Ulnar-sided wrist pain is a common cause of upper-extremity disability. Presentation can vary from acute traumatic injuries to chronic degenerative conditions. Because of its overlapping anatomy, complex differential diagnosis, and varied treatment outcomes, the ulnar side of the wrist has been referred to as the "black box" of the wrist, and its pathology has been compared with that of low back pain. Common causes of ulnar-sided wrist pain include triangular fibrocartilage complex injuries, lunotriquetral ligament injuries, and ulnar impaction syndrome.