Mandibular implants, I’m scared it will look like this (Photo)

Custom jaw implants provide a better solution than stock implants. Every jaw at the angle is slightly different. The best fir and contour is achieved with custom implants. In many cases the implant does not extend beyond the angle of the jaw. Chin implants can be customized as well. Good luck

Without an exam your question cannot be answered.  You will need to see an Oral/Maxillofacial surgeon to see if othognathic surgery, genioplastyor using an implant is best for your specific case. It should be noted that patients with severely weak jaws or abnormally functioning jaws maybe better treated with other facial surgery (orthognathic surgery), although a chin augmentation may be an option at a later time. These patients should seek the advice of a plastic surgeon to determine which course is right for them. Here is some information to help you make thisdecision: Candidates for Chin Augmentation - Patients whose chin profiles are weak but have normally functioning jaws are candidates for Chin Augmentation. Many of these candidates have used injectable fillersin the past to strengthen the protrusion of their chins, but are looking for a permanent solution. If you are one of these patients, thenyou are a likely candidate for chin augmentation

One of the important considerations in jaw angle implants is whether one has the right type of face for it. (thinner) Fuller faces can just end up looking fuller not more defined. The other consideration is the proper style and size of jaw angle implant, particularly the style. There are different styles of these facial implants that can have a significantly different look to them.

Your concerns are fair but should not occur with experienced surgeons. The entire jawline has to blend together seemlessly so that no one section looks irregular. Also the type of material of the implant significantly affects the contour 

 Hi, I have performed many facial shaping procedures using dermal fillers, facial implants (cheek, chin), liposuction and/or facelifts for over 30 years.  Following my beauty principles, men look chiseled and handsome with angularity in the cheeks, chin and mandibular angles.  The following procedures would create a more ruggedly handsome face.
Cheek augmentation with cheek implants to add angularity to the cheeks and mid face.  Liposuction can be combined to reduce any excess fat to further shape the cheeks and face.
Chin augmentation, using a chin implant, to add projection to the chin creating harmony and balance to the lower face.  I have performed many facial shaping procedures, including Chin Augmentation with dermal fillers or silastic chin implants, for over 30 years.  When the chin is weak, this creates an imbalance making the nose appear larger, the mid face top heavy, the lower face looks short, de-emphasizes the lips and allows early formation of a "double chin".  Proper placement of a silastic chin implant adds forward projection to the chin thereby creating harmony and balance to the lower face.  Using the same incision, liposuction can be performed to reduce the fat and further shape the neck.  Excess skin, from below the chin, can also be removed through the same incision.  I have found that placement of a silastic chin implant, through a small curved incision under the chin (also allows excess skin removal) to be very safe, quick, highly effective and far less invasive than a sliding genioplasty (requires extensive tissue dissection, bone cuts and placement of metal screws and plates to secure the cut bone segments).  I perform chin implant surgery in 30 minutes or less, often using a local anesthetic alone.  In my opinion, you are a good candidate for chin implant surgery.  
Augmentation of the mandibular angles using a dermal filler (jaw implants have too many unwanted side effects IMHO) to add volume, angularity and flare to the jaw line.  This will "not" give the unwanted jaw implant edge or line that you are looking to avoid.
Hope this helps.