Biomedical subjects
Publications and source records attributed to L B Kaban.
In 1973 methods for diagnosing and treating zygomatic complex fractures were reviewed, with emphasis on the lateral eyebrow incision for access to the zygomaticofrontal region. The following clinical update reviews alternative approaches to the zygomatic complex (coronal incision, upper eyelid incision), and current concepts of treatment for acute injuries and late deformities secondary to malunion.
A biologic classification based on clinical behavior and endothelial cell characteristics is used to divide vascular birthmarks into two groups: hemangiomas and vascular malformations. This system is applied to vascular anomalies of the maxillofacial region and is demonstrated with illustrative cases. The distinction between hemangioma and vascular malformation is important for maxillofacial surgeons because hemangiomas rarely affect bone, whereas malformations affect bone in 35% of cases.
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In studying macroglossia, no one has described normal tongue size or applied direct measurement to the pathologically enlarged tongue. Since macroglossia is primarily a condition that requires treatment on a symptomatic basis, definition of the problem in clinical terms is the most useful form for the practitioner. Based on published reports and our clinical experience, a classification scheme for macroglossia has been formulated. The concept of true macroglossia and relative macroglossia form a framework that categorizes acquired and congenital forms of tongue enlargement. True macroglossia exists when histologic abnormalities correlate with the clinical findings of tongue enlargement. Vascular malformations, muscular enlargement, and tumors are the most common forms of true macroglossia. Relative macroglossia includes those cases of apparent tongue enlargement in which the histology does not provide a pathologic explanation. Down's syndrome is a commonly quoted cause for tongue enlargement and is a form of relative macroglossia. The development of this classification system establishes an approach and common terminology on which therapy, research, and communication can be based.
In 1983, we evaluated the stability of midface position after Le Fort III advancement for midface hypoplasia secondary to Crouzon's or Apert's syndromes. The patients were operated upon from 1972 to 1980, and mean follow-up was 5.8 years (Kaban et al, 1984). In this study, we present an additional 3 1/2 year follow-up of these patients to look at what happens to midface position after Le Fort III osteotomy in growing and nongrowing patients.
Based on longitudinal observation of more than 80 patients, we concluded that mandibular hypoplasia is the earliest skeletal manifestation of hemifacial microsomia. The clinical defect becomes worse with time as a result of continued asymmetric growth and progressive secondary deformation of the midface. We hypothesize that midface growth is restricted by the hypoplastic mandible. Therefore, early elongation of the mandible should result in a more symmetrical growth pattern by eliminating mandibular restriction and creating a space for vertical midface growth.
This is a retrospective study of skeletal changes in 19 patients with corrected hypertelorism. A favorable outcome, defined as relapse less than 5 mm, occurred in patients with an average interorbital distance of 32 mm, whereas patients with an average interorbital distance of 40 mm tended to relapse over 5 mm. Neither age, interorbital configuration, nor diagnosis affected the stability of orbital translocation. At last evaluation (mean 6.7 years postoperatively), the mean interorbital distance was 22.4 mm in the favorable outcome group and 28.3 mm in the unfavorable category. This study suggested that the standard hypertelorism operation may interfere with anterior facial growth. Unless psychosocial factors predominate in a child with mild deformity, repair should be postponed until late adolescence. In a young child with gross telorbitism, nasoethmoidal resection and transmaxillary osteotomies or facial bipartition is justified. Another long-term skeletal problem was resorption of the reconstructed nasal complex. Technical and biological explanations for this are given. The correction of hypertelorism is surgery of the nose and of the midface.
A shortened prophylactic regimen of antibiotics for maxillofacial and craniofacial surgery is evaluated. Eighty-five patients were divided into two groups on the basis of the type of incision used. Forty-nine patients undergoing intraoral procedures received penicillin perioperatively and were given one postoperative dose (regimen A). Thirty-six patients undergoing extraoral or combined intraoral and extraoral procedures received penicillin and oxacillin perioperatively, with nine receiving one postoperative dose and 27 receiving an average of seven postoperative doses (regimen B). One infection was observed in the regimen A group, and three were observed in the regimen B group. This infection rate compares favorably to that encountered in the authors' previously reported study on longer prophylactic courses of antibiotics.
A retrospective review of experience with jaw tumors in 48 children over a ten-year period was made. These were predominantly benign, nonodontogenic, mesenchymal tumors. Clinical behavior was variable and often did not correspond to the histologic patterns. The clinically aggressive variants displayed rapid growth usually with associated pain. Resection rather than curettage is appropriate therapy when there has been earlier treatment failure by local tumor removal or rapid tumor expansion, or when tumor extensively invades the jaw. When resection is carried out, facial growth is not adversely affected if early reconstruction with autogenous bone is performed.
Uptake of a bone-seeking radiopharmaceutical is correlated with growth changes in the rat mandible. Uptake was highest in newborn rats, decreasing with increasing age.
An analysis of associated deformities in 74 patients with isolated microtia is reported. Microtia should be considered a microform of hemifacial microsomia because of similar (1) asymmetrical nature of the defects, (2) incidence and pattern of seventh nerve paresis, (3) correlation of the degree of seventh nerve weakness with grade of auricular deformity and not with the severity of mandibular hypoplasia, (4) right-sided preponderance, (5) incidence of associated cleft lip and palate, (6) male predilection, and (7) equivocal mode of inheritance. These clinical observations confirm the concept that microtia and hemifacial microsomia have the same etiopathogenesis which is not shared by mandibulofacial dysostosis.
Complex orthopedic and craniofacial surgical procedures have stimulated renewed interest in the physiology of bone grafting. The experimental and clinical evidence that a nonvital implant can stimulate local host cells to become bone-forming cells (osteoinduction) is reviewed. Studies of induced osteogenesis were derived from old clinical observations of heterotopic ossification in scars and muscle. When demineralized bone is placed within soft tissues of a rat, a remarkable sequence of endochondral ossification occurs. In contrast, mineral-containing bone particles stimulate obligatory resorption by host mono- and multinucleated cells. The biochemical, endocrine, and physicochemical aspects of induced osteogenesis are actively being investigated. Present understanding of the mechanism of bone induction is discussed along with descriptions of preliminary clinical trials with allogeneic demineralized implants.
Normal standards of technetium-99m methylene diphosphonate (99mTc-MDP) uptake in the jaws of adults and growing children have previously been established. This study utilizes the technique of skeletal scintigraphy for diagnosis and treatment planning in 21 patients with mandibular asymmetry. Diagnoses included hemifacial microsomia (n = 6), condylar hyper or hypoplasia (n = 10), and generalized mandibular asymmetry (n = 5). 99mTc-MDP uptake was measured in the right and left condyle, ramus, and body. Uptake was then compared with the known age-adjusted standards. The data were used to determine 1) mandibular growth activity, 2) normal vs. abnormal side, and 3) the effects of operative and functional therapy. The presence of end stage deformity was predicted when mandibular uptake reached the adult norm.
Nineteen of 30 patients who had midface advancement procedures between 1972 and 1980 had sufficient cephalometric data to be included in this retrospective study. The position of the midface in relation to the cranium and mandible was evaluated immediately postoperatively and for a period of 2 to 11 years (mean 5.8 years). At 1 year, midface position after LeFort III advancement was stable in 12 of 19 patients. Of these 12 patients, 8 showed some evidence of downward and/or forward movement of the midface. The remaining 7 patients showed a minor degree of midface relapse in the first year of follow-up. In 15 of 19 patients, at 2 years or more postoperatively, the final position of the midface was either at, anterior to, or inferior to its immediate postoperative location. Correction of exorbitism remained stable in all but one patient, who required a second advancement of the orbital segment. Three patients required subsequent LeFort I osteotomy to correct class III occlusion. Prognathism was determined to be secondary to mandibular growth, not midface relapse.
Morbidity following 104 bone graft harvesting operations (60 iliac, 44 rib) in 72 patients is documented. Early morbidity of iliac donor sites was found, as expected, to be far greater than that of rib donor sites. However, long-term follow-up reveals that while hip symptoms largely resolve, a significant number of chest-wall sites cause persistent, unpleasant pain. Technical ways of minimizing problems are also discussed. When procuring an iliac graft, a lateral skin incision and a medial bony approach are used if possible. If full-thickness ilium is required, the crest should be left intact or raised and replaced as a trapdoor .
Our experience over the past 25 years leads us to conclude that hemifacial microsomia is a progressive skeletal and soft-tissue deformity with the earliest skeletal manifestations in the mandible. We find that not only does the mandibular asymmetry become worse with time, but as the contralateral side grows, the deformed mandible also increases ipsilateral secondary deformation of the maxilla, nose, and orbit. We also find that there is virtually no "catch up" growth on the affected side of the face and that these patients always become more deformed with age. The psychological problems also increase with time and progression of the facial deformity. Based on our experience with correction of end-stage deformities, we now treat these patients at the earliest possible age, as determined by the patient's skeletal classification. We treat the mandible first in the hope that this repositioning in a more physiologic position will unlock the growth potential of the adjacent structures, minimize secondary deformity, and improve function and appearance to the greater benefit of the skeletal and psychological growth of the patient.
Five hundred and eighty birthmarks were reviewed; 356 were hemangiomas and 224 were malformations. Bony alterations occurred in association with only 1 percent of hemangiomas, in contrast with 34 percent of patients with vascular malformations. These alterations in bone development were classified according to size, shape, and density changes. Hypertrophy and distortion were typical of lymphatic malformations. Hypoplasia and demineralization were characteristic findings in the extremity venous malformations. Destructive and intraosseous changes were more commonly noted in the arterial or high-flow lesions. Possible mechanisms of altered skeletal growth include mechanical, physiological, and developmental processes.
Demineralized bone implants were placed as onlays in submucosal pockets on the edentulous segment of the rat mandible, between the incisor and posterior teeth. These implants, predictably, induced osteogenesis. The mass of induced bone and implant was united to the ridge by two weeks, and there was little or no resorption over a six-month follow-up period. This study suggests that demineralized bone implants may be useful for mandibular ridge augmentation.