Can osteoarthritis (OA) of the proximal interphalangeal (PIP) joint present with acute soft tissue swelling?

Osteoarthritis of PIP Joints Can Present with Acute Soft Tissue Swelling

Yes, osteoarthritis (OA) of the proximal interphalangeal (PIP) joint can present with acute soft tissue swelling, particularly in the erosive subtype of hand OA which typically has an abrupt onset with inflammatory symptoms and signs including soft tissue swelling and erythema. 1

Types of Hand OA and Their Presentations

Hand OA can be categorized into several subtypes with different clinical presentations:

Non-Erosive (Primary) OA

• Typically presents with gradual onset of symptoms
• Characterized by joint space narrowing, osteophytes, and subchondral sclerosis
• May have mild to moderate soft tissue swelling
• Usually affects DIP joints more than PIP joints 2

Erosive OA

• Targets interphalangeal joints (IPJs) specifically 1
• Presents with:
  • Abrupt onset
  • Marked pain and functional impairment
  • Inflammatory symptoms and signs including stiffness, soft tissue swelling, and erythema
  • Mildly elevated C-reactive protein (CRP) levels
  • Radiographic subchondral erosion 1
• Progresses to marked bone and cartilage attrition, instability, and possibly bony ankylosis
• Has worse outcomes than non-erosive IPJ OA 1

Diagnostic Features and Considerations

When evaluating acute soft tissue swelling in PIP joints:

1. Radiographic assessment:

   • Posteroanterior radiograph of both hands on a single film is adequate for initial diagnosis 3
   • Look for characteristic features:
     • Joint space narrowing (sensitivity 0.75-1.0, specificity 0.18-0.71)
     • Osteophytes
     • Subchondral bone sclerosis
     • Subchondral cysts 3
   • In erosive OA, look specifically for subchondral erosions 1

2. Clinical examination:

   • Assess for coarse crepitus, bony enlargement, reduced range of movement, and joint-line tenderness 4
   • Check for muscle wasting and joint deformity in severe cases
   • Note that mild-moderate effusions can be common 4

3. Laboratory findings:

   • In erosive OA, CRP levels may be mildly elevated 1
   • Serum CRP levels correlate with radiographic severity scores and number of joints involved 1

Differential Diagnosis

When encountering acute soft tissue swelling in PIP joints, consider:

• Erosive OA: Targets IPJs with inflammatory signs and subchondral erosions 1
• Rheumatoid arthritis: Primarily targets MCPJs and PIPJs with non-proliferative marginal erosions 3
• Psoriatic arthritis: May affect just one ray or target DIPJs 3
• Gout: Can superimpose on pre-existing OA with periarticular erosions 3
• Hemochromatosis: Mainly targets MCPJs and wrists 3

Management Considerations

For PIP joint OA presenting with acute soft tissue swelling:

1. Pharmacological options:

   • Intra-articular glucocorticoid injections may be considered specifically for painful interphalangeal joints with inflammation 1
   • These are more effective than placebo for pain during joint movement and joint swelling in interphalangeal OA 1

2. Surgical options (for advanced disease):

   • Arthroplasty (typically silicone implants) is the preferred surgical technique for PIP joints, except for PIP-2 (index finger) 1
   • For PIP-2, arthrodesis may be considered due to concerns over implant longevity and stability from coronal forces during pinch 5
   • However, recent evidence suggests silicone arthroplasty can provide good results even in index finger PIP joints 5

Clinical Pearls and Pitfalls

• Pearl: The presence of acute soft tissue swelling in PIP joints should raise suspicion for erosive OA, which has a worse prognosis than non-erosive OA 1
• Pitfall: Mistaking erosive OA for inflammatory arthritis like rheumatoid arthritis
• Pearl: Ultrasound can help differentiate erosive OA from normal joints (ROC 0.75) but is less effective at distinguishing erosive from non-erosive OA 1
• Pitfall: Overlooking that PIP joint OA can significantly impact hand function, with erosive OA causing worse functional outcomes than nodal OA 1

Remember that hand OA is heterogeneous, and the long-term follow-up should be adapted to the patient's individual needs, particularly for those with erosive disease who may have more clinical and structural progression 1.