Physiology of the nail apparatus: Surgical consequences.

Knowledge of nail physiology is mandatory to understand nail pathologies, and to know what to repair and what to expect from your repair. Unfortunately, nail physiology in humans is not completely understood. However, there are some data that have been validated and must be known before treating patients. The nail plate is mostly made of keratins. It is produced solely by the nail matrix. The nail bed is mostly responsible for nail pate adhesion. At the hyponychium, the plate loses its adherence. The hyponychium is the first barrier of defense preventing bacteria and fungi from invading the subungual area. All these structures, along with the nail folds, are responsible for the orientation of nail-plate growth. However, many questions, such as whether to replace the nail plate at end of procedure, remain open.