Major Upper Limb Replantation and Nerve Repair under Intraoperative Neurophysiologic Monitoring in a One-Year-Old Infant

Abstract

Major upper extremity replantation in pediatric patients remains a challenge despite advances in techniques and surgical devices. We present the case of a one-year-old child from an underserved rural area who sustained a traumatic transhumeral amputation caused by a farming machine. Replantation was performed within four hours of the injury, followed by staged reconstructive microsurgery. The initial surgery focused on vascular, musculoskeletal, and soft tissue repair, with delayed nerve reconstruction performed under intraoperative neurophysiologic monitoring (IONM). Sural nerve grafts were used for neurorrhaphy of the median, ulnar, and musculocutaneous nerves. At the three-year follow-up, the patient achieved a Chen Grade three functional outcome. This case highlights the value of IONM as an innovative tool in pediatric nerve reconstructive microsurgery, offering a potential novel dimension of intraoperative precision that may enhance surgical decision-making and improve functional outcomes in replantation.

Introduction

Major upper extremity amputations are defined as those occurring through or proximal to the radiocarpal joint, including the forearm, elbow, humerus, and shoulder¹⁾. There is still no standardized international consensus regarding the indications and contraindications for performing replantation. However, it is generally accepted in most medical centers worldwide that replantation should always be considered in any child²⁾. Children have greater neuroplasticity and, therefore, are likely to have better outcomes compared to other age groups. In fact, a recent study demonstrated that although the survival rate is lower in pediatric digit replantation, infants typically achieve better functional outcomes than adults³⁾. We herein present the case of an infant who underwent replantation in the emergency setting and reconstructive microsurgical nerve repair under intraoperative neurophysiologic monitoring (IONM).

Case Presentation

The patient is a one-year-and-four-month-old infant who sustained a major upper-limb amputation caused by a rotating farming machine shaft. The patient and his family live in an underserved community in the southwest region of our country. He was transferred by air to our hospital with the aid of the national health system and arrived at our institution four hours after the accident. Regarding the mechanism of injury, it was not a sharp transection; rather, it was a mixed type combining sharp and avulsion components, with expected but slight shearing of soft tissues and other anatomical structures, without any crushing mechanism. The decision to perform replantation was made by the surgical team after consultation with the parents of the child. A thorough explanation was provided, including the benefits, complications, and realistic expectations of the procedure. The need for secondary revision surgical procedures was also explained. Written consent was obtained from the parents.

Surgical procedure

Our protocol of care for patients undergoing replantation procedures has been described elsewhere⁴⁾. In brief, we follow universal surgical principles, with two surgical teams working simultaneously. The first team operates on the recipient area, while the second team examines and prepares the amputated part. This allows for efficient and optimal patient care⁴⁾. X-rays were conducted on both the amputated part and the recipient site. The type and level of injury was a very short transhumeral amputation, just below the insertion sites of the deltoid, latissimus dorsi, and pectoralis major muscles (Figure 1 and 2). Bone fixation was performed by the on-call Orthopedic Surgery team. Intramedullary pins were placed to provide osteosynthesis (Figure 3). We performed an end-to-end anastomosis of the humeral artery and vena comitans, along with repair of the cephalic and basilic vein. Vessel reconstruction was carried out with the aid of left saphenous vein grafts (five cm long each). All vessel anastomoses were performed under surgical microscope magnification (Zeiss Pentero) with nylon 9-0 sutures. Myorrhaphy was performed for the coracobrachialis, brachialis, biceps, triceps, deltoid, latissimus dorsi, and teres major muscles. Repair of the major nerves at the site of injury was postponed to a second surgical procedure. Severe swelling did not permit for a thorough evaluation of the nerve structures; therefore, nerve repair was postponed for a secondary revision procedure, during which we could also rely on intraoperative neurophysiologic monitoring (for real-time monitoring and assessment of the nervous system's function). A seven cm gap was found between the proximal and distal ends of the nerves. Both the median and ulnar nerves were elongated and showed macroscopic characteristics compatible with severe inflammatory reaction secondary to the trauma mechanism. The radial nerve exhibited total transection, and the distal end could not be clearly identified. At the hand level, we performed decompression of both the median and ulnar nerves with open surgical release of the carpal tunnel and Guyon's canal, respectively. Following replantation, splinting and positioning devices were used to immobilize and protect the limb during the initial healing phase. The shoulder, elbow, wrist, and fingers were positioned to optimize perfusion, minimize tension on microsurgical repairs, and prevent joint stiffness. The limb was further immobilized in a functional position: shoulder in slight abduction and internal rotation, elbow flexed at approximately 90°, wrist in 20-30° extension, metacarpophalangeal joints in 60-70° flexion, and interphalangeal joints in full extension. This position was maintained for four weeks, with strict monitoring of vascular and soft tissue healing, followed by a gradual transition to passive and then active range of motion (ROM) under close supervision. A thorough depiction of rehabilitation will be presented in another section.

Figure 1.

Patient condition at arrival. Very Short above-elbow amputation.

Figure 2.

Amputated part. Volar and Dorsal condition.

Figure 3.

Bone preparation for fixation.

Secondary revision procedure

Four months after the initial procedure, we identified delayed bone non-union, which was treated with new solid osteosynthesis using titanium hardware. At this time (during the second surgical intervention), we also performed reconstructive microsurgical nerve repair under IONM (Figure 4). This approach consists of evaluating somatosensory evoked potentials (SEPs), evoked electromyography (eEMG), and nerve action potentials (NAPs) during the procedure⁵⁾. The IONM was performed by a board-certified neurophysiologist. In brief, the intervention IONM includes placement of electrodes on the patient's skin, muscles, or directly on nerves or the brain. Electrical signals (such as evoked potentials or NAPs) are generated and monitored. The neurophysiologist then interprets these signals during surgery on a monitor to detect changes that may indicate potential injury. The final step involves the surgeons using this feedback to perform nerve repair, relying on the real-time monitoring and assessment of the nervous system's function. As for the procedure itself, viable axons were found in the musculocutaneous nerve, as well as in the median and ulnar nerves. We performed nerve repair with the interposition of sural nerve grafts (12 cm long each). Neurorrhaphy was performed on the median nerve, ulnar nerve, and musculocutaneous nerve, including branches to the coracobrachialis, biceps brachii, and brachialis muscles (Figure 5). Nerve repair was carried out under surgical microscope magnification (Zeiss Pentero) with nylon 11-0 sutures. A segment of the ulnar nerve was prepared and placed into the deltopectoral groove, with insetting onto the pectoralis major and deltoid muscles, providing a neuromuscular target for the regenerating axons of the transected nerve.

Figure 4.

IONM.

IONM: intraoperative neurophysiologic monitoring

Figure 5.

Nerve identification and preparation for neurorrhaphy.

Rehabilitation

While we cannot provide a detailed timeline of each of the phases, we present herein the main key points of the process. Rehabilitation following replantation and nerve repair was carefully structured and individualized, with progression guided by a combination of radiographic, clinical, and functional criteria assessed by a multidisciplinary team. The transition from passive to ROM was determined by multiple interrelated factors, including the stage of tissue healing, the mechanical stability of the surgical repair, pain control, and the child's neuromuscular readiness. Adequate passive ROM and the ability to perform controlled, pain-free movements were considered prerequisite benchmarks before initiating active movement. Progression through rehabilitation phases was tailored to the patient's evolving postoperative status, with radiographic evidence of bony union required prior to the introduction of resistive activities or weight-bearing tasks. Particular attention was given to vascular integrity and soft tissue healing. From our past experience, signs of compromised perfusion, abnormal scarring, impaired wound healing, or infection are considered significant limiting factors that often delay the protocols of our colleagues in the specialty of Physical Medicine and Rehabilitation. Objective criteria and close interdisciplinary coordination enabled safe and timely transitions between phases of therapy. Functional milestones, including the achievement of near-complete passive ROM and demonstrable pain-free, controlled active ROM without compensatory actions or movements, served as indicators of readiness for further progression. We consider that in the pediatric population (patients undergoing reconstructive microsurgical procedures), rehabilitation goals should be aligned with age-appropriate developmental activities, emphasizing universal hand functions such as grasping, motor coordination, and self-care activities. Functional play and spontaneous bimanual use were closely monitored as practical markers of recovery. This involved comparing patterns of use and observing how the child used the replanted limb compared to the unaffected (contralateral) limb during daily activities, especially in functional or spontaneous settings such as play.

Clinical outcome

At the three-year follow-up, the patient presented with a Grade three functional outcome according to Chen's Functional Criteria, meaning the patient is able to carry out daily activities, exhibits a range of joint motions exceeding 30% of normal, has partial recovery of sensibility in the median and ulnar nerve distributions, and shows muscular power of Grade 3-4 according to the Medical Research Council Score (active movement against gravity and some resistance) (Figure 6). Although from a surgical perspective, the case represents a successful replantation procedure, the outcome cannot be reported as excellent (Grade 1) because normal muscular power has not been completely achieved. There is also a moderate limitation of wrist ROM, with 10-15 degrees of restriction in flexion and extension, and approximately five degrees in both radial deviation (moving the wrist towards the thumb) and ulnar deviation (moving the wrist towards the fifth finger). In addition, the radial nerve could not be addressed during the primary procedure. Although the patient is still a young child, he is able to perform essential daily activities such as showering, eating, and dressing, as well as engaging in age-appropriate developmental activities. Despite impairment of the radial nerve, the quality of life has not been significantly affected at this stage. In our experience with similar cases of radial nerve injury, such as in the setting of brachial plexus injury or radial nerve palsy, we perform a free gracilis muscle flap transfer to assist with elbow extension. This secondary procedure is planned for the near future to further optimize the patient's functional recovery. We also envision the possibility of a microsurgical procedure aimed at enhancing the function of the intrinsic musculature of the hand (innervated by the ulnar nerve and its deep branch). This would be particularly beneficial in improving fine motor control, grip strength, and other specific finger movements.

Figure 6.

A) Clinical condition at four-month follow-up. B) Clinical condition at three-year follow-up.

Discussion

The burden of losing a limb might be even greater at an earlier age and can have a significant impact on the patient's mental health. In fact, it has been demonstrated that almost 40% of traumatic upper-limb amputation victims show several degrees of post-traumatic stress related to pathological grief⁶⁾. We concur with the notion that, with regard to replantation, the goal should strive not only survival but also function of the replanted part⁷⁾. We have tested and found IONM to be quite resourceful in several clinical and surgical scenarios, such as dynamic facial nerve reanimation and brachial plexus reconstruction⁵⁾. We believe that IONM can improve patient safety and quality of care by providing the surgeon with real-time information on the functional integrity of the nerves involved in the procedure. We have found that IONM has the potential to improve outcomes and reduce neurological complications in different settings⁵⁾. For instance, intraoperative recording of NAPs is recommended during plexus and peripheral nerve surgeries to assist in several critical tasks: identifying the nerve, localizing existing lesions, assessing functional continuity across injured segments, detecting root avulsions, guiding biopsy site selection, avoiding iatrogenic injury to healthy nerves, and aiding in the choice of the most suitable surgical approach to enhance functional outcomes⁵⁾. In this replantation case, the level of intraoperative insight was especially valuable given the complexity of the procedure and the young age of the patient, enabling a more tailored and precise surgical intervention aimed at optimizing long-term functional recovery.

Although the use of IONM in pediatric upper-limb replantation is scarcely documented, broader evidence from peripheral nerve surgery supports its value. For instance, intraoperative NAPs and triggered EMG have been shown to reliably differentiate intact but compressed or neuroma-in-continuity nerve fibers from non-conductive lesions, thereby guiding whether neurolysis or grafting is warranted, ultimately influencing surgical decisions and improving functional outcomes⁸⁾.

Technical series on intraoperative NAP recordings in peripheral nerve continuity lesions demonstrate that a positive NAP across a lesion correlates with favorable postoperative recovery in over 90% of cases, underscoring the predictive value of real-time electrophysiologic feedback during nerve repair⁹⁾. Moreover, IONM modalities adapted for pediatric use, including SEPs, MEPs (motor evoked potentials), and EMG, have demonstrated utility across complex pediatric surgeries in preserving neural function, guiding surgical navigation, and reducing postoperative deficit¹⁰⁾.

A recent systematic review found that although the survival rate is lower in pediatric replantation compared with adults, children achieve better functional outcomes³⁾. Nevertheless, we consider it of utmost importance to emphasize that replantation alone is not the sole or final stage of treatment. In fact, it has been reported that following successful replantation, the average number of secondary surgical procedures is three per patient (with a range of zero to seven)¹¹⁾. These secondary interventions are aimed at improving functional outcomes, and some of the most common include free functioning muscle transfer and tenolysis, among others¹¹⁾. Moreover, researchers have found that replantation of a traumatically amputated arm generally yields more favorable functional outcomes and greater patient satisfaction compared to prosthetic limb use, even when objective functional measures are similar^12,13). Key advantages of replantation include restored sensation and improved psychological well-being^12,13). While both studies report similar findings, the first group of colleagues emphasizes the role of sensory recovery in driving patient satisfaction, whereas the latter further highlights the psychological benefits as central to the perceived success of replantation. In this particular case, we strategically implanted the remaining nerve into the deltopectoral groove, anchoring it to the pectoralis major and deltoid muscles to create a physiologic neuromuscular target for regenerating axons, preserving the possibility of future functional reconstruction. Importantly, this concept mirrors the principles of Regenerative Peripheral Nerve Interface and Targeted Muscle Reinnervation, techniques that not only recreate functional targets for nerve growth but also have demonstrated compelling efficacy in alleviating chronic limb pain in amputees^14,15).

In our case, the patient's social context played a significant role in shaping the rehabilitation plan. The child comes from a rural, underserved community where access to specialized rehabilitation services and consistent follow-up care is limited. These socioeconomic factors were considered by the rehabilitation team when designing a realistic and adaptable rehabilitation strategy, with an emphasis on caregiver education and simplified therapy protocols that could be carried out in a non-clinical setting. We believe that cultural, logistical, and resource-related barriers should be addressed through coordinated social support and outreach efforts to encourage continuity of care despite geographic and socioeconomic limitations.

We consider major upper-limb amputations a challenge due to the greater need for postoperative care arising from the large muscle volume of these anatomical segments, as well as concurrent nerve damage (proximal injuries usually lead to worse outcomes). However, we believe that with proper reconstructive surgical care and rehabilitation, children's resilience following amputations can be maximized.

Conclusion

This case highlights the value of IONM as an innovative tool in pediatric nerve reconstructive microsurgery, offering a potential novel dimension of intraoperative precision that may enhance surgical decision-making and improve functional outcomes in cases of replantation.

Author Contributions: D.P. Corresponding author. Conceptualization, Writing, original draft preparation, investigation, research, supervision, validation, writing final draft, reviewing, and final editing; A.C. Conceptualization, investigation, research, supervision, validation, evaluation of the final draft, reviewing, and final editing.

Conflicts of Interest: There are no conflicts of interest.

Ethical Approval: The authors declare the following:

1) Written consent has been obtained from the patient and the patient's parent in order to perform the surgical procedure (according to the institution's protocols).

2) Written consent has been obtained from the patient and the patient's parent in order to use photographs (according to the institution's protocols).

3) Approval has been obtained from the Ethics Department at the institution where the procedure was performed (Plastic and Reconstructive Surgery Department, Hospital General “Dr. Manuel Gea González”, Mexico City, Mexico)

Registration Approval number (Ethics) at the Plastic and Reconstructive Surgery Department: CPR 05/16

Consent to Participate: The patients/participants provided their written informed consent to participate in this study

Consent for Publication: The patients/participants provided their written informed consent to participate in this study

Funding Statement

The authors declare there are no sources of funding to declare. Author's own work.