made thumb orthosis worn during activities plus topical NSAIDs, while prescribing hand exercises for long-term benefit. 1

Differential Diagnosis Based on Clinical Presentation

The location and character of pain determine the underlying pathology:

• Thumb base (carpometacarpal joint) pain suggests osteoarthritis, which affects 33% of postmenopausal women radiographically and is the most common site requiring surgical reconstruction in the upper extremity 2, 3
• Pain along the radial wrist with thumb/wrist movement indicates de Quervain tenosynovitis, particularly common in frequent mobile phone users and those performing repetitive thumb motions 2, 4
• Triggering or catching sensation points to stenosing tenosynovitis (trigger thumb), affecting up to 20% of diabetics and 2% of the general population 2
• Numbness in thumb, index, middle, and radial ring finger suggests carpal tunnel syndrome rather than isolated thumb pathology 2, 5

Key Physical Examination Findings

• Localized tenderness over the thumb base with pain reproduced by axial loading or grind test indicates carpometacarpal arthritis 3, 6
• Positive Finkelstein test (pain with ulnar deviation of wrist while thumb is flexed into palm) confirms de Quervain tenosynovitis 2
• Palpable swelling, erythema, or asymmetry at the tendon suggests active tendinopathy 7
• Muscle atrophy indicates chronicity and warrants more aggressive intervention 7

First-Line Conservative Management

Orthotic Intervention (Highest Priority)

Prescribe a custom-made thermoplastic long thumb orthosis to be worn during all activities of daily living for at least 3 months. 1

• A full splint covering both thumb base and wrist provides superior pain relief compared to half splints, with an effect size of 0.64 and number needed to treat of 4 1
• Benefits are not evident with use less than 3 months, so patient counseling about duration is critical 1
• Long-term use is advocated by EULAR guidelines for sustained symptom control 7

Pharmacological Treatment

Apply topical diclofenac gel as first-line pharmacological therapy. 1

• Topical NSAIDs are preferred over systemic treatments due to superior safety profile, particularly regarding gastrointestinal side effects 7, 1
• Topical diclofenac shows small but significant improvements in pain and function after 8 weeks, with efficacy comparable to oral NSAIDs but dramatically fewer adverse effects 1
• Oral NSAIDs should only be used at the lowest effective dose for the shortest duration if topical therapy fails, and only after assessing cardiovascular, gastrointestinal, and renal risk 7, 1

Exercise Prescription

Initiate hand exercises targeting joint mobility, muscle strength, and thumb base stability. 1

• Exercise regimens must be tailored to the specific joint involved (carpometacarpal exercises differ from interphalangeal joint exercises) 1
• Multiple trials demonstrate beneficial effects on pain, function, joint stiffness, and grip strength 7, 1
• Benefits are not sustained when patients stop exercising, requiring ongoing compliance 1

Activity Modification

Provide education on ergonomic principles, activity pacing, and assistive devices. 1

• This foundational intervention improves self-management and has demonstrated efficacy across multiple studies 7, 1
• Relative rest to decrease repetitive loading of damaged tendons is essential for healing 7
• Avoid complete immobilization, as strength loss is most dramatic during the first week of immobilization 8

Second-Line Interventions

If conservative management fails after 3 months:

Corticosteroid Injection

Consider intra-articular corticosteroid injection for painful flares, especially in trapeziometacarpal joint osteoarthritis. 1

• Steroid injections relieve symptoms in approximately 72% of patients with de Quervain tenosynovitis when combined with immobilization 2
• For carpometacarpal arthritis, injections provide temporary relief but do not alter disease progression 2, 6
• Injections may be more effective than oral NSAIDs for acute-phase pain relief but show no difference in long-term outcomes 7

Alternative Injection Therapy

Intra-articular hyaluronic acid may be considered for trapeziometacarpal osteoarthritis. 1

• One RCT suggests hyaluronan was as effective as corticosteroid for pain relief with potentially more prolonged benefit 1

Surgical Intervention

Refer for surgical consultation if marked pain and/or disability persist despite 3-6 months of appropriate conservative treatment. 1

• Surgery is clinically effective for refractory thumb base osteoarthritis, with numerous supporting studies 1
• Simple trapeziectomy alone is as effective as combined procedures but with fewer complications 1
• For de Quervain tenosynovitis, surgical release of the first dorsal extensor compartment is appropriate for recurrent symptoms 2
• Arthrodesis of metacarpophalangeal and interphalangeal joints yields stable, functional results with reliable long-term pain relief 1

Diagnostic Imaging Considerations

Obtain plain radiographs (minimum 2 views: PA and lateral) if trauma history exists or structural abnormality is suspected. 1

• Plain films remain the gold standard for morphological assessment, showing joint space narrowing, osteophytes, and subchondral sclerosis 9
• Radiographic severity does not necessarily correlate with clinical symptoms—"treat patients, not x-rays" 6
• Reserve advanced imaging (ultrasound or MRI) for unclear diagnosis after thorough examination, recalcitrant pain despite adequate conservative management, or preoperative planning 7

Critical Pitfalls to Avoid

• Do not rely on acetaminophen alone—its efficacy is limited compared to NSAIDs for thumb pain 1
• Do not prescribe oral NSAIDs without cardiovascular, gastrointestinal, and renal risk assessment, particularly in elderly patients 1
• Do not expect benefit from orthoses used less than 3 months—counsel patients about the required duration 1
• Do not continue conservative management indefinitely without reassessment—escalate to injections or surgical consultation if symptoms remain severe after 3 months 1
• Do not immobilize completely—this promotes muscle deconditioning, learned non-use, and increases pain risk 8
• Do not overlook the specific joint involved—treatment differs significantly for interphalangeal, metacarpophalangeal, or thumb base joint pathology 1