What is the best approach for perineural injections to manage knee pain?

Perineural Injections for Knee Pain: Evidence-Based Approach

For chronic knee pain, perineural injection therapy (PIT) targeting sensory nerves around the knee with local anesthetic and corticosteroid combinations shows promise as an adjunctive treatment, though the evidence base is limited and this approach should not replace established first-line therapies like intra-articular injections or femoral nerve blocks for specific indications.

Clinical Context and Indications

The question of perineural injections for knee pain must be distinguished from established regional anesthesia techniques and intra-articular therapies, as the evidence bases differ substantially:

For Postoperative Total Knee Arthroplasty Pain

• Femoral nerve block (FNB) is the evidence-based standard for postoperative analgesia following total knee arthroplasty, with strong guideline support 1
• Single-injection FNB is recommended over continuous infusions due to insufficient comparative data on functional recovery and mobilization impacts 1
• Perineural adjuvants (clonidine, epinephrine) are not recommended due to lack of efficacy in procedure-specific studies 1

For Chronic Postsurgical Pain After TKA

Perineural injection therapy targeting peripheral sensory nerves shows clinical benefit when added to standard protocols for chronic postsurgical pain management 2:

• Three rounds of PIT combined with standard rehabilitation produced significantly better VAS and WOMAC scores at 1,3, and 6 months compared to standard treatment alone 2
• 93.5% of patients receiving PIT reported excellent or good outcomes versus 89.6% with standard treatment 2
• This represents the strongest evidence for perineural injections specifically for knee pain management 2

For Osteoarthritis-Related Knee Pain

Intra-articular injections remain the guideline-recommended approach, not perineural injections 1:

• Long-acting corticosteroid intra-articular injection is indicated for acute exacerbation of knee pain, especially with effusion 1
• Periarticular (not perineural) lidocaine-corticosteroid injections into soft tissue structures may provide early pain relief when combined with intra-articular hyaluronic acid, but benefits are limited to the first 3 weeks 3

Technical Approach for Perineural Injections

When perineural injections are indicated (primarily for chronic postsurgical pain), follow these principles:

Preparation and Setting 1

• Professional, clean, quiet, private, well-lit room 1
• Patient positioned appropriately on examination table, able to lie flat 1
• Strict aseptic technique is mandatory 1
• Equipment for aseptic procedures readily available 1
• Resuscitation equipment close by 1

Imaging Guidance

• Ultrasound guidance should be used when available to improve accuracy and reduce complications 1
• Accuracy depends on joint location, route of entry, and practitioner expertise 1

Medication Selection

Based on available evidence for perineural approaches:

• Local anesthetic plus corticosteroid combination appears most effective for chronic pain 2, 3
• For extended analgesia in surgical contexts, bupivacaine with buprenorphine-clonidine-dexamethasone extends duration to 26-39 hours versus 11-21 hours for plain bupivacaine 4
• However, perineural local anesthetic and steroid do NOT provide benefit for trauma- or compression-related peripheral neuropathic pain 5

Local Anesthetic Considerations

• Offer local anesthetic to patients, explaining pros and cons 1
• Calculate safe doses to prevent systemic toxicity 6
• Consider lower concentrations when compartment syndrome risk exists 6

Treatment Protocol

For chronic postsurgical knee pain, the evidence supports 2:

• Three rounds of perineural injections at weekly intervals combined with standard rehabilitation
• Target sensory nerves supplying the painful knee region
• Combine with multimodal analgesia including paracetamol and NSAIDs 1

Critical Safety Considerations

Patient-Specific Factors

• Diabetic patients must be counseled about transient hyperglycemia risk, especially days 1-3 post-injection, with glucose monitoring advised 1
• Not contraindicated in patients with bleeding disorders or on antithrombotic medications unless bleeding risk is high 1
• During pregnancy, consider whether the compound is safe for mother and baby 1

Post-Injection Management

• Avoid overuse of injected joints for 24 hours, but immobilization is discouraged 1
• Monitor for complications including infection and systemic toxicity 6

Common Pitfalls to Avoid

1. Do not confuse perineural injections with established regional anesthesia techniques - femoral nerve blocks for surgical analgesia have much stronger evidence 1

2. Do not use perineural injections as first-line for osteoarthritis - intra-articular corticosteroids are the guideline-recommended approach 1

3. Do not expect benefit for neuropathic pain from trauma/compression - evidence shows no analgesic benefit in this population 5

4. Do not add perineural adjuvants routinely - clonidine and epinephrine lack efficacy evidence for knee procedures 1

5. Do not perform without proper aseptic technique - infection risk is real and preventable 1

6. Do not ignore baseline pain catastrophizing - higher catastrophizing scores predict reduced analgesic benefit 5

When to Consider Perineural Injections

The most appropriate indication is chronic postsurgical pain after total knee arthroplasty that has not responded adequately to standard rehabilitation and oral analgesics 2. In this context, three weekly perineural injections targeting sensory nerves around the knee, combined with ongoing multimodal therapy, provides meaningful clinical improvement with minimal side effects 2.

For other knee pain etiologies, prioritize guideline-recommended approaches: intra-articular corticosteroids for osteoarthritis flares 1, femoral nerve blocks for surgical analgesia 1, and comprehensive multimodal analgesia including paracetamol, NSAIDs, and appropriate opioids for breakthrough pain 1.