Regional anatomic structures of the elbow that may potentially compress the ulnar nerve

Ultrasound of the Ulnar Nerve: A Pictorial Review: Part 1: Normal Ultrasound Findings

This is the first of a two-part article in which we focus on the ultrasound (US) appearance of the normal ulnar nerve (UN) and its main branches. The detailed US anatomy of the UN course is presented with high-resolution US images obtained with the latest-generation US machines and transducers.

Ulnar nerve anteposition with adipofascial flap, an alternative treatment for severe cubital syndrome

BACKGROUND

Ulnar nerve entrapment at the elbow is the second most common cause of nerve entrapment in the upper limb. Surgical techniques mainly include simple decompression, decompression with anterior transposition and medial epicondylectomy.

METHODS

We performed decompression with anterior transposition and protected ulnar nerve by adipofascial flap (a random flap with radial based vascularization, harvested through the avascular plane of Scarpa's fascia. We analyzed patients who underwent ulnar nerve ante-position from 2015 to 2022 according to inclusion and exclusion criteria for a total of 57 patients. All patients included were graded on the McGowan's classification Messina criteria and the British Medical Research Council modified by Mackinnon and Dellon.

RESULTS

The average McGowan's score was 2.4 (± 0.6), Messina's criteria 91.2% indicated a satisfactory or excellent result, sensibility at 6 months was 98.5% S3 or more. A preferential technique has not yet been defined.

CONCLUSIONS

The adipofascial flap offers numerous advantages in providing a pliable, vascular fat envelope, which mimics the natural fatty environment of peripheral nerves and creates favorable micro-environmental conditions to contribute to neural regeneration via axon outgrowth.

Anatomical Variants of the Upper Limb Nerves: Clinical and Preoperative Relevance

Profound knowledge of nerve variations is essential for clinical practice. It is crucial for interpreting the large variability of a patient's clinical presentation and the different mechanisms of nerve injury. Awareness of nerve variations facilitates surgical safety and efficacy. Clinically significant anatomical variations can be classified into two main groups: variability in the course of the nerve and variability of structures surrounding the nerve. In this review article we focus on the most common nerve variants of the upper extremity and their clinical relevance.

Morphological Changes of Medial Epicondyle-Olecranon Ligament and Ulnar Nerve in the Cubital Tunnel Syndrome: An Ultrasonic Study

Objective

Few studies have performed detailed ultrasound measurements of medial epicondyle‐olecranon (MEO) ligament that cause the entrapment of ulnar nerve. This study aims to comprehensively evaluate dynamic ultrasonographic characteristics of MEO ligament and ulnar nerve for clinical diagnosis and accurate treatment of cubital tunnel syndrome (CuTS).

Methods

Thirty CuTS patients (CuTS group) and sixteen healthy volunteers (control group) who underwent ultrasound scanning from October 2016 to October 2020 were retrospectively collected, with 30 elbows in each group. Primary outcomes were thickness at six points, length and width of MEO ligament. Secondary outcomes were thickness of ulnar nerve under MEO ligament at seven parts and the cross‐sectional area (CSA) of ulnar nerve at proximal end of MEO ligament (P_0 mm). The thickness of MEO ligament and ulnar nerve in different points of each group was compared by one‐way ANOVA analysis with Bonferroni post hoc test, other outcomes were compared between two elbow positions or two groups using independent‐samples t test.

Results

Thickness of MEO ligament in CuTS group at epicondyle end, midpoint in transverse view, olecranon end, proximal end, midpoint in axial view, and distal end was 0.67 ± 0.31, 0.37 ± 0.18, 0.89 ± 0.35, 0.39 ± 0.21, 0.51 ± 0.38, 0.36 ± 0.25 at elbow extension, 0.68 ± 0.34, 0.38 ± 0.27, 0.77 ± 0.39, 0.32 ± 0.20, 0.48 ± 0.22, 0.32 ± 0.12 (mm) at elbow flexion, respectively. Compared with control group, they were significantly thickened except for proximal end at elbow flexion. MEO ligament thickness at epicondyle end and olecranon end was significantly larger than midpoint in two groups. No significant difference was found in length and width of MEO ligament among different comparisons. Ulnar nerve thickness at 5 mm proximal to MEO ligament (P_5 mm, 3.25 ± 0.66 mm) was significantly increased than midpoint of MEO ligament (Mid), distal end of MEO ligament (D_0 mm), 5 mm (D_5 mm), 10 mm (D_10 mm) distal to MEO ligament at extension in CuTS group. Compared with control group, ulnar nerve thickness at P_5 mm in CuTS group was significantly increased at extension position, at D_5 mm and D_10 mm was significantly decreased at flexion position. CSA of ulnar nerve at extension position (14.44 ± 4.65 mm²) was significantly larger than flexion position (11.83 ± 3.66 mm²) in CuTS group, and CuTS group was significantly larger than control group at two positions.

Conclusions

MEO ligament in CuTS patients was thickened, which compressed ulnar nerve and caused its proximal end swelling. Ultrasonic image of MEO ligament thickness was a significant indicator for CuTS and can guide surgeons in selecting the appropriate treatment.

Imaging the intermuscular septum in the context of ulnar neuropathy

Impingement/entrapment of the ulnar nerve by the intermuscular septum at the distal arm is a common cause of recurrent or recalcitrant ulnar neuropathy following ulnar nerve decompression or anterior transposition. Primary entrapment/impingement of the ulnar nerve along the intermuscular septum may also occur. Evaluation with both ultrasound (US) and MRI can identify entrapment of the ulnar nerve at the intermuscular septum, while dynamic assessment with US can also identify dynamic subluxation of the ulnar nerve over the intermuscular septum.

Length of affected nerve segment in ulnar neuropathies at the elbow

OBJECTIVE

To establish length of the affected nerve segment (LANS) in ulnar neuropathy at the elbow (UNE).

METHODS

In a group of our previously reported UNE patients we identified 2-cm segments with reduced motor nerve conduction velocity (MNCV) on electrodiagnostic (EDx) studies and increased nerve cross-sectional areas (CSA) on ultrasonographic (US) studies. LANS was obtained by summation of these abnormal 2-cm segments separately for each approach. We also studied effect of selected independent parameters on LANS.

RESULTS

Altogether we studied 189 patients (194 arms). Mean (SD) LANS determined in 171 arms with reduced ulnar MNCV was 4.15 (1.89) cm, and was similar (p = 0. 21) to LANS obtained in 147 arms with increased CSA 4.46 (2.29) cm. Longer LANS were found in right arms, clinically severe UNE, axonal UNE and UNE due to entrapment. The most commonly affected 6 cm segment included 89% of abnormal 2-cm segments, with 50% of included 2-cm segments being normal. By contrast, the whole 10 cm segment included all abnormal 2-cm segments, with 66% of included segments being normal.

CONCLUSIONS

In UNE both EDx and US studies revealed average LANS of around 4 cm. LANS was longer in more severe UNE.

SIGNIFICANCE

LANS needs to be taken into account in discussion of the mechanisms of UNE and approach to EDx diagnosis of UNE, particularly length of the segment used in nerve conduction studies across the elbow.

Diffusion tensor imaging in cubital tunnel syndrome

Cubital tunnel syndrome (CuTS) is the 2nd most common compressive neuropathy. To improve both diagnosis and the selection of patients for surgery, there is a pressing need to develop a reliable and objective test of ulnar nerve 'health'. Diffusion tensor imaging (DTI) characterises tissue microstructure and may identify differences in the normal ulnar from those affected by CuTS. The aim of this study was to compare the DTI metrics from the ulnar nerves of healthy (asymptomatic) adults and patients with CuTS awaiting surgery. DTI was acquired at 3.0 T using single-shot echo-planar imaging (55 axial slices, 3 mm thick, 1.5 mm2 in-plane) with 30 diffusion sensitising gradient directions, a b-value of 800 s/mm2 and 4 signal averages. The sequence was repeated with the phase-encoding direction reversed. Data were combined and corrected using the FMRIB Software Library (FSL) and reconstructed using generalized q-sampling imaging in DSI Studio. Throughout the length of the ulnar nerve, the fractional anisotropy (FA), quantitative anisotropy (QA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) were extracted, then compared using mixed-effects linear regression. Thirteen healthy controls (8 males, 5 females) and 8 patients with CuTS (6 males, 2 females) completed the study. Throughout the length of the ulnar nerve, diffusion was more isotropic in patients with CuTS. Overall, patients with CuTS had a 6% lower FA than controls, with the largest difference observed proximal to the cubital tunnel (mean difference 0.087 [95% CI 0.035, 0.141]). Patients with CuTS also had a higher RD than controls, with the largest disparity observed within the forearm (mean difference 0.252 × 10-4 mm2/s [95% CI 0.085 × 10-4, 0.419 × 10-4]). There were no significant differences between patients and controls in QA, MD or AD. Throughout the length of the ulnar nerve, the fractional anisotropy and radial diffusivity in patients with CuTS are different to healthy controls. These findings suggest that DTI may provide an objective assessment of the ulnar nerve and potentially, improve the management of CuTS.

The prevalence of anconeus epitrochlearis muscle and Osborne's ligament in cubital tunnel syndrome patients and healthy individuals: An anatomical study with meta-analysis

BACKGROUND

Anconeus epitrochlaeris muscle and Osborne's ligament are anatomical variants that are occasionally found at the cubital tunnel of the elbow. In certain individuals, these two structures may compress the ulnar nerve resulting in a cubital tunnel syndrome. Although these variants have been reported extensively, its prevalence is still unclear and its contribution to cubital tunnel syndrome is debatable. The aim of this study is to generate weighted frequency values of the anconeus epitrochlearis and Osborne's ligament, as well as to identify any association of these two structures with gender, side, ethnicity and the development of cubital tunnel syndrome.

METHODS

An anatomical study and a meta-analysis were performed to more accurately study the prevalence of anconeus epitrochlearis and Osborne's ligament. A total of 40 original studies including the present study met the inclusion criteria for meta-analysis and 6 case reports for descriptive analysis.

RESULTS

Crude pooled prevalence estimate of the anconeus epitrochlearis was significantly higher (p < 0.001) in healthy subjects (14.2%) than in subjects diagnosed with cubital tunnel syndrome (4.5%). No significant difference was found for gender, side or laterality. The anconeus epitrochlearis was significantly more common in Europeans populations (18.2%) when compared with North American (6.8%) (p = 0.012) and Asian populations (7.5%) (p < 0.001). Anconeus epitrochlearis had a tendency to be hypertrophied when associated with cubital tunnel syndrome. The definition of Osborne's ligament is unclear, resulting in inconsistent reported prevalence across studies.

CONCLUSION

The present study provides a more accurate estimate of anconeus epitrochlearis across the populations. There was a negative correlation between the presence of anconeus epitrochlearis and the development cubital tunnel syndrome, supporting the idea that the muscle may be protective against cubital tunnel syndrome. Future studies are needed to give proper definition of Osborne's ligament and accurately study its prevalence across populations.

Osseous morphology of the medial epicondyle: an anatomoradiological study with potential clinical implications

PURPOSE

The cubital tunnel is limited anteriorly by the medial epicondyle (ME), laterally by the medial collateral ligament, and superiorly by Osborne's fascia and the cubital tunnel retinaculum. Previous studies were mostly dedicated to the roof of the cubital tunnel, in the way that the study of the groove for ulnar nerve and ME anatomy is relatively scarce in the literature. We sought to describe the radiological anatomy of the groove for ulnar nerve and ME in healthy volunteers with multiplanar computed tomography (CT).

METHODS

We analyzed 3D CT images of 30 healthy volunteers (mean age 39 years, range 18-66 years). Nine variables were measured from the right elbow, including sizes, areas and angles in two different planes (coronal and axial).

RESULTS

Mean ME width and length were 17.3 ± 3.5 mm and 31.7 ± 4.5 mm, respectively. According to categorical correlation studies, ME width (X) was deemed the most representative morphological characteristic because of the positive correlation to five other different anatomical measurements. A three-tiered anatomical classification was proposed based on data distribution.

CONCLUSION

Large individual variation is found in the shape of ME, both in coronal and axial planes. The knowledge of individual osseous morphology is of great value potentially contributing to the surgical decision-making in patients affected by cubital tunnel syndrome.

Classification and Treatment of Ulnar Nerve Subluxation Following Endoscopic Cubital Tunnel Release

Purpose

Endoscopic cubital tunnel release (ECuTR) is an effective procedure to alleviate cubital tunnel syndrome. To improve patient outcomes and lessen concerns regarding ulnar nerve subluxation (UNS) after ECuTR, the current study proposes an intraoperative UNS classification system and subsequent treatment protocol. We present a preliminary report of patients treated under these guidelines.

Methods

We retrospectively reviewed 87 patients (100 ECuTRs). Nerve mobility was classified during surgery, in which grade 1 = no movement or partial subluxation; deep retrocondylar groove and/or no generalized hypermobility (no further intervention); grade 2 = partial subluxation; shallow retrocondylar groove and/or inherent generalized hypermobility (required medial epicondylectomy); and grade 3 = complete anterior dislocation (required medial epicondylectomy or anterior transposition). Clinical outcomes at final follow-up (mean ± SD, 34 ± 20.3 weeks; range, 5–89 weeks) were collected and included Disabilities of the Arm, Shoulder, and Hand questionnaires, visual analog scale pain score, grip and pinch strength, 2-point discrimination, and range of motion.

Results

We report 37 patients (42 cases), grade 1 (n = 30), grade 2 (n = 1), and grade 3 (n = 11). Gross grip strength, lateral, 3-jaw chuck, and precision pinch strength recovered 87%, 90%, 105%, and 87%, respectively. Wrist and elbow range of motion returned to normal limits, 2-point discrimination improved to normal scores at final follow-up, Disabilities of the Arm, Shoulder, and Hand scores were reduced from 59.8 before to 29.9 after surgery, and visual analog scale pain score improved from 7.2 before to 2.5 after surgery (P < .001).

Conclusions

To our knowledge, this is the first study to classify UNS after ECuTR and describe a guideline for ensuing treatment. Our preliminary report of patients shows satisfactory outcomes, which suggests that our intraoperative UNS classification system has promise in preventing adverse complications of ulnar nerve hypermobility after ECuTR.

Type of study/level of evidence

Therapeutic IV.

Analysis of the Anatomical Factors Associated with Cubital Tunnel Syndrome

BACKGROUND

Previous studies demonstrated that soft tissues, such as retinaculum, fibrous band, and anconeus, cause ulnar nerve compression, whereas other studies showed that the bony structures strain the ulnar nerve that runs directly behind the medial epicondyle constituting the boundary of the cubital tunnel during elbow flexion. However, no studies have reported the association of the shape of the bony structure with cubital tunnel syndrome symptoms. Are computed tomography (CT) and magnetic resonance imaging (MRI)-measured parameters of the bony cubital tunnel related to idiopathic cubital tunnel syndrome symptoms?

HYPOTHESIS

We hypothesized that CT and MRI-measured parameters of the bony cubital tunnel were related to idiopathic cubital tunnel syndrome symptoms. We aimed to investigate the relationship between the radiographic parameters based on CT and MRI and idiopathic cubital tunnel syndrome symptoms.

PATIENTS AND METHODS

We analyzed 224 elbows (77 affected elbows of patients with idiopathic cubital tunnel syndrome, 77 unaffected elbows of patients with cubital tunnel syndrome, 70 elbows of patients without cubital tunnel syndrome symptoms) using CT and MRI. Cubital tunnel cross-sectional area, cubital tunnel volume, and ulnar nerve cross-sectional area were measured in the three groups at flexion and extension. A new cubital tunnel center with a new boundary was proposed that could play a role in ulnar nerve compression symptoms.

RESULTS

The cross-sectional areas and volumes of the cubital tunnel measured in the elbow flexion state were the smallest among the group with the affected elbows in patients. There was no difference between unaffected elbows and the non-patient group. The cross-sectional area of the ulnar nerve highly correlated with cubital tunnel symptoms in the flexion state.

DISCUSSION

The shape of the cubital tunnel is an important factor in cubital tunnel syndrome, and normal variations in the volume and cross-sectional area of the cubital tunnel and ulnar nerve could influence the occurrence of idiopathic cubital tunnel syndrome.

LEVEL OF EVIDENCE

III, Therapeutic study.

Validity of computed tomographic measurements and morphological comparison of cubital tunnel in idiopathic cubital tunnel syndrome

Background

Ulnar neuropathy is a common reason for referral to hand surgeons, and 10 to 30% of cubital tunnel syndrome (CuTS) is idiopathic. We hypothesized that the cause of idiopathic CuTS is in the bony structure.

Methods

We analyzed 79 elbows (39 idiopathic CuTS and 40 without CuTS symptom) using computed tomography and Materialize Mimics software to compare the differences between the two groups. We proposed a new bony cubital tunnel with a new boundary that could play a role in ulnar nerve compression symptom.

Results

The mean cubital tunnel volume was 1245.6 mm³ in all patients, 1180.6 mm³ in CuTS patients, and 1282.3 mm³ in the control group. A significant difference (p = 0.015) between two groups was found. Bony cubital tunnel cross-sectional area, cubital tunnel depth, and cubital tunnel angle also showed significant differences.

Conclusion

The shape of the bony cubital tunnel is an important cause of CuTS, and the normal variation of the volume and cross-sectional area of the cubital tunnel and cubital tunnel angle could influence the occurrence of idiopathic CuTS.

The 7 Structures Distal to the Elbow That Are Critical to Successful Anterior Transposition of the Ulnar Nerve

Background: Ulnar nerve transposition (UNT) surgery is performed for the treatment of cubital tunnel syndrome. Improperly performed UNT can create iatrogenic pain and neuropathy. The aim of this study is to identify anatomical structures distal to the medial epicondyle that should be recognized by all surgeons performing UNT to prevent postoperative neuropathy. Methods: Ten cadaveric specimens were dissected with attention to the ulnar nerve. Intramuscular UNT surgery was simulated in each. Distal to the medial epicondyle, any anatomical structure prohibiting transposition of the ulnar nerve to a straight-line course across the flexor-pronator mass was noted and its distance from the medial epicondyle was measured. Results: Seven structures were found distal to the medial epicondyle whose recognition is critical to ensuring a successful anterior transposition of the ulnar nerve: (1) Branches of the medial antebrachial cutaneous (MABC) nerve; (2) Osborne's fascia; (3) branches from the ulnar nerve to the flexor carpi ulnaris (FCU); (4) crossing vascular branches from the ulnar artery to the FCU; (5) the distal medial intermuscular septum between the FCU and flexor digitorum superficialis (FDS); (6) the combined muscular origins of the flexor-pronator muscles; and (7) the investing fascia of the FDS. Measurements are given for each structure. Conclusions: Poor outcomes and unnecessary revision surgeries for cubital tunnel syndrome can be avoided with intraoperative attention to 7 structures distal to the medial epicondyle. Surgeons should expect to dissect up to 12 cm distal to the medial epicondyle to adequately address these and prevent kinking of the nerve in transposition.

Visualization During Endoscopic Versus Open Cubital Tunnel Decompression: A Cadaveric Study

PURPOSE

To determine the minimum incision size needed using an open cubital tunnel technique to obtain equivalent visualization comparable with an endoscopic technique.

METHODS

Visualization was assessed in 10 fresh-frozen cadavers with a 2-cm incision, using percutaneous needle localization with the endoscopic system. The most proximal and distal extent of the field of view was marked. Next, an open cubital tunnel release was performed on each cadaver specimen. The incision size was increased incrementally, and the most proximal and distal extents of visualization were recorded for each incision size. The mean visualization distance and standard deviation for each incisional length were calculated.

RESULTS

The mean proximal field of view with the endoscopic technique was 8.1 cm. The mean distal field of view was 8.3 cm. Using the open technique, a 2-cm incision allowed 5.9 cm visualization proximally and 5.2 cm distally, which was significantly less than the endoscopic view. A 4-cm open incision provided similar visualization as the endoscopic technique. A 6-cm open incision was required to obtain statistically significant improvements in visualization compared with an endoscopic technique.

CONCLUSIONS

A 4-cm open incision allowed visualization of approximately 9 cm proximal and 9 cm distal to the medial epicondyle, which was equivalent to the 2-cm endoscopic technique for cubital tunnel release.

CLINICAL RELEVANCE

Although the endoscopic release allows greater visualization of the ulnar nerve with a smaller incision, it is unclear whether this improvement in visualization improves the surgeon's ability to decompress the ulnar nerve.

Cubital tunnel syndrome: Anatomy, clinical presentation, and management

Cubital tunnel syndrome is the second most common peripheral nerve compression seen by hand surgeons. A thorough understanding of the ulnar nerve anatomy and common sites of compression are required to determine the cause of the neuropathy and proper treatment. Recognizing the various clinical presentations of ulnar nerve compression can guide the surgeon to choose examination tests that aid in localizing the site of compression. Diagnostic studies such as radiographs and electromyography can aid in diagnosis. Conservative management with bracing is typically trialed first. Surgical decompression with or without ulnar nerve transposition is the mainstay of surgical treatment. This article provides a review of the ulnar nerve anatomy, clinical presentation, diagnostic studies, and treatment options for management of cubital tunnel syndrome.

The Deep Fascia of the Forearm and the Ulnar Nerve: An Anatomical Study

Introduction

A reoperation for a cubital tunnel syndrome is not uncommon. Patients often complain of sensorimotor symptoms in the ulnar nerve distribution after their primary surgery. The documented etiologies for such a phenomenon include a “new” kinking of the distal ulnar nerve and a “new” compression of the ulnar nerve by the fascial septum in between or tendinous bands over the muscles of the forearm. The deep fascial plane along which the ulnar nerve travels in the forearm has had scant attention. We present an anatomical study to provide a better understanding of such etiologies to aid physicians in performing successful primary ulnar nerve release that does not lead to risky reoperations and ultimately yields improved patient satisfaction.

Materials and methods

The forearms of 12 fresh frozen cadavers (24 arms) underwent dissection, during which the fascial relationships between the ulnar nerve and muscles of the anterior compartment were explored with a blunt technique. The relationship between the fascial planes and the ulnar nerve was quantitatively and qualitatively documented. The ranges of motion of the elbow were also observed for any potential compression points on the nerve during the movement.

Results

In all specimens (n = 24), the ulnar nerve entered the forearm between the humeral and ulnar heads of the flexor carpi ulnaris, after which it routed deep to a deep fascia between the anterior surface of the flexor carpi ulnaris and the posterior surface of the flexor digitorum superficialis. Ulnar nerve branches to the flexor carpi ulnaris pierced this fascial septum while en route to the posterior surface of the muscle. Medially, the branches to the flexor digitorum profundus also pierced this fascial plane. In most arms, the fascia became thinner near the junction between the proximal two-thirds and distal one-third of the forearm. On no side was the ulnar nerve found to be grossly compressed by this deep fascia. However, with the extension of the elbow, a degree of angulation of the proximal ulnar nerve was observed due to its compact connection with the deep fascia.

Conclusion

Our study revealed that there is an intimate relationship between the ulnar nerve and the deep fascia of the forearm. Since the ulnar branches to the overlying flexor carpi ulnaris pierce this deep structure, a care should be given to its anatomical course during surgery in this region to prevent denervation of the muscle.

3-Tesla MRI-assisted detection of compression points in ulnar neuropathy at the elbow in correlation with intraoperative findings

INTRODUCTION

Releasing the ulnar nerve from all entrapments is the primary objective of every surgical method in ulnar neuropathy at the elbow (UNE). The aim of this retrospective diagnostic study was to validate preoperative 3-Tesla MRI results by comparing the MRI findings with the intraoperative aspects during endoscopic-assisted or open surgery.

METHODS

Preoperative MRI studies were assessed by a radiologist not informed about intraoperative findings in request for the exact site of nerve compression. The localizations of compression were then correlated with the intraoperative findings obtained from the operative records. Percent agreement and Cohen's kappa (κ) values were calculated.

RESULTS

From a total of 41 elbows, there was a complete agreement in 27 (65.8%) cases and a partial agreement in another 12 (29.3%) cases. Cohen's kappa showed fair-to-moderate agreement.

CONCLUSION

High-resolution MRI cannot replace thorough intraoperative visualization of the ulnar nerve and its surrounding structures but may provide valuable information in ambiguous cases or relapses.

Medial elbow pain

Medial elbow pain is uncommon when compared with lateral elbow pain.

Medial epicondylitis is an uncommon diagnosis and can be confused with other sources of pain.

Overhead throwers and workers lifting heavy objects are at increased risk of medial elbow pain.

Differential diagnosis includes ulnar nerve disorders, cervical radiculopathy, injured ulnar collateral ligament, altered distal triceps anatomy or joint disorders.

Children with medial elbow pain have to be assessed for ‘Little League elbow’ and fractures of the medial epicondyle following a traumatic event.

This paper is primarily focused on the differential diagnosis of medial elbow pain with basic recommendations on treatment strategies.

Cite this article: EFORT Open Rev 2017;2:362-371. DOI: 10.1302/2058-5241.2.160006

Clarification of Eponymous Anatomical Terminology: Structures Named After Dr Geoffrey V. Osborne That Compress the Ulnar Nerve at the Elbow

BACKGROUND

In 1957, Dr Geoffrey Osborne described a structure between the medial epicondyle and the olecranon that placed excessive pressure on the ulnar nerve. Three terms associated with such structures have emerged: Osborne's band, Osborne's ligament, and Osborne's fascia. As anatomical language moves away from eponymous terminology for descriptive, consistent nomenclature, we find discrepancies in the use of anatomic terms. This review clarifies the definitions of the above 3 terms.

METHODS

We conducted an extensive electronic search via PubMed and Google Scholar to identify key anatomical and surgical texts that describe ulnar nerve compression at the elbow. We searched the following terms separately and in combination: "Osborne's band," "Osborne's ligament," and "Osborne's fascia." A total of 36 papers were included from 1957 to 2016.

RESULTS

Osborne's band, Osborne's ligament, and Osborne's fascia were found to inconsistently describe the etiology of ulnar neuritis, referring either to the connective tissue between the 2 heads of the flexor carpi ulnaris muscle as described by Dr Osborne or to the anatomically distinct fibrous tissue between the olecranon process of the ulna and the medial epicondyle of the humerus.

CONCLUSIONS

The use of eponymous terms to describe ulnar pathology of the elbow remains common, and although these terms allude to the rich history of surgical anatomy, these nonspecific descriptions lead to inconsistencies. As Osborne's band, Osborne's ligament, and Osborne's fascia are not used consistently across the literature, this research demonstrates the need for improved terminology to provide reliable interpretation of these terms among surgeons.

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.

A reliable technique for ultrasound-guided perineural injection in ulnar neuropathy at the elbow

INTRODUCTION

Ulnar neuropathy at the elbow (UNE) is a common peripheral compression neuropathy and, in most cases, occurs at 2 sites, the retroepicondylar groove or the cubital tunnel. With regard to a potential therapeutic approach with perineural corticosteroid injection, the aim of this study was to evaluate the distribution of injection fluid applied at a standard site.

METHODS

We performed ultrasound-guided (US-guided) perineural injections to the ulnar nerve halfway between the olecranon and the medial epicondyle in 21 upper limbs from 11 non-embalmed cadavers. In anatomic dissection we investigated the spread of injected ink.

RESULTS

Ink was successfully injected into the perineural sheath of the ulnar nerve in all 21 cases (cubital tunnel: 21 of 21; retroepicondylar groove: 19 of 21).

CONCLUSION

US-guided injection between the olecranon and the medial epicondyle is a feasible and safe method to reach the most common sites of ulnar nerve entrapment. Muscle Nerve 56: 237-241, 2017.

IS RDW A PREDICTIVE PARAMETER FOR CUBITAL TUNNEL SYNDROME PATIENTS REQUIRING SURGERY?

OBJECTIVE

The aim of this study was to investigate whether haemogram parameters are predictive factors for both the severity of the disease and a decision in favor of surgical treatment in patients with an established diagnosis of cubital tunnel syndrome (CuTS) .

METHODS

The medical files of patients with a diagnosis of CuTS who were followed-up conservatively (n=92) or surgically treated (n=92) were retrospectively screened and the haemogram parameters were recorded .

RESULTS

The receiver operating characteristic (ROC) curve analysis revealed an area of 0.665 under the curve, with 76.3% sensitivity and 84.8% specificity at the cut-off of a red cell distribution width (RDW) level grater than 15.45%. RDW levels higher than 15.5%, electromyography (EMG) severity, and a clinical score higher than three were found to be independently associated with surgery .

CONCLUSION

An elevated RDW value was related to the severity of the electromyogram. RDW may, therefore, be a useful independent predictor for the decision to surgical treatment of CuTS. Level of Evidence III, Retrospective Study.

Intermuscular aponeuroses between the flexor muscles of the forearm and their relationships with the ulnar nerve

INTRODUCTION

The aim of this study was to clarify the morphological characteristics of the intermuscular aponeurosis between the flexor carpi ulnaris (FCU) and flexor digitorum superficialis (FDS; IMAS), and that between the FCU and flexor digitorum profundus (FDP; IMAP), and their topographic relationships with the ulnar nerve.

MATERIALS AND METHODS

Fifty limbs of 38 adult cadavers were studied.

RESULTS

The IMAS extended along the deep surface of the FCU adjoining the FDS, having the appearance of a ladder, giving off "steps" that decreased in width from superficial to deep around the middle of the forearm. Its proximal part divided into two bands connected by a thin membrane, and was attached to the medial epicondyle and the tubercle (the most medial prominent part of the coronoid process of the ulna), respectively. The IMAP extended deep between the FCU and FDP from the antebrachial fascia, and its distal end was located on the posterior border of the FCU. The IMAP became broader toward its proximal part, and its proximal end was attached anterior and posterior to the tubercle and the olecranon, respectively. The ulnar nerve passed posterior to the medial epicondyle and then medial to the tubercle, and was crossed by the deep border of the IMAS at 58.3 ± 14.1 mm below the medial epicondyle.

CONCLUSION

The deep border of the IMAS and aberrant tendinous structure passing across the ulnar nerve, or the parts of the IMAS and IMAP passing posterior to the ulnar nerve are potential causes of ulnar nerve compression.

Clinical classification and treatment of cubital tunnel syndrome

The aim of the present study was to investigate a new clinical classification of cubital tunnel syndrome that provides an improved basis for the clinical diagnosis and treatment of the disease. Retrospective analysis was performed on 341 patients with cubital tunnel syndrome. Based on the etiology, signs and symptoms, neurophysiological tests and computed tomography (CT) imaging, a new clinical classification was proposed. The patients enrolled in the study were treated according to the new classification. According to the new classification, cubital tunnel syndrome cases were divided into types I-IV. Treatment for patients with type I consisted of rest, immobilization or physiotherapy, while patients with type II received simple ulnar neurolysis. Type III patients underwent ulnar neurolysis with expansion of the ulnar nerve sulcus or ulnar nerve anterior transposition surgery. Type IV patients represented a subgroup of cubital tunnel syndrome cases caused by factors other than degenerative joint diseases, including cysts, tumors, traumatic fracture, deformity and elbow deformity. Patients of this type received appropriate surgical treatment according to the specific etiology. Based on previous classifications that relied on sensation and strength symptoms, a new clinical classification of elbow tunnel syndrome has been established in the present study that adopts a CT imaging evaluation index. The new classification is reasonable, simple and practical, and therapies based on this classification are more targeted than those based on previous classifications.

The cubital tunnel: a radiologic and histotopographic study

Entrapment of the ulnar nerve at the elbow is the second most common compression neuropathy in the upper limb. The present study evaluates the anatomy of the cubital tunnel. Eighteen upper limbs were analysed in unembalmed cadavers using ultrasound examination in all cases, dissection in nine cases, and microscopic study in nine cases. In all cases, thickening of the fascia at the level of the tunnel was found at dissection. From the microscopic point of view, the ulnar nerve is a multifascicular trunk (mean area of 6.0 ± 1.5 mm(2) ). The roof of the cubital tunnel showed the presence of superimposed layers, corresponding to fascial, tendineous and muscular layers, giving rise to a tri-laminar structure (mean thickness 523 ± 235 μm). This multilayered tissue was hyperechoic (mean thickness 0.9 ± 0.3 mm) on ultrasound imaging. The roof of the cubital tunnel is elastic, formed by a myofascial trilaminar retinaculum. The pathological fusion of these three layers reduces gliding of the ulnar nerve during movements of the elbow joint. This may play a role in producing the symptoms typical of cubital tunnel syndrome. Independent from the surgical technique, decompression should span the ulnar nerve from the triceps brachii muscle to the flexor carpi ulnaris fascia.

Endoscopic robotic decompression of the ulnar nerve at the elbow

Ulnar nerve entrapment can be treated by a number of surgical techniques when necessary. Endoscopic techniques have recently been developed to access the ulnar nerve by use of a minimally invasive approach. However, these techniques have been considered difficult and, many times, dangerous procedures, reserved for experienced elbow arthroscopic surgeons only. We have developed a new endoscopic approach using the da Vinci robot (Intuitive Surgical, Sunnyvale, CA) that may be easier and safer. Standardization of the technique was previously developed in cadaveric models to achieve the required safety, reliability, and organization for this procedure, and the technique was then used in a live patient. In this patient the nerve entrapment symptoms remitted after the surgical procedure. The robotic surgical procedure presented a cosmetic advantage, as well as possibly reduced scar formation. This is the first note on this surgical procedure; the procedure needs to be tested and even evolved until a state-of-the-art standard is reached.

Minimum 6-year follow-up after ulnar nerve decompression and submuscular transposition for primary entrapment

PURPOSE

To retrospectively evaluate patients with 6-year minimum follow-up after submuscular transposition of the ulnar nerve for primary entrapment.

METHODS

From 1992 to 2005, 142 patients were treated surgically for ulnar neuropathy at the elbow by 2 senior surgeons using a technique that preserved nerve vascularity. A total of 99 cases were eligible, and 82 elbows in 76 patients, average age 48 years, were followed for at least 6 years (average, 8.3 y). Thirty-two (42%) were male, and the dominant limb was involved in 49 (64%). The average duration of symptoms before surgery was 25 months. Clinical records were reviewed, and sensory (S0-2) and motor (M0-5) testing was performed. Dellon scores were determined, and visual analog scale and modified questionnaires from Novak et al and Kleinman and Bishop were completed. Preoperatively, 48 elbows were Dellon grade III, 33 were grade II, and one was grade I.

RESULTS

There were clinically and statistically significant improvements in patient and surgeon-reported data regardless of the preoperative disease severity. Visual analog scale questionnaires, sensory scale, and motor strength all improved, with at least antigravity strength in all subjects. Dellon scores also improved, and 38 elbows had normalized to Dellon 0. Of the 33 preoperative elbows that were grade III, 15 improved to grade II, 13 to grade I, and 5 normalized. Of the 48 preoperative elbows that were grade II, 16 improved to grade I and 32 normalized. Preoperative Dellon III elbows had more residual symptoms than grade II elbows. A total of 73 elbows (89%) had a good or excellent outcome. There were no reoperations or infections.

CONCLUSIONS

Submuscular transposition is a safe and durable option for primary ulnar neuropathy at the elbow. Overall, good or excellent results were achieved in 89% of patients with a low complication rate.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Evaluation and treatment of upper extremity nerve entrapment syndromes

Nerve entrapment syndromes in the upper extremity are being recognized with increasing frequency. Prompt and correct diagnosis of these injuries is important. This article is a review of the common entrapment nerve injuries seen in the upper extremity. Each of these clinical syndromes is discussed independently, reviewing the anatomy, compression sites, patient presentation (history and examination), the role of additional diagnostic studies, and management.

Compression and entrapment neuropathies

Peripheral nerve entrapments are frequent. They usually appear in anatomical tunnels such as the carpal tunnel. Nerve compressions may be due to external pressure such as the fibular nerve at the fibular head. Malignant or benign tumors may also damage the nerve. For each nerve from the upper and lower limbs, detailed clinical, electrophysiological, imaging, and therapeutic aspects are described. In the upper limbs, carpal tunnel syndrome and ulnar neuropathy at the elbow are the most frequent manifestations; the radial nerve is less frequently involved. Other nerves may occasionally be damaged and these are described also. In the lower limbs, the fibular nerve is most frequently involved, usually at the fibular head by external compression. Other nerves may also be involved and are therefore described. The clinical and electrophysiological examination are very important for the diagnosis, but imaging is also of great use. Treatments available for each nerve disease are discussed.

Medial epicondyle fractures in the pediatric population

Humeral medial epicondyle fractures in the pediatric population account for up to 20% of elbow fractures, 60% of which are associated with elbow dislocation. Isolated injuries can occur from either direct trauma or avulsion. Medial epicondyle fractures also occur in combination with elbow dislocations. Traditional management by cast immobilization increasingly is being replaced with early fixation and mobilization. Relative indications for surgical fixation include ulnar nerve entrapment, gross elbow instability, and fractures in athletic or other patients who require high-demand upper extremity function. Absolute indications for surgical intervention are an incarcerated fragment in the joint or open fractures. Radiographic assessment of these injuries and their true degree of displacement remain controversial.

Ulnar neuropathy at the elbow: a review and single case cadaveric study

Introduction

Ulnar neuropathy at the elbow (UNE) causes sensory and motor dysfunction of the ulnar nerve and can lead to permanent loss of hand function. Hand therapists frequently encounter this pathology and are required to be cognisant of symptoms, diagnosis, therapeutic and surgical management. A detailed understanding of the anatomical structures will give the therapist greater expertise in managing this pathology.

Methods

A single case cadaveric study was undertaken to investigate known sites of ulnar nerve compression and observe the mechanisms by which compression occurs. A literature review reports on knowledge relating to the pathology, diagnosis, therapeutic and surgical management of UNE.

Results

Anatomic structures compressing the ulnar nerve are the Arcade of Struthers, the medial intermuscular septum, the cubital tunnel and the deep flexor aponeurosis. UNE is attributable to mechanical compression from fibrous and bony structures at these sites and to traction on the ulnar nerve from elbow flexion. Provocative tests are a useful tool in the diagnosis of UNE but should be used cautiously due to limitations in statistical accuracy. Conservative treatment approaches of splintage, ergonomic adaptations, education and neural mobilizations lack high-quality evidence but may have benefit primarily for early or mild to moderate disease. There is some evidence in support of conservative management in longer standing disease.

Discussion

Therapists play an important role in the diagnosis and management of UNE and should have a sound understanding of the relevant anatomy, pathology, diagnosis and treatment. Conservative treatment may be efficacious for UNE but lacks evidence from randomized, controlled trials. Further research is needed to verify current precepts and traditional approaches.

Endoscopically assisted release of the ulnar nerve for cubital tunnel syndrome

PURPOSE

Recently, the simple decompression of the ulnar nerve has been advocated as the best surgical approach for the treatment of the cubital tunnel syndrome. Encouraged by the positive results observed with the use of the endoscopic approach for the treatment of the carpal tunnel syndrome, there have been reports about the use of endoscopes for decompression of the ulnar nerve at the level of the elbow since 1999. The objective of this study was to demonstrate the surgical results obtained with a simple and replicable technique employed for endoscopic release of the ulnar nerve in cases of cubital tunnel syndrome.

METHODS

It was retrospectively studied thirteen patients who presented signs and symptoms of cubital tunnel syndrome and who were operated on by an endoscopically assisted technique, from 2007 to 2009. The approach included the use of a 0 degrees lens neuroendoscope usually employed for ventricular endoscopy. Preoperative clinical and electrophysiological data were collected and compared to those observed 6 months after the surgery. The Dellon's scale was used for rating the severity of the lesions, and the postoperative outcome was assessed based on the Bishop rating system.

RESULTS

All procedures were completed successfully via the endoscopically assisted approach, and no surgery had to be converted to an open operation. Postoperatively, 76.9% of the cases were completely free of signs and symptoms (8 and 9 points on the Bishop scale), 15.3% presented with light complaints (7 points), and only one subject (7.6%) reached 5 points on the outcome scale. Complete normalization of the electrophysiological studies was also observed in seven patients, most of whom were classified preoperatively as Dellon's grades I and II, but three of whom were classified as grade III. Normalization of the sensory conduction studies was observed in ten cases, normalization of the motor conduction studies in six subjects, and in four patients, there was improvement in electromyographic parameters.

CONCLUSIONS

The endoscopically assisted approach for decompression of the ulnar nerve at the level of the elbow is a minimally invasive technique that demonstrated surgical results similar to those reported via the open approach. It may have additional advantages such as the reduction of soft tissue manipulation, faster mobilization of the arm, and quicker return of the patients to their daily activities.

Cubital tunnel syndrome

Cubital tunnel syndrome is the second most common compression neuropathy in the upper extremity. Patients complain of numbness in the ring and small fingers, as well as hand weakness. Advanced disease is complicated by irreversible muscle atrophy and hand contractures. Ulnar nerve decompression can help to alleviate symptoms and prevent more advanced stages of dysfunction. Many surgical treatments exist for the treatment of cubital tunnel syndrome. In situ decompression, transposition of the ulnar nerve into the subcutaneous, intramuscular, or submuscular plane, or medial epicondylectomy have all been shown to be affective in the treatment of this disease process. Comparative studies have shown some short-term advantages to one or another technique, but overall results between the treatments have essentially been equivocal. The choice of surgical treatment is based on multiple factors, and a single surgical approach cannot be applied to all clinical situations. Through careful consideration of the potential sites of nerve compression and the etiologies for these local irritations, the appropriate surgical technique can be selected and a good outcome anticipated in most patients.