What is the rate of complications from steroid (corticosteroid) knee injections?

Complication Rates of Corticosteroid Knee Injections

Intra-articular corticosteroid injections for knee osteoarthritis have a low overall complication rate of approximately 1%, with severe complications being rare. Corticosteroid knee injections are generally safe with few adverse events reported compared to placebo at 6 months, though providers must consider potential long-term effects on bone health, joint structure, and meniscal thickness with repeated administration 1.

Common Complications

• Infection risk:

  • 0.6% infection rate in prosthetic knees (1 infection per 625 injections) 1
  • Very low risk in native knees

• Post-injection flare:

  • Temporary increase in pain and swelling
  • Self-limiting, typically resolves within 24-48 hours

• Systemic effects:

  • Transient hyperglycemia in diabetic patients (days 1-3 post-injection) 1
  • No reports of severe adverse events like hyperosmolar hyperglycemic state or ketoacidosis 1

• Serious complications (1% overall rate) 2:

  • Osteonecrosis
  • Insufficiency fractures
  • Rapid progressive osteoarthritis
  • These typically occur between 2-9 months after injection

Risk Factors for Complications

• Female sex: Women experience disproportionately higher rates of serious complications (90% of complications despite representing only 54% of patients) 2

• Timing related to surgery:

  • Increased infection risk when TKA performed within 2-4 weeks after injection 3
  • Injections within 3 months prior to total knee arthroplasty may slightly increase prosthetic infection risk (from 0.5% to 1.0%) 1

• Frequency of injections:

  • General recommendation: limit to 3-4 injections per year in the same joint 1
  • No clear evidence-based recommendations on optimal frequency 1

Long-Term Effects

• Joint structure impact:
  • Potential negative effects on bone health, joint structure, and meniscal thickness with repeated injections 1
  • Some studies show increased risk of requiring knee arthroplasty (HR 1.57) with each injection increasing absolute risk by 9.4% at 9 years 4
  • Contradictory evidence exists: one study found no deleterious effects on cartilage volume with injections every 3 months for 2 years 5

Timing Considerations for Surgery

• Pre-surgical timing:

  • Corticosteroid injections should be avoided for 3 months preceding joint replacement surgery 1
  • Highest risk period is within 4 weeks before surgery, particularly within 2 weeks 3
  • Beyond 4 weeks, no additional infection risk reduction was observed 3

• Post-surgical considerations:

  • Injections in prosthetic joints should generally be avoided in routine practice 1
  • Should only be considered by orthopedic surgeons after strict screening for prosthetic infection 1

Practical Recommendations

1. Limit injections to 3-4 per year in the same joint
2. Avoid injections within 3 months prior to planned knee replacement
3. Monitor diabetic patients for hyperglycemia for 3 days post-injection
4. Avoid overuse of the injected joint for 24 hours following injection, but complete immobilization is not necessary 1
5. Consider alternative treatments if multiple injections are required

Despite potential risks, corticosteroid injections remain an effective second-line treatment option for knee osteoarthritis when core pharmacological and nonpharmacological treatments are inadequate 1.