Age / Sex : 3 / M

Chief complaint: Right elbow pain and swelling for 10 days

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

(Quiz는 quiz일 뿐이오니 답안은 한개만 보내주시기 바라오며, 복수의 답안을 보내주시는 분은 정답이 포함되어 있더라도 부득이 semi-correct answer로 처리토록 하겠습니다.)

Courtesy: 김옥화(Kim Ok Hwa)  인제대학교 해운대 백병원 영상의학과(Inje University Haeundae Paik Hospital Radiology Department)

Nursemaid’s elbow (babysitter's elbow, pulled elbow, or radial head subluxation).

Discussion

Findings:

1. AP and lateral radiographs of right elbow show no bony fractures.

2. Coronal STIR T2WI, sagittal SPIR PDWI and axial T2WI show a torn, displaced annular ligament in the radiocapitellar joint, covering one-third of the widest radial head diameter. Edema and/or hemorrhage are present along the radial head. Small elbow joint effusion is also seen.

Differential Diagnosis:

Elbow bony fracture.

Diagnosis:

Nursemaid’s elbow with annular ligament entrapment (babysitter's elbow, pulled elbow, or radial head subluxation).

Discussion:

Nursemaid’s elbow, also known as pulled elbow or radial head subluxation, is an injury usually occurring in early childhood, in which the annular ligament is entrapped between the radial head and the capitellum. The median age of presentation is 2 years, and it more frequently affects the left arm and females. Characteristic clinical history and presentation are generally successful in diagnosing nursemaid’s elbow. Clinical presentation is characteristic, and radiographs are not commonly taken. The usual mechanism that makes the annular ligament slide proximally to the radial head is a longitudinal traction on the extended arm with the forearm pronated. The second most common mechanism of injury is a fall. Normally, the slipped annular ligament coverage of the radial head does not exceed the widest part of its antero-posterior diameter and reduction is possible by standard maneuvers. But, if the ligament slides beyond the widest radial head diameter, the closed reduction is not possible. MRI can be used to both determine the diagnosis of annular ligament entrapment and confirm successful reduction.

References:

1. Richardson M, Kuester VG, Hoover K.The Usefulness of MRI in Atypical Pulled/Nursemaid’s Elbow: A Case Report. 2012;32:e20-e22.

2. Corella F, Horna L, Villa A, et al. Irreducible‘pulled elbow: report of two cases and review of the literature. J Pediatr Orthop B. 2010; 19:304–306.

3. Choung W, Heinrich SD. Acute annular ligament interposition into

the radiocapitellar joint in children (nursemaid’s elbow). J Pediatr

Orthop. 1995;15:454–456.