The Effect of Regenerative Peripheral Nerve Interface (RPNI) Surgery on Neuropathic Pain and Functional Outcomes in Major Lower Extremity Amputations
This prospective, observational cohort study evaluates the long-term outcomes of Regenerative Peripheral Nerve Interface (RPNI) surgery in patients with major lower extremity amputations suffering from symptomatic neuromas. RPNI is a surgical technique where the transected nerve end is implanted into a free autologous muscle graft to serve as a physiological target for reinnervation. The study aims to objectively assess the reduction in mechanical hypersensitivity using Pressure Pain Threshold (PPT) measurements via a digital algometer. Additionally, it monitors subjective neuropathic pain levels, functional mobility, and prosthesis satisfaction over a 24-month follow-up period compared to pre-operative baselines.
• Age: Adults aged 18 to 70 years.
• Amputation Status: Unilateral major lower extremity amputation (Transtibial, Transfemoral, or Knee Disarticulation).
• Radiological Baseline: Absence of Heterotopic Ossification (HO) in the residual limb, confirmed by pre-operative X-rays (Walter Reed Classification Grade 0).
• Diagnosis: Confirmed diagnosis of Symptomatic Neuroma validated by the Clinical Triad:
‣ Neuropathic Pain: DN4 Questionnaire score ≥ 4.
⁃ Pain Intensity: Numeric Rating Scale (NRS) score ≥ 4.
⁃ Physical Exam: Positive Tinel's sign or palpation tenderness at a specific trigger point.
⁃ Radiology: Diagnostic Ultrasound visualization of the neuroma bulb.
• Surgical Indication: Scheduled for RPNI surgery as part of the routine standard of care treatment protocol due to prosthesis intolerance or severe pain.
• Consent: Willing and able to provide informed consent and attend follow-up visits.