What is the recommended approach for knee joint steroid injections in an adult patient with confirmed osteoarthritis or other inflammatory condition who has already tried conservative management options?

Knee Joint Steroid Injection Approaches

Intra-articular corticosteroid injection should be offered for moderate to severe knee pain from osteoarthritis or inflammatory conditions when conservative measures (exercise, weight loss, acetaminophen, topical NSAIDs) have provided inadequate relief, with expected pain reduction lasting 1-12 weeks. 1, 2

Indications for Injection

• Offer intra-articular corticosteroid for persistent knee pain inadequately relieved by other interventions, particularly when moderate to severe pain is present 1, 2
• Particularly effective for acute flares of knee pain, especially when accompanied by effusion 1, 2
• Evidence supports use with pain relief within 1-2 weeks, though benefits are relatively short-lived (typically 1-12 weeks, with most studies showing benefit up to 4 weeks) 1, 2, 3
• Should be considered after core treatments (exercise, weight loss, acetaminophen/topical NSAIDs) have been tried 1

Injection Technique and Medication Selection

Corticosteroid Choice

• Triamcinolone hexacetonide is superior to other corticosteroids and should be the intra-articular steroid of choice when available 4
• Triamcinolone hexacetonide was superior to betamethasone for pain reduction up to 4 weeks post-injection 5
• Alternative options include triamcinolone acetonide (20 mg) or methylprednisolone 2, 6

Dosing Guidelines

• For larger joints like the knee: 5-15 mg for standard dosing, with doses up to 40 mg for larger areas typically sufficient 6
• Initial dose range: 2.5-5 mg for smaller joints, 5-15 mg for larger joints 6
• Single injections into several joints up to a total of 80 mg have been given 6

Technical Approach

• Strict aseptic technique is mandatory 6
• Shake vial before use to ensure uniform suspension; inspect for clumping or granular appearance (agglomeration) - discard if present 6
• Inject without delay after withdrawal to prevent settling in syringe 6
• Consider arthrocentesis with synovial fluid analysis before injection to exclude septic arthritis, crystalline arthropathy, or inflammatory arthritis 2
• If excessive synovial fluid present, aspirate some (but not all) to aid pain relief and prevent undue dilution of steroid 6
• Prior use of local anesthetic may be desirable 6

Anatomical Considerations

• Accurate intra-articular placement is not achieved in up to 20% of injections, with accuracy varying considerably by anatomical approach 7
• No evidence that medial approach is more accurate than other approaches 7
• Avoid injecting into tissues surrounding the injection site, as this may lead to tissue atrophy 6

Expected Outcomes and Duration

• Pain relief is significant for 1-4 weeks, with some benefit extending to 12 weeks 1, 5
• Effect size for pain reduction at 1 week: -21.91 on 100mm VAS (95% CI -29.93 to -13.89) 5
• Number needed to treat (NNT) is 3-4 for both pain and patient global assessment at one week 5
• Evidence for functional improvement is less robust than for pain relief 1, 5
• Benefits are relatively short-lived compared to hyaluronic acid products, which show more durable effects between 5-13 weeks 3, 5

Safety Considerations and Complications

• Serious infectious complications range from 1 in 3,000 injections, potentially higher in high-risk patients 7
• Few side effects have been reported in clinical trials 5
• Avoid both corticosteroid and hyaluronic acid injections within 3 months prior to knee replacement surgery due to increased infection risk 2
• Care should be taken with repeated injections because of potential harm 3
• Atrophy of subcutaneous fat may occur if injection is not properly given 6

Clinical Predictors of Response

• Evidence for predictors of response remains unclear and inconsistent 1
• One study found better outcomes in patients with effusion present 1
• However, another study found no clinical predictors of response, suggesting steroid injection should not be reserved just for those with effusion 1
• Patients over 60 years with important functional impairment may have greater efficacy with hyaluronic acid rather than corticosteroids 1

Common Pitfalls to Avoid

• Do not use corticosteroid injections as first-line treatment - ensure core treatments (exercise, weight loss, acetaminophen) have been tried first 1
• Do not expect long-term benefit beyond 12 weeks 1, 5
• Do not assume all injections are accurately placed intra-articularly - up to 20% miss the joint space 7
• Do not inject if infection cannot be excluded - always consider arthrocentesis first in unclear cases 2
• Counsel patients to avoid acetaminophen-containing products (including over-the-counter cold remedies and combination opioid products) if also taking oral acetaminophen 2