The changing role of platysma in face lifting

Since the 1970s, surgical procedures on platysma muscle, aiming to achieve better results in face lifting, became popular and turned out to be an important surgical step for the plastic surgeon. Many plastic surgeons have contributed to the topic throughout these years, as several articles on the subject have been published. Articles dealing with platysma muscle still bring great interest among plastic surgeons. My concern with platysma muscle began in the mid-1970s and since then has grown continuously. I have steadily been studying the importance of the platysma muscle in the surgeries for facial rejuvenation, involving its anatomy, the techniques proposed, the results obtained, the recommendations for the best surgical procedure for each patient, and the complications. My experience and studies regarding platysma muscle, and the contributions I have brought into this field, are thoroughly described and discussed in this article.     

Combined erbium:YAG laser resurfacing and face lifting

Facial aging occurs secondary to gravity-induced tissue ptosis and photoaging. Combined face lifting and carbon dioxide laser resurfacing provides a comprehensive one-stage approach to facial rejuvenation but is condemned by many plastic surgeons due to the nonspecific thermal effects of the laser and risk of skin necrosis. Newer high-energy erbium:YAG lasers allow precise tissue ablation with minimal thermal effect. In this study, various facial rejuvenation techniques were combined with simultaneous erbium:YAG laser resurfacing to assess results and complications. A total of 257 patients from Florida, Melbourne, Australia, and Tel Aviv, Israel, underwent combined erbium:YAG laser resurfacing and surgical facial rejuvenation. Various face-lift methods were used, including endoscopic, deep plane, and subcutaneous. Simultaneous, full-facial laser resurfacing was performed using a variety of erbium:YAG lasers. It was found that combined laser resurfacing and face lifting was successful in greater than 95 percent of patients with minimal morbidity. Two patients (1 percent) (both heavy smokers) developed small areas of skin necrosis that healed with minor pigment changes. Five patients (2 percent) developed synechia that was treated with no residual effect. Two additional patients (1 percent) developed temporary ectropion. There were no other cases of scarring, infection, or cosmetically obvious hypopigmentation. Although larger studies are necessary, it seems that the lack of thermal injury from the erbium:YAG laser makes it possible to safely perform laser resurfacing with surgical facial rejuvenation in nonsmokers. However, the authors caution that familiarity with the nuances of erbium:YAG laser resurfacing be obtained before performing combined laser resurfacing and face lifting.     

Short-scar face lift with extended SMAS platysma dissection and lifting and limited skin undermining

In the past 8 years, short-scar cervicofacial rhytidectomy has been used with great success and a high level of patient satisfaction. The operation involves limited incisions in the sideburn and preauricular areas, extending just around the fold of the ear lobule. Extensive undermining of the superficial musculoaponeurotic system (SMAS)/platysma is performed, and lifting of the face and neck is performed mainly at this level. Skin undermining is kept to a minimum, eliminating the need for extended incisions to reduce dog-ears. The preservation of fibrous bands between the skin and the SMAS/platysma unit is an important factor in making such an operation practical and is the reason why the skin incisions can be kept short. Dissection of large areas of skin and separation of the skin from the underlying SMAS necessitate larger incisions. The operation is safe, speedy, less traumatic, and well tolerated among patients at high risk, such as smokers. The risks of complications are also reduced with this operation.     

Refinements in face lifting: enhanced facial contour using vicryl mesh incorporated into SMAS fixation

As we have gained experience with the extended superficial musculoaponeurotic system (SMAS) technique in face lifting, refinements in our procedure have led to increased consistency in results. The important factors that have led to our technical modifications include the following: (1) the significance of the retaining ligaments of the midface, which determine the degree of surgical dissection required for both skin and SMAS in rhytidectomy; (2) the changes in facial shape that occur with aging, secondary to the descent of facial fat; (3) the possibility of modifying facial shape through the repositioning of facial fat in an extended SMAS face lift; (4) the improved longevity of result to be obtained by incorporating Vicryl mesh into SMAS fixation; (5) the artistic nuances of incision design that help to minimize scar perceptibility. Understanding these factors enables surgeons to use the extended SMAS technique successfully with more challenging cases, enhancing facial appearance while minimizing signs that the patient has undergone a surgical procedure.     

Restoring facial shape in face lifting: the role of skeletal support in facial analysis and midface soft-tissue repositioning

Aesthetic analysis in facial rejuvenation has traditionally been subordinate to technical solutions. While concerns regarding correction of facial laxity, a reduction in the depth of the nasolabial fold, and improvement of both the jowl and the jawline are worthy goals in rhytidectomy, the aesthetic concept of restoring facial shape to a more youthful appearance is equally important. Restoring facial shape in face lifting requires an understanding of how the face ages and then the formulation of a treatment plan that is individualized for the patient. Re-establishment of facial contour is significantly influenced by the re-elevation of descended facial fat through superficial musculoaponeurotic system manipulation; it can be approached through a variety of technical solutions. Underlying skeletal support affects not only the appearance of the face in youth but also how the face ages and influences the operative plan in terms of the requirements for fat repositioning. Formulating a treatment plan that is patient specific and based on the artistic goals as influenced by skeletal support is the key element for consistency in restoring facial shape in face lifting.     

Postural control during lifting

Any voluntary motion of the body causes an internal perturbation of balance. Load transfer during manual material handling may increase these perturbations. This study investigates effects of stance condition on postural control during lifting. Nineteen healthy subjects repeatedly lifted and lowered a load between a desk and a shelf. The base of support was varied between parallel and step stance. Ground reaction force and segmental kinematics were measured. Load transfer during lifting perturbed balance. In parallel stance postural response consisted of axial movements in the sagittal plane. Such strategy was accompanied by increased posterior shear forces after lift-off. Lifting in step stance provided extended support in anterior/posterior direction. The postural control mechanisms in the sagittal plane are less complex as compared to parallel stance. However, lifting in step stance was asymmetrical and thus accompanied by distinct lateral transfer of the body. Lateral shear forces were larger as compared to parallel stance. Both lifting techniques exhibit positive and negative aspects. We cannot recommend either one as being better in terms of postural control.     

Influence of lifting technique on perceptual and cardiovascular responses to submaximal repetitive lifting

Oxygen consumption ( O₂), heart rate, ventilation and central rating of perceived exertion (RPE) in repetitive lifting while executing squat and stoop techniques were investigated in ten male forestry workers. In all five mass/frequency combinations studied, O₂ was significantly higher for the squat than for the stoop technique. No differences were found in RPE between the techniques. The O₂ and RPE recordings were also related to those obtained during maximal repetitive lifting (same lifting technique) and maximal treadmill running. The O₂ expressed as a percentage of that obtained during maximal repetitive lifting with the same lifting technique was defined as relative aerobic intensity (% O_{2max, lifting}). The % O_{2max, lifting} was not significantly different between the techniques except for the lowest mass lifted (1 kg). This study therefore would support the hypothesis that RPE is more closely related to % O_{2max, lifting} than to absolute aerobic intensity. Related to maximal treadmill running, it was demonstrated for both lifting techniques that relative RPE (percentage of the RPE during maximal running) was more accurate than relative O₂ (percentage of maximal O₂ during maximal running) for determining the % O_{2max, lifting} in repetitive lifting. The study showed that the higher O₂ during squat. lifting compared to stoop lifting was caused by the O₂ expended in lifting and lowering the body rather than the O₂ expended lifting and lowering the external mass. It was concluded that the stoop technique was not superior to the squat technique in terms of central RPE. Based on % O_{2max, lifting}, there may be a rationale for choosing the stoop technique during repetitive lifting with light masses, but not with heavy masses.     

Comparison of isokinetic and isoinertial lifting tests as predictors of maximal lifting capacity

This study compared the relationship between isokinetic lifting test (ILT) performance and a maximal operational lifting test (OLT) with that between an isoinertial progressive lifting test (PLT) and OLT. Fifty subjects performed the ILT, PLT and OLT after familiarization trials. OLT was defined as the weight of the heaviest crate that could be lifted to 1.34 m with a progressive, incremental test. ILT performance was the force generated during a single maximal simulated lift on an isokinetic dynamometer. PLT performance was the maximal weight lifted to 1.52 m with a progressive, incremental protocol on a weight stack. OLT was highly correlated with ILT (r = 0.96) and PLT (r = 0.97); the standard error was similar for both linear regression equations. The results demonstrate that a single maximal voluntary lift on an isokinetic dynamometer is as good a predictor of OLT as in the PLT presently used in military recruit centers.     

Volumetric components of seed imbibition

Swelling parameters were determined for 15 seed species; the swelling quotients were found to range from less than 1.1 (castorbean) to 2.8 (mungbean) and swelling coefficients ranged from 0.09 (castorbean) to 0.42 (cowpea). Swelling leads to a lowering of specific gravity of those seeds with high initial specific gravity, and an elevation of those with low initial specific gravity. The extent of swelling bears a linear relationship with moisture content. Redrying to air dryness only partially restores the original volume, but oven drying completely restores it. Temperatures alter both the rate and the extent of swelling. Solutes in the imbibing solution alter the dynamics of the volume increases, indicating several types of influences; these include osmotic effects, salt effects, valence effects, pH effects, and lyotropic effects. It is suggested that deformation resulting from imbibitional swelling may contribute to the stresses experienced by seed tissues during hydration.     

Volumetric growth in gammaridean Amphipoda

A non-destructive, direct volumetric method is described for measuring absolute growth rates throughout embryonic and postembryonic life of gammaridean Amphipoda. The method is demonstrated by following embryonic and early postembryonic growth of individuals from a population of Platorchestia platensis Krøyer 1844 living on a fixed shingle shore in the Bay of Fundy, Canada.     

Volumetric properties of nucleic acids

Volumetric studies can yield useful new information on a myriad of intra- and intermolecular interactions that stabilize nucleic acid structures. In particular, appropriately designed volumetric measurements can characterize the conformation-dependent hydration properties of nucleic acids as a function of solution conditions, including temperature, pressure, ionic strength, pH, and cosolvent concentration. We have started to accumulate a substantial database on volumetric properties of DNA and RNA, as well as on related low molecular weight model compounds. This database already has provided unique insights into the molecular origins of various nucleic acid recognition processes, including helix-to-coil and helix-to-helix conformational transitions, as well as drug-DNA interactions. In this article, we review recent progress in volumetric investigations of nucleic acids, emphasizing how these data can be used to gain insight into intra-and intermolecular interactions, including hydration properties. Throughout this review, we underscore the importance of volume and compressibility data for characterizing the hydration properties of nucleic acids and their constituents. We also describe how such volumetric data can be interpreted at the molecular level to yield a better understanding of the role that hydration can play in modulating the stability and recognition of nucleic acids.     

Volumetric imaging of fish locomotion

Fishes use multiple flexible fins in order to move and maintain stability in a complex fluid environment. We used a new approach, a volumetric velocimetry imaging system, to provide the first instantaneous three-dimensional views of wake structures as they are produced by freely swimming fishes. This new technology allowed us to demonstrate conclusively the linked ring vortex wake pattern that is produced by the symmetrical (homocercal) tail of fishes, and to visualize for the first time the three-dimensional vortex wake interaction between the dorsal and anal fins and the tail. We found that the dorsal and anal fin wakes were rapidly (within one tail beat) assimilated into the caudal fin vortex wake. These results show that volumetric imaging of biologically generated flow patterns can reveal new features of locomotor dynamics, and provides an avenue for future investigations of the diversity of fish swimming patterns and their hydrodynamic consequences.