What is the best method for injecting into the knee joint?

Best Method for Knee Joint Injection

The superolateral (lateral midpatellar) approach is the most accurate method for knee joint injection, achieving 91-93% accuracy compared to 71-75% for other approaches. 1, 2

Optimal Approach: Superolateral (Lateral Midpatellar) Technique

Patient Positioning and Setup

• Position the patient supine on an adjustable examination table with the knee extended or slightly flexed (10-15 degrees) 1
• Ensure a clean, well-lit, private room with resuscitation equipment readily available (vasovagal reactions occur in 2.6% of cases) 1, 3
• Consider having another healthcare professional present for assistance 1

Anatomical Landmarks for Superolateral Approach

The injection site is located 1 cm superior and 1 cm lateral to the superolateral corner of the patella 4, 2

• Palpate the superior lateral border of the patella
• Mark the entry point 1 cm above and 1 cm lateral to this corner
• Direct the needle at a 45-degree angle toward the intercondylar notch 4
• Insert the needle 1 to 1.5 inches deep into the patellofemoral joint space 4

Why Superolateral Approach is Superior

• Highest accuracy rate: 91-93% compared to anteromedial (75%) or anterolateral (71%) approaches 1, 2
• More reliable even in the absence of joint effusion 2
• Provides better access to the patellofemoral joint space 2

Alternative Approaches (Lower Accuracy)

Medial Midpatellar Approach

• Some evidence suggests the medial patellofemoral angle is larger than lateral, potentially favoring medial access 5
• However, clinical accuracy studies show only 75% success rate 2
• May produce more local bruising compared to lateral approaches 6

Anterolateral Approach

• Lowest accuracy at 71% 2
• Not recommended as first-line approach

Procedural Technique

Aseptic Preparation (Critical for Safety)

• Strict aseptic technique is mandatory - infection risk is 0.035% (3 per 7,900 procedures) 1
• Wear surgical gloves 1
• Prepare skin with alcohol, chlorhexidine, or iodine disinfectant 1
• Change needles between drawing medication and injecting to reduce infection risk 1

Needle Selection and Insertion

• Use a 20-24 gauge needle, 1.5-2 inches in length 7, 4
• Aspirate slightly before injection to confirm intra-articular placement 7, 4
• Aspiration of even a few drops of synovial fluid confirms proper needle placement 7

Medication Administration

• Typical corticosteroid dose for knee: 20-80 mg methylprednisolone or equivalent 7
• Consider adding local anesthetic (lidocaine) to reduce procedural discomfort 1, 3
• After injection, gently move the joint a few times to distribute medication 7

Enhancing Accuracy

Ultrasound Guidance

• Ultrasound improves injection accuracy but does not improve clinical outcomes compared to landmark-guided technique 1
• Consider ultrasound if multiple failed attempts or difficult anatomy 1
• Not routinely necessary for knee injections (unlike hip injections where imaging is strongly recommended) 1

Critical Safety Considerations

Pre-Injection Screening

• Obtain informed consent explaining procedure, benefits, risks, and post-injection care 1, 3
• Screen for contraindications: overlying skin infection, bacteremia, or prosthetic joint 4
• Do not discontinue anticoagulation - bleeding risk is low 3

Special Populations

• Diabetic patients: Warn about transient hyperglycemia days 1-3 post-injection; monitor glucose closely 1, 3
• Prosthetic joints: Avoid routine injection; only consider after consultation with orthopedic surgery and strict infection screening 1
• Pre-surgical patients: Maintain at least 3-month interval before total knee arthroplasty to minimize infection risk 1, 3

Repeat Injections

• Limit to 3-4 injections per year in the same joint 1
• Consider repeat injection if initial injection provided ≥75% relief or ≥50% relief lasting 2 months 3

Post-Injection Care

• Avoid overuse for 24 hours but do not immobilize - immobilization provides no benefit 1
• Cover injection site with small sterile dressing 7
• Advise patients about potential side effects: injection-site soreness (most common), transient pain flare, facial flushing 3

Common Pitfalls to Avoid

• Failure to enter joint space is the most common cause of treatment failure 7
• Injecting into surrounding soft tissue or anterior fat pad provides little benefit 2
• Using anterolateral approach when superolateral has superior accuracy 2
• Forgetting to aspirate before injection to confirm intra-articular placement 7, 4
• Injecting into tendon substance rather than tendon sheath when treating periarticular structures 7