The inferior arc injury: an addition to the family of complex carpal fracture-dislocation patterns.

Traditionally, complex wrist injuries were identified and characterized on the basis of observation of bony injury and presumption of soft tissue embarrassment, followed by employment of a classification scheme or cumbersome nomenclature. The extent of tissue compromise was often underestimated, leading to undertreatment and inferior results. This paper encourages physicians to think more mechanistically about the pattern of injury by relying on the concept of "transverse" force transmission to identify the global extent of wrist trauma. By employing a basic understanding of the components of the wrist "system" and superimposing the flow of energy through it, one can better grasp these complex topics. The standard "greater arc" and "lesser arc" injuries are explained in this context. Another recognizable injury pattern in the transverse instability spectrum, that of the "inferior arc," is introduced, along with clues for its identification. The large fragment and small fragment fracture variants of the inferior arc injury are emphasized, and their significance is described. Basic evaluation and treatment recommendations for inferior arc injuries are offered.