Abstract

Introduction: Kuiken et al. found that an amputated nerve transferred into a nearby muscle produced a transcutaneously detectable electromyographic signal corresponding to the transferred nerve, the targeted muscle reinnervation (TMR) technique, for controlling the prosthesis. However, it is ideal to select and transfer each motor fascicle to achieve highly developed myoelectric arms with multiple degree-of-freedom motions. Methodology: We treated 4 men with post-injury transhumeral amputation. We first identified the amputated median and radial nerves. The sensory fascicles were identified using somatosensory evoked potential. The motor fascicles were divided into an innervating digit flexion and an innervating forearm pronation/wrist flexion in the median nerve; and into an innervating digit extension and an innervating forearm supination/wrist extension in the radial nerve. Each median nerve fascicle was transferred to the biceps short head or the brachialis branch while the biceps long head branch was retained for elbow flexion. Each radial nerve fascicle was transferred to the triceps medial or lateral head branch while the triceps long head branch was retained for elbow extension. EMGs and physical test results were evaluated. Results: In needle EMG, myogenic potentials were detected at all six motions such as digit flexion/extension, forearm pronation/supination, and elbow flexion/extension within 6 months postoperatively in all cases. In surface EMG, the identification rate was 97.7%, i.e. one-to-one correspondence was almost achieved 12 months postoperatively. Holding functions, VAS, and DASH significantly improved after acquiring six motions with the surgery compared with only two motions of digit flexion/extension before surgery (p<.05). Conclusions: We noted functional improvement with marked identification rate for each motion after the selective nerve transfers as well as pain relief after neuroma excision and detection of favorable myogenic potentials after subcutaneous fat tissue removal. Thus, more selective nerve transfers are required for highly developed prostheses with multiple degrees of freedom.

Abstract

Abstract

Iatrogenic nerve injury around the wrist frequently causes neuromas, resulting in severe pain and significantly impairing quality of life. Diagnosis is readily made using Tinel's sign at the surgical scar or ultrasound examination, but complete cure through surgical treatment is difficult, with approximately 20% of cases becoming refractory. Nerves susceptible to injury around the wrist include the common trunk of the median nerve and its palmar cutaneous branches, the common digital nerves, the superficial branch of the radial nerve, the lateral antebrachial cutaneous nerve, and the dorsal branch of the ulnar nerve. Among these, injury to the superficial branch of the radial nerve and the lateral antebrachial cutaneous nerve is considered a poor prognostic factor. The causes have been attributed to the thin subcutaneous tissue on the radial side of the wrist and friction with the brachioradialis tendon. However, these two nerves frequently interconnect anatomically, and neuromas occurring distally from this connection site contain fibers from both nerves. Therefore, treatment targeting only a single nerve is likely to be insufficient. Even TMR for AIN does not resolve all issues under these circumstances. Furthermore, even in the absence of anastomosis, the influence of collateral sprouting pain (painful hyperalgesia) from adjacent nerves (such as the lateral cutaneous nerve of the forearm or the palmar branch of the median nerve in cases of radial nerve superficial branch injury) cannot be ignored. The fundamental treatment approach is to consider neurorrhaphy with or without artificial nerves, or nerve grafting, as the first choice in addition to neuroma excision when a distal nerve stump is available. When a distal stump is unavailable, we perform a combination of endto- end and/or end-to-side neurorrhaphy, considering the aforementioned anatomical features during surgery and being mindful of the neuroma location and the presence of nerve branches. Furthermore, when significant surrounding scar tissue or adhesions are present, coverage using a radial artery perforator flap is added. Other poor prognostic factors include multiple surgeries. This is likely due to the progression of CRPS caused by central sensitization. In such situations, recognizing that surgical treatment may yield limited benefits, it is essential to establish a good physician-patient relationship and thoroughly pursue conservative treatment through oral medications, stellate ganglion blocks, and physical therapy modalities such as mirror therapy.

Abstract

Purpose: Neuromas causing sensory disturbance can substantially affect nerve function and quality of life. Historically, passive termination of the nerve end and proximal relocation to muscle or bone has been performed after neuroma resection, but this method does not allow for neurologic recovery or prevent recurrent neuromas. Recently, Targeted Muscle Reinnervation (TMR) & Regenerative Peripheral Nerve Interfaces (RPNI) have been introduced and used as an active treatment for neuroma treatment. We performed the surgery for the prevention or treatment of neuroma in various cases, and we would like to introduce the results of the surgery and various application cases. Materials and Method: We retrospectively reviewed the use of RPNI to treat symptomatic hand and digital neuromas at our institutions. Between July 2021 and June 2023, we performed 3 TMRs & 14 RPNIs on 8 patients for treatment or prevention of symptomatic neuroma. During postoperative follow-up, the improvement of Tinel's sign and free of neuroma symptoms was checked. Results: The average patient follow-up was 29 weeks (6–101 weeks); 93.7% of patients were pain-free or considerably improved at the last office visit. There were 13 cases for the treatment of symptomatic neuroma and 4 cases for the prevention of neuroma. At the digit level, RPNI was used (3cases), and at the wrist & palm level, 2 cases of TMR and 5 cases of RPNI were used. In Forearm, 1 case of TMR and 6 cases of RPNI were used. There were no complications reported in other literature such as Infection. Conclusions: The RPNI & TMR can serve as a safe and effective surgical solution to treat symptomatic neuromas after hand & upper extremity trauma. Early clinical outcomes are promising and demonstrate reduction in phantom limb pain and a decrease in residual limb pain.

Abstract

Chronic pain after amputation is an underappreciated problem that affects millions of people suffering from limb loss. Regenerative peripheral nerve interface (RPNI) surgery has transformed the landscape of postamputation rehabilitation by offering a novel surgical solution for neuroma pain and phantom limb pain. Furthermore, RPNI surgery has the potential to facilitate control of an advanced neuroprosthetic device with multiple degrees of freedom. This presentation will focus on the proposed mechanisms by which RPNI surgery mitigates postamputation pain, clinical outcomes after RPNI surgery, and future directions for expanded indications.

Abstract

1. Introduction Orthopedic microsurgery mainly consists of flap surgery and nerve surgery. Ultrasound has become an increasingly important tool because it is noninvasive, provides real-time imaging, and enables detailed preoperative and intraoperative assessment. For perforator flap surgery, high-resolution B-mode combined with Doppler ultrasound allows accurate identification of small perforator arteries passing through the muscle and subcutaneous tissue. Color and power Doppler are useful for evaluating vessel direction and flow, while pulsed Doppler can measure flow velocity for functional assessment. Compared to CT angiography or MRA, ultrasound provides real-time visualization of vascular anatomy without radiation exposure. In peripheral nerve surgery, ultrasound plays a growing role in diagnosis and surgical planning. It allows real-time and high-resolution visualization of nerve continuity, swelling, compression, and dynamic movement. These capabilities make ultrasound particularly valuable in diagnosing nerve torsion, compressive neuropathy, and traumatic nerve injuries, as well as for precise preoperative localization. This presentation introduces practical applications of ultrasound in both flap and nerve microsurgery, illustrated by representative clinical cases. 2. Ultrasound in Flap Surgery 2.1 Anterolateral Thigh (ALT) Flap Perforators of the ALT flap usually originate from branches of the lateral circumflex femoral artery (LCFA), especially from the descending branch passing between the rectus femoris and vastus lateralis. Ultrasound enables accurate localization and characterization of these perforators before surgery. It also differentiates septocutaneous from musculocutaneous perforators and allows tracing of the intramuscular course when necessary, thus improving surgical safety and efficiency. 3. Ultrasound in Nerve Surgery 3.1 Diagnosis of Peripheral Nerve Torsion Nerve torsion most often involves the ulnar, median, common peroneal, or tibial nerves. Ultrasound can reveal abnormal twisting or spiral configuration of the nerve with loss of normal fascicular pattern and localized swelling. It is particularly useful when MRI is limited by metal artifacts after fracture fixation. Preoperative marking of the lesion with ultrasound helps minimize incision size and reduce tissue trauma. 3.2 Post-fixation Nerve Evaluation After fracture fixation—such as radial nerve palsy after humeral shaft fracture or posterior interosseous nerve palsy after radial head fracture—ultrasound allows evaluation of nerve continuity, compression, or adhesion even in the presence of metal plates. It provides essential information for planning nerve grafting or neurolysis before reoperation. 4. Conclusion Ultrasound is a powerful adjunct in orthopedic microsurgery, offering precise anatomical and functional information that enhances surgical planning and outcomes. Through selected cases in flap and nerve surgery, this presentation demonstrates its clinical value and future potential for integration into microsurgical practice.

Abstract

Peripheral nerve injuries often present complex diagnostic and localization challenges, which can result in delays in proper intervention. Magnetic resonance neurography (MRN) has increasingly become a valuable part of the diagnostic and preoperative toolkit. Recent advancements in hardware and software technologies have greatly enhanced MRN’s capabilities, turning it into a powerful modality for both preoperative planning and postoperative assessment of persistent neurological deficits. As an adjunct to electrodiagnostic studies, high-resolution MRN provides a comprehensive overview of the neuromuscular system that enables precise localization of nerve injuries, assessment of severity, and visualization of surrounding muscles and adjacent structures. By directly depicting nerve signal abnormalities, discontinuities, and neuroma formation, MRN empowers clinicians with greater diagnostic confidence and equips surgeons with critical information to plan more effective interventions. Its integration into the surgical workflow can enhance targeting accuracy, allow for personalized surgical approaches, and ultimately lead to improved functional recovery and clinical outcomes.