Patient-Based Ratio Method for Permanent Zone Donor Area Calculation in Hair Transplant.

Area of Science:

• Dermatology
• Surgical Sciences
• Hair Restoration Science

Background:

• Androgenetic alopecia is the most common cause of hair loss.
• Orentreich's donor dominance theory and safe donor area definition are foundational in hair transplantation.
• Accurate estimation of the safe donor zone is crucial for preventing transplanted hair loss, but current methods lack patient-specific tailoring, especially in early stages.

Purpose of the Study:

• To establish a relationship between safe donor zone dimensions and other scalp measurements.
• To develop a method for predicting the complete safe zone in patients with early-stage hair loss.
• To improve the accuracy of safe donor area assessment in hair transplantation.

Main Methods:

• A ratio method was developed using measurements from the vertex to the occipital protuberance.
• The study included 100 patients with Norwood IV or higher hair loss to establish the ratio.
• The applicability of this ratio was then tested on 100 patients with Norwood II to IVa hair loss.

Main Results:

• A ratio range of 0.43-0.53 was identified for the permanent zone relative to the total distance from vertex to occiput.
• The formula derived is: Permanent zone = Total distance (vertex to occiput) × (0.43–0.53).
• Over 90% of patients showed no significant reduction in transplanted hair density using this method.

Conclusions:

• The proposed ratio method is a simple, effective, and easily applicable tool for determining the permanent zone dimensions.
• This method is particularly useful for patients with early grades of androgenetic alopecia (Norwood scale).
• The technique can ensure long-lasting results in hair transplant procedures by accurately identifying the safe donor area.