What is the recommended pain management strategy using Local Infiltration Analgesia (LIA) for patients undergoing Total Knee Replacement (TKR)?

Local Infiltration Analgesia (LIA) in Total Knee Replacement (TKR)

Femoral nerve block (FNB) is recommended as the primary regional anesthetic technique for TKR pain management, with single-injection LIA as an alternative when FNB is contraindicated or unavailable. 1

Primary Pain Management Strategy

Regional Anesthesia Options

1. First-line approach: Femoral nerve block (FNB)

   • Provides Grade A evidence-based pain reduction and decreased supplemental analgesic requirements 1
   • Can be performed as a single injection (duration 12-24 hours)
   • Consider continuous FNB techniques for prolonged analgesia, though evidence comparing continuous vs. single injection is limited 1

2. Alternative approach: Local Infiltration Analgesia (LIA)

   • Effective for reducing postoperative pain, opioid consumption, and hospital stay 2
   • Particularly useful when FNB is contraindicated or not feasible
   • Involves systematic infiltration of local anesthetic around all structures subject to surgical trauma 3

LIA Technique When Used

• Medication mixture:

  • Ropivacaine (long-acting local anesthetic): FDA-approved for local infiltration with doses up to 200 mg (0.5% concentration) 4
  • Consider adding ketorolac (NSAID) for multimodal effect 3, 5
  • Small amount of adrenaline to reduce systemic absorption 5

• Infiltration method:

  • Peri-articular infiltration is more effective than intra-articular injection alone 6
  • Target all tissues subjected to surgical trauma 3, 5
  • Timing: Performed intraoperatively before wound closure 2, 6

• Expected outcomes with LIA:

  • Time to first analgesic request: 2-6 hours 4
  • Reduced pain scores and analgesic consumption 4
  • Earlier mobilization (typically 5-6 hours post-surgery) 5
  • Shorter hospital stay by approximately 0.87 days 2

Multimodal Analgesic Protocol

Basic Analgesic Regimen (for all patients)

1. Paracetamol/acetaminophen: Regular dosing schedule
2. NSAIDs or COX-2 inhibitors: Unless contraindicated
3. Opioids:
   • Strong IV opioids for breakthrough high-intensity pain
   • Weak opioids for moderate to low-intensity pain 1

Non-Pharmacological Approaches

• Cooling and compression techniques 1
• Early mobilization (facilitated by effective pain control) 5

Important Considerations and Caveats

Safety Considerations for LIA

• Monitor for local anesthetic toxicity, particularly in elderly patients or those with renal impairment 3
• Plasma concentrations of ropivacaine generally remain below toxic thresholds in most patients 3
• Risk of infection with catheter-based continuous LIA techniques (4/735 reported deep knee infections in one analysis) 6

What to Avoid

• Not recommended based on evidence:
  • Intra-articular injection of NSAIDs, neostigmine, clonidine, or corticosteroids 1
  • Combination of femoral and sciatic nerve blocks (limited evidence of benefit over FNB alone) 1
  • Continuous LIA infusion (inconsistent evidence and infection risk) 1, 6
  • Epidural analgesia (increased risk of serious adverse events) 1

When to Consider LIA as Primary Technique

• When FNB is contraindicated (e.g., anticoagulation, patient refusal)
• When rapid mobilization is a priority 5, 7
• As part of an enhanced recovery protocol to reduce hospital stay 5, 2

Integration with Anesthetic Technique

• With general anesthesia: FNB or LIA for postoperative analgesia
• With spinal anesthesia: Consider spinal local anesthetic plus morphine as an alternative to regional techniques 1

LIA provides effective pain control when properly administered, but should be considered as part of a comprehensive multimodal approach rather than as the sole analgesic technique for TKR.