Arcus release for implant
If the implant is placed appropriately in the subperiosteal space then yes the arcus marginalis must be released. The arcus is a band of what we call connective tissue which is a condensation of bone lining from the floor of the orbit and the bones of the face. When it is incised an implant can be securely placed between it and bone.
There are much better alternatives than a tear trough implant for most people.
If you are going to have a tear trough implant place from an incision behind the eyelid, then yes the arcus marginalis must be releases. Generally for the purpose of this surgery, what we are talking about is incising the periosteum at the orbital rim and making a subperiosteal dissection onto the face of the cheek bone. The acrus is not actual cut in that case. Note that the arcus is simply the condensation of the orbital septum where it fuses with the periosteum of the cheek. Tear trough implants can also be placed from an intraoral approach, a facelift approach, and from a transcutaneous approach. I do not recommend these last three approaches but they are described. I my opinion, the tear trough implant is not a very satisfactory surgery. It provides very modest volume. It was state of the art 15 years ago but the field has moved on. A better approach is to avoid surgery altogether and get the volume effect and more without surgery using fillers. When a rim implant is truly needed, I find a hand carved ePTFE rim implant that is custom made for the individual at the time of surgery much more satisfactory. These are primarily use after unsatisfactory lower eyelid surgery. I personally believe that neither of these approaches are much good for unoperated eyelids that need cosmetic improvement.
Correction of tear trough defect (depressopm at lower orbital rim)
Tear trough implants and seperation of the orbital septum from the orbital perisostum has lost favor and popularity in the last decade. I have had a good experience with use of "Biomatrix" tissue regeneration placed under the orbicularis muscle orbital rim retraction. This strengthtens and fills the transition between orbital septum and anterior maxillary wall rejeuvinating this difficult area.