Role of the Posterior Fat Pad Sign in Treating Displaced Extension Type Supracondylar Fractures of the Pediatric Elbow Using the Blount Method

Abstract

The posterior fat pad sign (PFPS) on the lateral elbow X-ray is useful in the diagnosis of a suspected nondisplaced fracture about the elbow after a subtle injury. However, the presence of a PFPS hallmarks a continuous posterior periosteum-posterior capsule of the distal humerus. This anatomic structure is crucial for the stable anatomic reduction of a displaced extension type supracondylar fracture. Subsequently, the presence of a PFPS may predict the successful nonoperative treatment of a Gartland III-type fracture by means of the Blount method, implying less implant-related morbidity and less intraoperative radiation exposure for the patient and surgeon. Furthermore, it is concluded that a PFPS-positive displaced extension type supracondylar fracture is definitively classified as a Gartland III and not a Gartland IV-type fracture. A retrospective study of 75 displaced extension type supracondylar elbow fractures was performed. All fractures had an initial attempt at a closed reduction under general anesthesia. A stable reduction in 120 degrees of elbow flexion without vascular compromise of the affected limb was achieved in 45 fractures, which were splinted in this position. In the remaining 30 cases, fracture reduction was either inadequate or was achieved with excess elbow flexion, which impaired distal blood flow. These fractures were pinned percutaneously and splinted in 90 degrees of elbow flexion. The two treatment groups were retrospectively compared for the presence of a PFPS. The displaced extension type supracondylar fractures, which were treated successfully by the Blount method, had a statistically significant higher prevalence (chi-square-Yates =4.91, p<0.05) of a positive PFPS (28/45 patients, 62.22%) compared to the fractures treated by closed reduction and percutaneous pinning (10/30, 33.33%). No vascular complications were observed. The long-term outcome did not differ between groups.