What is the likely cause and management of wrist joint pain and foul odor in a 26-year-old female with a normal X-ray, wearing a splint and a metal plate?

Wrist Infection Under Splint

This is most likely a soft tissue or joint infection developing under the splint, and you need to remove the splint immediately, examine for signs of infection (erythema, warmth, fluctuance, purulent drainage), and perform joint aspiration if there is any concern for septic arthritis. 1

Immediate Clinical Assessment

When you examine her, specifically look for:

• Erythema, warmth, and swelling around the wrist joint or under where the splint was positioned 2
• Purulent drainage or skin breakdown from prolonged splint wear creating a moist environment 2
• Fluctuance suggesting abscess formation 1
• Fever or systemic signs of infection, though these may be absent in localized infection 2
• Range of motion limitation and pain with passive motion, which suggests intra-articular involvement 2

Diagnostic Approach

If you suspect any joint involvement (pain with passive motion, joint effusion), perform immediate joint aspiration without waiting for advanced imaging. 1 The ACR guidelines are explicit that joint aspiration should not be delayed to obtain advanced imaging studies when infection is suspected. 1

Aspiration Protocol

• Send aspirate for cell count, Gram stain, and cultures (aerobic, anaerobic, fungal if immunocompromised) 1
• Crystal analysis to exclude gout or pseudogout, which can mimic infection 1
• Aspiration can be performed without imaging guidance if joint is distended, but ultrasound or fluoroscopy can help target specific compartments if needed 1

Imaging Strategy

• X-rays are already done and normal, which is typical early in septic arthritis 1, 2
• Do not order MRI before aspiration - this delays definitive diagnosis and treatment 1
• Ultrasound can be useful to identify fluid collections or abscesses and guide aspiration simultaneously 1
• MRI with IV contrast has a role only AFTER aspiration is performed, to stage the extent of infection or identify abscesses requiring drainage 1

Management

If Infection is Confirmed or Highly Suspected

• Start broad-spectrum IV antibiotics immediately after obtaining cultures - vancomycin plus a third-generation cephalosporin or fluoroquinolone to cover Staphylococcus aureus (including MRSA) and gram-negative organisms 2
• Surgical consultation for irrigation and debridement if septic arthritis is confirmed, as joint aspiration alone is often insufficient 2
• Remove any foreign material (the metal plate you mentioned) if it's a source of infection, though this requires surgical evaluation 2

If Soft Tissue Infection Only (No Joint Involvement)

• Oral antibiotics covering skin flora (cephalexin or clindamycin) may be sufficient for superficial cellulitis 2
• Incision and drainage if abscess is present 1
• Wound care with dressing changes 2

Critical Pitfalls to Avoid

• Never ignore a foul odor from a splinted extremity - this indicates either infection or severe skin maceration that can become infected 2
• Do not continue splint immobilization if infection is present, as this creates a closed space for bacterial proliferation 2
• Do not wait for MRI results before performing aspiration when septic arthritis is suspected - this delays critical treatment and can lead to cartilage destruction within days 1, 2
• Do not assume the metal plate is causing the smell without ruling out infection first - hardware can become colonized and serve as a nidus for infection 2

The Metal Plate Consideration

If she has hardware from a previous surgery, this complicates the picture:

• Hardware-associated infections can present with subtle findings and may require removal for cure 2
• The "smell" could be from biofilm formation on the hardware, which is difficult to eradicate with antibiotics alone 2
• Orthopedic surgery consultation is essential if hardware infection is confirmed 2