What are the potential complications after a knee cortisone (corticosteroid) injection?

Complications of Knee Cortisone Injections: What to Monitor

The most significant complications after knee cortisone injections include infection risk (especially if surgery is planned within 3 months), transient hyperglycemia in diabetic patients, and potential acceleration of cartilage degeneration with repeated injections. 1, 2

Infection-Related Complications

• Post-injection infection: Though rare (approximately 0.035% or 3 per 7,900 procedures), joint infection is the most serious complication 3

  • Warning signs: Marked increase in pain, swelling, fever, malaise
  • If suspected, immediate joint aspiration and antimicrobial therapy are necessary 2

• Surgical timing risk: Increased risk of periprosthetic joint infection if knee arthroplasty is performed within 3 months of cortisone injection 1, 4, 5

  • Highest risk when surgery occurs within 2-4 weeks after injection 4
  • Guidelines recommend waiting at least 3 months between injection and joint replacement surgery 1

Metabolic and Systemic Complications

• Blood glucose effects: Transient hyperglycemia in diabetic patients, particularly from day 1-3 post-injection 1

  • Patients with diabetes should monitor glucose levels for 3 days after injection
  • No severe events like hyperosmolar hyperglycemic state or ketoacidosis have been reported

• Adrenal suppression: Potential for temporary hypothalamic-pituitary-adrenal axis suppression 2

  • May require gradual reduction in dosage when discontinuing treatment
  • Could persist for months after discontinuation

• Cardiovascular effects: Possible sodium retention with resultant edema and potassium loss 2

  • Use with caution in patients with congestive heart failure, hypertension, or renal insufficiency

Local Tissue Complications

• Post-injection flare: Temporary increase in pain 24-48 hours after injection 6

  • Usually self-limiting and responds to ice and over-the-counter analgesics

• Skin and soft tissue changes: 2, 6

  • Skin hypopigmentation and atrophy at injection site
  • Subcutaneous fat atrophy leading to tissue depression

• Cartilage and bone effects: 6

  • Accelerated progression of osteoarthritis with repeated injections
  • Potential for osseous injury with improper technique

• Tendon weakening: Risk of tendon rupture if injected directly into tendon tissue 2, 6

Special Considerations

• Prosthetic joints: Injections into prosthetic joints should be avoided in routine practice 1

  • If necessary, should be performed by orthopedic surgeons after strict screening for prosthetic infection
  • Reported infection rate of 0.6% (1 in 625 injections)

• Frequency limitations: While not evidence-based, a generally accepted guideline is to avoid more than 3-4 cortisone injections in the same joint per year 1

• Contraindications: Absolute contraindications include active infection at or near the injection site 2, 6

Monitoring and Management

• Rest the injected joint for 24 hours following injection 3
• Use ice, rest, and over-the-counter analgesics for post-injection pain 3
• Monitor for signs of infection (increased pain, swelling, fever)
• For diabetic patients, monitor blood glucose levels for 3 days post-injection 1

By understanding these potential complications, you can better monitor for adverse effects and take appropriate action if they occur. The benefits of pain relief and improved function must be weighed against these potential risks.