Hair loss represents a distressing issue affecting a large portion of the population, including up to 85% of males and 40% of females, and its incidence increases with age for both sexes. Though many causes of hair loss exist, by far the most common etiology is androgenic alopecia (AGA), an androgen-sensitive pattern of hair loss that affects both men and women. Indeed, non-surgical modalities exist which may halt the progression of androgenic alopecia and even help grow new hairs (i.e., minoxidil, finasteride, dutasteride, low-level laser light therapy, platelet-rich plasma, adenosine, ketoconazole)  Nevertheless, recent advancements in surgical hair restoration have made hair transplantation (HT) an increasingly effective, safe, and reliable way for patients distressed by androgenic alopecia to regain a more youthful and natural appearance of their hair.
It is essential to understand the relevant anatomy and physiology of hair, and the hair cycle, in order to maximize the outcomes of hair transplantation. Key elements in hair restoration include:
Scalp Hair Growth cycle:
Androgenetic alopecia (AGA) – the most common etiology of hair loss wherein androgenetic effects, namely testosterone and dihydrotestosterone (DHT), disrupt the growth cycle (the anagen to telogen ratio decreases). Hallmark characteristics of AGA include thinning and subsequent miniaturization of terminal hairs to vellus hairs.
Donor site: the non-alopecic areas (not influenced by androgenic alopecia) where donor terminal hairs can be harvested for implantation. The safe donor site of the scalp lies in the mid-occipital region between the upper and lower occipital protuberances. In general, there are 65 to 85 FUs per square centimeter (cm) in the occipital donor scalp. Of note, hairs are finer in the inferior portion of the donor area and coarsest at the superior margin. The donor site represents the primary limiting factor in hair transplantation, regardless of the technique employed. In general, harvesting more than 15 to 20 FU per squared cm is ill-advised, as this may cause donor site thinning. NOTE: If necessary, the parietal scalp, submental region, chest and other parts of the body may be used as donor sites, though data regarding efficacy is limited and the hair characteristics can be very different from scalp hairs.
Identifying appropriate candidates for hair transplantation includes an evaluation of the following:
Two types of hair transplantation techniques predominate, including the follicular unit transplantation (FUT) and follicular unit extraction (FUE) techniques. Currently, FUE represents the more common approach due to its potential advantages over FUT, which include:
On the contrary, FUT may be preferable to FUE given FUT’s reported advantages, which include:
Still, controversy remains as to which hair transplantation procedure is superior. Nevertheless, most HT surgeons would agree that deciding on whether to use FUE or FUT depends on several factors, some of which have been enumerated above. In summary, both FUT and FUE represent powerful techniques for improving the aesthetic appearance of the hair, and the astute hair transplantation surgeon should be knowledgable of the nuances of each.
During the preoperative HT consultation, the HT surgeon should identify patients who may not be candidates for surgery by eliciting the following information:
Depending on the findings as obtained from the above examination, the surgeon should refer the patient to the appropriate physician or specialist (i.e., primary care, dermatology, rheumatology, endocrinology, psychiatry, pathologist) for further workup and/or management.
In summary, potential exclusionary criteria, or “red flags” for HT would include:
Contemporary hair transplantation requires a well-trained and efficient surgical team, including:
The desired recipient graft number (total number of grafts needed) is calculated by multiplying the measured recipient area by the desired graft density (target density should be around 30 FUs per cm^2). If planning FUT for graft harvest, the strip length is calculated by dividing the desired recipient graft number by the donor site density (using a densitometer). The strip should be around 1 to 1.5 cm wide, but no larger to allow tension-free wound closure.
Anxiolytics may be given pre-operatively, per surgeon and patient preference.
The administration of antibiotics covering skin flora should is necessary pre-operatively.
A single dose of pre-operative systemic steroids (i.e., 40 mg of prednisone) may help with scalp swelling.
The recipient area is marked, including the proposed hairline and direction/pattern of native FUs.
The donor site is shaved and marked according to the technique employed.
Anesthesia is obtained using a combination of local injections and regional nerve blocks (supraorbital, supratrochlear, zygomaticofrontal, and occipital).
Tumescent anesthesia and tumescent saline are infiltrated to the proposed donor and implantation sites as needed to facilitate graft harvest and placement, respectively.
While several surgical treatment options (plug grafts, scalp reductions, transposition flaps) have been used historically to treat androgenic alopecia, we outline the two most common techniques of HT based on the follicular unit-principle, namely the follicular unit transplantation (FUT) and the follicular unit excision (FUE).
In general, complications after hair transplantation are rare, given the vigorous blood-supply to the scalp, which allows for quick healing and low rates of infection. Nevertheless, potential complications include:
Hair transplantation represents a powerful tool that can restore a more youthful appearance to those affected by androgenic alopecia. When performing hair transplantation, proper patient evaluation and execution of a comprehensive treatment plan can produce safe, reliable, and satisfactory outcomes.
It remains imperative to identify the risk factors and perform a thorough assessment of the patient prior to performing hair transplantation. A team approach is an ideal way to limit the complications of this procedure. Before surgery, the patient should have the following done:
Evaluation by a surgeon experienced in selecting the appropriate patient for HT.
Evaluation by a primary care physician to diagnose and/or treat potentially reversible causes of hair loss (e.g., hypothyroidism, hormonal imbalance, malnutrition), if applicable.
Evaluation by a dermatologist to diagnose and/or treat inflammatory causes of hair loss (e.g., lichen planopilaris), if suspected either on physical exam, laboratory studies, or histopathological analysis.
The pharmacist will have some involvement, depending on the medication needs surrounding the procedure. The pharmacist should examine the patient's medication record and ensure everything is in place for the hair transplantation, and that there are no drug interactions. Any concerns should be reported to the nurse to pass on to the clinician. Nursing will have extensive involvement, including preparation, assistance intraoperatively, and monitoring and followup. Nursing duties are covered in more detail in the following sections.
An interprofessional team of an experienced surgeon, hair technicians, and operative nurses should be involved during the HT to maximize outcomes. Close follow-up during the initial post-operative period, either by a wound care nurse and/or clinician experienced in the post-operative care of HT, should monitor the patient for possible complications including infection or hematoma. It is also important to provide patient education on properly maintaining the surgical wounds. The patient should also avoid strenuous activity for 1 to 2 weeks to help prevent complications. This overall interprofessional approach will result in the best patient outcomes with minimal adverse events.[Level V]
Adequate pain medication is appropriate, as patients often report mild harvest and donor site pain for 1 to 2 days postoperatively. To minimize edema and ecchymosis, the patient may intermittently ice the affected areas for 48 hours, sleep with their head elevated for one week, and avoid vigorous activity for two weeks. The patient may be given a low-dose corticosteroid taper to help lessen bruising and swelling as well. Post-operative antibiotics are often prescribed as well to mitigate infection, though data supporting its routine use is limited. To promote wound healing, the patient is instructed to keep the affected areas moist by routine application of an emollient for the first several days. Also, a small spray bottle may be used to gently apply moisture to the area, which also helps prevent scabbing. Regular shampooing may resume on postoperative day 2, though caution is advised against scratching/itching the scalp, and to avoid direct water contact from a high-pressure faucet or showerhead. Patients are asked to return at seven days for suture removal (if applicable) and are followed closely over the following months until the maturation of the implanted grafts (around 6 to 12 months) occurs. Photographic documentation should occur at around 6 to 12 months postoperatively. Topical minoxidil, oral finasteride, and low-level light therapy may be continued throughout the perioperative period and indefinitely after that to help maximize results.
Close follow-up during the initial post-operative period, either by a wound care nurse and/or clinician experienced in the post-operative care of HT, should monitor the patient for possible complications including infection and ingrown hair formation. The patient should receive counsel that loss of the implanted hairs normally occurs after several days and may take several months to grow. There may also be surrounding native hair loss at the donor or recipient site, though the patient should understand that this “shock loss” is normally transient and to expect a full recovery after a few months.
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