Chin osteotomy

The standard osteotomy to correct genial deformities is a horizontal osteotomy, which allows 3 dimensional movements of the chin. It can be performed in a single…

…or double osteotomy fashion. A double osteotomy allows moving two chin segments separately.

For transverse genial deformities, vertical osteotomies/ostectomies can also be performed. This allows widening or narrowing of the chin. In case of widening, additional bone grafts or alloplastic implants (eg, ceramic blocks) are needed.

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For this procedure the transoral approach to the chin is used.

To make the later mobilization and positioning of the chin segments easier a screw can be inserted into the chin prominence and used in a joystick like fashion.

After marking the osteotomy lines on the bone surface, the osteotomies are performed. The osteotomy should be at least 5 mm below the mental foramen to avoid nerve injury.

Vertical reference lines should be scored into the bone to allow for accurate mediolateral positioning of the genial segment.

Anterior movements should only be performed to such an extent that there is still bone contact between the chin segment(s) and the mandible, unless bone grafts are planned.

Downward movements are associated with gap formation. This gap needs to be filled with either autogenous bone or a bone substitute.

Reducing chin height requires an additional osteotomy with removal of the intervening bone.

Internal fixation is usually performed with two parallel miniplates on either side. Some surgeons prefer to use prebent chin plates, especially for advancements.

To reduce swelling, the application of ice-packs or cooling devices during the early post-operative phase is advice. Intravenous steroids should also be continued for a short period postoperatively for the same purpose.

Antibiotic prophylaxis is continued for 1-5 days depending on the nature, complexity, and duration of the surgical procedure.

Early post-operative x-rays are obtained to verify correct segment position. Additional postoperative imaging is performed as needed.

Regular follow up examinations to monitor healing.

At each appointment, the surgeon must evaluate the patient's ability to perform adequate oral hygiene and wound care and should provide additional instructions if necessary.

Postoperatively, patients will have to follow three basic instructions:

1. Diet
With the intraoral approach in orthognathic chin surgery, wound healing must be supported by a soft diet for 10-14 days, starting with liquids for the first 3-4 days.

2. Oral hygiene
Patients with intraoral wounds must be instructed in appropriate oral hygiene procedures. For a time of up to 10 days care must be taken not to mechanically irritate the wound area. Toothbrush and toothpaste can be applied but must be used carefully. Medical rinses can be used for support.

3. Functional training/physiotherapy
Functional training or physiotherapy are usually not necessary. In case of persistent edema, lymph drainage is recommended.