Understanding Varus Posteromedial Instability: Biomechanics, Injury Patterns, and Achieving Successful Stability.

Understanding the varus posteromedial rotatory instability requires a detailed clinical examination and better radiographic characterization of the anteromedial facet fractures with the aid of 3-dimensional computed tomography humeral subtraction views. A better understanding of these injuries allows for the development of more reliable management algorithms to avoid overtreatment with increased risk of complications or undertreatment with the risk of progressive post-traumatic arthritis. An algorithm based on the detailed assessment of the radiographic features of the varus posteromedial rotatory instability to reliably determine the appropriate nonoperative versus operative management of these subtle injuries is discussed.