The correct answer is 24538-LT.
This is a supracondylar fracture of the elbow repaired by percutaneous fixation. In the CPT index fracture/Supracondylar/Humerus/Percutaneous fixation is referred to as 24538. Modifier LT is attached to suggest the procedure is done on the left side. The application of the sphint or the first cast is included in the fracture codes.