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

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.

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

Abstract

Ultrasound has emerged as a valuable diagnostic tool for peripheral nerve disorders, offering higher soft-tissue resolution, real-time and dynamic imaging, and cost-effectiveness compared with conventional MRI. While radiologists traditionally perform most nerve ultrasound examinations, orthopedic surgeons can apply this modality directly in clinical practice to bridge diagnosis and surgical decision-making. Based on my clinical experience as a hand surgeon, I present a series of representative cases where ultrasound played a critical role. These include postoperative neuroma detection, compressive neuropathies of the posterior interosseous nerve, median nerve pathologies such as thrombosed persistent median artery and torsion, and ulnar nerve entrapments at the elbow and wrist. In each case, ultrasound enabled accurate localization, assessment of dynamic changes, and guidance for appropriate surgical management. Ultrasound demonstrates great versatility in the evaluation of peripheral nerve lesions. However, its effectiveness is highly operator-dependent, requiring solid knowledge of peripheral nerve anatomy and pathology. The greatest teacher is always the clinical case itself, and surgeons—who examine patients directly and perform operations—can gain the deepest understanding from these cases. Therefore, there is a distinct advantage when surgeons themselves perform and interpret nerve ultrasound, as it directly connects clinical findings, imaging, and surgical strategy.