What type of local anesthetic (e.g. lidocaine, bupivacaine) is recommended for knee injections?

Recommended Local Anesthetic for Knee Injections

For knee joint injections, use lidocaine (1-2%) combined with corticosteroid, as local anesthetics can be safely combined with corticosteroids to reduce procedural discomfort, and this combination is supported by guideline recommendations and safety data. 1

Primary Agent Selection

• Lidocaine is the preferred local anesthetic for knee injections based on its established safety profile and extensive clinical use in joint infiltration procedures 1
• The maximum safe dose of lidocaine with epinephrine is 7.0 mg/kg, providing a wide safety margin for typical knee injection volumes 2
• Lidocaine concentrations of 1-2% (10-20 mg/mL) are standard for joint infiltration, with duration of action of 90-200 minutes 2

Practical Dosing Considerations

• For knee arthroscopy, a combination of 25 cc of 1% lidocaine with epinephrine (1:100,000) has been shown to maintain serum levels well within safe ranges 3
• Calculate the maximum allowable dose (mg/kg) before administration to ensure the patient will not receive an excessive dose 2
• The addition of epinephrine to lidocaine provides vasoconstriction that slows systemic absorption and prolongs the anesthetic effect 4

Alternative Agent: Ropivacaine

• Ropivacaine may be preferred when chondrocyte toxicity is a concern, as it demonstrates the lowest toxic potential on human chondrocytes compared to lidocaine and bupivacaine 5
• Ropivacaine has a maximum dose of 3.0 mg/kg with epinephrine and provides 180-600 minutes of anesthesia 2
• This longer-acting agent may be particularly useful when extended post-procedural analgesia is desired 2

Agent to Avoid

• Bupivacaine should be avoided for knee injections due to demonstrated increased chondrocyte toxicity compared to lidocaine and ropivacaine 5
• While bupivacaine provides longer duration (180-600 minutes), the potential for cartilage damage outweighs this benefit in intra-articular use 2, 5

Combination with Corticosteroids

• Local anesthetics should be combined with long-acting corticosteroids for knee pain flares, especially when accompanied by effusion 1
• This combination provides immediate pain relief from the local anesthetic while the corticosteroid provides sustained anti-inflammatory effect 1
• The combined treatment leads to earlier pain relief and faster return to daily activities compared to either agent alone 6

Critical Safety Parameters

• Use strict aseptic technique for all joint infiltrations 1
• Avoid infiltration at least 3 months before planned joint replacement surgery 1
• The risk of septic arthritis after intra-articular infiltration is very low (0.035%) 1
• Imaging guidance (ultrasound or fluoroscopy) can improve injection accuracy 1

Common Pitfall to Avoid

• Do not mix lidocaine and bupivacaine in a 50/50 combination, as there is no clinical advantage in onset or duration compared to using lidocaine alone, and this unnecessarily exposes the patient to bupivacaine's chondrotoxicity 7, 5