What is the diagnosis and treatment for a reddened bump on the thumb joint that becomes inflamed at times?

Diagnosis and Management of Reddened Thumb Joint Bump with Intermittent Inflammation

Most Likely Diagnosis

This presentation is most consistent with thumb carpometacarpal (CMC) osteoarthritis, characterized by bony prominence at the thumb base with intermittent inflammatory flares. 1

The key diagnostic features include:

• Bony enlargement near the thumb base - a clinical hallmark of thumb CMC osteoarthritis 1
• Intermittent inflammation - typical of osteoarthritis with superimposed inflammatory flares 1
• Location specificity - the thumb CMC joint is a characteristic target site for osteoarthritis 1

Diagnostic Workup Algorithm

Step 1: Initial Imaging

Obtain plain radiographs (3-view hand series) immediately - this is always indicated as initial imaging for suspected wrist/thumb pathology 1. Look specifically for:

• Joint space narrowing at the CMC joint 1
• Osteophytes (bony spurs) 1
• Subchondral sclerosis 1
• Subchondral cysts 1

Step 2: Advanced Imaging (If Radiographs Equivocal)

• CT without IV contrast can confirm suspected pathology when radiographs are unclear 1
• MRI without IV contrast can detect occult fractures and soft tissue pathology 1

Step 3: Laboratory Testing (Selective)

Blood tests are NOT routinely required for diagnosis of thumb CMC osteoarthritis 1. However, consider testing if:

• Marked inflammatory symptoms suggest coexistent inflammatory disease 1
• Acute inflammatory episodes raise concern for gout superimposed on osteoarthritis 1

Treatment Algorithm

First-Line Conservative Management

Begin with non-pharmacological interventions 2, 3:

• Activity modification - avoid repetitive thumb movements and forceful gripping 2
• Patient education about avoiding adverse mechanical factors 2
• Heat application (paraffin wax or hot packs) before exercise 2
• Splinting of the thumb CMC joint for symptom relief 2
• Exercise regimens for range of motion and strengthening 2

Second-Line Pharmacological Management

For mild to moderate pain 2:

• Topical NSAIDs - first choice when only thumb is affected 2
• Oral paracetamol (up to 4g/day) - first-line oral analgesic due to safety profile 2

For inadequate response to paracetamol 2:

• Oral NSAIDs at lowest effective dose for shortest duration 2
• Add gastroprotective agent or use selective COX-2 inhibitor if increased GI risk 2
• Avoid COX-2 inhibitors if increased cardiovascular risk; use non-selective NSAIDs cautiously 2

Third-Line Invasive Non-Surgical Treatment

Corticosteroid injection is effective for painful inflammatory flares, particularly for CMC joint involvement 2, 3. This provides temporary symptom relief 3.

Fourth-Line Surgical Intervention

Surgery should be considered when 2:

• Conservative treatments have failed 2
• Patient has marked pain and/or disability limiting activities of daily living 2

Surgical options include 2, 3:

• Interposition arthroplasty 2
• Osteotomy 2
• Arthrodesis 2
• Trapeziectomy 3

The EULAR guidelines provide Level III evidence (strength 68,95% CI: 56-79) supporting surgery for severe thumb base OA refractory to conservative treatment 2.

Critical Clinical Distinctions

True bony prominence strongly suggests degenerative (osteoarthritis) rather than inflammatory pathology 1. However, be aware that:

• Gout can superimpose on pre-existing osteoarthritis, complicating the clinical picture 1
• Gout presents with acute inflammatory episodes rather than chronic bony prominence 1

Common Pitfalls to Avoid

• Do NOT proceed to surgery without exhausting conservative measures first - the treatment algorithm requires stepwise progression through non-pharmacological, pharmacological, and invasive non-surgical options 2
• Do NOT delay radiographs - plain films should be obtained immediately to confirm diagnosis 1
• Do NOT order routine blood tests unless marked inflammatory symptoms suggest coexistent inflammatory disease 1
• Do NOT use NSAIDs long-term without gastroprotection in high-risk patients 2