A chin implant is the standard treatment for a weak or short chin. It is tremendously effective, very simple to perform, and a wide variety of implant sizes and shapes are available for use. While chin augmentation is performed on both men and women, it is most commonly performed on patients under the age of 40.
This younger age group is also often involved in numerous sporting activities. Many of these sporting activities may involve face contact, either intentional or inadvertent. If you have a chin implant, does participation in these sports put you at risk for a problem with facial trauma?
It is therefore of interest to know if chin implants can fracture or fragment due to traumatic impact. None of the manufacturers were able to provide any information on this potential. Therefore, I test them using the ASTM (American Society of Testing Materials) drop test. I have previously used this method to test the fracture potential of cranioplasty materials. Using an 8 lb. weight dropped from a meter and a half, silicone, PTFE (Gore-tex) and Medpor chinstraps were tested. Silicone and PTFE implants were unaffected, one Medpor chin developed a fracture.
This drop test, however, doesn’t really replicate what would happen with a chin implant in a human. With the implant against the bone, the impact force is transmitted to the underlying bone. As a result, the implant does not absorb the full force on its own or without the support of an underlying structure. Therefore, fracture of the implant is highly unlikely unless the impact force is of such a magnitude that the bone would fracture.
What is most likely due to trauma is the chin implant becoming dislodged or shifted. Chin implant displacement or migration is a well-known complication that can occur even in the absence of trauma. So it would make sense to protect the implant from that potential in the young athletic man or woman. This can be done by simply screwing the implant to the bone during surgery.
Screws can easily be placed through the implant into the underlying bone. But a single screw can act as a pivot point. Therefore, two screws placed parasagittally would make it virtually impossible for me to change position after surgery. It could be argued that a single midline screw may suffice, but it is just as easy to place two screws as one.
If a patient is concerned about the risk of problems with the chin implant due to athletic participation, screw fixation is a simple preventive measure. They can be easily placed whether the implant is placed from inside the mouth or under the chin.