The facial retaining ligaments are ligamentous structures that originate from the periosteum or deep facial fascia and travel perpendicularly through facial layers to insert onto the dermis. They support and stabilize facial soft tissues in normal anatomical position. With aging, these ligaments attenuate, which leads to the stigma of aging features.1,2 We evaluate the viscoelastic properties of zygomatic ligaments, mandibular ligaments, and orbital ligaments.
Five fresh Chinese cadaveric heads were dissected to fully expose zygomatic, orbital, and mandibular ligaments, which were detached from the surrounding soft tissues. Biomechanical testing of each ligament was performed within 2 hours after excision from cadaveric heads using an Instron5567A Mechanical Testing Apparatus (Instron, Norwood, Mass.) with the sensing element set to 100 N. The stress-strain, stress-relaxation, creep, and tensile strength were tested at room temperature (15°C).
In this study, these ligaments all demonstrated viscoelastic properties, such as stress-strain, stress relaxation, and creep. It may be inferred that facial retaining ligaments all have inherent viscoelastic properties. When the specimens were loaded with the same force, the mandibular ligament revealed the maximum amount of displacement, followed by the orbital ligament and the zygomatic ligament. The mandibular ligament demonstrated more stress-relaxation and creep than the orbital ligament or the zygomatic ligament. No statistical difference can be found between the orbital ligament and the mandibular ligament; the rest of the intergroup comparisons showed statistically significant differences with values of p < 0.05. The tensile strength in the zygomatic ligament was shown to be strongest, followed by the orbital ligament and the mandibular ligament. Statistical significances can be found between these groups.
Brandt et al. first studied the biomechanic properties of facial retaining ligaments in 2012.3 Even though their work has some differences compared with ours, the mechanical properties of the zygomatic ligaments, orbital ligaments, and mandibular ligaments proved to be the same. The zygomatic ligament, which is less likely to deform under the same force, proved to be the strongest, followed by the orbital ligament and the mandibular ligament. If we correlate these ligaments to their facial areas, the lower face descends fairly easily downward with the force of gravity, followed by lateral brow descent, and by malar soft-tissue descent. This sequence of soft-tissue descent coincides with our clinical observation that ptotic jowls in the mandibular region and brow ptosis are early signs of aging.
Despite its careful design and performance, the results of this investigation have their own limitations. First, we explored only five cadavers in this study to measure their mechanical properties, and thus the conclusion of this work lacks persuasion in some depth. Second, in vitro biomechanical testing results of ligaments will certainly have some variation compared with outcomes measured in vivo because of differences of temperature, hormones, and so on. Therefore, further study is needed to clarify the accurate biomechanical properties of facial retaining ligaments.
In conclusion, the facial retaining ligaments all have inherent viscoelastic properties. The mechanical properties of the zygomatic ligament might be stronger than those of the orbital ligament and the mandibular ligament. Knowledge of the mechanical properties of facial retaining ligaments can help to determine the facial aging process and evaluate facial rejuvenation techniques.
This work was supported by the National Natural Science Foundation of China (no. 31300782).
The authors have no financial interest to disclose related to the work presented herein.
Heng Shi, M.M.
Ningze Yang, M.D.
Zhijun Wang, M.D., Ph.D.
Department of Plastic Surgery
Xinhua Hospital affiliated to Dalian University
Dalian, Liaoning, People’s Republic of China
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2. Alghoul M, Codner MARetaining ligaments of the face: Review of anatomy and clinical applications.Aesthet Surg J201333769–782
3. Brandt MG, Hassa A, Roth K, Wehrli B, Moore CCBiomechanical properties of the facial retaining ligaments.Arch Facial Plast Surg201214289–294
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