Malunions of the Distal Humerus

Distal humerus malunions most commonly develop following distal humerus fractures in children and adolescents and on occasion following distal humerus fractures in adults. These malunions are thought to result from inadequate reduction and fixation of the fracture initially, or as a result of a loss of fracture reduction, or failure of the implants, in the setting of a delayed union. Distal humerus malunions may result in an unfavorable cosmetic deformity (“gun stock deformity”) and decreased elbow and upper extremity motion and function. Generally, the malunion deformity is associated with extension and varus and internal rotation of the distal fragment, although malunions of previous distal humerus fractures may be associated with a variety of deformities. Successful treatment of these symptomatic malunions begins with achieving a thorough understanding of the function and range of motion of the upper extremity, as well as a thorough understanding of the actual bony deformity. In order to thoroughly understand the consequences of the malunion, a thorough history and physical examination are essential. To gain a thorough understanding of the bony anatomy, complete radiographic assessment of the malunited humerus and the contralateral humerus are necessary. Additionally, CT scans are helpful to further assess the anatomy of the malunited humerus, particularly in regard to rotational deformity. Three-dimensional (3D) reconstruction of these CT scans facilitates further understanding of the deformity and also aids in the preoperative planning. After thorough assessment and preoperative planning, deformity correction involves osteotomy(ies) of the distal humerus to allow deformity correction and internal fixation while avoiding complications. Successful correction, fixation, and healing, while avoiding complications, often lead to a cosmetically pleasing and functionally improved upper extremity. This chapter highlights the assessment and preoperative planning for distal humerus malunion correction and presents several examples of successful corrections.