Displaced Pediatric Supracondylar Humerus Fractures: Biomechanical Analysis of Percutaneous Pinning Techniques

Supracondylar humerus fractures are a common childhood occurrence. Displaced fractures are typically treated with closed reduction and percutaneous pinning. Controversy continues over the appropriateness of various pinning techniques. The most common include crossed or lateral pins. A biomechanical comparison of crossed pins, "parallel" lateral pins, and "divergent" lateral pins was performed using a pediatric synthetic bone model. Mechanical testing of each pin configuration was performed in extension, varus, valgus, internal rotation, and external rotation. The divergent configuration provided statistically greater stability than parallel pins under varus and valgus loading. Divergent pins had similar stability compared with crossed pins in extension, varus, and valgus testing. In axial rotation testing, crossed pins were more stable. If the surgeon feels confident in the ability of lateral pins to provide satisfactory fracture stability, divergent lateral pins provide greater stability than parallel lateral pins while avoiding ulnar nerve injury (associated with crossed pins).