The usefulness of ultrasound and the posterior fat pad sign in pulled elbow

Imaging Assessment of the Pediatric Elbow: Developmental Variants and Common Pathologies

The pediatric elbow is a complex joint that undergoes rapid growth and development. The normal anatomy of the elbow varies depending on the age of the patient, which can be challenging for imaging interpretation. This article reviews developmental variants and common pathologies of the pediatric elbow, with a focus on their radiologic features. Normal anatomy and development of the pediatric elbow are discussed, including the six ossification centers and elbow alignment. Congenital anomalies such as longitudinal deficiencies of the upper extremity are reviewed. Some common injuries that affect the elbow, such as supracondylar fracture, lateral condyle fracture, medial epicondyle avulsion, and radial head dislocation are also described.

Nursemaid's elbow: Radial head subluxation injuries in children

ABSTRACT

Radial head subluxation, or nursemaid's elbow, is a common orthopedic complaint in children and often is the result of a pulling injury to the affected arm. Although this injury largely is a clinical diagnosis, different imaging modalities may be used to identify it and confirm successful reduction. Multiple manipulative techniques can be used to treat this injury and methods are generally specific to clinician preference. This article reviews the causes, evaluation, and management of radial head subluxation.

The Usefulness of Dynamic Ultrasonography in Nursemaid's Elbow: A Prospective Case Series of 13 Patients Reconsideration of the Pathophysiology of Nursemaid's Elbow

BACKGROUND

Nursemaid's elbow is a common musculoskeletal disorder among children under 5 years of age. However, diagnostic imaging to confirm a nursemaid's elbow diagnosis is still unavailable. Through the use of a high-frequency ultrasound probe, we determined the etiology and possible pathophysiology of nursemaid's elbow.

METHODS

Thirteen consecutive patients with the clinical suspicion of nursemaid's elbows were examined. A high-frequency linear array 6 to 24 MHz hockey stick transducer was used to detect small changes (partial eclipse signs) of the radial head in the axial view before and after manipulation.

RESULTS

All patients in this study had a successful reduction. A partial eclipse sign was found in all patients before reduction and disappeared after successful reduction.

CONCLUSION

These pathologic features detected through high-frequency ultrasonography suggest the role of the escaped posterior synovial fringe in the pathogenesis of the nursemaid's elbow. The specific finding of a "partial eclipse sign" could be a useful additional clue leading to the correct diagnosis of the nursemaid's elbow and may help avoid the unnecessary reduction in patients who do not have a "partial eclipse sign".

LEVEL OF EVIDENCE

Level II, diagnostic studies.

Children With Elbow Injuries and Sonographic Elevated Posterior Fat Pad but No Identifiable Posterior Fat Pad on Lateral Radiographs: A Case Series

Point of Care Ultrasound (POCUS) is used to evaluate the injured pediatric elbow. Standard of care, however, remains radiography. POCUS performed in the setting of normal radiographs have been obtained may demonstrate radiologic occult lipohemarthrosis indicative of occult fracture. We reviewed our pediatric emergency department (PED) POCUS archive for lipohemarthrosis, and then isolated those cases with normal elbow radiography. Radiography was deemed to be normal per the interpretation of the treating PED physician, and was reviewed for this series by an experienced ABR board certified pediatric radiologist. Fracture on POCUS was defined as fracture line or lipohemarthrosis in a posterior sagittal or transverse view of the distal humerus. Fracture was confirmed by signs of cortical healing on follow-up radiography, or clinical course consistent with fracture as documented by an orthopedist. We identified four children with elbow fractures who had no fracture line or elevated posterior fat pad on radiography but demonstrated lipohemarthrosis on POCUS. POCUS may elicit evidence of fracture even after normal radiography, and POCUS findings suggesting occult fracture may allow for more effective guidance on discharge.

Ultrasonography of the pediatric elbow

Ultrasound of the elbow can be incorporated into routine pediatric practice in the radiology department, emergency department, orthopedic clinic, and interventional suite. Ultrasound is complementary to radiography and magnetic resonance imaging for the evaluation of elbow pain in athletes with overhead activities or valgus stress, focusing on the ulnar collateral ligament medially and capitellum laterally. As a primary imaging modality, ultrasound can be used for a variety of indications including inflammatory arthritis, fracture diagnosis, and ulnar neuritis/subluxation. Ultrasound is also well-suited to guide diagnostic and therapeutic elbow joint interventions with precise localization of anatomic landmarks and needle placement. Here, we describe technical aspects of elbow ultrasound and illustrate its application in pediatric patients from infants to teen athletes.