Would a hair transplant on only the frontal area without crown look natural?

It is common to focus on the frontal hairline and midsection of the scalp during an initial hair transplant.  This is what you see when you look in the mirror and what people see when you are interacting with them so it makes sense to focus your transplant there. Plus, many people do not have ample donor hair and will never be able to achieve a “full head of hair” through transplantation.  When designed properly for your facial structure, your age, and with the future in mind, transplantation of a front hairline can blend very well with a bald or thinning crown. As far as number of grafts, that is best determined through consultation.  There are variables such as donor availability, your hair texture, and the size of the area you wish to have transplanted.  

Having a hair transplant to restore the front while leaving the crown bald is common and natural because there're some male's baldness patterns that the bald spot is only at the crown. However, I agree to focus on the front as it's the frame of the face. 

It is common to focus on the front and/or top areas first without addressing the crown.  Reframing the face makes a big difference and will give you a natural look.

Thank you for your question. You are asking if a transplant concentrated at the frontal hairline and scalp will look natural, while not transplanting at the crown.
I can certainly give you some guidance about this, with the photos you shared for reference, and without a physical exam. I’m a Board Certified Cosmetic Surgeon and Fellowship-trained Oculoplastic Surgeon. I’ve been in practice in Manhattan and Long Island for over 20 years. I’ve been performing hair transplants since I started my practice, and have been prescribing finasteride to male pattern hair loss patients since 1997. I’m also the founder of TrichoStem Hair Regeneration Centers, based on a system originally developed to help hair transplants and the donor area heal better, but has since become a non-surgical treatment for pattern hair loss for men and women.
It’s important to know the limited density and numbers of grafts a hair transplant can achieve before going into a hair transplant procedure. Hair grafts that contain 1-3 hair follicles can only be safely placed at about 20 per square centimeter of scalp. Exceeding this number compromises the blood supply and nutrition needed for the grafts to survive. Native hair usually numbers 50-100 hairs per square centimeter, depending on the individual, so it’s difficult to impossible to get the same hair density as native hair through a transplant alone. Often a second or third hair transplant is needed to get a natural-looking result. With hair count, the donor area can yield anywhere from 1500-4500 grafts. However, peak hair count in the early teenage years is about 100,000, and hair loss when it’s first noticed means about half of hair is already lost. Looking at your pictures, you have lost more than half your hair, and your pattern does look very aggressive.
Hair transplants have to be strategic because they can’t replace all the hair that’s been lost. Normally, transplanted hairs are concentrated first at the frontal hairline to help frame the face. Other grafts will concentrate on the mid scalp for gradual coverage to make it look more natural. With your pattern, it doesn’t look like there would be enough grafts to transplant to your crown, so whatever can be harvested from donor area would be concentrated at your hairline and mid-scalp.
We do hair restoration a little differently in our practice, where transplant is not the first treatment. If you feel your scalp, or look at it closely with microscope exam like I would do, you’ll notice that seemingly bald areas actually have miniaturized hair. I would first thicken these hairs with our Hair Regeneration treatment as native hair, even when thinning, is more numerous than available grafts, and also grows more tightly together than can be achieved by transplantation. Hair transplants often overlook thinning hair, and even transplant grafts through their still active follicles, as surgeons figure they are thinning and will be lost anyway. Even if your hair loss is quite advanced, we can thicken your native hairs first with 1-2 treatment sessions, spread about 18 months apart. We can also stimulate growth from dormant but still viable hair follicles currently not growing with the treatment. We will monitor your progress after the first month, then at 3 months, 6 months, then every 6 months after that. After monitoring progress after the booster treatment at about 18 months, we can then plan for a more strategic transplantation, where each graft is maximized in key areas. Most of our patients avoid a transplant altogether, or at least delay it indefinitely. We have had patients with similar patterns to yours that were able to get enough coverage to avoid a transplant, but judging your pictures alone, you will likely need a transplant. However, we can maximize your grafts and your native hair much better than if you were to jump straight into transplantation.
I suggest you look into treatments like Hair Regeneration that provide hair coverage from existing hair before undergoing transplant surgery. Native hair has greater volume and density than a transplant can achieve, even in advanced hair loss cases. By saving and thickening native hair, and stimulating growth from dormant follicles that would be lost in hair transplant trauma, grafts can be concentrated in areas where the follicles are already dead, and no native hair is present. It’s also important to note that hair transplants do not treat continuing hair loss progression, so treatments like Hair Regeneration and finasteride are important to treat progression after a transplant. I hope you found this information helpful. Thank you for your question.

I always tell my patients to go to a Mall and from the second floor look down on the men who pass. You will see many men with full frontal hair coverage and an absent crown. It is one variation of normal