Postamputation Pain

Acute post-amputation pain remains a significant clinical challenge in patients with combat-related lower limb injuries and may negatively affect early rehabilitation, mobility, and opioid consumption. Various regional analgesia techniques and cryoanalgesia have been proposed to improve pain control; however, evidence regarding their feasibility and clinical utility in military trauma populations remains limited. The aim of this pilot study is to assess the feasibility of conducting a future randomized controlled trial evaluating different approaches to acute post-amputation pain management in patients with combat-related lower limb injuries. This prospective non-randomized pilot study will enroll 36 adult patients undergoing lower limb amputation or reamputation following combat-related trauma. Participants will be allocated to one of three groups according to clinical indications and multidisciplinary team decision: continuous peripheral nerve blocks, preoperative cryoablation, or standard multimodal analgesia. The primary outcomes will assess study feasibility, including recruitment rate, study completion rate, protocol adherence, and completeness of data collection. Secondary outcomes will include pain intensity assessed using the Numeric Rating Scale (NRS), opioid consumption expressed as Morphine Milligram Equivalents (MME), early mobility assessed using the Basic Amputee Mobility Score (BAMS), time to first standing and ambulation, and treatment-related complications. Participants will be followed for 7 days after surgery, with an additional assessment at 1 month.

Postamputation pain is a complex condition that includes phantom limb pain (PLP), stump pain and residual limb pain (RLP), the latter of which may be referred from joints, the spine and inflamed bursa and tendons. PLP may have peripheral, spinal and central etiologies. The evidence of peripheral mechanisms includes the relief of both PLP and RLP during local anesthetic (LA) infusions, the relief of PLP and RLP with sympathetic blocks and neuroma injections, and the development of phantom radicular pain in amputees with a herniated disc. Neurolysis and defunctionalization are long-lasting treatments for pain when LA blocks provide temporary benefit, being most commonly used for cancer pain (e.g., celiac plexus neurolysis). Neurolysis has also been used to treat PAP, with uncontrolled studies showing benefit for both RLP and PLP. However, there are no controlled studies demonstrating efficacy. In this small study, we will evaluate the effectiveness of alcohol neurolysis of lower extremity neuromas (femoral or saphenous; sciatic or common peroneal and/or tibial; obturator and/ or lateral femoral cutaneous when pain is in those distributions) in individuals with RLP and PLP. For individuals with upper extremity amputation in whom non-selective neurolysis may affect the ability to use certain prosthetics that depend on functioning nerve and muscle signals, high-concentration capsaicin will be injected in an observational arm. The investigators will also examine factors associated with treatment outcome in a subset of patients (e.g., functional MRI, quantitative sensory testing).