Regenerative Peripheral Nerve Interface (RPNI) Surgery
Regenerative Peripheral Nerve Interface (RPNI) Surgery: The surgical procedure is standardized as follows to preserve the residual limb (stump) anatomy:
* Approach: An 8-10 cm incision is made on the lateral thigh. For transtibial (below-knee) amputees, the incision is placed approximately 15 cm proximal to the knee joint. For transfemoral (above-knee) amputees, it is placed 5-10 cm proximal to the distal end of the residual limb.
* Nerve Dissection: The sciatic nerve is isolated, dissected, and transected at its most distal point. Subsequently, it is separated into the Common Peroneal and Tibial divisions.
* Fascicular Separation: Based on nerve thickness, intraneural dissection is performed to split the Common Peroneal nerve into 1 or 2 fascicles, and the Tibial nerve into 2 to 4 fascicles.
* Graft Harvesting: Autologous muscle grafts are harvested to wrap these created fascicles. The donor site is standardized by amputation level: Vastus Lateralis muscle for transtibial amputees and Biceps Femoris muscle for transfemoral amputees.
Study summary
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.
Eligibility
Sex
ALL
Min age
18 Years
Max age
70 Years
Healthy volunteers
No
Inclusion Criteria:
* 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:
1. Neuropathic Pain: DN4 Questionnaire score ≥ 4.
2. Pain Intensity: Numeric Rating Scale (NRS) score ≥ 4.
3. Physical Exam: Positive Tinel's sign or palpation tenderness at a specific trigger point.
4. 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.
Exclusion Criteria:
* CRPS: Diagnosis of Complex Regional Pain Syndrome (CRPS Type 1 or 2).
* Concurrent Bone Surgery: Patients requiring simultaneous stump revision surgery (e.g., bone shortening, osteotomy, spur excision) or having existing HO (Walter Reed Grade \> 0).
* Systemic Conditions: Uncontrolled diabetes mellitus (HbA1c \> 8.5%) or severe peripheral arterial disease compromising wound healing.
* Cognitive Status: Cognitive impairment or psychiatric conditions preventing reliable completion of patient-reported outcome measures (PEQ, DN4).
* History: Previous RPNI surgery at the same site (Recurrent RPNI cases).
Primary outcome measure(s)
Change in Pressure Pain Threshold (PPT) — Baseline (Pre-op), 3, 6, 12, and 24 months post-operation. Objective measurement of mechanical hypersensitivity at the neuroma site using a digital pressure algometer. The device applies increasing pressure in kg/cm² until the patient reports pain. Measurements are taken from the most tender point of the neuroma and a control point. Higher values indicate higher pain tolerance (improvement).
Trial sites (1)
Facility
City
Region
Status
University of Health Sciences, Gulhane Training and Research Hospital, Department of Orthopedics and Traumatology
Ankara
Ankara
Recruiting
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This page summarises publicly available registry data for informational purposes — not medical advice. Eligibility is determined by each study team; patients should discuss participation with their clinician.
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