The Youthful Cervicomental Angle and Digastric Tendon Plication to Lift the Hyoid Bone. a Cadaveric Study, an Interventional Prospective Study, and a Clinical Retrospective Study.
In more than a quarter of patients, however, soft tissue excess is not the cause of the cervicomental obtusion. Instead, a low position of the hyoid bone is the cause. Historically, many techniques have been introduced that involve weakening of the anterior digastric muscles to allow the hyoid to retract unopposed. More recently, improvements of the cervicomental angle have been attempted by plication of the digastric muscles to lift the hyoid bone.
Despite the growing popularity of digastric plication, little evidence currently supports this relatively new surgical maneuver. This study was set up to investigate the anatomical basis and safety of digastric plication as well as the long-term efficacy.
Methods/Technique: This multicentered study on the effects of anterior digastric tendon plication on the hyoid position involved an anatomical dissection study, an interventional prospective study, and a retrospective study.
The anatomical dissection study involved sixteen embalmed cadavers and twelve fresh unfrozen cadavers. Anthropometric data of the suprahyoid musculature and the relationship to the hypoglossal nerve were obtained on the embalmed cadavers. The immediate effect (short-term) of digastric plication on the hyoid position was assessed on the fresh cadavers, distinguishing between targeting the digastric muscle belly and tendon. Ethical approval for the anatomical dissection study was granted by the Human Ethics Advisory Group (Project number LR 2021-4306-4761).
The interventional prospective study involved the follow-up of the continued effect (median-term) of digastric plication on the hyoid bone by radiographic imaging pre-operatively and 6 months post-operatively.
The retrospective study reviewed the long-term effect in all patients who had undergone digastric plication by the senior surgeons AA, LAA and TGOD over a 3-year period (January 1st, 2017, to December 31st, 2019). Recorded variables included age, gender, presence of comorbidities, smoking, previous aesthetic facial procedures, simultaneous procedures performed, complications, revision procedures and duration of clinical follow up.
Results/Complications: The anatomical dissection study demonstrated that isolated plication of the anterior digastric muscle bellies did not significantly lift the hyoid bone (range 0 - 3 mm). Plication of the anterior digastric tendons, however, lifted the hyoid bone with a mean of 10 mm (range 7 - 16 mm) and generally advanced the hyoid by 3 mm (range 0 – 6 mm) although in one cadaver, a similar plication caused a 7 mm posterior displacement. The hypoglossal nerve was never at risk as it was protected by the mylohyoid and the geniohyoid muscle.
The interventional prospective radiography study demonstrated is still ongoing, with the last radiograph planned in March 2022.
The retrospective study retained 450 patients, 91% women, mean age 57 years [range 17 – 81] who underwent digastric tendon plication during the three-year period. The mean follow-up was 26 months (range 1 - 47 months).
The most common complication was postoperative pain and tightness managed with intraoperative injection of long-acting local anaesthetic. Another common complication was submental skin crusting related to prolonged manipulation, currently largely controlled by excision of the traumatized skin edges before closing. Central suprahyoid depression related to excessive subplatysmal fat removal, which was more common in the beginning of this series, is currently largely avoided by lifting the subplatysmal fat as an inferiorly based flap and then redraped over the plicated digastric construct. Dysphagia and a clicking noise, which were present in the early days of the technique, were not present in this retrospective series thanks to the change to resorbable sutures. Despite the use of resorbable sutures, no recurrence of a low-positioned hyoid bone position was noted. No deep hematoma or infections were noted.
Conclusion: A low positioned hyoid contributes to the blunt cervicomental angle in about a quarter of obtuse necks. If the desired cervicomental angle cannot be obtained by volume reduction alone, shortening the digastric tendon, by plication lifts the hyoid to sharpen the angle further. This contrasts with anterior digastric muscle shortening, which is shown not to be effective.
Plication of the digastric tendon is a simple, safe, and effective procedure with lasting results. The main drawback of the procedure, pain in the immediate postoperative period, is minimised by long-acting local anaesthetic.