Normal MR imaging anatomy of the elbow

The Role of Ultrasound in the Evaluation of Elbow Medial Ulnar Collateral Ligament Injuries in Throwing Athletes

PURPOSE OF REVIEW

Although ultrasound (US) imaging is commonly used to evaluate the elbow medial ulnar collateral ligament (mUCL) in throwing athletes, significant technical heterogeneity exists in the published literature and in practice. This has resulted in variable and often ambiguous US diagnostic criteria for mUCL injury. This review summarizes the literature on sonographic evaluation of the mUCL and outlines recommendations for consistent descriptive terminology, as well as future clinical and research applications.

RECENT FINDINGS

Both acute and chronic throwing loads in overhead athletes cause the mUCL to become thicker and more lax on stress testing, and these changes tend to revert after a period of prolonged rest. Stress US (SUS) can aid in the diagnosis of mUCL tears and may help identify athletes at risk of mUCL injury. Variability exists in terminology, elbow flexion angle, amount of stress applied, and technique of stress testing. Recent studies have suggested an injured elbow stress delta (SD-change in ulnohumeral joint (UHJ) space with valgus stress) of 2.4 mm and a stress delta difference (SDD-side-side difference in SD) of 1 mm each denote abnormal UHJ laxity due to mUCL injury. US imaging is a powerful and widely accessible tool in the evaluation elbow mUCL injuries. Sonologists should consider how their US techniques compare with published methods and use caution when applying diagnostic criteria outside of those circumstances. Currently, an SD of 2.4 mm and an SDD of 1 mm provide the best diagnostic accuracy for mUCL tears requiring surgery. Finally, preliminary work suggests that shear wave elastography may be helpful in evaluating the biomechanical properties of the mUCL, but additional research is needed.

MRI of the Elbow: Interpretation of Common Orthopaedic Injuries

MRI is a valuable diagnostic tool that has become an essential part of an orthopaedic surgeon's practice. When acquired in the appropriate clinical setting, an MRI can direct patient management as surgical versus nonsurgical, guide surgical decision making, and even predict patient outcomes. The quality of MRI obtained and quality of the radiology report received varies. Ultimately, the orthopaedic surgeon must interpret the available imaging and apply these findings to treat the patient. The current day practicing orthopaedic surgeon should be familiar with interpreting common MRIs. Although subspecialized orthopaedic surgeons usually have experience and understanding of MRIs in their field, the general orthopaedic surgeon and those in-training will encounter the gamut of musculoskeletal MRIs. This review focuses on common injuries that can occur in the elbow and provides an approach to minimize missed findings.

Radiographic Evaluation of Elbow Fractures

Fractures and dislocations of the elbow are a common cause of emergency department visits each year. Radiography remains the bedrock of an initial injury assessment, and recognition of distinctive injury patterns based on fracture location, morphology, and severity, guides optimal clinical decision-making. This article reviews basic elbow anatomy, frequently seen fractures and injury patterns, and highlights how these findings influence surgical planning and patient management.

Elbow Imaging: Variants and Asymptomatic Findings

One of the key principles in the interpretation of radiology images is the ability to differentiate between normal and abnormal findings. This article provides a comprehensive overview of normal structures and anatomical variants occurring around the elbow including potential diagnostic pitfalls. We discuss frequently observed anatomical variants found in routine clinical practice associated with osseous, ligamentous, musculotendinous, and neurovascular structures at the elbow that may simulate pathology or predispose to symptoms under specific circumstances.

Practical ultrasonographic technique to precisely identify and differentiate tendons and ligaments of the elbow at the level of the humeral epicondyles: anatomical study

OBJECTIVES

To develop a practical step-by-step technique to precisely identify and differentiate tendons and ligaments attaching to the humeral epicondyles, to confirm through gross anatomical study the accurate structure identification provided by this technique and to determine the frequency at which each structure can be identified in healthy volunteers.

MATERIALS AND METHODS

First, ten fresh frozen cadavers (6 men, age at death = 58-92 years) were examined by two musculoskeletal radiologists and a step-by-step technique for the identification of tendons and ligaments at the level of humeral epicondyles was developed. Second, the accurate identification of structures was confirmed through gross anatomical study including anatomical sections on five specimens and layer-by-layer dissection technique on five others. Finally, 12 healthy volunteers (6 men, average age = 36, range = 28-52) were scanned by two radiologists following the same technique.

RESULTS

An ultrasonographic technique based on the recognition of bony landmarks and the use of ultrasonographic signs to differentiate overlapping structures was developed and validated through gross anatomical study. In healthy volunteers, most tendons and ligaments were identified and well-defined in ≥ 80% of cases, except for the extensor carpi radialis brevis and extensor digiti minimi tendons on the lateral epicondyle (having common attachments with the extensor digitorum communis) and the palmaris longus tendon on the medial epicondyle (absent, or common attachment with the flexor carpi radialis).

CONCLUSION

A step-by-step approach to the ultrasonographic assessment of tendons and ligaments at the humeral epicondyles allowed accurate identification of and differentiation among these structures, in particular those relevant to pathological conditions.

Comprehensive Update of Elbow Magnetic Resonance Imaging

We present a comprehensive update of elbow magnetic resonance imaging, detailing the complex anatomy and pathology of the elbow. A variety of pathologies may affect the elbow joint, and many of the symptoms overlap. As such, magnetic resonance imaging of the elbow serves as an invaluable clinical tool for the clinician in the diagnosis and management of patients presenting with elbow pain.

[Normal variants and pitfalls at the elbow joint]

The elbow joint is comprised of three different bones with a combined hinge and a ball joint. Several nerves, tendons and muscles cross the joint. Anatomical variations at the elbow are common and may be the cause of certain pathologies. Despite the high quality of modern cross-sectional imaging, certain normal findings on CT or MRI have the risk of being misinterpreted. This article describes more common but also rare, normal variants around the elbow joint. Classic pitfalls are illustrated and compared to similar pathological findings.

Ultrasound evaluation of bursae: anatomy and pathological appearances

A bursa is an extra-articular sac that may communicate with a joint and functions to decrease friction between tendons and either bone or skin. Bursae can be classified as native and non-native (adventitious) bursae. The native bursae are lined with a synovial membrane and occur at predictable anatomical sites; knowledge of these normal structures can help distinguish them from other pathological entities. An adventitious bursa can form at sites of friction rather than at predictable anatomical sites, but otherwise have imaging features similar to native bursae. Bursal distention can occur from many pathological processes, most commonly resulting from chronic overuse injury. When imaging bursal pathological conditions, there is often an overlap of imaging findings, regardless of the cause. In general, ultrasound of a distended bursa reveals a fluid collection with either simple anechoic or more complex hypoechoic fluid. Bursal distention is characteristically unilocular and compressible, unlike other structures such as ganglion cysts, which are usually multilocular and non-compressible. This article reviews the anatomical locations of common bursae and shows pathological examples using ultrasound. Knowledge of typical locations and imaging appearances of bursae can aid in narrowing the differential diagnosis and guiding further management and treatment decisions.

Elbow Imaging in Sport: Sports Imaging Series

Elbow pain is a frequent presenting symptom in athletes, particularly athletes who throw. The elbow can be injured as a result of acute trauma, such as a direct blow or a fall onto an outstretched hand or from chronic microtrauma. In particular, valgus extension overload during the throwing motion can precipitate a cascade of chronic injuries that can be debilitating for both casual and high-performance athletes. Prompt imaging evaluation facilitates accurate diagnosis and appropriate targeted interventions.

Magnetic resonance imaging of the elbow in athletes

Acute and chronic elbow pain is common, particularly in athletes. Although plain radiographs, ultrasound, and computed tomography all have a role to play in the investigation of elbow pain, magnetic resonance imaging (MRI) has emerged as the imaging modality of choice for diagnosis of soft tissue disease and osteochondral injury around the elbow. The high spatial resolution, excellent soft-tissue contrast, and multiplanar imaging capabilities of MRI make it ideal for evaluating the complex joint anatomy of the elbow. This article reviews imaging of common disease conditions occurring around the elbow in athletes, with an emphasis on MRI.

Detailed MRI-anatomic study of the lateral epicondyle of the elbow and its tendinous and ligamentous attachments in cadavers

OBJECTIVE

The objective of our study was to document discrete bone landmarks in the lateral epicondyle of the humerus that represent the "footprints" of those tendons and ligaments that attach to it using MRI-anatomic correlation in cadavers.

MATERIALS AND METHODS

Thirty-three dried humeral specimens were inspected to document bone landmarks in the lateral epicondyle. MRI with anatomic correlation was performed in 10 additional cadaveric elbows. The locations of the tendinous and ligamentous attachments to the lateral epicondyle were determined with respect to the same osseous landmarks.

RESULTS

The surface of the lateral epicondyle ranged from a flat surface to a surface with up to six discrete landmarks: superior tubercle, anterior tubercle, posterior tubercle, intertubercular sulcus, rough area surrounding the tubercles, and epicondylar ridge. The radial collateral ligament attached to the superior aspect of the intertubercular sulcus and inferior aspect of the superior tubercle and was indistinguishable from the attachment of the lateral ulnar collateral ligament. The extensor carpi radialis brevis, extensor digitorum communis, and extensor digiti minimi had a common origin in the superior aspect of the lateral epicondyle. The extensor carpi ulnaris tendon arose from the posteroinferior aspect of the lateral epicondyle.

CONCLUSION

Our investigation documents osseous landmarks that are useful in the identification of the footprints of the tendons and ligaments that attach to the lateral epicondyle. Knowledge of these structures contributes to correct interpretation of MR images in persons with tendinous and ligamentous abnormalities in this region.

Coronoid process of the ulna: paleopathologic and anatomic study with imaging correlation. Emphasis on the anteromedial "facet"

OBJECTIVE

The purpose of this study was to provide a detailed description of the anatomy of the coronoid process of the ulna and to use magnetic resonance (MR) images and anatomic correlation with cadavers to show the macroscopic configuration of this structure.

MATERIALS AND METHODS

Photography and high-resolution radiography were performed in 26 ulna specimens from the collection of a local museum. MR imaging of the coronoid process of 11 cadaveric elbows was performed. The images were compared with those seen on anatomic sectioning.

RESULTS

The anteromedial rim of the coronoid process of the ulna had a regular surface, without osseous irregularities or facets in 69.2% of the specimens. In 30.8% of the specimens, the anteromedial rim was not regular and a small ridge could be identified. The insertion site of the joint capsule was onto the anterior aspect of the coronoid process, at an average distance of 5.9 mm distal to the tip. The attachment of the anterior band of the ulnar collateral ligament at the sublime tubercle was flush with the articular margin in 63.6% of the specimens. In 36.4% of the specimens, a more distal attachment, with a separation between the undersurface of the ligament and the adjacent tubercle, was seen. The brachialis tendon was attached to the coronoid process at a mean distance of 12.1 mm distal to the tip.

CONCLUSION

The coronoid process of the ulna is a small osseous structure with a complex anatomy and presents some anatomical variations.