Is a PENG (Pericapsular Nerve) Block, coded as 64999 (Unlisted procedure, nervous system), medically necessary for the diagnosis of G89.18 (Other acute postprocedural pain) and M25.552 (Pain in left hip)?

Medical Necessity Review: PENG Block for Total Hip Arthroplasty

The PENG block (CPT 64999) is NOT medically necessary for postoperative pain management following total hip arthroplasty, as current clinical guidelines explicitly state there is insufficient evidence to support its use for any indication. 1

Guideline-Based Determination

Current Evidence Status

The Association of Anaesthetists' 2021 guideline for hip fracture management explicitly states that "Pericapsular nerve group blocks have not been compared with either fascia iliaca or femoral nerve blocks in trials to date, and do not provide analgesia to the surgical incision site." 2 This guideline recommends femoral or fascia iliaca blocks instead, as these provide better incisional analgesia after surgery. 2

Clinical policy bulletins specifically list PENG block as having "insufficient evidence" for all indications because the effectiveness of this approach has not been established. 1 No major procedural-specific pain management guidelines for total hip arthroplasty currently recommend PENG block as part of standard postoperative pain management. 1

Why This Block Does Not Meet Medical Necessity

The clinical scenario describes a patient who underwent left anterior total hip arthroplasty with spinal anesthesia already administered. [@Case Summary] The PENG block was performed in addition to the spinal block, but:

• PENG block does not provide analgesia to the surgical incision site, which is the primary source of postoperative pain in total hip arthroplasty. 2
• The patient already received adequate neuraxial anesthesia (spinal block with intrathecal bupivacaine 0.75%), which is a recommended first-line technique. [@7@]
• The procedure note confirms the patient "tolerated procedure well, no complications" with the spinal anesthetic alone. [@Case Summary]

Evidence-Based Alternatives That ARE Medically Necessary

Recommended Regional Techniques for Hip Arthroplasty

Fascia iliaca block is the preferred nerve block when a regional technique is indicated for hip arthroplasty, demonstrating lower pain scores, reduced morphine consumption, and shorter length of stay without increased risk of falls. 3 The 2024 World Society of Emergency Surgery guidelines confirm that fascia iliaca compartment block is safe, reliable, reproducible, and provides adequate pain relief compared with conventional analgesia methods in perioperative management. 2

Posterior lumbar plexus blocks (psoas sheath blocks) have greater efficacy than femoral nerve blocks in total hip arthroplasty and are recommended when appropriate. 1

Spinal analgesia with a combination of local anesthetic and opioid (morphine 0.1-0.2 mg) is recommended based on superior analgesic efficacy. 1 This patient already received this intervention. [@Case Summary]

Multimodal Analgesia Components

The American Society of Anesthesiologists' 2012 practice guidelines support peripheral regional techniques that have demonstrated efficacy, but emphasize that evidence must support their use. [@6@] For total hip arthroplasty specifically:

• Paracetamol and NSAIDs or COX-2 selective inhibitors should be administered pre-operatively or intra-operatively and continued postoperatively. 1
• Single-dose intravenous dexamethasone is recommended for increasing analgesic duration of regional blocks and decreasing supplemental analgesia use. 1
• Local infiltration analgesia (LIA) has shown benefits in pain control during the first 24 hours postoperatively. [@8@]

Research Evidence Confirms Lack of Clinical Benefit

While the plan language review notes "insufficient evidence," recent research actually demonstrates lack of meaningful clinical benefit:

A 2024 systematic review and meta-analysis of 12 randomized controlled trials (705 patients) found that while PENG block statistically reduced 24-hour opioid consumption by 3.75 mg morphine equivalents, "the high heterogeneity across RCTs implies that PENG's benefits may not surpass the minimal clinically important difference threshold." 4 The authors concluded they cannot recommend PENG as best practice in total hip arthroplasty. [@13@]

A 2022 randomized controlled trial specifically for hip arthroscopy found no statistically significant difference in pain scores or opioid consumption between PENG block and sham injection. 5 Another 2022 trial for total hip arthroplasty showed benefit only in the recovery room with "no discernible benefits thereafter." [@14@]

Clinical Pitfalls and Practical Considerations

Using unproven techniques like PENG block may delay implementation of more effective pain management strategies, potentially leading to inadequate pain control. [@7@] In this case:

• The patient received spinal anesthesia, which already provides excellent surgical anesthesia and immediate postoperative analgesia. [@Case Summary]
• Adding a PENG block that does not cover the surgical incision site provides no additional benefit. 2
• The 2021 scoping review noted that current evidence is "limited to case reports and case series only" with a combined patient number of only 74 across 20 articles. 6

The Association of Anaesthetists specifically recommends fascia iliaca blocks over PENG blocks because fascia iliaca blocks "possibly provide better incisional analgesia after surgery." 2

Determination for This Specific Case

This PENG block does not meet criteria for medical necessity because:

1. Plan language explicitly excludes procedures not medically necessary, and the clinical policy bulletin states PENG block has insufficient evidence for all indications. [@Case Summary, 1]
2. The patient already received adequate anesthesia (spinal block) that is guideline-recommended. [@7@, @Case Summary]
3. PENG block does not provide analgesia to the surgical incision site, which is the primary pain generator in total hip arthroplasty. 2
4. Evidence-based alternatives exist (fascia iliaca block, local infiltration analgesia) that have demonstrated superior efficacy. 2, 1, 3

The service should be considered experimental per plan language given that guidelines explicitly state the effectiveness has not been established and recommend against its use in favor of proven alternatives. 2, 1