Anatomy of the ulnocarpal compartment

Abstract

The form of the ulnar side of the human wrist represents progressive evolutionary development. In prosimians, the ulna continued to articulate with the pisiform and triquetrum, aiding in weight transmission across the wrist [1]. The monkey wrist showed the first step to change from the weight-bearing wrist to the mobile wrist (Fig. 1.1). In the gibbon, the ulna has migrated proximally and does not articulate directly with the pisiform and triquetrum. Instead, a thick meniscus was interposed between these three bones [1]. Chimpanzees developed a wrist that was similar to humans. There is a formal distal radioulnar joint that is bounded distally by the triangular fibrocartilage (TFC). In addition, a blind recess or prestyloid recess develops [1]. Humans have wrists characterized by further withdrawal of the ulnar styloid with loss of the articular cartilage from the ulnar styloid [2]. In addition, the distal ulna has evolved to allow greater pronosupination. The embryologic and clinical material suggests there is a tremendous variation in the development of the ulnar side of the wrist. The data also support the concept that evolution continues and that we are all different in terms of our ulnocarpal and distal radioulnar joints. Different configurations may require careful consideration before applying singular solutions to such a complex area [3].