Graft Production

37 Graft Production

Sharon A. Keene

Summary

Optimal graft production requires an integral understanding of the factors that influence graft survival in order to apply this information in handling and producing grafts, which will survive transplantation and continue to grow and provide enduring cosmetic benefits to patients with hair loss. Furthermore, knowledge of the technical considerations for graft production allows the hair restoration surgeon to select tools that optimize conditions for efficient and viable graft production. This also allows for appropriate training and assessment, as well as supervision and maintenance of a competent surgery team.

Keywords: follicular unit dermal papilla dermal sheath intradermal fat cells (adipocytes) transillumination hypothermia microscopic graft dissection graft dissection slivering (adipocytes)

Key Points

•Knowledge of hair graft anatomy is necessary to preserve structures needed for follicle survival and growth cycle propagation. Implicitly this includes avoiding transection of the dermal sheath (hair shaft) and preventing crush injury to the critical stem cell populations of the bulge region and dermal papilla.

•During graft production, follicles must be protected from two highly detrimental environmental stressors: desiccation and out-of-body time.

•Appropriate tools, instruments, holding solutions, and temperature are necessary for optimal production quality and efficiency, including microscopic magnification, devices that maintain hydration, and instruments that limit the risk of trauma to the graft.

37.1 Introduction

Regardless of the donor harvesting technique used to produce grafts for hair transplantation, there are common considerations during the production process that must be observed to ensure optimum graft survival. When donor hair is harvested using an elliptical excision and grafts are dissected microscopically ex vivo, graft dissection is commonly delegated to assisting staff members. However, it is critical for hair restoration surgeons to be competent to perform microscopic graft dissection themselves and to know all factors impacting successful graft production in order to appropriately train, evaluate, and supervise staff for this task. Furthermore, technical competency allows the surgeon to select tools and equipment necessary to optimize ergonomics and efficiency to achieve and maintain excellent and rapid graft production, from a well-trained surgical team. A more thorough examination of these points will be discussed in this chapter (Video 37.1). The topic of holding solutions is more completely reviewed in Chapter 38.

37.2 Hair Graft Anatomy

Currently, all methods of hair transplantation depend on redistribution of existing “permanent” donor hair, and utilize the naturally occurring “follicular unit” or hair bundles (Fig. 37.1a) to achieve natural results. These are observed to generally contain one to four hairs, though in some patients five- to six-hair bundles can be seen.

Fig. 37.1 (a) Follicular unit or hair bundles. (b) Anatomy of a hair follicle.

Fig. 37.1b illustrates the various anatomical structures of the follicular unit. Structures critical to graft survival and growth cycle propagation are the dermal papilla (DP), dermal sheath (DS), and the bulge area of the hair shaft containing stem cells, which communicate with one another.¹ Crush injury to these areas should be avoided in order to preserve their survival and promote future growth. Equally important is protecting the DS by avoiding transection of the DS during graft dissection. Studies suggest transection at certain levels of the DS may be not be lethal to the follicle, with greater survival for two-thirds of intact DS, compared to upper or lower halves. Nonetheless, it is uniformly agreed that transection reduces hair survival and every effort must be made to avoid this during graft production, for maximal hair/graft yield.²^,³^,⁴^,⁵

The role of intradermal fat cells (adipocytes) surrounding the hair shaft, a population distinct from subcutaneous fat, is currently being studied in great detail, and they are believed to play an important role in hair growth cycle propagation.⁶ These findings also suggest that preservation of fat around the follicle offers advantages beyond protection of the exposed bulb to trauma, and may actually contribute functional importance.

Finally, while grafts can survive de-epithelialization, leaving a small skin cap is useful as this provides an area that can be safely grasped during handling without functional injury to the hair follicle.

37.3 Set-up of the Room

During follicular unit transplant using microscopic dissection, the production of thousands of grafts requires thousands of repetitive movements. The effect of ergonomics as applied to activities in the hair restoration suite has not been reported in randomized controlled trials. However, recommendations from the field of dentistry where small repetitive motions commonly occur seem applicable. Methods and tools to reduce movements and maintain neutral positions for head, neck, shoulders, and hands during this process may reduce fatigue and maintain staff productivity and wellness.7 Room set-up for microscopic dissection should provide ergonomic height for dissecting counter tops where forearms rest comfortably, not raised—this can be individualized by the use of hydraulic chairs with adjustable height. The latter finds clinical support in a review paper where employees were found to have reduced musculoskeletal complaints when provided individually adjustable chairs.⁸ In addition, greater comfort during long cases can be achieved with lower back support in chairs (Fig. 37.2a). In another paper, a published review of workplace interventions gave resistance training high marks for reducing musculoskeletal complaints, while moderate evidence exists to support arm rests and stretching exercises.⁹ The author uses arm and wrist cushions, as well as interval stretching (Fig. 37.2b). Placing dissection tools and graft storage containers in close proximity to the work surface avoids reaching, reduces movements, and enhances efficiency.

Fig. 37.2 (a) Height adjustable chair with lumbar support. (b) Forearm rest and stretching.

37.4 Tools for Graft Production

37.4.1 Magnification and Backlighting (Transillumination)

Since the publication of the study by Bernstein and Rassman in 1998 that established superior graft yield for microscopic magnification compared to loupes for graft dissection,¹⁰ use of microscopes has become the standard of care for this task. Three types of microscopes are commonly used for magnification of follicular units and will be compared later. The goal of these devices is to facilitate visualization and preservation of critical graft structures, and to prevent inadvertent transection of hair DS during the slivering and dissection process.

The following three types of microscopes are most commonly used:

1. Binocular microscopes (e.g., Meiji, Zeiss, Unitron): These allow for direct, stereoscopic magnified vision of tissue. They are comparatively inexpensive and mobile. The Meiji Zoom Microscope offers 7 to 35× magnification. This is a popular device, but some feel it is difficult to adjust properly to avoid unnatural head/neck positions. Haber presented a poster showing the appropriate adjustment and reported excellent results for staff (Fig. 37.3a). The Unitron is newer and offers greater options for vertical adjustments compared to fixed-angle heads, but it is also more expensive.

2. Stereo microscopes (Mantis): These scopes include a series of lenses to provide a three-dimensional view of tissue and allow users to avoid bending of the head/neck during dissection. This improves ergonomics—however, the head must remain static, providing a limited range of motion. These scopes are more expensive, larger, and less mobile than binocular microscopes. They provide 6 to 8X magnification (Fig. 37.3b).

3. Video screen microscopes: These are two-dimensional view of grafts projected on a TV screen of varying size. These allow full range of motion for head, shoulders and neck, achieving improved ergonomics. The screen image facilitates teaching, and easy oversight of graft quality. However, because they do not allow direct eye–hand visual cues, greater eye–hand coordination is necessary, and longer learning curve is required for some staff. Videoscopes have variable pricing, from a few hundred to thousands of dollars. “Do it yourself” systems are least expensive and involve CCTV camera with magnifying lenses, projected on to a TV monitor (Fig. 37.3c). They provide 8 to10× or higher magnification with greater zoom lens, and are less mobile than other microscopes.