Occult Fractures in Children with a Radiographic Fat Pad Sign of the Elbow: A Meta-Analysis of 10 Published Studies

Abstract

Background: A radiographic fat pad sign after an elbow injury in children may indicate an occult fracture. Different incidences and locations of occult fractures have been reported. The primary objective of this meta-analysis was to assess the overall rate of occult fractures in children with a positive fat pad sign from the data of original studies. Secondary objectives were to assess the fracture types and to identify risk factors for sustaining an occult fracture.

Methods: A systematic literature search of the Embase, MEDLINE, and Cochrane databases was performed according to PRISMA guidelines. Studies on pediatric populations with a positive fat pad sign identified using a lateral elbow radiograph and with follow-up imaging were included in this meta-analysis. Included studies were assessed for risk of bias with use of the MINORS (Methodological Index for NOn-Randomized Studies) instrument.

Results: Ten studies with a total of 250 patients, of whom 104 had an occult fracture, were included. Accounting for heterogeneity between the studies, the overall occult fracture rate was 44.6% (95% confidence interval: 30.4% to 59.7%). The most common fracture locations were the supracondylar humerus (43%), proximal ulna (19%), proximal radius (17%), and lateral humeral condyle (14%). Definitions of a positive pad fad sign were not uniform among studies, and the follow-up imaging modality also varied (radiography, magnetic resonance imaging, or computed tomography). The average MINORS score was 10.1 for the 7 noncomparative studies and 18.7 for the 3 comparative studies, with both averages classified as moderate quality. We were not able to identify risk factors for an occult fracture in the presence of a positive fat pad sign.

Conclusions: The occult fracture rate was 44.6% in pediatric elbow injuries with a positive fat pad sign. Supracondylar humeral fractures were the most frequently encountered type. The findings of this meta-analysis underline the potential clinical relevance of a positive fat pad sign in children and denote the opportunity for future studies to create evidence-based guidelines.

Level of evidence: Level II. See Instructions for Authors for a complete description of levels of evidence.