Knee Injection Options for Pain Management
For patients with persistent knee pain due to osteoarthritis that is inadequately relieved by other interventions, intra-articular corticosteroid injections are recommended as an effective treatment option. 1
Treatment Algorithm for Knee Pain
First-Line Treatments (Try Before Considering Injections)
Non-pharmacological interventions:
- Exercise therapy (aerobic, strengthening, range of motion)
- Weight loss for overweight patients
- Physical therapy
- Activity modification
- Assistive devices (braces, canes) if needed
Oral and topical medications:
- Acetaminophen (up to 4g daily divided every 8 hours)
- Topical NSAIDs (diclofenac 3-4 times daily)
- Oral NSAIDs (lowest effective dose for shortest duration)
- Avoid opioids including tramadol (increased adverse effects without consistent improvement) 1
Injection Options (When First-Line Treatments Are Inadequate)
1. Corticosteroid Injections
- Evidence strength: Strong recommendation with substantial evidence 1
- Dosage: 5-15mg for larger joints like the knee 2
- Efficacy: Provides rapid relief of inflammatory symptoms, especially with effusion
- Duration: Effects typically last 1-7 weeks 3
- Best candidates: Patients with inflammatory flares and joint effusion
- Limitations: Short-term relief; potential concerns with repeated injections
2. Platelet-Rich Plasma (PRP) Injections
- Evidence strength: Limited recommendation 1
- Efficacy: May reduce pain and improve function
- Best candidates: Patients with mild to moderate knee osteoarthritis
- Limitations: Less effective in severe osteoarthritis; concerns about cost and standardization
- Considerations: Inconsistent evidence but may benefit select patients
3. Hyaluronic Acid Injections
- Evidence strength: Not routinely recommended (moderate recommendation against) 1
- Efficacy: Inconsistent evidence despite common use
- Number needed to treat: 17 patients
- Limitations: Current evidence doesn't identify which subset of patients benefit
- Considerations: May be considered when other options have failed, but not as a first-line injection
Important Considerations for Knee Injections
Technique and Safety
- Use strict aseptic technique for all injections 2
- Inspect suspension for clumping before administration
- For intra-articular injections, aspirate excessive synovial fluid if present
- Consider using local anesthetic prior to injection 2
- Avoid injecting into the tendon substance when treating tenosynovitis
Monitoring and Follow-up
- Assess response to injection after 2-4 weeks
- Consider alternative treatment if inadequate response
- Limit frequency of corticosteroid injections (generally no more than 3-4 per year in the same joint)
- Monitor for potential adverse effects including post-injection flare, skin changes, and infection
Common Pitfalls to Avoid
- Overreliance on injections: Injections should complement, not replace, comprehensive management including exercise and weight loss
- Ignoring mechanical symptoms: Patients with true mechanical symptoms from meniscal tears may need surgical evaluation
- Inadequate injection technique: Poor placement can reduce efficacy and increase complications
- Inappropriate patient selection: Not all knee pain is suitable for injection therapy
Special Considerations
- For patients with diabetes, monitor blood glucose levels after corticosteroid injections
- In anticoagulated patients, avoid NSAIDs but corticosteroid injections can be performed with caution
- Consider referral for surgical evaluation if conservative measures including injections fail after 6-8 weeks 3
By following this evidence-based approach to knee injections, clinicians can provide effective pain relief while minimizing risks and optimizing outcomes for patients with knee osteoarthritis.