Superficial thrombophlebitis in the forearm leading to entrapment of the radial nerve branch: a first case report and literature review.

This article reports a case of a female patient admitted with swelling and subcutaneous mass in the right forearm, initially suspected to be multiple nerve fibroma. However, through preoperative imaging and surgery, the final diagnosis confirmed superficial thrombophlebitis. This condition resulted in entrapment of the radial nerve branch, leading to noticeable nerve entrapment and radiating pain. The surgery involved the excision of inflammatory tissue and thrombus, ligation of the cephalic vein, and complete release of the radial nerve branch. Postoperative pathology confirmed the presence of Superficial Thrombophlebitis. Through this case, we emphasize the importance of comprehensive utilization of clinical, imaging, and surgical interventions for more accurate diagnosis and treatment. This is the first clinical report of radial nerve branch entrapment due to superficial thrombophlebitis.

Elbow Arthroscopy: Pearls to Avoid Nerve Injuries.

Elbow arthroscopy is a useful tool that can be applied in a variety of surgical indications. However, performing the procedure safely demands a thorough understanding of the proximity of neurovascular structures around the elbow. Although nerve injuries in elbow arthroscopy are rare, complications can further be avoided by adhering to a set of principles designed to protect the surrounding neurovascular structures. Before making portals, the surgeon should palpate and mark the ulnar nerve to confirm its location in the groove. Next, the joint should be insufflated with fluid to distend the joint capsule and increase the distance between instruments and the anterior neurovascular structures. Anterior portals ideally should be made proximal to the medial and lateral epicondyles, thereby increasing distance from the median and radial nerve, respectively. Once in the joint, it is critical to stay oriented by maintaining instruments and the articular surfaces in the same view. Special caution should be exercised when in proximity to the capsule in the posteromedial gutter to protect the ulnar nerve. Similarly, the anterior inferior capsule should be approached with caution, as its violation puts branches of the radial nerve, specifically the posterior interosseous nerve, at risk. Elbow arthroscopy can be safely performed with proper knowledge and application of anatomy around the elbow when making portals and understanding at-risk areas beyond the capsule when working within the joint.

A Fresh Cadaver Study on the Innervation of Brachioradialis and Extensor Carpi Radialis Longus Muscles.

PURPOSE: Distal nerve transfers have revolutionized peripheral nerve surgery by allowing the transfer of healthy motor nerves to paralyzed ones without causing additional morbidity. Radial nerve branches to the brachialis (Ba), brachioradialis (Br), and extensor carpi radialis longus (ECRL) muscles have not been investigated in fresh cadavers. METHODS: The radial nerve and its branches were dissected in 34 upper limbs from 17 fresh cadavers. Measurements were taken to determine the number, origin, length, and diameter of the branches. Myelinated fiber counts were obtained through histological analysis. RESULTS: The first branch of the radial nerve at the elbow was to the Ba muscle, followed by the branches to the Br and ECRL muscles. The Ba and Br muscles consistently received single innervation. The ECRL muscle showed varying innervation patterns, with one, two, or three branches. The branches to the Br muscles originated from the anterior side of the radial nerve, whereas the branches to the Ba and ECRL muscles originated from the posterior side. The average myelinated fiber counts favored the nerve to Br muscle over that to the ECRL muscle, with counts of 542 versus 350 and 568 versus 302 observed in hematoxylin and eosin and neurofilament staining, respectively. CONCLUSIONS: This study provides detailed anatomical insights into the motor branches of the radial nerve to the Ba, Br, and ECRL muscles. CLINICAL RELEVANCE: Understanding the anatomy of the radial nerve branches at the elbow is of utmost importance when devising a reconstructive strategy for upper limb paralysis. These findings can guide surgeons in selecting appropriate donor or recipient nerves for nerve transfer in cases of high tetraplegia and lower-type brachial plexus injuries.

Radial Nerve Palsy in the Setting of Humeral Shaft Fracture.

The upper limb has a complex anatomy comprised of many nerve and vascular structures, making humeral shaft fractures extremely important. Injury to the humeral shaft commonly occurs due to trauma and affects younger male or older female patients. The radial nerve travels along the spiral groove of the humerus, placing it at an increased risk of damage in humeral shaft fractures. If injured, there are a variety of classifications of radial nerve injury, different indications for exploration, and treatment methods that orthopedic surgeons have available in treating these injuries. This review aims to discuss the etiology of humeral shaft fracture-associated radial nerve palsy, tools for diagnosis, and treatment.

Case-based report of graded motor imagery experience in traumatic brachial plexus injury: The art of moving without moving.

BACKGROUND: We reported a 24-year-old woman who sustained multiple upper limb injuries after a traffic accident in March 2017. She sustained a C7-T1 brachial plexus injury and radial nerve injury on the left side diagnosed in November 2017. The patient underwent radial nerve reconstruction. The patient began her comprehensive therapy program in January 2018. PURPOSE: To describe the use of graded motor imagery (GMI) and outcomes after traumatic brachial plexus palsy. We presented changes in electromyographic (EMG) activity of target muscles during task execution and functional status following 10-session GMI therapy. STUDY DESIGN: Case report. METHODS: The program included 4 sessions of motor imagery and 6 sessions of a combination of motor imagery and mirror therapy. RESULTS: The patient successfully participated in the program with reported improvements in EMG activity, functional status, emotional well-being, and body awareness. CONCLUSIONS: GMI therapy appears to have peripheral motor effects, including altered surface EMG activity and contributes to a favorable outcome in the functional level of the affected arm. An improved emotional state and awareness of the affected hand could have a positive effect on function. Future long-term randomized controlled trials are needed to investigate the cumulative peripheral effects of treatment of graded motor imagery and the effects of variables mediating its effects on functional performance in patients with nerve injury.

A bilateral four-headed brachialis muscle with a variant innervation: a cadaveric report with possible clinical implications.

PURPOSE: Anterior compartment muscles of the arm present high morphological variability, with possible clinical significance. The current cadaveric report aims to describe a bilateral four-headed brachialis muscle (BM) with aberrant innervation. Emphasis on the embryological background and possible clinical significance are also provided. METHODS: Classical upper limb dissection was performed on an 84-year-old donated male cadaver. The cadaver was donated to the Anatomy Department of the National and Kapodistrian University of Athens. RESULTS: On the left upper limb, the four-headed BM was supplied by the musculocutaneous and the median nerves after their interconnection. On the right upper limb, the four-headed BM received its innervation from the median nerve due to the musculocutaneous nerve absence. A bilateral muscular tunnel for the radial nerve passage was identified, between the BM accessory heads and the brachioradialis muscle. CONCLUSION: BM has clinical significance, due to its proximity to important neurovascular structures and frequent surgeries at the humerus. Hence, knowledge of these variants should keep orthopedic surgeons alert when intervening in this area. Further dissection studies with a standardized protocol are needed to elucidate the prevalence of BM aberrations and concomitant variants.

Superficial branch of the radial nerve passing through the supinator canal, emerging between the extensor digitorum and abductor pollicis longus muscles and consequently supplying the second finger and radial portion of the third finger: a case report and clinical implications.

Awareness of unique path of the superficial branch of the radial nerve and its unusual sensory distribution can help avoid potential diagnostic confusion. We present a unique case encountered during a routine dissection of a Central European male cadaver. An unusual course of the superficial branch of the radial nerve was found in the right forearm, where the superficial branch of the radial nerve originated from the radial nerve distally, within the supinator canal, emerged between the extensor digitorum and abductor pollicis longus muscles and supplied the second and a radial half of the third digit, featuring communications with the lateral antebrachial cutaneous nerve and the dorsal branch of the ulnar nerve. Due to dorsal emerging of the superficial branch of the radial nerve the dorsal aspect of the thumb was innervated by the lateral antebrachial cutaneous nerve. To our best knowledge such variation of the superficial branch of the radial nerve has never been reported before. This variation dramatically changes aetiology and manifestation of possible entrapment syndromes which clinicians should be aware of.

Anatomical study of the safety corridor for bridge plating positioned on the lateral border of the humerus.

PURPOSE: This study shows the danger zone and the safety corridor in the lateral approach with bridge plating by measuring the distance between the lateral side of the plate positioned on the lateral aspect of the humerus and the radial nerve after it pierces the lateral intermuscular septum, in the different forearm positions. METHODS: Forty arms of 20 human cadavers were used, the radial nerve was identified and marked on the lateral surface the radial nerve at the exit of the lateral intermuscular septum and anteriorisation of the nerve in relation to the humeral shaft and the lateral epicondyle was also marked. The distances were measured with a digital caliper. A submuscular extraperiosteal corridor was created, proximally between the biceps brachialis and deltoid muscle and distally between the triceps and brachioradialis muscle, followed by the positioning of the low contact large fragments contoured plate with 14 combined holes (fixed and cortical angle), inserted from distal to proximal. Measurements were performed in four positions (elbow flexion with forearm pronation, elbow flexion with forearm supination, elbow extension with forearm pronation and elbow extension with forearm supination). RESULTS: Significant statistical differences occurred with the different positions, and the elbow flexion with forearm supination was shown to be the position that provides the safest submuscular extraperiosteal corridor in a lateral approach of the humerus. CONCLUSION: The danger zone of radial nerve is an area that extends from 15 cm to 5 cm proximal to the lateral epicondyle and the safest way to create a submuscular and extraperiosteal corridor in the lateral region of the humerus is with the elbow in flexion and the forearm in supination.

Superficial Branch of the Radial Nerve Versus Sural Nerve Grafting After Traumatic Adult Brachial Plexus Injury.

The purpose of this study was to compare two sources of nerve graft for brachial plexus reconstruction: the denervated superficial branch of the radial nerve (SBRN) and the sural nerve. Ninety-seven patients who underwent brachial plexus reconstruction with denervated SBRN nerve (24 patients with 24 grafts) or with sural nerve grafting (73 patients with 83 nerve grafts) were included. The two groups were compared with respect to postoperative muscle reinnervation, disabilities of the arm, shoulder, and hand (DASH) scores. In the SBRN group, only four (17%) of the nerve grafts provided grade III or higher muscle function. In the sural nerve group, 31 (37%) of the nerve grafts provided grade III or higher muscle function. Smoking had a negative impact on muscle recovery. Denervated SBRN grafts are associated with inferior outcomes when compared with sural nerve grafts in the treatment of traumatic adult brachial plexus injuries. (Journal of Surgical Orthopaedic Advances 33(2):080-083, 2024).

Ancient Schawanoma of radial nerve: a rare case report.

Soft tissue swellings on the forearm can present with a range of clinical and histopathological diagnosis. Ancient Schawanoma is a rare benign condition that can develop over the flexor surface of the forearm as a cystic swelling and can involve the median or the ulnar nerve. However, the presentation of this condition on the extensor surface with involvement of the radial nerve is an extremely uncommon diagnosis. A 69 year old female presented at the outpatient department with a swelling on the extensor aspect of her right forearm for the past 2 years. Ultrasound examination showed a mixed cystic solid mass and MRI report revealed a complex predominantly cystic mass in the extensor compartment of the forearm, measuring 4.3 x 5.3 x 7.2 cm size. After obtaining informed consent, the patient was operated under tourniquet control and the mass was removed sparing the radial nerve that was adherent to its capsule. The final histopathological report confirmed the diagnosis as Ancient Schawanoma.

Safe zones in dorsal portals for wrist arthroscopy: a cadaveric study.

The standard dorsal portals are the most commonly used in wrist arthroscopy. This cadaveric study aims to determine safe zones, by quantitatively describing the neurovascular relationships of the dorsal wrist arthroscopy portals: 1-2, 3-4, midcarpal radial, midcarpal ulnar, 4-5, 6-radial and 6-ulnar. The neurovascular structures of twenty-one fresh frozen human cadaveric upper limbs were exposed, while the aforementioned portals were established with needles through portal sites. The minimum distance between portals and: dorsal carpal branch of radial artery, superficial branch of radial nerve, posterior interosseous nerve and dorsal branch of ulnar nerve, were measured accordingly with a digital caliper, followed by statistical analysis of the data. The median and interquartile range for each portal to structures at risk were determined and a safe zone around each portal was established. Free of any neurovascular structure safe zones surrounding 1-2, 3-4, midcarpal radial, midcarpal ulnar, 4-5, 6-radial and 6-ulnar portals were found at 0.46mm, 2.33mm, 10.73mm, 11.01mm, 10.38mm, 5.95mm and 0.64mm respectively. Results of statistical analysis from comparisons between 1-2, 3-4 and midcarpal radial portals, indicated that 1-2 was the least safe. The same analysis among 3-4, midcarpal radial, midcarpal ulnar and 4-5 portals indicated that midcarpal portals were safer, while 3-4 was the least safe. Results among midcarpal ulnar, 4-5, 6-radial and 6-ulnar portals indicated that 6-radial and specifically 6-ulnar were the least safe. This study provides a safe approach to the dorsal aspect of the wrist, enhancing established measurements and further examining safety of the posterior interosseous nerve.

Regeneration of starfish radial nerve cord restores animal mobility and unveils a new coelomocyte population.

The potential to regenerate a damaged body part is expressed to a different extent in animals. Echinoderms, in particular starfish, are known for their outstanding regenerating potential. Differently, humans have restricted abilities to restore organ systems being dependent on limited sources of stem cells. In particular, the potential to regenerate the central nervous system is extremely limited, explaining the lack of natural mechanisms that could overcome the development of neurodegenerative diseases and the occurrence of trauma. Therefore, understanding the molecular and cellular mechanisms of regeneration in starfish could help the development of new therapeutic approaches in humans. In this study, we tackle the problem of starfish central nervous system regeneration by examining the external and internal anatomical and behavioral traits, the dynamics of coelomocyte populations, and neuronal tissue architecture after radial nerve cord (RNC) partial ablation. We noticed that the removal of part of RNC generated several anatomic anomalies and induced behavioral modifications (injured arm could not be used anymore to lead the starfish movement). Those alterations seem to be related to defense mechanisms and protection of the wound. In particular, histology showed that tissue patterns during regeneration resemble those described in holothurians and in starfish arm tip regeneration. Flow cytometry coupled with imaging flow cytometry unveiled a new coelomocyte population during the late phase of the regeneration process. Morphotypes of these and previously characterized coelomocyte populations were described based on IFC data. Further studies of this new coelomocyte population might provide insights on their involvement in radial nerve cord regeneration.

Optimal timing of needle electromyography to diagnose lesion severity in traumatic radial nerve injury.

INTRODUCTION/AIMS: In patients with traumatic radial nerve injury (RNI), the chance of spontaneous recovery must be balanced against the benefits of early surgical reconstruction. We aimed to explore the time-specific value of needle electromyography (NEMG) to diagnose nerve lesion severity. METHODS: In this retrospective diagnostic accuracy study at Leiden Nerve Center, patients at least 12 years of age with RNI caused by fractures or fracture treatment were included. The sensitivity and specificity of the patients' first NEMG examination were assessed, stratified by the timing after the nerve injury. The absence of motor unit potentials (MUPs) in muscles distal to the nerve lesion was considered a positive test result. Lesion severity was dichotomized to moderate injury (spontaneous Medical Research Council grade ≥3 recovery) or severe injury (poor spontaneous recovery or surgical confirmation of a mainly neurotmetic lesion). RESULTS: Ninety-five patients were included in our study. The sensitivity of NEMG to detect severe RNI was 75.0% (3 of 4) in the fourth, 66.7% (2 of 3) in the fifth, and 66.7% (2 of 3) in the sixth month after the nerve injury. The specificity in the first to the sixth month was 0.0% (0 of 1), 50.0% (2 of 4), 77.3% (17 of 22), 95.5% (21 of 22), 95.8% (23 of 24), and 100.0% (12 of 12), respectively. DISCUSSION: The specificity of NEMG is higher than 95% and therefore clinically relevant from the fourth month after the nerve injury onward. Absence of MUPs at this time can be considered an indication to plan nerve exploration. Moreover, the presence of MUPs on NEMG does not completely exclude the necessity for surgical reconstruction.

Sonographic peripheral nerve cross-sectional area in adults, excluding median and ulnar nerves: A systematic review and meta-analysis.

INTRODUCTION/AIMS: Although electromyography remains the "gold standard" for assessing and diagnosing peripheral nerve disorders, ultrasound has emerged as a useful adjunct, providing valuable anatomic information. The objective of this study was to conduct a systematic review and meta-analysis evaluating the normative sonographic values for adult peripheral nerve cross-sectional area (CSA). METHODS: Medline and Cochrane Library databases were systematically searched for healthy adult peripheral nerve CSA, excluding the median and ulnar nerves. Data were meta-analyzed, using a random-effects model, to calculate the mean nerve CSA and its 95% confidence interval (CI) for each nerve at a specific anatomical location (= group). RESULTS: Thirty groups were identified and meta-analyzed, which comprised 16 from the upper extremity and 15 from the lower extremity. The tibial nerve (n = 2916 nerves) was reported most commonly, followed by the common fibular nerve (n = 2580 nerves) and the radial nerve (n = 2326 nerves). Means and 95% confidence interval (CIs) of nerve CSA for the largest number of combined nerves were: radial nerve assessed at the spiral groove (n = 1810; mean, 5.14 mm2 ; 95% CI, 4.33 to 5.96); common fibular nerve assessed at the fibular head (n = 1460; mean, 10.18 mm2 ; 95% CI, 8.91 to 11.45); and common fibular nerve assessed at the popliteal fossa (n = 1120; mean, 12.90 mm2 ; 95% CI, 9.12 to 16.68). Publication bias was suspected, but its influence on the results was minimal. DISCUSSION: Two hundred thirty mean CSAs from 15 857 adult nerves are included in the meta-analysis. These are further categorized into 30 groups, based on anatomical location, providing a comprehensive reference for the clinician and researcher investigating adult peripheral nerve anatomy.

A standardized ultrasound approach in neuralgic amyotrophy.

Neuralgic amyotrophy (NA), also referred to as idiopathic brachial plexitis and Parsonage-Turner syndrome, is a peripheral nerve disorder characterized by acute severe shoulder pain followed by progressive upper limb weakness and muscle atrophy. While NA is incompletely understood and often difficult to diagnose, early recognition may prevent unnecessary tests and interventions and, in some situations, allow for prompt treatment, which can potentially minimize adverse long-term sequalae. High-resolution ultrasound (HRUS) has become a valuable tool in the diagnosis and evaluation of NA. Pathologic HRUS findings can be grouped into four categories: nerve swelling, swelling with incomplete constriction, swelling with complete constriction, and fascicular entwinement, which may represent a continuum of pathologic processes. Certain ultrasound findings may help predict the likelihood of spontaneous recovery with conservative management versus the need for surgical intervention. We recommend relying heavily on history and physical examination to determine which nerves are clinically affected and should therefore be assessed by HRUS. The nerves most frequently affected by NA are the suprascapular, long thoracic, median and anterior interosseous nerve (AIN) branch, radial and posterior interosseous nerve (PIN) branch, axillary, spinal accessory, and musculocutaneous. When distal upper limb nerves are affected (AIN, PIN, superficial radial nerve), the lesion is almost always located in their respective fascicles within the parent nerve, proximal to its branching point. The purpose of this review is to describe a reproducible, standardized, ultrasonographic approach for evaluating suspected NA, and to share reliable techniques and clinical considerations when imaging commonly affected nerves.

Radial nerve compression: anatomical perspective and clinical consequences.

The radial nerve is the biggest branch of the posterior cord of the brachial plexus and one of its five terminal branches. Entrapment of the radial nerve at the elbow is the third most common compressive neuropathy of the upper limb after carpal tunnel and cubital tunnel syndromes. Because the incidence is relatively low and many agents can compress it along its whole course, entrapment of the radial nerve or its branches can pose a considerable clinical challenge. Several of these agents are related to normal or variant anatomy. The most common of the compressive neuropathies related to the radial nerve is the posterior interosseus nerve syndrome. Appropriate treatment requires familiarity with the anatomical traits influencing the presenting symptoms and the related prognoses. The aim of this study is to describe the compressive neuropathies of the radial nerve, emphasizing the anatomical perspective and highlighting the traps awaiting physicians evaluating these entrapments.

Restoration of intrinsic hand function by superficial radial nerve: an anatomical study.

BACKGROUND: The contralateral seventh cervical (cC7) nerve root transfer represents a cornerstone technique in treating total brachial plexus avulsion injury. Traditional cC7 procedures employ the entire ulnar nerve as a graft, which inevitably compromises its restorative capacity. OBJECTIVE: Our cadaveric study seeks to assess this innovative approach aimed at preserving the motor branch of the ulnar nerve (MBUN). This new method aims to enable future repair stages, using the superficial radial nerve (SRN) as a bridge connecting cC7 and MBUN. METHODS: We undertook a comprehensive dissection of ten adult cadavers, generously provided by the Department of Anatomy, Histology, and Embryology at Fudan University, China. It allowed us to evaluate the feasibility of our proposed technique. For this study, we harvested only the dorsal and superficial branches of the ulnar nerve, as well as the SRN, to establish connections between the cC7 nerve and recipient nerves (both the median nerve and MBUN). We meticulously dissected the SRN and the motor and sensory branches of the ulnar nerve. Measurements were made from the reverse point of the SRN to the wrist flexion crease and the coaptation point of the SRN and MBUN. Additionally, we traced the MBUN from distal to proximal ends, recording its maximum length. We also measured the diameters of the nerve branches and tallied the number of axons. RESULTS: Our modified approach proved technically viable in all examined limbs. The distances from the reverse point of the SRN to the wrist flexion crease were 8.24 ± 1.80 cm and to the coaptation point were 6.60 ± 1.75 cm. The maximum length of the MBUN was 7.62 ± 1.03 cm. The average axon diameters in the MBUN and the anterior and posterior branches of the SRN were 1.88 ± 0.42 mm、1.56 ± 0.38 mm、2.02 ± 0.41 mm,respectively. The corresponding mean numbers of axons were 1426.60 ± 331.39 and 721.50 ± 138.22, and 741.90 ± 171.34, respectively. CONCLUSION: The SRN demonstrated the potential to be transferred to the MBUN without necessitating a nerve graft. A potential advantage of this modification is preserving the MBUN's recovery potential.

Anatomic consideration of the radial nerve in relation to humeral length for unilateral external fixation: a retrospective study using magnetic resonance imaging findings in korean.

BACKGROUND: This study aimed to present a safe zone for distal pin insertion for external fixation using magnetic resonance imaging (MRI) images. METHODS: All patients who took at least one upper arm MRI from June 2003 to July 2021 were searched via a clinical data warehouse. For measuring the humerus length, proximal and distal landmarks were set as the highest protruding point of the humeral head and lowermost margin of ossified bone of the lateral condyle, respectively. For children or adolescents with incomplete ossification, the uppermost and lowermost ossified margin of the ossification centers were set as proximal and distal landmarks respectively. The anterior exit point (AEP) was defined as the location of the radial nerve exiting the lateral intermuscular septum to the anterior humerus and distance between the distal margin of the humerus and AEP was measured. The proportions between the AEP and full humeral length were calculated. RESULTS: A total of 132 patients were enrolled for final analysis. The mean humerus length was 29.4 cm (range 12.9-34.6 cm). The mean distance between the ossified lateral condyle and AEP was 6.6 cm (range 3.0-10.6 cm). The mean ratio of the anterior exit point and humeral length was 22.5% (range 15.1-30.8%). The minimum ratio was 15.1%. CONCLUSION: A percutaneous distal pin insertion for humeral lengthening with an external fixator may be safely done within 15% length of the distal humerus. If pin insertion is required more proximal than distal 15% of the humeral shaft, an open procedure or preoperative radiographic assessment is advised to prevent iatrogenic radial nerve injury.

Compare the clinical value of two minimally invasive approaches to locating radial nerve in the posterior humeral approach.

PURPOSE: To compare the clinical value between locating radial nerve (RN) guided by Color Doppler ultrasonography and posterior antebrachial cutaneous nerve (PACN) in the posterior humeral approach. METHODS: The five fresh adult cadavers (ten upper arms) were selected to compare the two methods of locating the RN in the posterior humeral approach (guided by ultrasound and PACN) by measuring the operation time, the length of incision, and the area of subcutaneous free. And the comparison between the two groups was statistically analyzed by paired t-test. RESULTS: The results of this study demonstrated that the length of incision and the area of subcutaneous free in the ultrasound group were smaller than that in the PACN group (P < 0.05), while the operation time was just the opposite (P < 0.05). However, after excluding the time of ultrasound location, the operation time in the ultrasound group was shorter than that in the PANC group, and the difference was statistically significant (P < 0.05). CONCLUSION: The RN can be quickly and safely exposed by both methods. The ultrasound approach requires a long learning curve, but is more minimally invasive and can help determine whether the intraoperative nerve is compressed by the plate. And the PACN method requires a longer incision and a wider area of subcutaneous free, while specialized equipment and professional training for surgeons are not required. In a word, these two methods have advantages and disadvantages, so they should be selected based on the exact situation.

Deep branch of the radial nerve: effect of pronation/supination on longitudinal nerve alignment.

OBJECTIVE: To evaluate the effect of maximal pronation and supination of the forearm on the alignment and anatomic relationship of the deep branch of the radial nerve (DBRN) at the superior arcade of the supinator muscle (SASM) by using high-resolution ultrasound (HRUS). MATERIALS AND METHODS: In this cross-sectional study, HRUS in the long axis of the DBRN was performed in asymptomatic participants enrolled from March to August 2021. DBRN alignment was evaluated by measuring angles of the nerve in maximal pronation and maximal supination of the forearm independently by two musculoskeletal radiologists. Forearm range of motion and biometric measurements were recorded. Student t, Shapiro-Wilk, Pearson correlation, reliability analyses, and Kruskal-Wallis test were used. RESULTS: The study population included 110 nerves from 55 asymptomatic participants (median age, 37.0 years; age range, 16-63 years; 29 [52.7%] women). There was a statistically significant difference between the DBRN angle in maximal supination and maximal pronation (Reader 1: 95% CI: 5.74, 8.21, p < 0.001, and Reader 2: 95% CI: 5.82, 8.37, p < 0.001). The mean difference between the angles in maximal supination and maximal pronation was approximately 7° for both readers. ICC was very good for intraobserver agreement (Reader1: r ≥ 0.92, p < 0.001; Reader 2: r ≥ 0.93, p < 0.001), as well as for interobserver agreement (phase 1: r ≥ 0.87, p < 0.001; phase 2: r ≥ 0.90, p < 0.001). CONCLUSION: The extremes of the rotational movement of the forearm affect the longitudinal morphology and anatomic relationships of the DBRN, primarily demonstrating the convergence of the nerve towards the SASM in maximal pronation and divergence in maximal supination.