Sliding genioplasty

What it is

The chin is bone covered by muscle, fat and skin, and the soft tissue follows the bone: when the chin segment moves forward, the skin over it moves about 9 mm for every 10 mm of bone (PMID 16849066, PMID 26321067). Because the surgeon moves the bone itself, the operation can correct a chin that is too small, too prominent, too long, too short or off center; an implant can only add projection (PMID 11176712, PMID 40555381).

For a person having a facelift, the chin is also the front support of the jawline and neck. Moving the bone forward improves the projection of the lower face, tightens loose tissue under the jaw and supports the soft tissue around the mouth (PMID 35704425). The advanced chin pulls the muscles under the chin tighter (PMID 9105353).

Where it came from

• Trauner and Obwegeser described the chin osteotomy in 1957, in their work on correcting the lower jaw (PMID 13441284). Converse published the horizontal osteotomy of the lower jaw in 1964 (PMID 14223248).
• In 1987 Spear showed it could be done as an outpatient operation under local anesthesia, taking under an hour on average (PMID 3299418).
• In 1990 Guyuron compared it with chin implants: patients were satisfied with both, and the bone operation gave a more predictable soft-tissue result and a better angle between chin and neck (PMID 2399851).
• In 1996 Ousterhout showed that keeping the bone cut well below the canal of the chin nerve prevents permanent numbness (PMID 9133835). In 1997 Wider reported two decades of genioplasty done at the same sitting as a facelift (PMID 9105353).
• Recent work refines planning and the soft tissue: computer planning and ultrasonic bone saws (PMID 40555381), fixation that leaves the chin muscle attached to the bone (PMID 34529592) and fat grafting beside the cut (PMID 37452130).

Who it suits

• A small or receding chin. Advancement alone gave the highest long-term satisfaction of any chin movement (PMID 39193247). Aesthetic patients need smaller advancements than reconstructive patients (PMID 9105353).
• Loose tissue under the chin and jaw. In selected patients the advance improves the jawline and neck along with the chin (PMID 35704425), and combining it with contouring under the chin improves the result when the new projection suits the face (PMID 17549558).
• A chin that is long, short, asymmetric or too prominent. Only the bone operation changes chin height and corrects asymmetry (PMID 11176712). Patients who had the chin set back were the least satisfied (PMID 39193247).
• An older patient with a mildly small chin. Guyuron considered an implant a reasonable choice for this patient (PMID 2399851).
• A chin implant that has to come out. Removing an implant can leave a sagging, puckered chin, so an osteotomy at the same operation is advised (PMID 2052662); problem silicone implants are often replaced with a sliding genioplasty (PMID 41753014).
• Snoring or sleep apnea. Moving the chin changes the airway: lengthening the chin was linked to a wider airway and shortening it to a narrower one (PMID 41569264).

How it is done

• Through an incision inside the lower lip, the surgeon cuts the bone horizontally below the tooth roots, moves the segment and fixes it with a plate or screws (PMID 11176712, PMID 40555381). Movements can be planned on scans with virtual surgical planning and cut with an ultrasonic saw (PMID 40555381).
• Protecting the nerve. The mental nerve leaves the bone on each side of the chin and gives feeling to the lower lip and chin. Ousterhout kept at least 6 mm between the cut and the nerve canal, and after that change no patient had a permanent nerve injury (PMID 9133835).
• Protecting the soft chin. Stripping the chin muscle off the bone (degloving) and failing to reattach it allows the soft chin to sag below the bone, the "witch's chin". Fixing the segment with lag screws and a plate that needs no degloving prevented it and gave higher patient satisfaction (PMID 34529592).
• Fat grafting. The sliding cut does not move the crease between lower lip and chin, so an advance can deepen it; fat injected there prevents that (PMID 37452130).
• Anesthesia. Local anesthesia as an outpatient (PMID 3299418), or general anesthesia when it is combined with a facelift or other operations (PMID 9105353).
• Bone healing. The gap left between the bone segments fills in; a wider gap slowed healing only slightly (PMID 40965831).

Results and how long they last

• The bone stays where it is put. A year or more after an advancement, the chin point had lost between a fraction of a millimeter and about 2 mm of the forward move, and the loss did not depend on how far the chin moved or how it was fixed (PMID 33583665). At 3 years no patient had a change that mattered clinically (PMID 16849066).
• The soft chin keeps following the bone. At 2 years and later the skin of the chin had moved about 8 to 9 mm for every 10 mm of bone (PMID 34383152). Soft tissue tracks bone more closely after an osteotomy than over an implant (PMID 40666078, PMID 2399851).
• Satisfaction is high. Patients are satisfied after both osteotomy and implants, and comparisons favor the osteotomy (PMID 2399851, PMID 37059630, PMID 40666078). Satisfaction stayed high unless the chin was moved too far forward (PMID 9105353). The most common complaint afterward was a chin that sat off center (PMID 39193247).
• Measured change in the face. Face-analysis software found small gains in attractiveness scores, larger in patients 35 and older (PMID 41530558).
• Studies measure outcomes in different ways, which makes them hard to compare (PMID 40271466).

Risks and how surgeons lower them

• Numb lower lip and chin. Almost every patient has some numbness at first (PMID 17549558). Temporary nerve symptoms followed about 1 in 6 osteotomies in a pooled review, against about 1 in 40 implants (PMID 36729154), and numbness lasted in roughly 1 in 8 to 1 in 13 osteotomy patients (PMID 40666078). After a chin cut alone, without other jaw surgery, feeling returned fully in one surgeon's series (PMID 17549558), and formal testing found a lasting light-touch deficit only rarely (PMID 3422277); numbness is more frequent when the chin cut is combined with a split of the lower jaw (PMID 12377203). A wide margin between the cut and the nerve canal prevents permanent injury (PMID 9133835).
• A second operation. About 1 in 13 patients needed one, for loose fixation, appearance, a step felt along the jaw edge or remaining sleep apnea; patients over 35 needed it more often than those 25 or younger (PMID 33905017).
• Any complication. About 1 in 5 after osteotomy and 1 in 6 after implants in a pooled review, with the difference mostly temporary numbness (PMID 36729154). Implants carried more infection, up to about 1 in 4 in some series, and more wound opening (PMID 40666078, PMID 37059630).
• Sagging soft chin. About 1 in 4 patients after the traditional degloving technique, and none after the no-degloving technique (PMID 34529592).
• Too much chin. In Wider's facelift series the most common complaint was a chin that looked too strong; most of those patients had surgery early in the series, and the bone was burred down (PMID 9105353).
• Bleeding under the tongue. Rare, but a hematoma in the floor of the mouth can push the tongue back and block the airway; the arteries at risk run under the tongue and under the chin (PMID 36730838).
• With jaw surgery. Adding a genioplasty to two-jaw surgery lengthened the operation without raising 30-day complications in national data (PMID 34510068).
• Revision. A second chin operation works through scar, changed anatomy and a reduced blood supply (PMID 9246516).

Recovery

• Care includes a compression dressing on the chin, treatment of swelling and a liquid diet for a period (PMID 40555381).
• Pain was mild after outpatient surgery under local anesthesia (PMID 3299418).
• Lower lip numbness usually lasts a few weeks; at a year or more, more than 9 in 10 patients reported normal feeling (PMID 17549558). In a randomized trial, numbness had resolved on both sides by 6 months (PMID 35210126).
• Platelet products placed at the bone cut sped the return of feeling: concentrated growth factor in one trial (PMID 35210126), and platelet-rich fibrin at 1 and 4 months, with no difference by 12 months, in another (PMID 37612225).

With a facelift

• Genioplasty can be done safely at the same sitting as a facelift and liposuction under the chin (PMID 9105353). Chin complications in Wider's series were minor: hematomas drained in the office, a temporary weakness of the lower lip, a temporary numb lip and an infection cleared with antibiotics (PMID 9105353).
• Jones combines it with facelifts and prefers it to implants for its range of movement and long-term stability (PMID 17046627).
• Dekker and Baker read the bone of the lower face to decide when an osteotomy should support the soft tissue, alone or with a neck lift, liposuction or facelift (PMID 35704425).

Questions to ask a surgeon

• Would a sliding genioplasty or an implant suit my chin better? (PMID 2399851)
• How far will you move the bone, and will my chin change in height? (PMID 11176712)
• How will you keep the cut away from the nerve to my lower lip? (PMID 9133835)
• Will you strip the chin muscle off the bone, and how will you reattach it? (PMID 34529592)
• How will the crease between my lip and chin change? (PMID 37452130)
• Will moving my chin change my breathing at night? (PMID 41569264)
• How often do your genioplasty patients need a second operation? (PMID 33905017)

Open questions

• Airway: isolated genioplasty enlarged the airway in one study (PMID 37883707) and in pooled data (PMID 40626109), while another study found overall narrowing tied to shortening the chin (PMID 41569264).
• Osteotomy or implant: more nerve symptoms with osteotomy, more infection and wound problems with implants, and higher satisfaction with osteotomy, mostly from single-center studies (PMID 40666078, PMID 37059630).
• Outcome measures are not standardized (PMID 40271466).
• Platelet products for faster nerve recovery rest on small trials (PMID 35210126, PMID 37612225).
• Scoring results with face-analysis software is new and has not been tied to what patients report (PMID 41530558).

Terms

• Genioplasty: surgery that changes the shape or position of the chin (PMID 40555381).
• Osseous (sliding) genioplasty: a horizontal cut through the chin bone with the segment moved and fixed (PMID 11176712).
• Pogonion: the most forward point of the chin (PMID 33583665).
• Relapse: the part of the chin movement lost over time (PMID 33583665).
• Soft-to-hard tissue ratio: how far the skin moves for each millimeter the bone moves (PMID 26321067).
• Mental nerve: the nerve that gives feeling to the lower lip and chin (PMID 9133835).
• Degloving: stripping the soft tissue off the chin bone to expose it (PMID 34529592).
• Witch's chin (chin ptosis): soft tissue of the chin sagging below the bone (PMID 34529592).
• Labiomental groove: the crease between the lower lip and the chin (PMID 37452130).
• Microgenia: a small chin (PMID 40666078).

Papers