PRP treatment at hair transplanted area. Will it improve hair thickness? (Photo)

PRP injections with microneedling of the transplanted areas can in most cases give great results. You have to make sure you are getting PRP not PPP (PLATLET POOR PLASMA). Also, the technique is important and 3-4 treatments are recommended. We add the new ALMI (autologous lipocyte injection) procedure as one of our 3-4 treatments. Fat stem cells with PRP can give an even better result to thinning and transplanted hair follicles. Check that procedure out as well. Hope this was helpful. JB

PRP is used to stimulate hair growth. Shock loss is due to the loss of normal hair whether it is from donor site or recipient area.  It can occur with both FUE and strip procedures.  Usually if it occurs it will take place in the recipient area.  
Shock loss from hair transplant can occur due to the following:
Anesthesia-  excessively long procedures taking longer than 12 hours can induce shock loss more likely.  the repeated use of lidocaine, marcaine, and perhaps most importantly epinephrine can affect nourishment of the hairTraumatic harvest-  In strip surgery, traumatic harvest can induce shock loss.  Recipient area trauma- during the incision making process the hairs are either crushed or cut and damaged during the process.Ways to minimize shock loss are as follows:
Improve recipient bed and donor area environment.  Make your recipient environment improved by addition of growth factors and/or PRP to help reduce incidence of shock loss to native hairs.Use of Rogaine and Propecia- can help miniaturized hair become more stable and less likely to fall out during procedure9xRobotArtas-  The latest version of the robot can make recipient sites and can determine angle of existing hair and help ensure that the angle will not damage existing hair.  Especially helpful in patients where you are transplanting hair to create densityMinimize anesthesia time and procedure time- We limit number of grafts to a safe number per session.  Extended anesthesia periods and harvest times can cause patients to have a higher chance of shock loss.  The 9x Robot harvests between 1000-1500 grafts per hour making it superior to previous additions and traditional FUE approaches.Best,
Anil Shah

in order to benefit from PRP treatment, the one needs to get the treatment periodically at least for 3-4 sessions. 

PRP (anecdotally speaking) has proven to be effective in the arena of hair restoration both as an adjunct to grafting as well as standalone treatment for those who may not (yet) be a candidate for grafting. Patients have demonstrated slowed loss, thickening of existing hair and regrowth. The typical duration of effect is 6-9 months with most patients being treated 2x yearly (at least initially).
Ultimately, whether or not PRP will be effective will be dependent upon the patient. Some patient's blood is inherently richer in factors than others leading to a more robust response. PRP is by no means a magic bullet.With regards to your specific question, PRP can help. However, results will vary and outcomes are by no means guaranteed. It is a procedure with low risk and potentially high reward.
As always, discuss your concerns with a board certified plastic surgeon (ABPS) with experience in hair restoration. 

PRP likely will not help you at this time you seem to be too far past the time any hair injetions would help however a formal consultation will be best for us to know for sure.  Best, Dr. Emer.

PRP can thicken transplanted hair approximately 30%. It will not increase the density unless hair loss has been less than three to 5 years and  the follicular units are still present. Find a PRP expert. Ask to see photos.
PRP hair md.com

PRP will help thicken hair wherever there are hair follicles. It will not help in areas where there are bald spots. It should help areas where hair follicles have been transplanted. Hair transplant doctors regularly incorporate PRP treatment after hair transplant .

Based on your photos submitted, it's unlikely PRP is going to help. You really did not explore why the transplant didn't work so well and rule out any scalp issues. If one considers that healthy transplanted grafts did not take well in your surgery, then it's quite unlikely PRP is going to be effective.

Dr. Baubac Hayatdavoudi has been offering Platelet Rich Plasma (PRP)
treatment in combination with a Hair Restoration procedure to hair loss patients for a few years now in our Alvi Armani Beverly Hills Clinic.
A patient will have a PRP Session along with the FUE Hair Restoration procedure on the same day.
What we have been seeing with these patients who receive both treatments are:
Faster healing times post-opMuch less shedding of the transplanted grafts after the procedureHigher retention of grafts post procedureQuicker regrowth of graftsWe have found that patients who have PRP with their FUE
procedure not only see better yield, but also faster healing post op and
earlier growth. The patients follicles come out of the resting phase
earlier and their results come in faster.

Thank you for your question.
Certainly, I have found that PRP can be quite successful in improving the
number of hairs growing in a treated area, as well as improving the quality of
the existing native hair shafts which remain. If the hair grafts which were
transplanted five years ago were taken from the right area, then they should
still be robust. Hair follicles are genetically preprogrammed to be
insensitive, or very sensitive, to the effects of male hormone
testosterone/DHT. Typically, transplanted hair follicles are taken from areas
where hair will thrive in the presence of testosterone/DHT and placed in areas
which have hair follicles which are genetically sensitive to testosterone/DHT.
Therefore, transplanted hair should thrive wherever it is placed, while native
hair follicles in areas of hair loss tend to be lost over time. PRP seems to
help the sensitive hair follicles resist the effects of testosterone/DHT for a
period of time. Unfortunately, in most cases, if PRP is successful at improving
the areas treated, it must be repeated every 6-12 months. However, it is an
excellent nonsurgical way to address an otherwise difficult problem which will
worsen with age.