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.

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.

Superficial branch of the radial nerve regularly contains fibers from the lateral antebrachial cutaneous nerve: A role in neuroma treatment.

BACKGROUND: Many surgical strategies aim to treat the symptomatic neuroma of the superficial branch of the radial nerve (SBRN). It is still difficult to treat despite many attempts to reveal a reason for surgical treatment failure. The lateral antebrachial cutaneous nerve (LACN) is known to overlap and communicate with SBRN. Our study aims to determine the frequency of spreading of LACN fibers into SBRN branches through a microscopic dissection to predict where and how often LACN fibers may be involved in SBRN neuroma. METHODS: Eighty-seven cadaveric forearms were thoroughly dissected. The path of LACN fibers through the SBRN branching was ascertained using microscopic dissection. Distances between the interstyloid line and entry of LACN fibers into the SBRN and emerging and bifurcation points of the SBRN were measured. RESULTS: The LACN fibers joined the SBRN at a mean distance of 1.7 ± 2.5 cm proximal to the interstyloid line. The SBRN contained fibers from the LACN in 62% of cases. Most commonly, there were LACN fibers within the SBRN's third branch (59%), but they were also observed within the first branch, the second branch, and their common trunk (21%, 9.2%, and 22%, respectively). The lowest rate of the LACN fibers was found within the SBRN trunk (6.9%). CONCLUSION: The SBRN contains LACN fibers in almost 2/3 of the cases, therefore, the denervation of both nerves might be required to treat the neuroma. However, the method must be considered based on the particular clinical situation.

Cadaveric study of flexor digitorum profundus and superficialis and flexor pollicis longus innervation patterns for application in selective neurectomy.

PURPOSE: Spasticity management in finger flexors (flexor digitorum profundus and superficialis and flexor pollicis longus) is a challenge. Recent studies demonstrated the short- and long-term efficacy of selective and hyperselective neurectomy for the spastic upper limb. However, hyperselective neurectomy of flexor digitorum profundus and flexor digitorum superficialis branches was incomplete, without impairing their muscular body and function. This cadaveric study describes a novel medial approach in the forearm, to reach all the muscular branches: flexor digitorum superficialis and profundus and flexor pollicis longus. MATERIAL AND METHODS: Fourteen cadaveric fresh frozen upper limbs were used. The feasibility of the medial surgical approach was studied, as well as the number, length and point of emergence of the muscular branches from the median and ulnar nerves to the flexor pollicis longus, flexor digitorum profundus and flexor digitorum superficialis. RESULTS: The medial approach to the forearm gave access to all the muscular branches from the median and ulnar nerves to the flexor pollicis longus, flexor digitorum superficialis and flexor digitorum profundus, in all cases. A Martin Gruber communicating branch was found in 7 cases out of 14. CONCLUSION: The medial approach to the forearm gave access to all the muscular branches from the median and ulnar nerve to the flexor pollicis longus, flexor digitorum superficialis and flexor digitorum profundus, without extensive transmuscular dissection of the pronator teres or flexor digitorum superficialis muscles. This approach opens the way for selective neurectomy of the flexor pollicis longus, flexor digitorum profundus and flexor digitorum superficialis muscles. LEVEL OF EVIDENCE: IV.

Systematic review of nerves at risk at the wrist in common surgical approaches to the forearm: Anatomical variations and surgical implications.

Three commonly used approaches to the forearm in orthopedic surgery are Henry's, Thompson's, and the ulnar approach, each of which has the potential to cause injury to nerves around the wrist. Preserving these nerves is important to prevent complications such as neuroma formation and motor and sensory changes to the hand. We conducted a review of the literature to assess the nerves at risk and whether 'safe zones' exist to avoid these nerves. An independent reviewer conducted searches in Embase and MEDLINE of the literature from 2010 to 2020. A total of 68 papers were identified, with 18 articles being included in the review. Multiple nerves were identified as being at risk for each of the approaches described. In the anterior approach, the palmar cutaneous branch of the median nerve (PCBMN) is most at risk of injury. An incision immediately radial to the flexor carpi radialis (FCR) or directly over the FCR is most likely to avoid injury to both superficial branch of the radial nerve (SBRN) and PCBMN. With Thompson's approach, the safest zone for an incision is directly over or slightly radial to Lister's tubercle to avoid injury to SBRN and lateral cutaneous nerve of the forearm. For the ulnar approach, a safe zone was shown to be on the ulnar side of the wrist around the ulnar styloid (US) when the forearm was in supination or a neutral position to avoid injury to the dorsal branch of the ulna nerve (DBUN). Care must be taken around the US due to the density of nerves and the proximity of the last motor branch of the posterior interosseous nerve to the ulnar head. This review highlighted the proximity of nerves to the three most common surgical incisions used to access the forearm. In addition, anatomical variations may exist, and each of the nerves identified as being at risk has multiple branches. Both factors increase the potential of intraoperative damage if the anatomy is not properly understood. The surgeon must adhere carefully to the established approaches to the wrist and distal forearm to minimize damage to nerves and optimize surgical outcomes for the patient.

Anatomy of the Superficial Radial Nerve and Its Target Nerves for Targeted Muscle Reinnervation: An Anatomical Cadaver Study.

BACKGROUND: Targeted muscle reinnervation (TMR) is a surgical procedure for treating symptomatic neuroma, in which the neuroma is removed and the proximal nerve stump is coapted to a donor motor branch innervating a nearby muscle. This study aimed to identify optimal motor targets for TMR of the superficial radial nerve (SRN). METHODS: Seven cadaveric upper limbs were dissected to describe the course of the SRN in the forearm and motor nerve supply-number, length, diameter, and entry points in muscle of motor branches-for potential recipient muscles. RESULTS: The radial nerve provided three (three of six) motor branches, two (two of six) motor branches, or one (one of six) motor branch to the brachioradialis muscle, entering the muscle 21.7 ± 17.9 to 10.8 ± 15 mm proximal to the lateral epicondyle. One (one of seven), two (three of seven), three (two of seven), or four (one of seven) motor branches innervated the extensor carpi radialis longus muscle, with entry points 13.9 ± 16.2 to 26.3 ± 14.9 mm distal from the lateral epicondyle. In all specimens, the posterior interosseous nerve gave off one motor branch to the extensor carpi radialis brevis, which divided into two or three secondary branches. The distal anterior interosseus nerve was assessed as a potential recipient for TMR coaptation and had a freely transferable length of 56.4 ± 12.7 mm. CONCLUSIONS: When considering TMR for neuromas of the SRN in the distal third of the forearm and hand, the distal anterior interosseus nerve is a suitable donor target. For neuromas of the SRN in the proximal two-thirds of the forearm, the motor branches to the extensor carpi radialis longus, extensor carpi radialis brevis, and brachioradialis are potential donor targets.

Pronator syndrome and anterior interosseous nerve palsy due to neurolymphomatosis: a case report.

Pronator syndrome is a median nerve entrapment neuropathy that can be difficult to diagnose due to its variable presentation and objective findings. Neurolymphomatosis is an uncommon disease in which malignant lymphocytes infiltrate central or peripheral nerve endoneurium and is often missed for prolonged periods prior to diagnosis. We present a rare case of pronator syndrome and anterior interosseous nerve palsy due to neurolymphomatosis that was occult on initial MRI in spite of the presence of a median nerve mass discovered intra-operatively during neurolysis. This case demonstrates the value of ultrasound for the examination of peripheral nerve pathology and illustrates its utility as an adjunct to MRI, in part due to the ability to screen a large region.

The 3D muscle morphology and intramuscular innervation of the digital bellies of flexor digitorum profundus: Clinical implications for botulinum toxin injection sites.

Spasticity of flexor digitorum profundus is frequently managed with botulinum toxin injections. Knowledge of the 3D morphology and intramuscular innervation of the digital bellies of flexor digitorum profundus is necessary to optimize the injections. The purpose of this study was to digitize and model in 3D the contractile and connective tissue elements of flexor digitorum profundus to determine muscle morphology, model and map the intramuscular innervation and propose sites for botulinum toxin injection. Fiber bundles (FBs)/aponeuroses and intramuscular nerve branches were dissected and digitized in 12 formalin embalmed cadaveric specimens. Cartesian coordinate data were reconstructed into 3D models as in situ to visualize and compare the muscle morphology and intramuscular innervation patterns of the bellies of flexor digitorum profundus. The 3rd, 4th and 5th digital bellies were superficial to the 2nd digital belly and located adjacent to each other in all specimens. Each digital belly had distinct intramuscular innervation patterns. The 2nd digital belly received intramuscular branches from the anterior interosseus nerve (AIN). The superior half of the 3rd digital belly was innervated intramuscularly by the ulnar nerve (n = 4) or by both the anterior interosseus and ulnar nerves (n = 1). The inferior half of the belly received dual innervation from the anterior interosseus and ulnar nerves in 2 specimens, or exclusively from the AIN (n = 2) or the ulnar nerve (n = 1). The 4th digital belly was innervated by intramuscular branches of the ulnar nerve. One main branch, after coursing through the 4th digital belly, entered the lateral aspect of the 5th digital belly and arborized intramuscularly. The morphology of the FBs, aponeuroses and intramuscular innervation of the digital bellies of FDP were mapped and modelled volumetrically in 3D as in situ. Previous studies were not volumetric nor identified the course of the intramuscular nerve branches within each digital belly. Based on the intramuscular innervation of each of the digital bellies, one possible optimized botulinum toxin injection location was proposed. This injection location, at the junction of the superior and middle thirds of the forearm, would be located in dense nerve terminal zones of the anterior interosseus and ulnar nerves. Future anatomical and clinical investigations are necessary to evaluate the efficacy of these anatomical findings in the management of spasticity.

Causes, symptoms, and treatments of nerve entrapments around the elbow: Current concepts.

The elbow is a joint extremely susceptible to stiffness, even after a trivial trauma. As for other joints, several factors can generate stiffness such as immobilisation, joint incongruity, heterotopic ossification, adhesions, or pain. Prolonged joint immobilisation, pursued to assure bony and ligamentous healing, represents the most acknowledged risk factor for joint stiffness. The elbow is a common site of nerve entrapment syndromes. The reasons are multifactorial, but peculiar elbow anatomy and biomechanics play a role. Passing from the arm into the forearm, the ulnar, median, and radial nerves run at the elbow in close rapport with the joint, fibrous arches and through narrow fibro-osseous tunnel. The elbow joint, in fact, has a large range of flexion which exposes nerves lying posterior to the axis of rotation to traction and those anterior to compression.

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.

Clinical anatomy of the lateral antebrachial cutaneous nerve: Is there any safe zone for interventional approach?

INTRODUCTION: The lateral antebrachial cutaneous nerve (LACN) is a somatosensory nerve coursing in the lateral portion of the forearm. The nerve is located in a close proximity to the cephalic vein (CV) all along its course with a danger of being injured during venipuncture. The LACN also overlaps and communicates with the superficial branch of the radial nerve (SBRN) in the distal forearm and hand, making the awareness of their relationship of great importance in the treatment of neuroma. The aim of the study was to observe the relationship of the LACN to surrounding structures as well as its branching pattern and distribution. MATERIALS AND METHODS: Ninety-three cadaveric forearms embalmed in formaldehyde were dissected. The relationship of the LACN to surrounding structures was noted and photographed, and distances between the structures were measured with a digital caliper. The cross-sectional relationships of the LACN and SBRN to the CV were described using heatmaps. RESULTS: The emerging point of the LACN was found distally, proximally or at the level of the interepicondylar line (IEL). The LACN branched in 76 cases (81.7 %) into an anterior and posterior branch at mean distance of 47.8 ± 34.2 mm distal to the IEL. The sensory distribution was described according to the relationship of the LACN branches to the medial border of the brachioradialis muscle. The LACN supplying the dorsum of the hand was observed in 39.8 % of cases. The LACN and the SBRN intersected in 86 % of upper limbs with communications noticed in 71 % of forearms. The LACN was stated as the most frequent donor of the communicating branch resulting in neuroma located distal to the communication and being fed from the LACN. The relationship of the LACN and the CV showed that the IEL is the most appropriate place for the venipuncture due to maximal calibers of the CV and deep position of the LACN. The LACN was adjacent to the cubital perforating vein and the radial artery in all cases. The medial border of the brachioradialis muscle was observed less than 1.8 mm from the LACN. CONCLUSION: The study provides morphological data on the LACN distribution, branching pattern and relationship to surrounding structures in a context of clinical use in different spheres of medicine. The branching pattern of the LACN appears to be more constant compared to data provided by previous authors. We emphasized the meaning of cross-sectional relationship of the LACN to the CV to avoid venipuncture outside the cubital fossa if possible. The posterior branch of the LACN was predicted as appropriate donor of the graft for a digital nerve. The LACN appeared to be in a close proximity within the whole length of the brachioradialis muscle what the orthopedic surgeons must be concerned of. The meaning of the donor-nerve of the communicating branch in neuroma treatment was also introduced.

Anatomical location of motor branch points in the flexor digitorum superficialis for the injection site of botulinum toxin.

OBJECTIVE: To locate the intramuscular nerve branches of the flexor digitorum superficialis (FDS) and determine the accurate site for botulinum toxin injection. DESIGN: This study anatomically dissected 24 arms of 12 fresh adult cadavers to find intramuscular nerve endings in the FDS. The motor branch points (MBPs), proximal limit points (PLPs), and distal limit points (DLPs) of the terminal intramuscular nerve endings were identified. These three parameters were expressed in longitudinal and transverse coordinates in relation to the FDS driving as a reference line. RESULTS: The mean length of the reference line was 234.6 ± 11.2 mm. In the longitudinal coordinate, the MBPs, PLPs, and DLPs were located at 41.6% (standard deviation (SD) 2.6%), 35.1% (SD 4.1%), and 53.4% (SD 4.6%) of the reference line in the first main branch and 72.4% (SD 4.5%), 67.5% (SD 1.5%), and 82.0% (SD 5.7%) in the second main branch, respectively. The mean value of the transverse coordinate was not greatly deviated from the reference line. CONCLUSION: The MBPs of the first and second main branches are located approximately 41.6% and 72.4% of the reference line, which considers the FDS direction, respectively. This finding helps determine the optimal injection site for botulinum toxin in the FDS.

Persistent Hourglass Constriction in Recovered Anterior Interosseous Nerve Palsy Due to Neuralgic Amyotrophy: A Case Report.

The current articles recommended the interfascicular neurolysis for anterior interosseous nerve (AIN) palsy with hourglass-like fascicular constrictions (FCs) detected by ultrasonography or surgical exploration to realign to the fascicular torsion for those who failed to recover spontaneously. We present the case report of spontaneous AIN palsy recovered after conservative treatment; however, ultrasonographic findings showed persistent FCs of AIN in the arm at the beginning, at 6 weeks, and subsequent 3-year follow-ups, even after complete clinical recovery of palsy. This finding calls into question the current notion that AIN paralysis is due to FCs and that neurolysis is the best surgical treatment when spontaneous recovery does not occur for a considerable observation period. Level of Evidence: Level V (Therapeutic).

Ultrasonographic examination of the safe zone for medial needle approach towards the median-innervated flexor digitorum profundus muscle: Effect of changes in position of the forearm.

The flexor digitorum profundus (FDP) is a forearm flexor muscle. Certain cases require the needle to be inserted accurately and safely into the deep, lateral portion of the FDP, which is innervated by the anterior interosseous nerve. In this study, we compared 2 techniques for approaching the median-innervated FDP (MFDP) medially, each according to the position of the forearm, supinated or pronated. The forearms of healthy volunteers without any musculoskeletal problems of the upper extremities were examined. Using high-resolution ultrasonography, the medial aspects of the forearms were scanned with elbows flexed at 90°. Using the images obtained, several parameters for distance and angle were measured in 2 different positions: forearm-supinated and forearm-pronated. Thirty-seven forearms from the volunteers were subject to examination. The angle α, which is the valid angle of insertion when approaching with the needle towards the deeply located MFDP, slightly increased from 22.89° to 23.41° when the forearm was pronated from the supinated position; however, this increase was not statistically significant. In contrast, the angle ß, which is the safe angle of insertion when approaching with the needle towards the MFDP without contacting the ulnar nerve, was significantly increased from 41.40° to 46.80° upon forearm pronation. Because the safe angle of insertion of the needle medially into the MFDP increases with forearm pronation, the forearm-pronated position is recommended, instead of the forearm-supinated position, when inserting a needle into the MFDP in the medial aspect of the forearm.

[Value of High-Frequency Ultrasound in the Diagnosis of Pronator Teres Syndrome].

Objective To investigate the clinical value of high-frequency ultrasound in the diagnosis of pronator teres syndrome (PTS). Methods The high-frequency ultrasound was employed to examine and measure the median nerve of the pronator teres muscle in 30 patients with PTS and 30 healthy volunteers (control group).The long-axis diameter (LA),short-axis diameter (SA) and cross-sectional area (CSA) of the median nerve were measured.The receiver operating characteristic curve of the median nerve ultrasonic measurement results was established,and the area under the curve (AUC) was calculated.The diagnostic efficiency of each index for PTS was compared with the surgical results as a reference. Results The PTS group showed larger LA[(5.02±0.50) mm vs.(3.89±0.41) mm;t=4.38,P=0.013],SA[(2.55±0.46) mm vs.(1.70±0.41) mm;t=5.19,P=0.009],and CSA[(11.13±3.72) mm2 vs.(6.88±2.68) mm2;t=8.42,P=0.008] of the median nerve than the control group.The AUC of CSA,SA,and LA was 94.3% (95%CI=0.912-0.972,Z=3.586,P=0.001),77.7% (95%CI=0.734-0.815,Z=2.855, P=0.006),and 78.8% (95%CI=0.752-0.821,Z=3.091,P=0.004),respectively.With 8.63 mm2 as the cutoff value,the sensitivity and specificity of CSA in diagnosing PTS were 93.3% and 90.0%,respectively. Conclusion High-frequency ultrasound is a practical method for diagnosing PTS,and the CSA of median nerve has a high diagnostic value.

Factors affecting functional outcomes after surgery to repair extensive volar forearm lacerations with nerve injuries identified via quantitative and qualitative methods.

OBJECTIVES: We aimed to investigate factors affecting the functional outcomes of patients with extensive volar forearm lacerations combined with nerve injuries who underwent surgery. PATIENTS AND METHODS: Between January 2012 and December 2018, a total of 71 patients (58 males, 13 females; mean age: 41±12.1 years; range, 20 to 66 years) with extensive volar forearm lacerations treated in our center were retrospectively analyzed. Demographic data and injury details of the patients were recorded. The functional results were quantitatively evaluated using the Rosén-Lundborg protocol (RLP) and qualitatively evaluated using the Quick Disability of Arm, Shoulder, and Hand (QuickDASH) scale. RESULTS: The mean follow-up time 69.8±36.7 (range, 18 to 148) months. The mean final RLP and QuickDASH scores were 2.17±0.4 and 8.03±10.55, respectively. There were no major complications such as infection, necrosis, re-rupture of a structure, or amputation. Patients with combined median and ulnar nerve injuries had poorer RLP scores than the others. Patients with combined median and ulnar nerve injuries, combined radial and ulnar arterial injuries, and who were of low education status, had lower QuickDASH scores than the others. CONCLUSION: The main factors affecting long-term functional outcomes are a combined artery or nerve injury and a low education status. Favorable results can be achieved with the cooperation of experienced surgeons and hand rehabilitation specialists for patients with severe hand injuries.

Proximal forearm nerve branching patterns: an anatomical study and its clinical significance.

OBJECTIVE: The aim of this study was to add to the understanding of nerve branching patterns in the proximal forearm and consider optimal nerve transfer options to address the various injuries that affect the function of the upper extremity. METHODS: Eleven upper-extremity cadaveric specimens were dissected to expose the radial, median, and ulnar nerves in the proximal forearm. The site of origin of nerve branches from the major nerves was assessed, with measurements made in reference to the lateral epicondyle for the radial nerve branches and the medial epicondyle for the median and ulnar nerve branches. The distances to where these branches entered their respective muscles (muscle entry point) were assessed using the same landmarks. To plan a transfer, the length of the nerve branches was then calculated as the difference from the apparent origin from the main nerve trunk to the location where the nerve entered the muscle. Importantly, the nerve branch origin was established as the location of obvious separation from the main nerve trunk without additional fascicular dissection from the major nerve trunk. The number of branches was determined, and the diameter for each branch was measured using a Vernier caliper. RESULTS: The radial nerve branch to the extensor carpi radialis brevis (ECRB) muscle had an average length of 50.7 mm and average diameter of 1.6 mm. The mean medial and lateral lengths of the radial branches to the supinator muscle were found to be 22.2 mm (diameter 1.4 mm) and 15.3 mm (diameter 1.3 mm), respectively. The anterior interosseous nerve (AIN) branch of the median nerve was found 67.8 mm distal to the medial epicondyle with a diameter of 2.3 mm. The flexor carpi ulnaris (FCU) muscle innervation from the ulnar nerve was provided by 3 or 4 branches in most specimens. The second and third of these branches were the longest, with means of 30.5 mm (diameter 1.4 mm) and 30.7 mm (diameter 1.3 mm), respectively. CONCLUSIONS: While there is variability of the nerve branching pattern in the proximal forearm between specimens, the authors provide evidence of commonalities (branching patterns and distances) that can facilitate planning for upper-extremity nerve reconstructions. Importantly, all measurements are provided with reference to easily identified bony landmarks and to their muscle entry points to aid operative decision-making. These data complement the growing practice of nerve transfers in the upper extremity for a variety of pathologies.

Avoiding the posterior interosseous nerve during 2-incision distal biceps tendon repair: an anatomic study.

BACKGROUND: The posterior interosseous nerve (PIN) is the most commonly injured motor nerve during distal biceps tendon repair resulting in severe functional deficits. Anatomic studies of distal biceps tendon repairs have evaluated the proximity of the PIN to the anterior radial shaft in supination, but limited studies have evaluated the location of the PIN in relation to the radial tuberosity (RT), and none have examined its relation to the subcutaneous border of the ulna (SBU) with varying forearm rotation. This study evaluates the location of the PIN in relation to the RT and SBU to help guide surgeons in safe placement of the dorsal incision and the safest zones of dissection. METHODS: The PIN was dissected from arcade of Frohse to 2 cm distal to the RT in 18 cadaver specimens. Four lines were drawn perpendicular to the radial shaft at the proximal, middle, and distal aspect of and 1 cm distal to the RT in the lateral view. Measurements were recorded with a digital caliper along these lines to quantify the distance between the SBU and RT to the PIN with the forearm in neutral, supination, and pronation with the elbow at 90° flexion. Measurements were also made along the length of the radius at the volar, middle, and dorsal surfaces at the distal aspect of the RT to assess its proximity to the PIN. RESULTS: Mean distances to the PIN were greater in pronation than supination and neutral. The PIN crossed the volar surface of the distal aspect of the RT -6.9 ± 4.3 mm (-13, -3.0) in supination, -0.4 ± 5.8 mm (-9.9, 2.5) in neutral, and 8.5 ± 9.9 mm (-2.7, 13) in pronation. One centimeter distal to the RT, mean distance to the PIN was 0.54 ± 4.3 mm (-4.5, 8.8) in supination, 8.5 ± 3.1 mm (3.2, 14) in neutral, and 10 ± 2.7 mm (4.9, 16) in pronation. In pronation, mean distances from the SBU to the PIN at points A, B, C, and D were 41.3 ± 4.2, 38.1 ± 4.4, 34.9 ± 4.2, and 30.8 ± 3.9 mm, respectively. CONCLUSION: PIN location is quite variable, and to avoid iatrogenic injury during 2-incision distal biceps tendon repair, we recommend placement of the dorsal incision no more than 25 mm anterior to the SBU and carrying out deep dissection proximally first to identify the RT before continuing the dissection distally to expose the tendon footprint. The PIN was at risk of injury along the volar surface at the distal aspect of the RT in 50% with neutral rotation and 17% with full pronation.

The communication patterns between the lateral antebrachial cutaneous nerve and the superficial branch of the radial nerve.

INTRODUCTION: The superficial branch of the radial nerve (SBRN) and the lateral antebrachial cutaneous nerve (LACN) are sensory nerves coursing within the forearm in a close relationship. This high degree of overlap and eventual communication between the nerves is of great surgical importance. The aim of our study is to identify the communication pattern and overlap of the nerves, to localize the position of this communication in relation to a bony landmark, and to specify the most common communication patterns. MATERIALS AND METHODS: One hundred and two adult formalin-fixed cadaveric forearms from 51 cadavers of Central European origin were meticulously dissected. The SBRN, as well as the LACN, were identified. The morphometric parameters concerning these nerves, as well as their branches and connections, were measured with a digital caliper. RESULTS: We have described the primary (PCB) and secondary communications (SCB) between the SBRN and the LACN and their overlap patterns. One hundred and nine PCBs were found in 75 (73.53%) forearms of 44 (86.27%) cadavers and fourteen SCBs in eleven hands (10.78%) of eight cadavers (15.69%). Anatomical and surgical classifications were created. Anatomically, the PCBs were classified in three different ways concerning: (1) the role of the branch of the SBRN within the connection; (2) the position of the communicating branch to the SBRN; and (3) the position of the LACN branch involved in the communication to the cephalic vein (CV). The mean length and width of the PCBs were 17.12 mm (ranged from 2.33 to 82.96 mm) and 0.73 mm (ranged from 0.14 to 2.01 mm), respectively. The PCB was located proximally to the styloid process of the radius at an average distance of 29.91 mm (ranged from 4.15 to 97.61 mm). Surgical classification is based on the localization of the PCBs to a triangular zone of the SBRN branching. The most frequent branch of the SBRN involved in the communication was the third (66.97%). Due to the frequency and position of the PCB with the third branch of the SBRN, the danger zone was predicted. According to the overlap between the SBRN and the LACN, we have divided 102 forearms into four types: (1) no overlap; (2) present overlap; (3) pseudo-overlap; and (4) both present and pseudo-overlap. Type 4 was the most common. CONCLUSION: The patterns of communicating branch arrangements appeared to be not just a rare phenomenon or variation, but rather a common situation highlighting clinical importance. Due to the close relationship and connection of these nerves, there is a high probability of simultaneous lesion.