Pediatric Type II Supracondylar Humerus Fractures: Factors Associated With Successful Closed Reduction and Immobilization

Purpose: The debate on the treatment of type IIa supracondylar humerus fractures has yet to be resolved. The purpose of this study was to assess the factors associated with successful closed reduction and immobilization and to assess the efficacy of a novel radiographic "hourglass" angle measurement in the management of type IIa supracondylar humerus fractures within the pediatric population. Methods: An institutional review board-approved retrospective review of all children who underwent closed reduction and casting or splinting of an isolated type IIa supracondylar humerus fractures treated at 2 pediatric hospitals from January 1, 2009 to August 31, 2016. Analyzed radiographic parameters included Baumann angle (BA), humerocondylar angle (HCA), perpendicular distance (PD) from the anterior humeral line to the capitellum, and the hourglass angle (HGA). These parameters were measured on injury radiographs (XR), postreduction XR, and at the first and final follow-up XR. The success of closed reduction was defined as maintenance of an acceptable reduction without a secondary procedure. The interobserver reliability was calculated. Results: There were 77 elbows treated with closed reduction and long-arm cast or splint immobilization. Of those closed reductions, 76.62% of elbows (59/77) maintained their reduction alignment and did not require surgical treatment for percutaneous pinning. In this series, the BA was not significantly different following closed reduction ( increment 1.04 degrees;P=0.081); however, the PD ( increment 1.89 mm), HGA ( increment 7.38 degrees), and HCA ( increment 5.07 degrees) had significant improvement following closed reduction (P<0.001 for all). The use of procedural sedation during reduction was strongly associated with success, 83.05% (49/59) with sedation compared with 55.56% (10/18) success without sedation (P=0.025). Furthermore, fractures that underwent a secondary procedure had 6.20 degrees less HGA following a closed reduction (P=0.016) and required additional follow-up visits (P=0.0037). The success of type IIa supracondylar humerus fractures did not significantly differ based on sex (P=0.5684), laterality (P=0.6975), mechanism of injury (P>0.9999), location of care-emergency department versus clinic (P=0.1160), or type of fracture immobilization (P=0.7411). The mean HGA in normal elbows was 177.8 degrees. The interobserver reliability for HCA was poor [intraclass correlation coefficient (ICC)=0.342]; fair for BA (ICC=0.458); and excellent for both PD and HGA (ICC=0.769 and 0.805, respectively) (P<0.001 for all). Conclusions: Improved and acceptable radiographic parameters were achieved by a closed reduction in the majority of minimally displaced type IIa fractures treated by closed reduction and immobilization in this series. HCA upon presentation was significantly greater in successful cases, and failure to improve and maintain HGA and PD following closed reduction was associated with loss of reduction. Procedural sedation during reduction was strongly associated with success. The HGA and PD were consistent parameters used to determine effective management of type IIa fractures. This study adds support for a nonoperative closed reduction under sedation with immobilization of selected type IIa supracondylar humerus fractures.