Ulnar nerve dislocation and snapping triceps syndrome: diagnosis with dynamic sonography--report of three cases

Ultrasound of the Ulnar Nerve: A Pictorial Review: Part 2: Pathological Ultrasound Findings

This is the second part of a two-part article in which we focus on the ultrasound (US) appearance of the pathological ulnar nerve (UN) and its main branches. Findings in a wide range of our pathological cases are presented with high-resolution US images obtained with the latest-generation US machines and transducers.

Cubital tunnel syndrome: anatomy, pathology, and imaging

Cubital tunnel syndrome (CuTS) is the second most common peripheral neuropathy in the upper limb. It occurs due to ulnar nerve compression within the fibro-osseous cubital tunnel at the elbow joint. Although CuTS is typically diagnosed clinically and with electrodiagnostic studies, the importance of imaging in evaluating the condition is growing. Knowing the typical imaging findings of ulnar nerve entrapment is necessary for precise diagnosis and proper treatment. In this article, we focus on the clinical features, workup and complex imaging of the "anatomic" cubital tunnel and relevant pathological entities.

A pictorial guide for performing dynamic musculoskeletal ultrasound techniques of the Upper Limb

INTRODUCTION

Dynamic techniques should be used to compliment static imaging in the field of Musculoskeletal ultrasound. Performing limb movements and imaging simultaneously, allows for diagnosing certain musculoskeletal conditions not otherwise confirmed by still images. This article aims to provide guidance on how to perform a selection of these dynamic musculoskeletal ultrasound techniques with a focus on the upper limb.

METHODS

This pictorial guide features techniques gathered from literature review and experience gained in the field.

RESULTS

Application of dynamic ultrasound techniques has been evidenced in the literature to diagnose conditions such as trigger finger, dislocating tendons and causes of peripheral neuropathy.

CONCLUSION

Musculoskeletal conditions only elicited during limb movement can be difficult to diagnose. Appropriate use of dynamic techniques increases likelihood of correct diagnosis of the described conditions.

IMPLICATIONS FOR PRACTICE

Ultrasound provides a unique opportunity to visualise these conditions thus ultrasound users should aim to familiarise themselves with dynamic ultrasound techniques to improve patient outcomes.

Snapping Triceps Syndrome: Surgical Technique

Snapping triceps syndrome is a rare cause of medial elbow pain and ulnar neuritis caused by subluxation and triggering of the medial tricipital muscle belly over the medial distal humeral ridge and condyle. The diagnosis and surgical management of snapping triceps syndrome can be challenging due to the subtlety of the symptoms and the infrequent presentation. Despite the diagnosis relying largely on clinical examination, noninvasive dynamic ultrasonography may facilitate detection. Correct recognition of this condition is crucial in the avoidance of surgical misadventure and revision surgery. This paper illustrates our surgical technique for the management of snapping triceps and reviews the available literature on this relatively obscure condition.

Pediatric musculoskeletal ultrasound

Musculoskeletal (MSK) ultrasound is an exciting area of growth for pediatric radiology. It is very well suited for pediatrics as it has no radiation, needs no intravenous contrast or sedation, is painless, and parents are present during the exam for comfort. Many diagnoses that are traditionally made with CT and MRI can be confidently made with ultrasound. In fact, ultrasound is often more helpful than MRI in a growing number if indications. Gaining an understanding and appreciation for pediatric MSK ultrasound will give pediatric radiologists a very useful diagnostic tool to benefit their patients. After the explosion of MSK ultrasound in adult imaging, it is a natural progression of this modality for the pediatric population.

Physical Examination Versus Ultrasonography for Detection of Ulnar Nerve Subluxation in Professional Baseball Pitchers

Background

Despite the importance of accurately detecting ulnar nerve subluxation in vulnerable athletes, few studies have compared the performance of physical examination and ultrasound in this population.

Purpose/Hypothesis

The purpose of this study was to compare the diagnostic validity of physical examination versus ultrasound in detecting ulnar nerve subluxation at the cubital tunnel of the elbow in professional baseball pitchers. It was hypothesized that ultrasound would more sensitively detect ulnar nerve subluxation.

Study Design

Cohort study (diagnosis); Level of evidence, 2.

Methods

Physical and sonographic examinations for ulnar nerve subluxation were performed on 186 elbows of 95 consecutive male professional baseball pitchers (age, 17-30 years) as a routine part of their spring training assessments. Provocative maneuvers consisting of the Tinel and elbow flexion-compression tests were evaluated over the cubital tunnel. The validity of physical examination for detecting ulnar nerve subluxation at the elbow was determined using ultrasonographic examination for comparison.

Results

Ulnar nerve subluxation was detected by physical examination in 58 (31.2%) elbows and by ultrasonography in 61 (32.8%) elbows. Of the 58 elbows with positive physical examination, 47 were positive on ultrasound. Using a positive ultrasound as a reference, the accuracy of the physical examination was 86.6%, with 77% sensitivity and 91.2% specificity. The positive and negative predictive values of physical examination were 81% and 89.1%, respectively. There was no relationship between nerve instability and positive provocative tests overall, in dominant versus nondominant arms, or in right versus left arms (P > .05 for all).

Conclusion

Physical examination had moderate sensitivity and high specificity for detecting ulnar nerve subluxation at the cubital tunnel of the elbow when compared with ultrasound. These findings suggest that when detecting the presence of a subluxating ulnar nerve is most important, it may be advisable to obtain an ultrasound evaluation instead of relying on a physical examination; however, physical examination alone may be appropriate for ruling out subluxation.

Intraoperative Biceps/Brachialis Stimulation for Snapping Triceps With Ulnar Neuritis

BACKGROUND AND IMPORTANCE

Snapping of the triceps muscle occurs when a portion of the medial head dislocates over the medial epicondyle with elbow flexion. Resection or redirection of a portion of the triceps muscle is the main surgical treatment. The extent of triceps resection/redirection is difficult to evaluate. A novel intraoperative technique, stimulating the musculocutaneous nerve, to simulate active elbow flexion is proposed to help ensure that the snapping triceps has been adequately treated.

CLINICAL PRESENTATION

A patient presented with a several year history of bilateral elbow pain, snapping, and ulnar nerve (UN) paresthesias. Previous staged bilateral subcutaneous UN transpositions were performed at another institution for documented UN dislocation and neuritis. Postoperatively symptoms of painful snapping persisted. Bilateral snapping triceps was diagnosed. The left elbow was reoperated. Intraoperative electrical stimulation of the musculocutaneous nerve was performed to reproduce the snapping triceps. Activation of the biceps/brachialis muscles produced powerful elbow flexion, allowed direct visualization of the forceful snapping triceps, and helped assess the adequacy of muscle resection/redirection.

CONCLUSION

Intraoperative biceps/brachialis stimulation can potentially help determine how much triceps muscle should be resected/redirected to treat patients with snapping triceps.

Hearing and Seeing Nerve/Tendon Snapping: A Systematic Review on Dynamic Ultrasound Examination

Nerve/tendon snapping can occur due to their sudden displacement during the movement of an adjacent joint, and the clinical condition can really be painful. It can actually be challenging to determine the specific anatomic structure causing the snapping in various body regions. In this sense, ultrasound examination, with all its advantages (especially providing dynamic imaging), appears to be quite promising. To date, there are no comprehensive reviews reporting on the use of dynamic ultrasound examination in the diagnosis of nerve/tendon snapping. Accordingly, this article aims to provide a substantial discussion as to how US examination would contribute to 'seeing' and 'hearing' these pathologies' different maneuvers/movements.

Ultrasound of peripheral nerve injury

Nerve injury in children is important to recognize early given the greater chance for recovery. Both children and adults have better outcomes the sooner nerve injuries are recognized and repaired. Children have even better functional results after surgical repair, thought to be related to their neural plasticity. Ultrasound is a powerful diagnostic tool for grading and mapping peripheral nerve injury and is complementary to electromyography and nerve conduction studies. Nerve injuries can be classified into low and high grade with ultrasound adding essential prognostic information and aiding in patient management. High-grade nerve injuries likely require surgical intervention. This article will review nerve anatomy and injury grading systems that radiologists can learn quickly in order to accurately communicate with their clinical partners. A practical approach to describe the sonographic appearance of nerve injury will be discussed. This article will show radiologists how the added value of ultrasound for peripheral nerve injury can directly affect clinical management.

Acute and Chronic Elbow Disorders

Elbow pain is very common and can be due to many pathologic conditions. After radiographs are obtained, advanced imaging is often necessary. Both ultrasonography and MR imaging can be used to evaluate the many important soft-tissue structures of the elbow, with each modality having advantages and disadvantages in certain clinical scenarios. Imaging findings between the two modalities often correlate. It is important for musculoskeletal radiologists to understand normal elbow anatomy and how best to use ultrasonography and MR imaging to evaluate elbow pain. In this way, radiologists can provide expert guidance to referring clinicians and best guide patient management.

Ultrasonographic features of ulnar nerve instability around the elbow in fresh cadavers

Ultrasound (US) is commonly used to evaluate ulnar nerve instability (UNI) and snapping of the medial head of the triceps brachii muscle (ST). We aimed to determine the diagnostic accuracy of US in evaluating UNI, through cadaveric dissection, and to evaluate the US features and relationships of UNI and ST according to elbow flexion. Dynamic US was performed with elbow extension, 90° flexion, and full flexion positions on 18 elbows from 9 fresh cadavers. UNI was classified into N (normal), S (subluxation), and D (dislocation) types. On US exams, the following findings and parameters were evaluated: the presence of UNI and ST; the horizontal distance from the apex of the medial epicondyle (ME) to the margins of the UN and medial head of the triceps brachii muscle (ME_UN and ME_TB, respectively); cross-sectional area and flattening ratio (FR) of UN. After US, all cadavers were dissected to expose the UN and TB, and elbow flexion and extension were simulated to confirm UNI and ST. The gross anatomic findings of UNI and ST were consistent with the US findings. In extension and 90° flexion positions, all cases were type N. In full flexion position, types N and S occurred in 10 (56%) and 8 (44%) elbows, respectively. FR and ME_UN in 90° flexion position, FR, ME_UN, and ME_TB in full flexion position differed significantly between types S and N. Positive correlations were found between ME_UN and ME_TB in 90° flexion and full flexion positions. Dynamic US accurately assessed UNI and ST. UNI was positively correlated to medial TB movement.

ACR Appropriateness Criteria® Chronic Elbow Pain

Chronic elbow pain can be osseous, soft tissue, cartilaginous, and nerve related in etiology. Imaging plays an important role in differentiating between these causes of chronic elbow pain. This document provides recommendations for imaging of chronic elbow pain in adult patients. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

The prevalence of the anatomical variation in a Turkish population: supernumerary muscle-anconeus epitrochlearis

INTRODUCTION

The anconeus epitrochlearis (AE) muscle is an accessory muscle located between the medial cortex of the olecranon and the inferior surface of the medial epicondyle, posterior to the ulnar nerve. This muscle may compress the ulnar nerve causing a clinical neuropathy. We aimed to determine the gender and side characteristics of the AE muscle in patients who underwent elbow magnetic resonance imaging (MRI) and report its prevalence in a Turkish population.

MATERIALS AND METHODS

A total of 209 patients (210 elbows) who underwent elbow MRI between January and December 2020 were retrospectively evaluated. Cases with the AE muscle were included in the study. The craniocaudal (CC) dimension was examined from the coronal section, and the transverse (TR) and anteroposterior (AP) dimensions from the axial sections. Statistical analyses were performed to determine the relationship between the presence of the AE muscle and age, gender, and side (right/left). Differences between sexes and sides in terms of muscle sizes were evaluated using statistical tests.

RESULTS

The AE muscle was detected in 17 patients (18 elbows) (8.1%). The mean age of the patients was 41.52 ± 14.63 years. There was no statistically significant difference between the male and female patients in terms of age. This accessory muscle was found in nine female (9.8%) and eight male (6.3%) patients in total. There was one (0.5%) patient with the bilateral AE muscle, who was female. The accessory muscle was located in the right elbow in 13 patients (10.71%), and left elbow in five (4.10%). It was more common in the right elbow in both genders. The muscle was larger in the male patients and the right elbow, but this was not statistically significant.

CONCLUSION

The prevalence of the AE muscle was determined to be 8.1% in a Turkish population, and this muscle was more common among the women and in the right elbow.

Regenerative medicine for neuropathic pain: physiology, ultrasound and therapies with a focus on alpha-2-macroglobulin

The currently available drugs to treat neuropathic pain do not provide adequate pain management. As such, other treatments including stem cells, platelet-rich plasma and plasma-derived molecules such as alpha-2 macroglobulin (A2M) are being explored because they show promising potential for neuropathic pain. The various mechanisms and immunomodulatory effects could be a desirable approach in targeting neuropathic pain. This review indicates that A2M can be highly efficacious due to its conformational change during activation and specificity of action on various cytokines. Its ability to reduce neuropathic pain can further the future of neuropathic intervention. However, there is a lack of robust clinical studies and thus further research is needed to verify and expand the understanding of its therapeutic effects.

Mass effect of the distal triceps brachii muscle on ulnar nerve movement during elbow flexion

INTRODUCTION/AIMS

Hypertrophic triceps brachii contributes to ulnar nerve movement, but the location of the mass effect of the triceps brachii muscle is not known This study aimed to investigate mass effect of distal medial head of the triceps brachii (DMTB) muscle on ulnar nerve movement.

METHODS

In 48 arms, the movement of the ulnar nerve at the medial epicondyle and muscle thickness (the medial and long head of the triceps brachii [MLTB], medial head of the triceps brachii [MTB], DMTB, and the biceps brachii [BB]) were measured using ultrasonography.

RESULTS

Ulnar nerve movement at the elbow was consistently correlated with the DMTB muscle thickness (horizontal ulnar nerve movement at the elbow [HM]/vertical ulnar nerve movement at the elbow [VM] with 90-degree elbow flexion: r=0.668/r=0.313, HM/VM with full elbow flexion: r=0.481/r=0.391). With multiple linear regression, the DMTB was the most important muscle with regard to the contribution of thickness to ulnar nerve movement. Individuals with partial and complete dislocation showed a thicker DMTB than those without dislocation.

DISCUSSION

Our data suggest that the mass effect of the triceps brachii muscle is exerted primarily by its distal portion. When ulnar nerve dislocation is observed, thickness and anatomical variation of DMTB in the retrocondylar area during elbow flexion should be assessed.

Possible points of compression of the ulnar nerve: Tricks and traps that await clinicians from an anatomical point of view

The ulnar nerve can be subject to numerous types of compression. The most common are cubital tunnel and ulnar tunnel syndromes, but there are many others with more uncommon etiologies. The existence of additional communicating branches, median nerve involvement, various types of injuries, and unusual anatomical variations can be a challenge for both diagnosis and treatment. This review presents a comprehensive depiction of ulnar nerve entrapment syndromes with particular reference to their anatomical background, risk factors, and clinical evaluation. Even common disorders can result from atypical morphological changes. It is important to be familiar with them as it is a key ability in daily medical practice.

Ultrasound in Sports Injuries

Utilization of musculoskeletal ultrasound, in particular for sports medicine, has dramatically increased in recent years. Ultrasound is an important adjunct tool to physical examination and other imaging methods in the evaluation and management of the injured athlete. It offers unique advantages in specific clinical scenarios. Dedicated training and a standardized scanning technique are important to overcome the inherent operator dependence and avoid diagnostic pitfalls. Ultrasound guidance can also improve accuracy in targeted percutaneous injection therapies. This article reviews the general ultrasound appearance of muscle, tendon, ligament, and nerve abnormalities in the athlete with a focus on sport-specific injuries.

Problem Solved: Integral Applications of Musculoskeletal Ultrasound

Musculoskeletal ultrasound has grown substantially in use over the past several years as an indispensable companion to magnetic resonance imaging and other imaging modalities. This article reviews 10 integral applications of musculoskeletal ultrasound as a problem-solving tool with correlative case examples. These applications include the following: (1) accessibility and portability, (2) targeted imaging, (3) dynamic imaging, (4) contralateral comparison, (5) Doppler imaging, (6) increased spatial resolution, (7) solid versus cystic comparison, (8) posttraumatic imaging, (9) postsurgical imaging, and (10) treatment delivery and optimization. The review will help the radiologist recognize the complementary uses of musculoskeletal ultrasound with radiography, computed tomography, and magnetic resonance imaging.

Ulnar Nerve Dislocation and Subluxation from the Cubital Tunnel Are Common in College Athletes

Background: Hypermobility of the ulnar nerve from the cubital tunnel reportedly occurs in healthy people without symptoms of ulnar neuropathy. However, the occurrence rate in athletes is unknown. We examined the occurrence rate of ulnar nerve hypermobility using ultrasonography, symptoms, and physical findings in athletes and compared the results of four types of sports. Methods: Medical charts of college athletes competing in baseball, rugby, soccer, and long-distance running between March and November 2018 were retrospectively examined. Dynamic evaluation of the ulnar nerve was performed using ultrasonography and categorized as Types N, S, and D respectively, indicating normal position, subluxation, and dislocation. Subjective and objective findings were evaluated. Results: The present study included 246 male athletes (mean age, 19.7 years; 492 elbows) including 46% Type D, 29.8% Type S, and 24.2% Type N. Subjective findings showed pain and dysesthesia in 9% and 4.5% of participants, respectively, whereas objective findings showed Tinel sign in 6%, nerve tension test in 1.3%, Froment’s sign in 0.5%, and weakness of strength of opponens digiti minimi muscle in 8% of patients with Types D and S. Conclusions: There was a high-frequency hypermobility of the ulnar nerve from the cubital tunnel with or without subjective and objective findings in college athletes.

Nerve entrapment around elbow

Entrapment neuropathy around elbow is a common cause of disability across all age groups. The major nerves that traverse the elbow are ulnar, median and radial nerves and their branches. Cubital tunnel syndrome leading to ulnar nerve compression can often present with significant pain, paresthesia or weakness. Median and Radial nerve compression around the elbow, albeit less frequent, can also lead to significant morbidity and must be kept in the differential diagnosis when dealing with patients complaining of persistent pain around the elbow and weakness of forearm/hand muscles. Electrodiagnostic studies can be a useful adjunct to clinical examination, to help localize the site and quantify the grade of compression. Management should involve a trial of conservative treatment and failing that, surgical treatment should be considered. We hereby provide an overview of nerve entrapments around the elbow including their applied anatomy, etiology, clinical assessment and overview of the current concepts in surgical treatment.

Distal insertional anatomy of the triceps brachii muscle: MRI assessment in cadaveric specimens employing histologic correlation and Play-doh® models of the anatomic findings

OBJECTIVES

Assess the insertional anatomy of the distal aspect of the triceps brachii muscle using magnetic resonance imaging (MRI) in cadavers with histologic correlation and Play-doh^® models of the anatomic findings.

MATERIALS

Elbows were obtained from twelve cadaveric arm specimens by transverse sectioning through the proximal portion of the humerus and the midportion of the radius and ulna. MRI was performed in all elbows. Two of the elbow specimens were then dissected while ten were studied histologically. Subsequently, Play-doh^® models of the anatomic findings of the distal attachment sites of the triceps brachii muscle were prepared.

RESULTS

MRI showed a dual partitioned appearance of the distal attachment sites into the olecranon in all specimens. In the deeper tissue planes, the medial head muscle insertion was clearly identified while superficially, the terminal portion of the long and lateral heads appeared as a conjoined tendon. Histologic analysis, however, showed continuous tissue rather than separate structures attaching to the olecranon.

CONCLUSION

Although MRI appeared to reveal separate and distinct attachments of the triceps brachii muscle into the olecranon, histologic analysis delineated complex but continuous tissue related to the attachments of the three heads of this muscle. The Play-doh^® models were helpful for the comprehension of this complex anatomy and might serve as a valuable educational tool when applied to the analysis of other musculoskeletal regions.

Ulnar nerve subluxation and dislocation: a review of the literature

The pathogenesis of ulnar nerve subluxation and dislocation is widely debated. Upon elbow flexion, the ulnar nerve slips out of the groove for the ulnar nerve, relocates medial or anterior to the medial epicondyle, and returns to its correct anatomical position upon extension. This chronic condition can cause neuritis or neuropathy; however, it has also been suggested that it protects against neuropathy by reducing tension along the nerve. This article reviews the extant literature with the aim of bringing knowledge of the topic into perspective and standardizing terminology.

Ultrasound Measurements and Assessments of the Ulnar Nerve at the Elbow and Cubital Tunnel: A Scoping Review

Ulnar neuropathy at the elbow (UNE) is the second most frequent peripheral nerve entrapment neuropathy in the upper extremity. The diagnosis is determined through a combination of history, physical examination, and electrodiagnostic testing. However, the use of high-resolution sonography is increasing, with sonographic measurements of ulnar nerve dimension established as a reliable diagnostic criterion for UNE. Sonographic imaging can describe anatomical features beyond ulnar nerve size, and therefore additional observations could potentially be used in UNE diagnosis and treatment follow-up. This review was a scoping of the literature on different sonographic measurements and assessments that have been reported to evaluate the ulnar nerve and cubital tunnel. This should provide a guide to scanning protocols for sonographers.

Retrospective study on the impact of ulnar nerve dislocation on the pathophysiology of ulnar neuropathy at the elbow

Introduction

High resolution ultrasonography (US) has been used for diagnosis and evaluation of entrapment peripheral neuropathy. Ulnar neuropathy at the elbow (UNE) is the second most common focal entrapment neuropathy. The ulnar nerve tends to move to the anteromedial side and sometimes subluxates or dislocates over the medial epicondyle as the elbow is flexed. Dislocation of the ulnar nerve during elbow flexion may contribute to friction injury. We aimed to investigate the effects which the dislocation of ulnar nerve at the elbow could have on the electrophysiologic pathology of UNE.

Materials

We retrospectively reviewed 71 arms of UNE. The demographic data, electrodiagnosis findings and US findings of ulnar nerve were analyzed. We classified the electrodiagnosis findings of UNE into three pathologic types; demyelinating, sensory axonal loss, and mixed sensorimotor axonal loss. The arms were grouped into non-dislocation, partial dislocation, and complete dislocation groups according to the findings of nerve dislocation in US examination. We compared the electrodiagnosis findings, ulnar nerve cross sectional areas in US and electrodiagnosis pathology types among the groups.

Results

A total of 18 (25.3%) arms showed partial dislocation, and 15 (21.1%) arms showed complete dislocation of ulnar nerve in US. In the comparison of electrodiagnosis findings, the partial and complete dislocation groups showed significantly slower conduction velocities and lower amplitudes than non-dislocation group in motor conduction study. In the sensory conduction study, the conduction velocity was significantly slower in partial dislocation group and the amplitude was significantly lower in complete dislocation group than non-dislocation group. In the comparison of US findings, patients in partial and complete dislocation groups showed significantly larger cross sectional areas of the ulnar nerve. The comparison of electrodiagnosis pathologic types among the groups revealed that there were significantly larger proportions of the axonal loss (sensory axonal loss or mixed sensorimotor axonal loss) in partial and complete dislocation groups than non-dislocation group.

Conclusion

The ulnar nerve dislocation could influence on the more severe damage of the ulnar nerve in patients with UNE. It might be important to evaluate the dislocation of the ulnar nerve using US in diagnosing ulnar neuropathy for predicting the prognosis and determining the treatment direction of UNE.

Indications for neuromuscular ultrasound: Expert opinion and review of the literature

Over the last two decades, dozens of applications have emerged for ultrasonography in neuromuscular disorders. We wanted to measure its impact on practice in laboratories where the technique is in frequent use. After identifying experts in neuromuscular ultrasound and electrodiagnosis, we assessed their use of ultrasonography for different indications and their expectations for its future evolution. We then identified the earliest papers to provide convincing evidence of the utility of ultrasound for particular indications and analyzed the relationship of their date of publication with expert usage. We found that experts use ultrasonography often for inflammatory, hereditary, traumatic, compressive and neoplastic neuropathies, and somewhat less often for neuronopathies and myopathies. Usage significantly correlated with the timing of key publications in the field. We review these findings and the extensive evidence supporting the value of neuromuscular ultrasound. Advancement of the field of clinical neurophysiology depends on widespread translation of these findings.

Is triceps hypertrophy associated with ulnar nerve luxation?

INTRODUCTION

The mechanism of ulnar nerve luxation is unclear, but the triceps brachii muscle may be a contributing factor. Therefore, we explored whether hypertrophy of the triceps brachii muscle is more frequently accompanied by nerve luxation.

METHODS

In this investigation we used a cross-sectional design to study a group of amateur bodybuilders (n = 31) in a comparison with a group of age-matched healthy controls (n = 31). Triceps hypertrophy was determined clinically and sonographically. The position of the ulnar nerve in relation to the medial epicondyle was classified according to a graded (0-4) scale.

RESULTS

In full flexion of 62 hypertrophic arms, 22 (35.5%) revealed subluxation and 27 (43.5%) complete luxation. In the controls, 21 (33.9%) demonstrated subluxation and 10 (16.1%) complete luxation.

DISCUSSION

The higher frequency of ulnar nerve luxation in arms with hypertrophic triceps indicates that triceps muscle mass may be a factor contributing to ulnar nerve luxation. Muscle Nerve 58: 523-527, 2018.

Snapping at the Lateral Aspect of the Elbow: A Case Report and Review of the Literature

CASE

A 59-year-old man presented with snapping at the lateral aspect of the elbow and associated pain. Magnetic resonance imaging demonstrated extensor tendinopathy and thickening of the radial collateral ligament. Ultrasonography showed entrapment of a synovial fold in the radiohumeral joint. Initial arthroscopic debridement did not alleviate the snapping. Three months later, the patient underwent open excision of a thickened and partially torn annular ligament; subsequently, all of the symptoms resolved.

CONCLUSION

Snapping elbow is a phenomenon that often coincides with pain and limited function. Accurate diagnosis is critical because misdiagnosis has been demonstrated to have serious consequences, including the need for repeat surgery.

Snapping elbow-A guide to diagnosis and treatment

AIM

To develop practical guidelines for diagnosis and treatment of the painful snapping elbow syndrome (SE).

METHODS

Clinical studies were searched in the databases PubMed and Scopus for the phrases “SE”, “snapping triceps”, “snapping ulnar nerve” and “snapping annular ligament”. A total of 36 relevant studies were identified. From these we extracted information about number of patients, diagnostic methods, patho-anatomical findings, treatments and outcomes. Practical guidelines for diagnosis and treatment of SE were developed based on analysis of the data. We present two illustrative patient cases-one with intra-articular pathology and one with extra-articular pathology.

RESULTS

Snapping is audible, palpable and often visible. It has a lateral (intra-articular) or medial (extra-articular) pathology. Snapping over the medial humeral epicondyle is caused by dislocation of the ulnar nerve or a part of the triceps tendon, and is demonstrated by dynamic ultrasonography. Treatment is by open surgery. Lateral snapping over the radial head has an intra-articular pathology: A synovial plica, a torn annular ligament or a meniscus-like remnant from the foetal elbow. Pathology can be visualized by conventional arthrography, magnetic resonance (MR) arthrography, high resolution magnetic resonance imaging (MRI) and arthroscopy, while conventional MRI and radiographs often turn out normal. Treatment is by arthroscopic or eventual open resection. Early surgical intervention is recommended as the snapping can damage the ulnar nerve (medial) or the intra-articular cartilage (lateral). If medial snapping only occurs during repeated or loaded extension/flexion of the elbow (in sports or work) it may be treated by reduction of these activities. Differential diagnoses are loose bodies (which can be visualized by radiographs) and postero-lateral instability (demonstrates by clinical examination). An algorithm for diagnosis and treatment is suggested.

CONCLUSION

The primary step is establishment of laterality. From this follows relevant diagnostic measures and treatment as defined in this guideline.

Intraoperative Ultrasound for Peripheral Nerve Applications

Offering real-time, high-resolution images via intraoperative ultrasound is advantageous for a variety of peripheral nerve applications. To highlight the advantages of ultrasound, its extraoperative uses are reviewed. The current intraoperative uses, including nerve localization, real-time evaluation of peripheral nerve tumors, and implantation of leads for peripheral nerve stimulation, are reviewed. Although intraoperative peripheral nerve localization has been performed previously using guide wires and surgical dyes, the authors' approach using ultrasound-guided instrument clamps helps guide surgical dissection to the target nerve, which could lead to more timely operations and shorter incisions.

Ultrasonographic and Electrophysiological Evaluation of Ulnar Nerve Instability and Snapping of the Triceps Medial Head in Healthy Subjects

OBJECTIVE

To evaluate the relationship between ulnar nerve instability and snapping of the triceps medial head during elbow flexion.

DESIGNS

Twenty-six healthy individuals were recruited. The primary outcome measures were ultrasonographic and electrophysiological parameters of the ulnar nerve. Ulnar nerve instability was classified into three types based on the degree of ulnar nerve movement: no dislocation (Type N), subluxation (Type S), and dislocation (Type D).

RESULTS

In the elbow 90-degree position, the incidences of Type N, S, and D were 41 (78.8%), 8 (15.4%), and 3 (5.8%) elbows, respectively; in the full flexion position, the incidences of Types N, S, and D were 24 (46.2%), 19 (36.5%), and 9 (17.3%) elbows, respectively. Spearman's correlation coefficients between ulnar nerve instability and snapping of the triceps medial head in the elbow 90-degree and full flexion positions were 0.808 and 0.889 (P < 0.001), respectively. The ulnar sensory response in Type S was of prolonged latency and decreased amplitude compared with that in Type N or D in the elbow full flexion position.

CONCLUSIONS

Ulnar nerve instability increased with elbow flexion and correlated with snapping of the triceps medial head. Ultrasonography of the ulnar nerve is an important tool in ulnar nerve instability assessment.

Pediatric musculoskeletal ultrasound

The expanding applications of musculoskeletal ultrasound include many examinations that are new to pediatric radiologists but are well known to our adult colleagues. In this review we present an introduction and guide to some of these entities for pediatric radiologists making inroads into the world of musculoskeletal ultrasound.

Distal triceps injuries (including snapping triceps): A systematic review of the literature

AIM

To review current literature on types of distal triceps injury and determine diagnosis and appropriate management.

METHODS

We performed a systematic review in PubMed, Cochrane and EMBASE using the terms distal triceps tears and snapping triceps on the 10^th January 2017. We excluded all animal, review, foreign language and repeat papers. We reviewed all papers for relevance and of the papers left we were able to establish the types of distal triceps injury, how these injuries are diagnosed and investigated and the types of management of these injuries including surgical. The results are then presented in a review paper format.

RESULTS

Three hundred and seventy-nine papers were identified of which 65 were relevant to distal triceps injuries. After exclusion we had 47 appropriate papers. The papers highlighted 2 main distal triceps injuries: Distal triceps tears and snapping triceps. Triceps tear are more common in males than females occurring in the 4^th-5^th decade of life and often due to a direct trauma but are also strongly associated with weightlifting and American football. The tears are diagnosed by history and clinically with a palpable gap. Diagnosis can be confirmed with the use of ultrasound (US) and magnetic resonance imaging. Treatment depends on type of tear. Partial tears can be treated conservatively with bracing and physio whereas acute tears need repair either open or arthroscopic using suture anchor or bone tunnel techniques with similar success. Chronic tears often need augmenting with tendon allograft or autograft. Snapping triceps are also seen more in men than women but at a mean age of 32 years. They are characterized by a snapping sensation mostly medially and can be associated with ulna nerve subluxation and ulna nerve symptoms. US is the diagnostic modality of choice due to its dynamic nature and to differentiate between snapping triceps tendon or ulna nerve. Treatment is conservative initially with activity avoidance and if that fails surgical management includes resection of triceps edge or transposition of the tendon plus or minus ulna nerve transposition.

CONCLUSION

Distal triceps injuries are uncommon. This systematic review examines the evidence base behind diagnosis, imaging and treatment options of distal triceps injuries including tears and snapping triceps.

Osborne's Ligament: A Review of its History, Anatomy, and Surgical Importance

When discussing the pathophysiology of ulnar neuropathy, Geoffrey Vaughan Osborne described a fibrous band that can be responsible for the symptoms seen in this disorder. In this paper, we take a glimpse at the life of Osborne and review the anatomy and surgical significance of Osborne’s ligament. This band of tissue connects the two heads of the flexor carpi ulnaris and thus forms the roof of the cubital tunnel. To our knowledge, no prior publication has reviewed the history of this ligament, and very few authors have studied its anatomy in any detail. Therefore, the aim of the present paper is to elucidate this structure that is often implicated and surgically transected to decompress the ulnar nerve at the elbow.

Elbow Injuries in Adult Overhead Athletes

OBJECTIVE

The purpose of this article is to review common elbow injuries found in overhead athletes with focus on mechanism, clinical features, imaging appearance, and treatment options.

CONCLUSION

The overhead throwing motion subjects the elbow to a variety of complex forces, which places both osseous and soft-tissue structures at high risk for injury.

Ultrasonography Detects Ulnar Nerve Dislocation Despite Normal Electrophysiology and Magnetic Resonance Imaging

BACKGROUND

Dislocation of the ulnar nerve (UN) occurs in a subset of patients with ulnar neuropathy. Electrodiagnostic and magnetic resonance imaging (MRI) studies are performed to support the clinical diagnosis. We report the case of a patient with ulnar neuropathy with normal electrodiagnostic and MRI studies but with ultrasonography (US) showing UN dislocation, which prompted successful treatment by UN submuscular transposition.

CASE DESCRIPTION

A healthy 15-year-old female softball player presented with right medial elbow pain and paresthesias of the fourth and fifth digits. She had 4+/5 strength in the right hand intrinsic muscles and a Tinel sign at the right elbow. A snap was palpated at the elbow upon flexion. MRI showed mild common flexor tendonitis, and electrodiagnostic studies showed normal motor responses and no conduction block at the elbow. High-resolution US showed dislocation of the UN over the medial epicondyle. UN dislocation was confirmed intraoperatively, and, after UN submuscular transposition, the patient reported complete resolution of her preoperative symptoms at 6-week follow-up and continued resolution at 1 year.

CONCLUSIONS

Normal findings on electrodiagnostic or MRI studies should not immediately dissuade surgeons from operating on a symptomatic patient with a clinical examination supporting ulnar neuropathy and with US evidence of UN dislocation, because such a patient may experience postoperative symptom relief. Furthermore, the dynamic capability of US imaging complements data obtained from electrodiagnostic and MRI studies, especially when these tests are normal, and it should be considered by clinicians when evaluating patients with medial elbow pain or signs of ulnar neuropathy.

Effect of Elbow Position on Short-segment Nerve Conduction Study in Cubital Tunnel Syndrome

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Sonography of Common Peripheral Nerve Disorders With Clinical Correlation

Sonography is now considered an effective method to evaluate peripheral nerves. Low cost, high resolution, the ability to image an entire limb in a short time, and dynamic assessment are several of the positive attributes of sonography. This article will review the normal appearance of peripheral nerves as shown with sonography. In addition, the most common applications for sonography of the peripheral nerves will be reviewed, which include entrapment neuropathies, intraneural ganglion cyst, nerve trauma, and peripheral nerve sheath tumors. Clinical information related to nerve disorders is also included, as it provides valuable information that can be obtained during sonographic examinations, increasing diagnostic accuracy.

MR anatomy and pathology of the ulnar nerve involving the cubital tunnel and Guyon's canal

Ulnar neuropathy is a common and frequent reason for referral to hand surgeons. Ulnar neuropathy mostly occurs in the cubital tunnel of the elbow or Guyon's canal of the wrist, and it is important for radiologists to understand the imaging anatomy at these common sites of impingement. We will review the imaging and anatomy of the ulnar nerve at the elbow and wrist, and we will present magnetic resonance imaging examples of different causes of ulnar neuropathy, including trauma, overuse, arthritis, masses and mass-like lesions, and systemic diseases. Treatment options will also be briefly discussed.

US for diagnosis of musculoskeletal conditions in the young athlete: emphasis on dynamic assessment

Ultrasonography (US) is increasingly recognized as an important tool for diagnosis and therapeutic management of a variety of musculoskeletal conditions. Advantages of US use in the young athlete include the ability to diagnose dynamic conditions that are occult with other modalities, provide additional diagnostic information, and aid in treatment. Uses of US in young patients include evaluation of acquired musculoskeletal conditions that manifest with symptoms and assessment of congenital variants that may manifest with pain or limitations in activity. Acquired conditions in the young athlete include tendon disorders, such as proximal tendinosis, and ligament disorders, such as anterior talofibular ligament or ulnar collateral ligament tears. While static images are frequently able to depict these disorders without difficulty, a dynamic examination that provides stress to the joint of interest may be able to uncover a ligament tear or insufficiency and concurrently provide the clinician with information regarding joint stability. Numerous congenital variants that occur throughout the musculoskeletal system can be associated with awkward sensations such as snapping, popping, and clunking and occasionally with pain. Pathologic processes associated with congenital variants in the upper extremities include slipping rib syndrome, atraumatic anterior subluxation of the sternoclavicular joint, and snapping triceps syndrome. Conditions that affect the lower extremities include internal and external snapping hip syndrome, snapping knee syndrome, and medial plica syndrome. The dynamic capability of US is ideal for diagnosis of many conditions that affect the musculoskeletal system of the young athlete, many of which would be difficult or impossible to identify with use of other imaging modalities.

The snapping medial antebrachial cutaneous nerve

Snapping elbow is a well-known condition where elbow flexion and extension elicits a painful, popping sensation. The most frequent etiology is anterior dislocation of the ulnar nerve over the medial epicondyle. Four patients (3 females and 1 male) presented with complaints of a popping sensation in the elbow, pain over the medial aspect of the forearm, and ulnar neuritis. All patients underwent preoperative dynamic ultrasound and surgical exploration of the medial elbow. Intraoperatively, snapping of the MABC over the medial epicondyle was discovered in all four patients. In three patients, there was abnormal displacement of the medial triceps and ulnar nerve: in two of these, both structures dislocated over the medial epicondyle and in one patient both structures subluxated. In each case, the MABC was decompressed (n = 1) and transposed (n = 3), and in three cases, the medial triceps and ulnar nerve were addressed as well. Symptomatic improvement was achieved in all cases. Retrospective review of the ultrasound revealed the snapping MABC, though it was less effective prospectively in the cases when snapping MABC was not suspected. In conclusion, snapping of the MABC broadens the spectrum of disorders that results in snapping elbow. To our knowledge, we are unaware of prior reports of this entity.

Postoperative ulnar neuropathy is not necessarily iatrogenic: a prospective study on dynamic ulnar nerve dislocation at the elbow

BACKGROUND

Patients who undergo surgery may develop ulnar neuropathy. Although the mechanism of ulnar neuropathy is still not clear, ulnar neuropathies are common causes of successful lawsuits against surgeons. Recently, the concept developed that endogenous patient factors can lead to postoperative peripheral neuropathies. We hypothesize that dynamic ulnar nerve dislocation at the elbow (DUNDE) may be a predisposing factor for ulnar irritation (i.e., neuropathy) in normal subjects.

METHODS

In a prospective investigation, patients aged 20 years and older presenting in our emergency department were asked to participate. Three physicians examined both elbows of subjects included in our study for evidence of DUNDE (through clinical and sonographic examination) and for clinical symptoms related to ulnar neuropathy.

RESULTS

Dynamic ulnar nerve dislocation was observed in 29.3% of examined subjects. No significant difference in its occurrence was observed in relation to gender or dominant side. Physical examination with provocation tests demonstrated significantly more positive Tinel tests and spontaneous signs of neuropathy in patients with dynamic dislocating ulnar nerves (14.7 vs. 1.1%).

CONCLUSION

Dynamic ulnar nerve dislocation may be linked to ulnar nerve irritability (i.e., ulnar neuropathy) in normal subjects without history of trauma, surgical procedure, or anesthesia. Considering the high incidence of this variant in the general population, our study supports previous investigations suggesting that many postoperative ulnar nerve deficits are traceable to chronic patient conditions. Our study suggests that dynamic ulnar nerve dislocation is a predisposing factor in the development of ulnar neuropathy in the postoperative period.

NOTES

(1) neuropathy should be viewed as a broad definition as signs of nerve irritation/inflammation, and independently of the pathophysiology and etiology; (2) because no specific term exists in the international anatomic nomenclature (Nomina Anatomica) to designate this variant, several synonyms have been used in the literature, leading to confusion and misleading conclusions concerning its traumatic etiologies and their consequences: (a) recurrent or habitual ulnar nerve luxation (or subluxation); (b) recurrent or habitual ulnar nerve dislocation; (c) ulnar nerve instability; (d) laxity of the ulnar nerve; and (e) ulnar nerve hypermobility.