The current method for hair transplantation is a four-part process completed in a single, 1-day session. These four overlapping steps include: (1) hair follicle grafts or follicular unit grafts (naturally occurring groups of 1-4 hairs) are harvested from the permanent donor area, either in a long-thin strip that is subsequently dissected into follicular units (follicular unit transplantation via strip method) or removed directly from the scalp one at a time (follicular unit extraction), (2) grafts are held in a chilled, physiologic solution, (3) needle-size wounds are made in a recipient area, and (4) follicular unit grafts are placed into the recipient sites.
In 1994, Dr. Richard Shiell proposed the concept of an X Factor, some unknown factor (or factors) which can lead to sub-optimal growth following a hair transplant. Over the years, as these “unknown” factors have been identified and addressed, graft survival has improved. Some of these factors that have been responsible for the improvements in growth have included: (a) minimizing surgical transection of the follicles at the time of harvesting, (b) preventing graft desiccation and warming, (c) reducing the time grafts are in the oxygen and nutrient poor environment outside the body, and (d) decreasing crush injury during placing.
In 1997, Dr. Bobby Limmer underscored the time concern by reporting decreased survival when grafts spend prolonged periods of time outside the body. Following that work, there has been a significant effort to streamline the surgical process so that grafts could be planted as quickly as possible—a particular concern in large surgical sessions. Graft survival has been enhanced by cooling the graft holding solution to temperatures ranging from 40 to 60° F. There have also been advances in the way grafts are stored, using special solutions that nourish the grafts, so that they are in a more physiologic environment while awaiting placement into the recipient sites.