Is it possible to use hand/finger hairs on an eyebrow transplant?

Using hand or finger hairs for an eyebrow transplant is generally not a common practice. The primary reasons include:

Hair Characteristics: While the length and texture might seem similar, the growth cycle and characteristics of hand/finger hair can differ significantly from eyebrow hair. Eyebrow hairs have a specific growth cycle and texture that are best matched by scalp hair, particularly from the nape of the neck.

Extraction Challenges: The skin on the hands and fingers is indeed different from the scalp or other common donor areas. It may be more challenging to extract hair follicles from these areas without causing noticeable scarring or damage.

Graft Survival and Aesthetics: Even if extraction is possible, the survival rate of these grafts might be lower, and the aesthetic outcome may not be ideal. The direction and angle of hair growth are crucial for natural-looking eyebrows, and this can be difficult to achieve with hair from non-traditional donor sites.

Scarring: As you mentioned, there is a risk of circular scars at the donor site, which might be more noticeable on the hands and fingers.

In practice, hair from the scalp, particularly from areas where the hair is finer, is typically used for eyebrow transplants to ensure the best match and outcome.

Survival would likely be very poor although this has not beed studied. also you are dealing with a situation that has never been studied to any significant degree which opens up much uncertainty.

Yes, there are way more potential problems that just circular scars! Infection being an important one. Abnormal healing leading to ligamentous dysfunction or injury being another.

This is not recommended given not only poor outcome but significant risk.