Long-term remodeling of vascularized and nonvascularized onlay bone grafts: a macroscopic and microscopic analysis.

The present study was performed to compare vascularized and nonvascularized onlay bone grafts to investigate the potential effect of graft-to-recipient bed orientation on long-term bone remodeling and changes in thickness and microarchitectural patterns of remodeling within the bone grafts. In two groups of 10 rabbits each, bone grafts were raised bilaterally from the supraorbital processes and placed subperiosteally on the zygomatic arch. The bone grafts were oriented parallel to the zygomatic arch on one side and perpendicular to the arch on the contralateral side. In the first group, vascularized bone grafts were transferred based on the auricularis anterior muscle, and in the second group nonvascularized bone grafts were transferred. Fluorochrome markers were injected during the last 3 months of animal survival, and animals were killed either 6 or 12 months postoperatively. The nonvascularized augmented zygoma showed no significant change in thickness 6 months after bone graft placement and a significant decrease in thickness 1 year after graft placement (p < 0.01). The vascularized augmented zygoma showed a slight but statistically significant decrease in thickness 6 months after graft placement (p < 0.003), with no significant difference relative to its initial thickness 1 year after graft placement. In animals killed 6 months after bone graft placement, both the rate of remodeling and the bone deposition rate measured during the last 3 months of survival were significantly higher in the vascularized bone grafts compared with their nonvascularized counterparts (p < 0.02). By 1 year postoperatively, there were no significant differences in thickness, mineral apposition rate, or osteon density between bone grafts oriented perpendicular and parallel to the zygomatic arch. These findings indicate that the vascularity of a bone graft has a significant effect on long-term thickness and histomorphometric parameters of bone remodeling, whereas the direction of placement of a subperiosteal graft relative to the recipient bed has minimal effect on these parameters. In vascularized bone grafts, both bone remodeling and deposition are accelerated during the initial period following graft placement. Continued bone deposition renders vascularized grafts better suited for the long-term maintenance of thickness and contour relative to nonvascularized grafts.

Craniofacial skeletal fixation using biodegradable plates and cyanoacrylate glue.

This study examined the feasibility of fixation of craniofacial bone using Lactosorb biodegradable plates adhered to bone with butyl-2-cyanoacrylate adhesive (Histoacryl) in a pig. The stability and bone-healing characteristics of this rigid fixation method were studied and compared with standard rigid fixation using metal plates and screws on osteotomy sites in the frontal bones and infraorbital rims. Rectangular osteotomies (2.0 x 3.0 cm) were performed on the right and left sides of the frontal bone and wedge-shaped osteotomies (1.5 x 1.7 cm) were made on the left and right infraorbital rims in seven Yorkshire pigs. Metal plates were applied with screws to the osteotomies on one side, and the other side was fixed with a biodegradable plate and butyl-2-cyanoacrylate. The animals were sacrificed at 8 weeks, and both sides were compared biomechanically and histologically. Radiographic, biomechanical, and histologic analyses were performed to evaluate skeletal stability, contour, accurate positioning of bony fragments, bone healing, and maximum torque to failure of the repair sites. Clinical and radiographic observations demonstrated stability of the bone fragments without any evidence of displacement. According to Student's t test for paired data, no statistical difference was found in the maximum torque to failure of fragments fixed with biodegradable plates and glue compared with those fixed with metal plates and screws (p > 0.05), whether or not a gap existed at the osteosynthesis site. Although the sample size was small, no differences were noted between the two types of treatment groups. This study demonstrates that rigid internal fixation of osteotomized cranial bone fragments using biodegradable plates and butyl-2-cyanoacrylate is as effective as metal plate and screw fixation in this animal model.

A dynamic analysis of changes in the nasolabial fold using magnetic resonance imaging: implications for facial rejuvenation and facial animation surgery.

An anatomic study was performed on living subjects using magnetic resonance imaging (MRI) to distinguish the relative contribution of skin, subcutaneous tissue, and muscle to dynamic changes in the nasolabial fold during facial animation and aging. MRI scans with the face in repose and then holding a full smile were performed in both young and old adult subjects. Anatomic landmarks were identified, and measurements characterizing their position were made on the MRI console. MRI resulted in excellent image resolution of facial tissue planes. Comparison between young and old subjects with the face in repose demonstrated that progressive thickening of the dependent portion of the check fat pad and overlying skin, with no appreciable change in the muscle plane comprising the levators of the upper lip, resulted in a deeper and more acute nasolabial fold in older subjects. In both age groups there was significant shortening of the mimetic muscles with smiling, with the lateral mimetic muscles drawn closer to the underlying facial bones. This was accompanied by redistribution of the cheek fat pad, thereby maintaining projection of surface landmarks within the cheek mass in young subjects with smiling. These findings indicate that in order to diminish the nasolabial fold, surgery for facial rejuvenation should be directed to the skin and subcutaneous tissue planes superficial to the mimetic muscles to the upper lip. In order to recreate a natural nasolabial fold during surgery for facial reanimation, contraction of the levator muscles to the upper lip should result in redistribution of the cheek fat pad without change in surface projection of the cheek mass or upper lip; this can only be accomplished if the reconstructed levator muscle is positioned deep to the cheek fat pad, with its insertion toward the deep (mucosal) surface of the upper lip.

Effects of laser versus scalpel tenolysis in the rabbit flexor tendon.

The use of surgical lasers has been shown to decrease adhesion formation as compared with scalpel control groups in various surgical procedures. The potential benefits of laser technology have not been assessed in the treatment of adherent tendons. The current study was designed to first develop a reliable and reproducible model for consistent adhesion formation following flexor tendon trauma. The second goal was to compare the effects of laser tenolysis procedures on tendon gliding with those of traditional scalpel tenolysis. In phase I, the adhesion-induction model utilized bilateral standardized crush- abrasion injuries to the hind limb digital flexor tendons of New Zealand White rabbits. Following 4 weeks of immobilization, the animals were sacrificed, and peritendoneal adhesions were assessed biomechanically. A significantly higher maximal force was required to extract the adherent tendons from the foot as compared with nontraumatized control tendons. In phase II, six groups of animals underwent the same standardized tendon trauma. Four weeks later the rabbits were randomly assigned to undergo either CO2 laser or holmium:YAG laser tenolysis on one foot. Scalpel lysis was used on the contralateral foot and served as an intraindividual control. Biomechanical assessment was performed at 1, 2, and 4 weeks following tenolysis. Significantly less force was required to extract the treated tendons at 1 and 2 weeks following holmium:YAG laser tenolysis when compared with scalpel or CO2 laser tenolysis. After 4 weeks, differences between holmium:YAG and CO2 laser and scalpel treatment were no longer significant. Extracted tendons were pulled apart to failure, and no difference in breaking strength was noted between groups. We conclude that holmium:YAG laser tenolysis results in easier tendon gliding as compared with scalpel or CO2 laser tenolysis at early time points. Laser tenolysis does not affect intrinsic tendon strength.

Bilateral cleft lip and palate associated with agenesis of the hand and distal forearm.

We report on a child who was born with an incomplete bilateral cleft lip and palate associated with agenesis of the left hand and distal forearm. No other anomalies were noted. The patient was the first child of a term pregnancy with a negative family history, and the mother took no prenatal medications. Ultrasonogram performed at 34 weeks' gestational age failed to detect any congenital anomalies. Thorough genetics evaluation, including chromosome analysis, showed no further abnormalities; the birth defects were believed to be nonsyndromic. To our knowledge, the association of bilateral cleft lip and palate with agenesis of the upper extremity has not been previously reported. Moreover, it is important to note that a prenatal ultrasonogram, even when performed late in the third trimester, may fail to detect these significant congenital anomalies.

Biomechanical evaluation of the canine and porcine models for experimental craniofacial surgery.

This investigation compared the variation of the biomechanical properties of canine and porcine craniofacial bones in homotypical (same site in opposite sides of an animal) and heterotypical (same site in different animals) sites. Biomechanical analysis is a reliable method to assess bone healing, because fracture repair correlates closely with the changes in biomechanical properties. Paired bone fragments were harvested in nine dogs and nine minipigs from each side of the skull from three different sites-the frontal bone, the supraorbital rim, and the zygomatic arch- and submitted to torque to failure. Maximum torque, stiffness, and toughness were recorded and comparative analysis performed. A normal range of variation between paired craniofacial bones in two useful animal models is provided. The results showed that the variability between homotypic left and right sides was not significant, whereas the variability between heterotypic sites in separate animals was. Maximum torque was the most reliable of the three parameters considered, because the data fell over a much narrower range. We conclude that the use of the contralateral side is a valid control in experimental procedures that may alter the biomechanical properties of one side.

Cyanoacrylate fixation of the craniofacial skeleton: an experimental study.

This study examined the feasibility of achieving bone fixation of the upper facial skeleton using n-butyl-2-cyanoacrylate. We compared the fixation obtained with this adhesive to that obtained with plates and screws in an animal model. The stability of fixation of both osteotomies and onlay grafts was studied in six minipigs. Three osteotomies were performed on each side of the skull. Additionally, a parietal split-thickness autograft was fixated to the nasal bone as an onlay. Plates and screws were used on the right and adhesive on the left. The animals were killed at 6 weeks, and both sides were compared biomechanically and histologically. Clinical assessment showed stability of all fragments. No statistical difference was found in the comparison of the maximum torque to failure between analogous plated and glued sides. Radiographic cephalometry revealed no significant displacement of the fragments. Histologic analysis demonstrated bony union. In this study, n-butyl-2-cyanoacrylate was as effective as plates and screws in the fixation of surgically created osteotomies of the upper facial skeleton.

Cranial versus iliac onlay bone grafts in the facial skeleton: a macroscopic and histomorphometric study.

We compared autologous bicortical ilial and cranial bone grafts onlaid to the facial skeleton in 60 adult New Zealand rabbits to evaluate the initial phase of incorporation of these grafts. The animals were distributed in two equal groups in which either cranial or iliac grafts were harvested and fixated, devoid of their periosteum, in direct contact with the nasal bone with micro screws. Each of these two groups were then subdivided into three groups, which corresponded to the three times the animals were killed: 18 days, 30 days, and 60 days. The grafts were measured in their linear dimensions and weighed before fixation and after harvesting when the animals were killed. Undecalcified histological sections were prepared, and histomorphometric parameters of bone formation (bone volume, osteoid volume, surface thickness, and osteoblastic surface) and resorption (osteoclastic surface and eroded surface) were measured. The results confirmed those of previous studies in that cortical grafts maintained their volumes to a greater extent than their cancellous counterparts indicating that the remodeling process may be uncoupled in the transplanted iliac grafts. It is postulated that the significant decrease in mechanical stimulus that the cancellous grafts undergo determines this imbalance in the remodeling activity, which results in greater bone resorption than formation and thus decreased volume.

Experimental orthotopic transplantation of vascularized skeletal allografts: functional assessment and long-term survival.

Vascularized skeletal tissue allografts would greatly expand the domain of reconstructive surgery. Few studies to date have examined the functional aspects of these allografts or their long-term fate. An orthotopic transplant model of rat distal femur and surrounding muscular cuff was developed to assess graft function in fracture healing and weight bearing. Isografts (RT1l to RT1l, n = 40), weak-barrier allografts (RT1l to RT1lv, n = 40), and strong-barrier allografts (RT1l to RT1n, n = 40) were transplanted. As the histocompatibility barrier increased between the donor and recipient animals, the graft viability and performance deteriorated according to radiographic, histologic, and immunologic analyses. Administration of cyclosporine led to survival of strong-barrier allografts similar to that of isografts. A long-term study of these allografts (RT1l to RT1n) was then performed on various immunosuppressive regimens. After an initial 10-week course of cyclosporine to achieve bony union and remodeling, subsequent cessation (n = 20) or intermittent "pulsing" (n = 20) of the immunosuppressant was insufficient in maintaining graft survival. However, graft viability and function were preserved through 1 year on continuous daily cyclosporine (n = 32). There was no evidence of host renal or hepatic toxicity by serum chemistry or histologic sections. Thus long-term survival of functional skeletal allografts was achieved in this orthotopic model without significant host toxicity from immunosuppression.

Autologous fat grafts: a quantitative and morphometric study in rabbits.

The aim of this study was to assess the fate of autologous fat tissue grafts harvested and processed by five different methods: blunt suction, sharp suction, dissection, treatment, and lavage. Fat was harvested from the subcutaneous tissue of the interscapular region in 25 rabbits and injected into the subcutaneous area of the convex surface of the ear. Harvesting was by either open surgical excision or suction. Where open surgical excision was used, the fragments were cut into smaller pieces with scissors. Suction in the blunt and sharp suction groups was through cannulas with blunt or sharp edged suction holes, respectively. In both suction groups and the dissection group the harvested tissue was injected without further processing. In the treatment group 2 ml of cell 199 culture medium and Earle's basic salt solution were added, and in the lavage group the tissue was washed with Ringer's lactate. Animals were killed at 7 (n = 9), 180 (n = 8), and 360 (n = 8) days. Serial cross sections were taken from each recipient area and the specimens processed for histology. The images from each section were digitised in a computer and, with the assistance of image analysis software, the volume of remaining fat cells was calculated for each recipient area. The percentage volumes of fat cells found in each group at 360 days were: blunt suction 14% sharp suction 35%, dissection 45%, treatment 27%, and lavage 16% (p = 0.003).

Bilateral multiple muscle hernias of the leg repaired with Marlex mesh.

We report a case of multiple muscle hernias of the legs, resulting from regular, intense, physical exertion. The multiple fascial defects were closed with Marlex mesh. On review after 5 years, there were no recurrences of the hernias.

[Surgical repair in the sequela of Fournier's syndrome]. / Cirurgia reparadora na seqüela da síndrome de Fournier.

Fournier's syndrome or necrotizing fasceitis of the abdominal-perineal region is a severe acute problem which may lead to a systemic impairment and eventually to death. Skin losses of the scrotum and penis can also be very incapacitating and difficult to repair. At the Hospital das Clínicas da FMUSP the Division of Surgery of Trauma has been able to reduce significantly the mortality rate of this syndrome. Cases with tissue losses were referred to the Division of Plastic Surgery for reconstruction. Several techniques were used in the period 1983-1986 but, in special, the reconstruction of the scrotum has been done using fascio-cutaneous flap the medial aspect of the thigh. Of the twenty nine patients reviewed the majority achieved social and professional rehabilitation.