Gregory S. LaTrenta

The role of rigid skeletal fixation in bone-graft augmentation of the craniofacial skeleton

The type of fixation (rigid skeletal vs. wire) was assessed against embryologic origin (membranous vs. endochondral) and recipient site (depository vs. resorptive) as variables affecting inlay and onlay bone-graft survival in 20 mature dogs. Wet weight and volume measurements were made at operation and at sacrifice (16 weeks). The results were as follows: (1) Rigid skeletal fixation increased bone-graft volume survival over wire fixation (p less than 0.05). (2) Fixation (i.e., rigid skeletal) and embryologic origin (i.e., membranous) were equal determinants of bone-graft volume survival (p less than 0.001); the recipient site was not significant for onlay bone graft survival. (3) Embryologic origin was the only significant determinant of weight survival (p less than 0.001). (4) Inlay bone grafts demonstrated greater weight and volume survival than onlay bone grafts (p less than 0.05). (5) Histologic and microradiographic studies demonstrated bony union of bone grafts fixed with rigid skeletal fixation, while fibrous union predominated in bone grafts fixed with wire technique.

The role of the Schirmer's test and orbital morphology in predicting dry-eye syndrome after blepharoplasty.

The Schirmers test for tear production has been recommended to identify patients with diminished tear production prior to blepharoplasty. The decision to operate may rest with this simple clinical test. This paper reports a prospective clinical evaluation of 100 consecutive blepharoplasty patients to determine the role of preoperative assessment of the orbital and periorbital morphology and the Schirmers test in predicting the likelihood of the development of the dry-eye syndrome (DES) postoperatively. Our findings indicate that the morphology of the orbital region is a more important and reliable method of evaluating a predisposition to developing dry eyes postoperatively than is the Schirmers test. The value of the Schirmers test is to flag patients prior to blepharoplasty, but it should not be relied on as the sole method of screening patients and it is definitely of less importance than the history and physical examination.

The role of the cranial base in facial growth : Experimental craniofacial synostosis in the rabbit

Craniofacial synostosis designates premature fusion in sutures of the cranial vault (calvarium). When craniofacial synostosis is associated with a syndrome (e.g., Apert, Crouzon), premature fusion of the cranial base has been postulated to occur as well. This study was designed to determine whether the primary growth disturbance in craniofacial synostosis is located at the cranial base (i.e., spheno-occipital synchondrosis) or the calvarial vault (i.e., coronal and sagittal sutures) or both. Sixty newborn New Zealand White rabbits were randomly assigned to six groups: (I) calvarial control, (II) cranial base control, (III) cranial base immobilization, (IV) coronal suture immobilization, (V) coronal and sagittal suture immobilization, and (VI) cranial base and coronal and sagittal suture immobilization. An anterior cervical microsurgical approach to the cranial base was used, while cranial vault sutures were exposed through a bicoronal scalp incision. All sutures were fused by periosteal abrasion and application of methyl cyanoacrylate. Cephalograms were taken at 30, 60, and 90 days postoperatively to assess craniofacial growth. Linear and angular measurements of facial, calvarial, and basicranial growth were subjected to multivariate analysis. Analysis indicated that (1) craniofacial length was shortened most significantly by cranial base fusion, (2) cranial base fusion and cranial vault fusion had an additive effect on craniofacial length restriction, (3) the anterior cranial base was significantly shortened by cranial base and cranial vault fusion (p < 0.05), (4) the posterior cranial base was shortened by cranial base fusion only (p < 0.05), and (5) cranial base fusion alone significantly flattened the cranial base angle (p < 0.05), whereas cranial vault fusion alone did not. These results suggest that cranial base fusion alone may account for many dysmorphic features seen in craniofacial synostosis. This model is consistent with the findings of other investigators and confirms both a primary directive and translational role of the cranial base in craniofacial growth.

Facial atrophy in HIV-related fat redistribution syndrome: anatomic evaluation and surgical reconstruction.

The use of highly active antiretroviral therapy (HAART) with protease inhibitors can result in a syndrome of peripheral wasting, facial fat atrophy, and central adiposity in as many as 64% of patients infected with human immunodeficiency virus (HIV) who are treated with this regimen for 1 year. In this study the authors evaluated 9 consecutive patients who presented with this disease to define further its anatomic features and to explore techniques for surgical correction. Three of these patients presented with severe facial atrophy, and underwent surgical exploration and reconstruction with submalar silicone implants. Two patients required additional soft-tissue augmentation with synthetic fillers and/or autologous fat. Outcomes were determined through clinical impressions of the patient and surgeons, and comparison of pre- and postoperative photographs. No extrusion or infection was encountered, although 1 patient required repositioning on one side. Both surgeons and patients were satisfied with the results at the long-term follow-up. Detailed anatomic evaluation revealed the presence of a fat pad of Bichat in all patients. Facial atrophy in HIV-related fat redistribution syndrome (HARS) is secondary to atrophy of the subcutaneous fat, but not of the deeper fat pads, as has been described. Durable surgical reconstruction is achieved with a combination of submalar silicone implantation and augmentation of the nasolabial fold. HARS causes noticeable disfigurement that stigmatizes the HIV-infected patient. Given the overall benefit of decreased morbidity and prolonged survival associated with HAART therapy, it is beneficial to attempt surgical correction of these debilitating sequelae before discontinuation of these drugs.

The le fort III advancement osteotomy in the child under 7 years of age

This is a longitudinal study of 12 patients with craniofacial synostosis syndromes (Crouzons, Aperts, Pfeiffers) who underwent Le Fort III advancement under the age of 7 years (average age 5.1 years, range 4.0 to 6.7 years). The average follow-up was 5.0 years and included clinical, dental, and cephalometric examinations according to a prescribed protocol. The study demonstrated that the procedure could be safely performed in the younger child with an acceptable level of morbidity. There was a remarkable degree of postoperative stability of the maxillary segment. However, although vertical (inferior) growth or movement of the midfacial segment was demonstrated, there was minimal, if any, anterior or horizontal growth. Any occlusal disharmony developing during the period of follow-up could be attributed to anticipated mandibular development and could be corrected by orthognathic surgery. The roles of surgical overcorrection and anterior-pull headgear therapy after release of intermaxillary fixation are also discussed. The Le Fort III osteotomy is justifiably indicated during early childhood for psychological and physiologic reasons.

Bone Graft Survival in Expanded Skin

The effect of tissue expansion on iliac bone graft (onlay) survival was studied on the skulls of 35 New Zealand white rabbits. Wet bone weights at the time of grafting and at sacrifice in control animals (group I) were compared to three experimental groups. Histologic sections of the developing and resolving pseudosheath and skin envelope were performed. A self-inflating 5-mil-thick silicone expander was used for soft-tissue expansion over the rabbit snout. Bone grafts were subsequently placed in this site. Elliptical snout excision without expansion (group II) demonstrated no statistically significant difference in bone graft survival when compared to controls (group I) (p = 0.350). Full tissue expansion followed by immediate bone grafting (group III) within the pseudosheath cavity likewise demonstrated no statistically significant difference in bone graft survival when compared to controls (group I) (p = 0.500); however, when full tissue expansion was followed by delayed (2 weeks) bone grafting to allow for resolution of the giant cell inflammatory reaction of the pseudosheath (group IV), a statistically significant increased bone graft survival was achieved (p less than 0.001). The study demonstrates that the increased vascularity in the pseudosheath and in the expanded soft-tissue envelope significantly increased bone graft survival only when bone grafting was delayed.

Midline Defects of the Orofaciodigital Syndrome Type VI (Váradi Syndrome)

The orofaciodigital syndromes (OFDS) represent a spectrum of anomalies of the palate, cranium, hands, and feet. Váradi syndrome, designated OFDS type VI, is a rare disorder that is additionally characterized by cerebellar anomalies. The following report is of a patient with OFDS VI and characteristic multiple midline defects: median cleft lip and palate, lingual cleft with nodules, and midline brain malformation. In addition, this case is uniquely associated with the presence of midline (metopic and sagittal) craniosynostoses as well. It is unusual that deformities which result from premature fusion of cranial vault sutures would appear synchronously in a syndrome based on the concept of failure of fusion or coalescence of facial growth centers. The midline represents an independent developmental field, whereby CNS defects and midline anomalies can present concurrently.

Donor leukocyte migration following extremity transplantation in an experimental model.

In an effort to further define the immunologic mechanisms leading to acute composite-tissue allograft rejection, the migratory patterns of donor leukocytes were evaluated. Using a rat model, 52 orthotopic vascularized hindlimb transplants were performed in strains representing major histocompatibility mismatches. In order to evaluate the effect of allogeneic skin on limb rejection, all donor skin was removed in a second group of allografts. Recipient lymphoid organs were examined during the week following transplantation for antigen-presenting cells using a donor-specific class II monoclonal antibody. Donor leukocytes, with dendritic cell morphology, were identified in recipient spleen and lymph nodes draining the allograft. Significantly higher numbers of donor leukocytes were present during postoperative days 1 through 4 for both groups. Association of these important passenger leukocytes with host T-lymphocytes may represent the site of initiation of the immune response.

Variations in digital nerve anatomy

One hundred digital nerves from 10 cadaver hands were dissected, and branching patterns were analyzed. Contrary to the traditional belief that the digital nerve predictably trifurcates at the distal interphalangeal crease, much variation exists. Terminal branching occurred distal to the crease in 60% of the thumb digital nerves and in 78% of the digital nerves supplying the other four digits. The number of terminal branches also varied from two to seven in the thumb and from two to five in the other four digits. No significant differences were seen in branching patterns between digits or between radial and ulnar sides. These findings are clinically relevant to the surgeon who is contemplating digital nerve repair.

Migration of donor leukocytes from limb allografts into host lymphoid tissues.

This study was undertaken in an initial effort to characterize the immunology of extremity transplantation by examining the pattern and kinetics of leukocyte migration from rat limb transplants. Migration of donor leukocytes was evaluated by examining recipient lymphoid tissues with a donor-specific, anti—major histocompatibility complex, class I monoclonal antibody. Double-antibody, two-color labeling was used to localize donor cells to specific regions within these tissues. Donor leukocytes, with dendritic cell morphology, were found in the T-cell-rich areas of lymph nodes draining the allograft and spleen. The donor cells were present on postoperative days 1 through 3 but were not present on days 5 to 7. Donor leukocytes were not present in distant lymph nodes or liver. These findings indicate a migration of leukocytes, most likely the highly immunogenic dendritic cell, from rat limb transplants to the draining lymphoid tissues. Migration occurs shortly after transplantation and may lead to the sensitization of alloreactive T-cells.