Biomedical subjects

L A Whitaker

Publications and source records attributed to L A Whitaker.

At least 19 recordsLinked to original sources

PubMed1992

Age-related changes of the craniofacial skeleton: an anthropometric and histologic analysis.

With the development of increasingly sophisticated methods for the alteration of bony facial form consequent to age, it is imperative that the surgeon have a fundamental knowledge of the age-related changes the skeleton may undergo. To understand these changes better, a detailed anthropometric and histomorphic analysis of the craniofacial skeleton as a function of age was undertaken. The study consisted of a detailed craniometric analysis of 160 skulls selected randomly from a Caucasian population of skeletal remains totaling 1500 specimens. Additionally, a histologic analysis of the supraorbital ridge in a separate preserved cadaver population was performed. Although the results showed individual variation as expected, definite changes in craniofacial morphology were observed. These included (1) appreciable reduction of facial height, most marked in the maxilla and mandible, and strongly correlated with loss of teeth, (2) modest increase in facial width, (3) modest increase in facial depth, except in those regions associated with tooth loss, and (4) general coarsening of bony prominences. Histomorphic analysis demonstrated increasing porosity with age, more marked in the female population. Although these changes represent population trends, in any given patient, any or all of them may be present to varying degrees. Surgeons should be aware of these possibilities and consider selective alterations of the skeletal foundation, either separately or in concert with the overlying soft-tissue envelope, in order to optimize the results of surgery for the aging face.

Adult↗

PubMed1991

An experimental study on the effect of rigid fixation on the developing craniofacial skeleton.

Rigid fixation of the craniofacial skeleton has proven of great value in adult orthognathic and traumatic reconstructive surgical procedures. This technique has gained increased acceptance in the surgical treatment of infants and young children with congenital malformations, despite the fact that its effects on subsequent craniofacial growth are unknown. To examine this question, an experimental model using 25 young kittens was developed to compare rigid fixation with conventional wire fixation, with and without osteotomy. Our findings demonstrate a regional restriction of growth in the developing craniofacial skeleton when both wire and plate and screw fixation are utilized in concert with osteotomy. Further, a compensatory growth was observed in individual animals when plate fixation was utilized that was not seen in the wire-treated group. This suggests that there is a dynamic growth interaction between restriction and compensation in this setting.

Animals↗

PubMed1991

Aesthetic augmentation of the posterior mandible.

The posterior mandible begins just behind the mental nerve and second bicuspid bilaterally, extends to the posterior edge of the ramus, and then runs superiorly to the zygomatic arch. Augmentation of the posterior mandible is possible by use of a synthetic implant that is tailored individually to each patient's specific needs. Implant plant thickness varies from 4 to 8 mm, with an average thickness of 6 mm. Careful preoperative planning is done based on an aesthetic assessment of the amount of highlighting desired, thickness of the soft tissues, and the use of life-size photographs and cephalometric and Panorex x-rays. A pattern is cut, and the implant is carved to fit the patient. Insertion of the material after careful tailoring to the individual patient's own mandibular size and configuration requires a generous posterior lower buccal sulcus incision. Antibiotic irrigation and systemic antibiotics are essential, and careful closure in two layers completes the procedure. One implant in the series extruded in a patient who had had radiation therapy, and one patient required repositioning of the implant. Otherwise, in 22 patients there were no infections or permanent morbidity. The procedure seems to be a realistic and safe one for both the youthful and aging face, as demonstrated in patients in this series, with ages varying from 16 to 40 years.

Adolescent↗

PubMed1991

Intraosseous vascular malformations of the orbit.

Intraosseous vascular malformations are rare benign tumors involving the bones of the orbit. The diagnosis should be considered when a patient presents with an enlarging mass fixed to bone in the upper face, and the characteristic x-ray appearance should be looked for on plain films. Treatment is local excision of the bone containing the tumor and immediate reconstruction with autogenous bone.

Adult↗

PubMed1991

Facial reconstruction consideration in rheumatic diseases.

In conclusion, the management of facial involvement in JRA, Romberg disease, and scleroderma is dictated by the degree of severity of the disease, age of onset, and length of activity. Functional occlusal abnormalities are best addressed through a team approach consisting of initial orthodontics followed by orthognathic surgery if needed. In all types of scleroderma, surgical facial reconstruction is best delayed until the disease is quiescent for at least a year. The ideal option for facial skeletal and soft-tissue augmentation has not yet been realized. Careful surgical planning and choice of grafts, flaps, or implants are critical to obtain the desired result.

Arthritis, Juvenile↗

PubMed1991

The skeletal treatment of orbital hypertelorism.

Orbital hypertelorism, strictly defined as an increase in bony interorbital distance, is not itself an isolated syndrome, but is instead an anomaly that may occur as either part of a syndrome or malformation sequence. Evaluation of orbital hypertelorism and the various anomalies that accompany it is best performed by a multidisciplinary craniofacial team. The timing of surgery involves considerations of multiple variables, but when performed can offer marked cosmetic improvements. Equally important as the skeletal surgery is correction of the associated soft-tissue problems.

Child↗

PubMed1991

Evaluation of facial skeletal aesthetics and surgical planning.

Proper surgical planning for aesthetic facial skeletal surgery requires of the surgeon not only intimate knowledge of available techniques but also an understanding of how and when to apply those techniques. To this end, proper facial form analysis is essential. In this introduction we have attempted to describe the elements of such an analysis, realizing that much remains to be learned about how the bone and soft tissue interact. In many ways the soft tissue--bone relations remain the unexplored area in aesthetic skeletal surgery. The further delineation of these relations by the use of anthropometry, laser light scanning, ultrasound, CT, and MRI remains an open area for investigation. The potential is enormous for using these data to study how bone and soft-tissue relationships combine to create facial form and how this form changes with both surgery and normal aging.

Esthetics↗

PubMed1991

Skeletal alterations as a basis for facial rejuvenation.

A slight decrease in overall facial bone bulk coupled with the increased soft-tissue expansion associated with aging produce effects that should be reversed in both the bone and soft tissue where possible. The changes are best done at the ledge areas: the supraorbital-temporal ridge areas, malar-midface, and chin mandible. However, the overall bone bulk may be increased in addition in the temporal fossae, in the infraorbital rim, at the lateral canthus, in the paranasal area, and at the alveolar ridges and dental areas. A combination of autogenous and synthetic materials is currently best, with synthetic materials most useful in the malar-midface, posterior mandibular, infraorbital, and paranasal areas. In the supraorbital ridge-temporal areas, it is a near equal choice between autogenous and synthetic materials. In the chin, the preferred method is by osteotomy using autogenous augmentation. The concept of increasing bone mass and decreasing expanded soft-tissue mass has application within the judgment of the surgeon coupled with the patient's desires. Subtle increases of bone mass to compensate for soft-tissue thinning as well as bone shrinkage, at the same time taking up lax soft tissue, can be done in conjunction with one another, effectively producing a three-layer face lift. The subperiosteal face lift is in reality an extended brow lift and can be used to enhance the brow-forehead area and the temporal, zygomatic, and paranasal areas. At the same time, the perioral, jowl, and submandibular regions must be treated by a combination of standard face lifting procedures and augmentation of the bone structures of the face.

Aging↗

PubMed1991

Temporal and malar-zygomatic reduction and augmentation.

The temporal fossa, zygomatic arch, and malar-midface should be considered jointly when augmentation of the temporal area or reduction of the zygomatic arch are to be carried out. These anatomic areas relate so closely to one another that altering one affects the other. In addition, augmentation of the malar-midface area may be done if one of the other two procedures is to be considered, or if a brow lift, subperiosteal face lift, or other reason for using a coronal incision exists. Use of the coronal incision for malar augmentation is probably not justified because of the large amount of surgery required in spite of the lesser morbidity associated with this approach in terms of amount of infections, lip stiffness, and hypesthesia. Planning a surgical procedure must be done in the office, by examining the patient at eye level to determine the amount of zygomatic arch reduction and the amount of temporal fossa augmentation necessary. Similarly, the three zones of the malar-midface complex must be assessed, with the amount of augmentation of each zone determined prior to the day of surgery. The surgical procedure is then executed through a coronal incision, with the dissection extending down to the zygomatic arch. If the temporal muscle is to be elevated out of its fossa, it is cut on its anterior, superior, and posterior edges, elevating it out of its fossa so that a Proplast implant, typically 3 to 4 mm thick and finely tapered on its superior and posterior edges, with suturing done anteriorly, may be inserted. The muscle is then resutured to its aponeurosis on all three edges. If the zygomatic arch and malar-midface area are to be approached, the dissection is carried to the deep and superior edge of the zygomatic arch, and the periosteal elevator is used to elevate the soft tissue off the lateral and inferior edge. The arch and malar-midface are cleared of soft tissue, extending the tunnel to the upper buccal sulcus. The arch is then reduced with a contouring burr to the thinness desired. Alternatively, the malar-midface area may be augmented with synthetic material precisely positioned, with a suture around the zygomatic arch, holding it in position as measured from the lateral orbital rim. The incision in the temporal fascia is then resutured, and the coronal incision is closed.(ABSTRACT TRUNCATED AT 400 WORDS)

Aluminum Oxide↗

PubMed1990

Secondary reconstruction of posttraumatic orbital deformities.

A retrospective analysis of our experience, techniques, and concepts for the secondary reconstruction of orbital injuries to 78 patients over a 15-year period is presented. Secondary orbital reconstruction has the following four basic steps: (1) freeing of the overlying soft tissues by extensive subperiosteal dissection; (2) skeletal reconstruction, usually with onlay bone grafting and contour osteoplasty; (3) restoration of palpebral shape and position by medial and lateral canthopexy; and (4) soft-tissue refinement. Reconstruction required an average of at least two operations. In this series, there were no mortalities, three infections, and no reoperations for bleeding. Thirty patients required a second operation to an area previously addressed reflecting inadequacies in technique, the unpredictability of bone grafts, and soft-tissue scarring. Distortion of the skeletal infrastructure is most amenable to secondary reconstruction. Soft-tissue distortions that accompany bone malposition are less well corrected. Soft-tissue contraction is the limiting factor in successful reconstruction dictating separate movement of the overlying soft tissues and ligaments, their overcorrection, and subsequent revisional surgery. Secondary orbital reconstruction, although providing significant improvement, usually fails to restore the preinjury appearance, and usually falls short of properly performed acute reconstruction.

Adolescent↗

PubMed1990

The operative treatment of isolated craniofacial dysostosis (plagiocephaly): a comparison of the unilateral and bilateral techniques.

Both the safety and efficacy of the treatment of isolated craniofacial dysostosis (plagiocephaly) in infancy have been demonstrated. Opinions remain divided, however, as to the optimal type of procedure to be undertaken. In an attempt to answer this question, we have retrospectively evaluated a study population of 48 children operated on in infancy by either a unilateral or bilateral approach. Results of treatment at a minimal follow-up of 3 years were assessed based on preoperative and postoperative photographs and direct patient examination. Based on this retrospective comparison of the unilateral and bilateral approaches to the treatment of isolated craniofacial dysostosis, we conclude that (1) either approach as specifically outlined will give excellent results in the majority of patients, (2) there is no statistically significant difference in the results obtained by using either procedure, (3) in the majority of instances, less than ideal correction was manifested by contour irregularities evident in the temporal and/or lateral forehead region, and strict attention should be given to these areas in an attempt to further improve results, and (4) in those cases where significant protrusion is observed on the "normal side," a bilateral approach is preferable.

Bone Transplantation↗

PubMed1990

A method for repositioning the external ear.

The malposition of an otherwise normal-appearing external ear is not uncommon in certain craniofacial syndromes. This paper presents a 10-year experience of 14 patients who underwent external ear repositioning. In this technique, a posterior incision is used to mobilize surrounding soft tissues circumferentially around the external auditory canal, which then serves as an axis for anterior rotation and elevation. Elevation of up to 8 mm and rotation up to 30 degrees can be achieved. Further elevation is limited by the ensuing constriction and resistance of the external auditory canal. More rotation can be achieved with a Z-plasty transposition of an inferiorly based postauricular skin flap.

Child↗

PubMed1990

Reconstruction of late craniofacial deformities after irradiation of the head and face during childhood.

Little is known about the results of surgical management of late craniofacial abnormalities arising after irradiation of the head and face for treatment of childhood cancers. The clinical records of 10 children (4 males and 6 females) who received 4500 to 6500 rads (mean 5160 rads) of craniofacial radiation between birth and 8 years of age (mean 5 years) and who subsequently had reconstructive surgery were reviewed. Six of the 10 patients received orbital radiation, 3 received maxillary-midfacial radiation, and 1 patient underwent radiation to the frontal bone. Histologic tumor types included retinoblastoma (4), rhabdomyosarcoma (3), Ewing's sarcoma (2), and neurofibrosarcoma (1). In addition to radiation, 7 of the 10 patients underwent surgical resection or debulking of their tumors and 6 received adjuvant chemotherapy. All patients presented from 4 to 20 years after treatment (mean 10 years) with varying, but severe degrees of soft-tissue and bony hypoplasia of the irradiated territories. Onlay bone grafting with soft-tissue reconstruction by a combination of local pedicle flaps and dermal-fat grafts was initially performed in 9 patients, and an occipitoparietal bone-flap switch procedure was done in 1 patient. Late follow-up ranged from 11 months to 7.5 years (mean 34 months). A total of 8 secondary procedures were necessary in 4 of the 10 patients (40 percent). Of these 4 patients, major revisions were performed in 3 and minor adjustments in 1. In addition, 2 patients in whom secondary procedures had not been done would benefit from further reconstruction. Therapy for cancer of the head and face during childhood has profound and ongoing effects on the growth of soft tissue and bone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1990

The effect of rigid fixation on the survival of onlay bone grafts: an experimental study.

Much attention has recently been focused on rigid fixation as a method of improving fracture healing. Whether such fixation, when applied to onlay grafting, improves graft take and volume is unknown. To examine this question, we compared survival of both endochondral and membranous grafts fixed rigidly and nonrigidly in areas of low motion (snout) and high motion (femur) in a rabbit model. Gross morphology, histologic analysis, and graft volume kinetics were evaluated. Findings demonstrate that in areas of high motion, the application of rigid fixation improves graft survival, whereas in a low-motion region, no differences in graft volume retention as a function of fixation were observed. Histologically, no differences with the method of fixation employed were seen, and similar revascularization patterns were noted. By kinetic analysis, rigid fixation appears to exert its most profound effect early in the postgraft period. Membranous bone grafts remain superior to endochondral grafts under all circumstances. From these studies, we conclude that rigid fixation is the method of choice in all circumstances where onlay bone grafts may be exposed to motion, shear, and torsional forces.

Analysis of Variance↗

PubMed1989

Growth and survival of vascularized and nonvascularized membranous bone: an experimental study.

Although nonvascularized membranous bone grafts to the craniofacial skeleton demonstrate improved survival over similar grafts of endochondral origin, the comparative fate of vascularized membranous grafts is unknown. It is also unknown whether onlay membranous bone grafts in immature animals have the ability to grow. To examine these questions, a model was developed in New Zealand white rabbits in which a segment of the zygomatic arch was transferred to the subjacent mandible as either a vascularized or nonvascularized transfer. At harvest 16 weeks later, residual graft volume and bone architecture were analyzed. Results demonstrate no improved survival for vascularized membranous grafts in adult animals (n = 7), while in the immature animals (n = 6), growth of the vascularized bone transfers was documented. We conclude that in the majority of instances in craniofacial reconstruction, nonvascularized onlay membranous grafts are to be preferred. Specific instances for the use of vascularized transfers will be discussed.

Animals↗

PubMed1989

Biological boundaries: a concept in facial skeletal restructuring.

The concept of biological boundaries is based on observations of craniofacial restructuring. It describes the body's intrinsic sense of physical surface and how this knowledge can be used to determine when to use bone grafts, segment shifts, or synthetic material.

Bone Development↗

PubMed1989

Aesthetic contouring of the facial support system.

The skeletal foundation and its attachments provide a basis for changing the basic structure of the face. Detailed preoperative evaluation and a clear understanding between the patient and surgeon of the aesthetic goals are essential prior to proceeding with surgery. Besides a knowledge of the normal aesthetic and arthropologic measurements, the surgeon must have an understanding of the range of methods available prior to proceeding with surgery. For minor alterations, contour reduction or augmentation should be considered. In the temporal fossa, augmentation with synthetic material is preferred. In the supraorbital ridge and chin autogenous tissue is generally the material of choice. An understanding of when and how to use these materials is the essence of achieving satisfactory results.

Esthetics↗

PubMed1988

Aglossia with congenital absence of the mandibular rami and other craniofacial abnormalities.

We describe a severe first branchial arch abnormality including nearly complete absence of mandible, hypoplasia of the maxilla and the zygomatic arches, and complete gingival fusion in a chromosomally normal child born to a nonconsanguineous couple who deny prenatal exposures. A tight orbicularis oris muscle caused the lips to be constantly pursed. Intraoral contents could only be defined after the fused gingiva were separated. The infant had hypoplasia of the buccal cavity with a persistent membrane separating it from the pharynx; palate structures and tongue were absent. The orbits and midface were severely hypoplastic. However, the ears were normal in shape and only slightly low in position. There was unilateral optic nerve coloboma and coronal craniosynostosis. The only noncraniofacial malformation was an atrial septal defect. Embryologically, there is severe malformation of structures arising from the cephalic neural crest cells of both the maxillary and mandibular prominences of the first branchial arch. However, the first branchial cleft region was spared.

Facial Bones↗