Proximal Nerve Cryoablation Versus Perineuroma Cryoablation for Chronic Neuroma Pain After Combat-Related Amputation

Chronic neuroma pain is a common and disabling complication following combat-related limb trauma and amputation. Persistent neuroma pain may contribute to residual limb pain, phantom limb pain, impaired prosthesis tolerance, reduced mobility, sleep disturbance, and decreased quality of life. Current treatment strategies frequently provide incomplete or temporary analgesia.

Cryoablation is an ultrasound-guided minimally invasive technique that induces controlled axonal injury using extreme cold temperatures. Although the direct freezing zone extends only a few millimeters around the cryoprobe, cryo-induced axonotmesis may trigger distal Wallerian degeneration along the affected nerve pathway while preserving connective tissue structures that support potential nerve regeneration.

The optimal anatomical target for cryoablation in painful neuromas remains unclear. Cryoablation performed directly adjacent to the neuroma may interrupt local nociceptive signaling, whereas proximal nerve cryoablation may produce broader distal analgesic effects by interrupting axonal conduction proximal to the neuroma-bearing segment.

The AXON-FREEZE Trial is a prospective multicenter controlled study designed to compare proximal nerve cryoablation versus perineuroma cryoablation for chronic neuroma pain after combat-related amputation.

Participants with ultrasound-confirmed painful neuromas will undergo ultrasound-guided cryoablation using one of the two treatment strategies according to study allocation and local clinical practice. Clinical follow-up will include assessment of neuroma pain intensity, neuropathic pain characteristics, phantom limb pain, residual limb pain, prosthesis tolerance, analgesic consumption, patient-reported improvement, and adverse events.

The study aims to improve understanding of cryoablation targeting strategies and evaluate whether proximal nerve cryoablation may provide stronger or longer-lasting pain relief compared with cryoablation performed adjacent to the neuroma.

Inclusion criteria

• Age ≥18 years
• Combat-related limb amputation
• Chronic neuroma pain lasting ≥3 months
• Ultrasound-confirmed painful neuroma
• Average pain intensity ≥4/10 on Numeric Rating Scale
• Positive Tinel sign
• Ability to undergo ultrasound-guided cryoablation
• Stable analgesic regimen for at least 14 days
• Ability to provide written informed consent

Exclusion criteria

• Active infection at the treatment site
• Open wound preventing safe procedure
• Previous cryoablation of the target nerve within 6 months
• Neuroma surgery within 3 months
• Severe coagulopathy or anticoagulation contraindicating procedure
• Pregnancy or breastfeeding
• Severe uncontrolled systemic disease
• Inability to complete follow-up assessments