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Background Many patients who receive breast implants eventually develop breast ptosis and a descent of the inframammary fold. This usually requires either exchange for a larger implant, mastopexy (vertical or “T” incision), or more recently, the use of the so-called “power lift” or suturing of the posterior leaf of the capsule to the pectoralis major muscle. Objective We report on a new technique for correction of postaugmentation ptosis, also called “implant ptosis,” (IP) without making any further incisions on the breast or producing any breast distortion. Methods A capsulotomy was performed through existing incisions, and the implant was removed. The posterior capsule was elevated from either the pectoralis major muscle (subglandular implants) or the anterior chest wall (submuscular implants). Approximately one half of the posterior capsule was reflected from its posterior attachments and then sutured to the anterior leaflet of the capsule, creating a “sandwich.” This internal autologous splint elevated and medialized the implant, while adding thickness and strength to the capsule. It was then sutured to the periosteum of the anterior rib at the level of the new inframammary fold. The new implant was then placed in the submuscular position. Results Operations were performed between 4 months and 8 years after the original augmentations in 11 women with bilateral breast implants who developed Grade II to III ptosis after augmentation in either the subglandular (n = 4) or submuscular (n = 7) positions. Preoperatively, all patients displayed Type 1 or 2 capsules. Follow-up was from 1 to 3 years after surgery. The technique produced an aesthetically pleasing breast with correction of the ptosis. No additional incisions on the breast were necessary, and no restrictions to breast shape were noted with full arm motion. Long-term follow-up displayed good position of the nipple-areolar complex and high patient satisfaction. Conclusions The autologous internal breast splint is a novel technique for the treatment of postaugmentation ptosis that both medializes and elevates the implant when necessary. Altlhough it was performed through previous incisions in this study, it may be coupled with a standard mastopexy procedure. This technique may solve many of the problems associated with postaugmentation breast ptosis and warrants further investigation.

Although abnormalities of vascular anatomy in the forearm are common, variations of the radial and ulnar arteries are rare. Nevertheless, arterial variants in the forearm may present clinically with neurovascular signs or symptoms. Even when anomalous arteries are not apparent, they may complicate surgery of the forearm and hand, as well as reconstructive surgery that involves the harvest of radial or ulnar artery-based forearm free flaps. For example, the superficial ulnar artery has an incidence of 2.7% and has been well described as a "hidden trap" in the harvest of radial forearm flaps. We present a case report of a variant of the radial artery-the superficial dorsal artery of the forearm. This artery has an estimated incidence of 0.75% and is associated with either an absent or small-caliber radial artery. We believe this is the first report of such an artery presenting to clinical attention, as well as the first imaging of this structure with magnetic resonance angiography. The embryology of this structure and its clinical implications to the hand surgeon, peripheral vascular surgeon, and reconstructive microsurgeon, are also discussed.

Distraction osteogenesis has evolved as a mainstream surgical technique for lengthening and augmentation of the hypoplastic mandible. As clinical experience accumulated, there developed the need to "mold" the bony regenerate to avoid the development of postdistraction malocclusion and to achieve the desired craniofacial form. Although the potential to mold the regenerate has important clinical implications, the safety and efficacy of such an acute manipulation of the bony regenerate form have not yet been investigated in the laboratory. The purpose of this study was to determine if the distraction regenerate could be molded and result in a bony union. Four adult female dogs underwent bilateral mandibular distraction with an external multiplanar device (Stryker, Osteonics). After a latency period of 5 days, the mandibles underwent linear (anteroposterior) and angular (superoinferior) distraction to produce an anterior open bite of approximately 30 degrees. At the conclusion of the distraction procedure, the distraction sites were molded to close the open bite. In two dogs, the maneuver was performed over 3 days by changing the angulation of the devices (gradual molding), and in the other two dogs, molding was achieved with a single movement (acute molding). In the latter, the distraction devices were adjusted and reapplied to allow for anatomical fixation during the consolidation period of 49 days. According to the research protocol, the mandibles were assessed serially by cephalograms and computed tomography (CT) scans. All dogs survived the study without complications. The bony regenerate was easily molded in both groups to close the surgically created open bite. After molding, all the regenerates showed CT scan evidence of solid bone (consolidation), which was classified as "extended" on the Hamanishi scale. After the dogs were killed and soft tissue was removed, the regenerate seemed to be robust on gross examination without any evidence of fibrous nonunion. In addition, histological study of the regenerate confirmed the bony union. The study demonstrates that the mandible can be successfully molded into a desired anatomical position immediately after distraction without producing a fibrous union. Furthermore, it has been demonstrated that the bony regenerate is sufficiently malleable before consolidation to undergo either acute or gradual angular molding without disturbing osteogenic potential. The ability to mold the regenerate without the fear of creating a fibrous union or destroying bony potential provides the surgeon the capability to optimize the dental occlusion and mandibular form as part of the distraction treatment process.

Transverse mandibular distraction osteogenesis involves moving the osteotomized segments of the mandible in either a varus or valgus direction. This maneuver allows for widening of the bigonial distance or for a lateral shift of an asymmetric mandibular midline. During this process, a significant amount of torque is placed on the mandibular condyles, because they act as the pivot point for the mandibular translation. Although standard linear distraction osteogenesis induces transient, reversible changes in the temporomandibular joint, it is not known what effect the varus and valgus stresses of transverse distraction have on the temporomandibular joint. We therefore designed a study to document the temporomandibular joint changes following various degrees of transverse distraction. Bilateral transverse mandibular distraction was performed on 10 adult, female mongrel dogs using an external, multiplanar mandibular distraction device. The distraction protocol was as follows: (1) complete osteotomy at the angle of the mandible, (2) 5-day latency period, (3) distraction rate of 1 mm/day, (4) rhythm of one turn per day, (5) linear activation 16 to 30 mm bilaterally, and (6) 8-week consolidation period. A variety of varus and valgus distraction vectors were applied to the mandible only after 10 mm of initial linear distraction had been achieved. Posteroanterior and lateral cephalograms were performed throughout the entire process. Pre-distraction and post-consolidation computed tomographic scans were also performed. Changes in mandibular conformation, axis of rotation, temporomandibular joint structure, and glenoid fossa changes were directly assessed by evaluating the postmortem craniofacial skeleton. The findings were compared with those of normal, age-matched mongrel dog skulls. Significant remodeling changes were observed in the temporomandibular joints of all animals involved in the study. The mandibular condyles demonstrated varying degrees of flattening and erosion at all contact points with the craniofacial skeleton. In some cases, the condyle became part of the distraction regenerate process and was hypertrophied in all dimensions. The condyles were frequently displaced out of the glenoid fossa, particularly on the side in the direction of varus distraction. When the latter occurred, a new fossa was created on the undersurface of the zygomatic arch. Varying degrees of mandibular rotation in the sagittal plane were also observed, which led to abnormal torquing of the condyles in the coronal plane, depending on whether the axis of rotation occurred primarily around the condyle or around the distraction regenerate zone.In conclusion, transverse mandibular distraction is an effective means of producing a varus or valgus shift in the gonion relative to the midsagittal plane. However, unlike linear or angular mandibular distraction, transverse distraction has a multitude of nontransient effects on the temporomandibular joint. Therefore it must be emphasized that in clinical practice, transverse distraction should be used cautiously. One must also be aware that such a maneuver in distraction can have negative effects on the temporomandibular joint.

Various agents have been theoretically and experimentally implicated as mediators of distraction osteogenesis (DO). The purpose of this study was to develop a vehicle for the potential delivery of these factors to the region of the distraction site in an attempt to manipulate this biologic process. Three adult mongrel dogs (12 months old) had oblique osteotomies performed bilaterally through the gonial regions. In group I, the external distracter was affixed to the right hemimandible of two dogs (n = 2 hemimandibles) with cannulated pins (external diameter = 1.5 mm; lumen diameter = 1.0 mm; length = 60 mm), whereas the distracter on the left was affixed with standard, noncannulated pins of the same dimensions. In group II, cannulated pins were used to affix the external distracter to both hemimandibles (n = 2 hemimandibles) of a dog. The devices were activated after a 5-day latency period and were lengthened at a rate of 1 mm/day for 20 days. During the distraction period, 0.1 ml/d of sterile india ink was injected into the cannulated pins, after which the sterile stylet was replaced. The activation protocol was followed by 28 days of fixation (consolidation period). The hemimandibles from group I underwent removal of soft tissues, acetone fixation, and gross examination/photography, whereas the hemimandibles from group II were prepared for histologic evaluation (whole mount, hematoxylin and eosin staining). All dogs survived to the end of the study and demonstrated successful DO without evidence of complications. Hemimandibles in group I displayed evidence of india ink on both the lingual and buccal cortex around the cannulated pin site, in the regenerate and on the neocortices of the distracted segment. Hemimandibles of group II showed histologic evidence of the india ink being deposited densely around the cannulated pin site and extending in a radial fashion around the pin site into the regenerate. This study demonstrates for the first time a vehicle device for the delivery of an inert dye to the regenerate site during distraction osteogenesis. This vehicle offers the potential of delivery of various factors implicated in distraction osteogenesis (i.e., mitogens) in an attempt to alter this process and also substances (i.e., chemotherapy, antibiotics, etc.) for use in the treatment of various osteopathies.

Newborns with in utero cranial vault molding can present with severe forms of plagiocephaly. Intrauterine constraint has been proposed as one cause for craniosynostosis. The purpose of this experiment was to investigate whether rigid plate fixation across a fetal cranial suture, representing a severe form of growth restriction in utero, would lead to cranial suture fusion in a fetal lamb model. Six fetal lambs at 85 to 95 days gestation (term = 145 days) underwent laparotomy, hysterotomy, fetal coronal scalp incision, and miniplate screw fixation across the right coronal suture in utero. Two unoperated twins and four unoperated age-matched lambs were used as controls (n = 12). Animals were killed at both 4 and 8 weeks postoperatively. Fetal head analysis consisted of gross examination, photography, basilar and lateral radiographs, and three-dimensional computed tomographic scans. Cranial suture analysis consisted of imaging by computed tomographic scan (axial and sagittal cuts) and histology of experimentally plated coronal sutures, contralateral nonplated coronal sutures and twin control coronal sutures. Gross examination, radiographs, and three-dimensional computed tomographic analysis of heads with cranial suture plating showed ipsilateral forehead flattening, contralateral forehead bossing, superiorly displaced ipsilateral orbital rim, anterolateral projection of ipsilateral malar eminence, and anterior position of the ipsilateral ear point compared with the contralateral side of the same animal and normal controls. There was no change in nasal root, chin point, or predentition occlusal plane. Although analysis of the plated coronal sutures by computed tomographic scans showed diminished width or even stenosis, the histology revealed narrowed but patent experimental coronal sutures at 4 and 8 weeks. Contralateral, nonplated coronal sutures were not only patent, but widened compared with normal control sutures. This finding may have represented compensatory changes in the contralateral coronal suture caused by growth restriction at the plated suture. These data demonstrate that intrauterine growth restriction across a cranial suture caused by compression plate fixation resulted in deformational skull changes, not craniosynostosis. In addition, these data strongly support a role for in utero positional molding secondary to growth restriction in the maternal pelvis as a cause for nonsynostotic plagiocephaly seen in newborns.

Poorly healing mandibular fractures and osteotomies can be troublesome complications of craniomaxillofacial trauma and reconstructive surgery. Gene therapy may offer ways of enhancing bone formation by altering the expression of desired growth factors and extracellular matrix molecules. The elucidation of suitable candidate genes for therapeutic intervention necessitates investigation of the endogenously expressed patterns of growth factors during normal (i.e., successful) fracture repair. Transforming growth factor beta1 (TGF-beta1), its receptor (Tbeta-RII), and the extracellular matrix proteins osteocalcin and type I collagen are thought to be important in long-bone (endochondral) formation, fracture healing, and osteoblast proliferation. However, the spatial and temporal expression patterns of these molecules during membranous bone repair remain unknown. In this study, 24 adult rats underwent mandibular osteotomy with rigid external fixation. In addition, four identically treated rats that underwent sham operation (i.e., no osteotomy) were used as controls. Four experimental animals were then killed at each time point (3, 5, 7, 9, 23, and 37 days after the procedure) to examine gene expression of TGF-beta1 and Tbeta-RII, osteocalcin, and type I collagen. Northern blot analysis was used to compare gene expression of these molecules in experimental animals with that in control animals (i.e., nonosteotomized; n = 4). In addition, TGF-beta1 and T-RII proteins were immunolocalized in an additional group of nine animals killed on postoperative days 3, 7, and 37. The results of Northern blot analysis demonstrated a moderate increase (1.7 times) in TGF-beta1 expression 7 days postoperatively; TGF-beta1 expression returned thereafter to near baseline levels. Tbeta-RII mRNA expression was downregulated shortly after osteotomy but then increased, reaching a peak of 1.8 times the baseline level on postoperative day 9. Osteocalcin mRNA expression was dramatically downregulated shortly after osteotomy and remained low during the early phases of fracture repair. Osteocalcin expression trended slowly upward as healing continued, reaching peak expression by day 37 (1.7 times the control level). In contrast, collagen type IalphaI mRNA expression was acutely downregulated shortly after osteotomy, peaked on postoperative days 5, and then decreased at later time points. Histologic samples from animals killed 3 days after osteotomy demonstrated TGF-beta1 protein localized to inflammatory cells and extracellular matrix within the fracture gap, periosteum, and peripheral soft tissues. On postoperative day 7, TGF-beta1 staining was predominantly localized to the osteotomized bone edges, periosteum, surrounding soft tissues, and residual inflammatory cells. By postoperative day 37, complete bony healing was observed, and TGF-beta1 staining was localized to the newly formed bone matrix and areas of remodeling. On postoperative day 3, Tbeta-RII immunostaining localized to inflammatory cells within the fracture gap, periosteal cells, and surrounding soft tissues. By day 7, Tbeta-RII staining localized to osteoblasts of the fracture gap but was most intense within osteoblasts and mesenchymal cells of the osteotomized bone edges. On postoperative day 37, Tbeta-RII protein was seen in osteocytes, osteoblasts, and the newly formed periosteum in the remodeling bone. These observations agree with those of previous in vivo studies of endochondral bone formation, growth, and healing. In addition, these results implicate TGF-beta1 biological activity in the regulation of osteoblast migration, differentiation, and proliferation during mandibular fracture repair. Furthermore, comparison of these data with gene expression during mandibular distraction osteogenesis may provide useful insights into the treatment of poorly healing fractures because distraction osteogenesis has been shown to be effective in the management of these difficult clinical cases.

Distraction osteogenesis has proven to be an effective technique for the correction of mandibular deficiencies. However, problems have been encountered in achieving a final, idealized form of the mandible when using distraction devices capable of moving the bone segments in only one dimension (uniplanar). Specifically, occlusal irregularities and deficiencies in lower facial contour have been seen following uniplanar distraction. To address these problems, a distraction device capable of independent movements in three planes (multiplanar) was developed. Previously reported studies in a canine model have demonstrated that this device can successfully distract the mandible along both the sagittal axis (anteroposterior or z-axis) and the vertical axis (superoinferior or y-axis). This study examines the ability of the multiplanar device to distract along the sagittal and horizontal axes (mediolateral or x-axis). A total of 12 dogs were included in the study. All animals underwent unilateral or bilateral mandibular distraction using an external multiplanar device. After a latency period of 5 days, primary distraction along the anteroposterior axis at a rate of 1 mm/day for 10 days (10 mm total) was performed. During the following 10 days, along with an additional 11 mm to 20 mm of anteroposterior axis distraction, concomitant secondary distraction was performed along the horizontal (mediolateral) axis at a rate of 5 degrees/day (50 degrees total). Cephalometric radiographs were obtained preoperatively and at the conclusion of both anteroposterior and combined anteroposterior-mediolateral distraction. Computed tomography (CT) scans were obtained preoperatively and at the end of consolidation (28 days), after which all animals were sacrificed and the dry skulls examined. In all animals, distraction along the mediolateral or x-axis was found to change the anteroposterior projection of the mandible. Varus angulation of the device with respect to the midline of the mandible caused compression of the distracted segments and reduced the anteroposterior thrust of the mandible. In contrast, valgus positioning of the device, with respect to the midline of the mandible, created the opposite effect, increasing the distracted length in the anteroposterior direction. The bone (mandibular) segments being distracted assumed the orientation of the device only for valgus positioning of the device (producing a decrease in the bigonial distance). Conversely, there was no effect from the mediolateral angulation on the distracted segments during varus positioning of the device. A possible explanation for this finding may be a greater resistance to an increase in the bigonial distance (varus positioning of the device) posed by obstruction of lateral movement of the condyle. This stands in contrast to a decrease in the bigonial distance observed following valgus positioning of the device. These findings confirm the clinical impression that distraction along the anteroposterior or sagittal axis remains the critical or keystone therapeutic maneuver in distraction of the mandible. Mediolateral or horizontal axis distraction is best used only as a supplementary movement; in essence, it only affects the anteroposterior dimension with little impact on clinically relevant changes to the bigonial distance.

A number of studies have demonstrated the critical role of angiogenesis for successful wound repair in the surgical patient. Vascular disruption from tissue injury due to trauma or surgery leads to a hypoxic zone in the healing wound. In this dynamic process, angiogenesis is vital for the delivery of oxygen, nutrients, and growth factors necessary to initiate the synthetic processes of wound healing. Fibroblasts, invading the wound early in the healing process, are involved in extracellular matrix (ECM) deposition as well as wound contraction. However, the exact mechanisms by which important genes are regulated remain unknown. In order to examine these processes, we studied the effects of hypoxia on fibroblasts for the expression of VEGF, type IalphaI collagen, and matrix-metalloproteinase-3, three genes essential for the regulation of angiogenesis, ECM deposition, and ECM degradation in wound healing. Primary cell cultures of normal human dermal fibroblasts (NHDFs) were placed in hypoxia for varying periods of time. Northern blot hybridization was performed with [alpha32P]dCTP-labeled cDNA probes for VEGF, type IalphaI collagen, and MMP-3. The results demonstrated a time-dependent VEGF mRNA upregulation (470% of baseline) under hypoxia. Type IalphaI collagen increased (170% of baseline) at 24 h, but was then abruptly downregulated to 3.8% of baseline at 48 h. MMP-3 was incrementally downregulated to 2.2% of baseline at 48 h. These experiments focused on the effect of hypoxia on genes thought to play a role in wound repair. VEGF upregulation in the hypoxic microenvironment of the early wound may serve to stimulate angiogenesis. Type IalphaI collagen, though upregulated early on, was abruptly downregulated at 48 h. This downregulation may reflect the in vivo requirement for angiogenesis to deliver oxygen for successful hydroxylation and collagen synthesis in the wound. MMP-3, also downregulated at 48 h, may also implicate the need for angiogenesis. These data support the theory that hypoxia-driven angiogenesis is critical for ECM formation and remodeling in successful soft tissue repair. Furthermore, they may represent the role of hypoxia as an important regulator to efficiently balance these complex processes in the healing wound.

The etiology of keloid formation is diverse. They are characterized grossly as thick scar tissue that extends beyond the boundaries of the original wound. Histologically, keloids are composed of excessive collagen with an abnormally large number of partially or totally occluded microvessels. This occlusion of keloid microvessels has been hypothesized to contribute to a hypoxic microenvironment within these pathological scars. Vascular endothelial growth factor (VEGF), a potent endothelial cell mitogen, and proangiogenic cytokine have been implicated in normal and pathological wound healing. The purpose of this study was to evaluate the amount of VEGF protein production by fibroblast cell lines derived from keloids and normal human dermal skin in hypoxic compared with normoxic culture conditions. By enzyme-linked immunosorbent protein assay, VEGF was increased in both keloid and normal human dermal fibroblasts in hypoxia over normoxic controls. There was not, however, a significant difference between upregulation of VEGF protein when comparing the keloid and normal fibroblast groups. As the result of the data, alternative hypotheses for hypoxia-induced keloid formation were explored: (1) downstream modulation or signal transduction of VEGF, (2) VEGF production from cells other than fibroblasts, (3) the importance of matrix accumulation stimulated by hypoxia, or (4) increased migration of cells (other than fibroblasts) specific to keloid biology. These hypotheses may help explain the possible role of hypoxia in the pathogenesis of keloid formation. Future studies involving in situ hybridization or immunohistochemical analysis may offer greater insight into the mechanisms underlying keloid formation. Ultimately, our therapeutic goal is the utilization of biomolecular approaches for the suppression of keloid formation.

The requirements for reconstruction in patients with midface hypoplasia can be formidable: a bicoronal scalp incision, Le Fort III or monobloc skeletal advancement, harvesting and insertion of bone grafts, application of rigid (and occasionally intermaxillary) fixation, blood transfusions, and prolonged operative time and hospitalization. The introduction of the endoscope offers the possibility of minimally invasive surgery with improved visualization of the osteotomy sites. The development of distraction osteogenesis as a surgical technique allows controlled and gradual advancement of the osteotomized skeletal segment and associated soft tissue. The purpose of this study was to develop a canine model of an endoscopically assisted Le Fort III osteotomy with attendant midface distraction. Four mongrels (20 kg in weight) were study subjects. Three 2-cm skin incisions were made (two perpendicular to the zygomaticomaxillary suture and one perpendicular to the nasofrontal suture). The soft tissue and periosteum were evaluated bluntly. Retractors specially designed for the project created a space for endoscopic visualization. Bilateral zygomatic, nasofrontal, and medial orbital wall osteotomies, corticotomies, or both were performed under endoscopic visualization using a reciprocating saw; the medial orbital wall sectioning was specifically not completed (i.e., corticotomy) to avoid laceration of the mucosa and attendant bleeding. The pterygomaxillary osteotomy was completed with an osteotome and mallet. Finally, the nasal septum was only partially divided with an osteotome to avoid excessive blood loss. Four distraction devices were placed across the above-noted osteotomies (two across the nasofrontal osteotomy and one across each lateral osteotomy). The animals were distracted 1 mm per day for 16 to 40 days after surgery (16-40 mm of linear distraction). Cephalograms and computed tomography scans were obtained before and after distraction. The animals were killed after remaining in fixation for 4 to 6 weeks after distraction. All soft tissue was removed and the skull was examined. Photos were obtained throughout the experiment for documentation. The study demonstrated that Le Fort III osteotomies can be performed successfully via small incisions with endoscopic assistance in canine subjects with excellent visualization and minimal bleeding. The advancement of the midface segment can be achieved by activation of an external distraction device.

Since its description in the 1970s, the radial forearm free flap has earned a clearly defined role in the armamentarium of reconstructive head and neck surgery. Three decades later, the donor site remains an intrinsic drawback primarily due to its esthetic impact, although functional morbidity is significant in a minority. These points do not outweigh significant advantages but are occasionally reasons for the choice of alternative flaps. Modifications evolved in an effort to improve these undesirable features include primary closure, rotation-advancement, proximal paddle placement, full-thickness skin graft (FTSG) and suprafascial dissection. We describe a novel technique of engineering a composite graft of cadaveric acellular dermal matrix and autologous split-thickness skin graft (STSG) for a better donor-site closure.From December 1995 to August 2003, 23 patients underwent radial forearm reconstruction of head and neck defects. Control patients (Group I; n = 5) had donor sites closed by conventional STSG technique (0.014-0.016 inch). In 18 patients (Group II), the donor site was closed with a composite technique (dermal allograft, 0.020-0.030 inch, and an ultrathin STSG, 0.0080 inch). Both groups of patients were retrospectively studied for comparative defects. Contralateral upper extremities also served as controls. All patients underwent a standardized functional examination of the donor and contralateral extremities, as well as an outcome questionnaire. All extremities were photographed for visual comparison by the author.Three of the 5 group I patients were available for follow-up, which averaged 64 months (60-72 months). Thirty-three percent had a decrease in functional parameters and 67% complained of paresthesia. Patient satisfaction was 3.5/5. Six of the 18 patients were excluded from Group II due to insufficient follow-up or inability to follow. Follow-up averaged 8 months (1-24 months). Functional parameters in all patients were comparable to the contralateral extremity, except in 1 patient. In this case, a 0.030-inch allograft was used which never revascularized, inhibiting wrist motion. Other patients exhibited excellent range of motion of the wrist and fingers. This was the only patient in this group that exhibited paresthesia of the donor site. Patient satisfaction was 4.6/5. Esthetic results were extremely gratifying as judged by the author. Esthetic results were better than those observed in Group I.Composite grafting with acellular dermal matrix and STSG provides a comparable (trending to superior) result with traditional STSG for the treatment of radial forearm graft donor sites. Even if functionally equivalent, it is esthetically superior and therefore a technique warranting further investigation.

Minimally invasive techniques have become the standard of care for multiple procedures. This paper demonstrates both the surgeons' capacity to perform an accurate anatomic evaluation of the hand and forearm (n = 10) and the use of this anatomic information to accurately perform sonographically guided, percutaneous carpal tunnel release using a single-portal endoscope without direct or indirect visualization in a cadaver model (n = 6). Open dissection was then performed to confirm complete ligament transection and to evaluate the surrounding structures for injury. In all 6 cadavers, the transverse carpal ligament was transected completely without injury to any surrounding structures. With further investigation, this novel technique may offer a less invasive, office-based method for the surgical treatment of carpal tunnel syndrome that may offer patients an expedited recovery.

Objective: A porcine model of thoracic aortic graft infection was created, and various anatomic sites and the timing of inoculation of the graft to induce infection were investigated. Ultimately, the ability of cryopreserved allograft to resist infection was compared with that of collagen-impregnated Dacron graft. Methods: Yorkshire pigs (n = 16) underwent placement of an expanded polytetrafluoroethylene patch graft in the ascending aorta and the left atrial appendage (phase I). Eight animals were immediately given a 50-mL bolus (1 × 10 8 cfu/mL) of Staphylococcus aureus whereas the other 8 received the infusion 24 hours later. Animals were put to death 8 weeks later and the grafts were sterilely explanted and analyzed via microbiologic culture and standard histologic procedures for evidence of infection. The results displayed that the aortic graft and a delay of induced bacteremia of 24 hours were more reliable methods of producing infection. During phase II, 13 pigs were randomized to receive either a collagen-impregnated Dacron graft (n = 6) or a cryopreserved allograft (n = 7) in the ascending aortic position only and infusion of S aureus 24 hours after the operation. The experiment then proceeded to completion. Results: Phase I results displayed that use of an aortic graft and induced bacteremia 24 hours after the operation was a more reliable and reproducible method of producing infection. In phase II, graft infection was present in 38.5% (5/13) of animals, with only 16.7% (1/6) in the collagen-impregnated Dacron graft group and 57.2% (4/7) in the cryopreserved allograft group becoming infected. There was no significant difference between the collagen-impregnated Dacron graft and cryopreserved allograft groups in the incidences of thoracic aortic graft infections ( P = .27, Fisher exact test). Conclusions: This novel porcine model of thoracic aortic graft infection is a reproducible method for the investigation of thoracic aortic graft infections. The phase I study investigated the timing of the induced bacteremia and the most susceptible position of a graft. Phase II demonstrated that collagen-impregnated Dacron grafts are equivalent, if not superior, to cryopreserved allografts in resisting central vascular graft infections in the ascending aorta. (J Thorac Cardiovasc Surg 1999;118:857-65)

Recruitment of a blood supply is critical for successful bone induction and fracture healing. Despite the clinical success of distraction osteogenesis (DO), an analysis of angiogenesis during membranous bone DO has not been performed. The purpose of this study was to evaluate the temporal and spatial pattern of angiogenesis during mandibular DO. The right hemimandible of adult male rats was osteotomized, and a customized distraction device was applied. Following a 3-day latency period, distraction was begun at a rate of 0.25 mm twice daily for 6 days (3.0 mm total; 12% increase in mandibular length). Three animals each were sacrificed on days 2, 4, and 6 of distraction (D1, D2, and D3 respectively), or after 1, 2, or 4 weeks of consolidation (C1, C2, and C3 respectively). Two experienced pathologists reviewed the regenerate histology, and angiogenesis was assessed by counting the number of blood vessels per intermediate-power field (IPF). Statistical analysis was performed using analysis of variance, with p < or = 0.05 considered significant. Results demonstrate that mandibular DO was associated with an intense vascular response during the early stages of distraction (D1). On average, 31.5+/-7.9 vessels were noted in each IPF examined during this time point. The number of blood vessels in the distraction regenerate decreased significantly during the later distraction time points, with approximately 14.0+/-2.0 and 14.7+/-3.5 blood vessels per IPF in sections obtained after days 4 and 6 of distraction (D2, D3) respectively. However, blood vessels at these time points took on a more mature histological pattern. During the consolidation period, the number of blood vessels noted in the regenerate decreased with 8.0+/-2.6, 9.3+/-2.1, and 4.0+/-2.0 vessels per IPF in sections obtained after 1, 2, or 4 weeks of consolidation (C1, C2, C3) respectively (p < 0.05 compared with vessel counts during the earliest distraction time point). This study demonstrates for the first time that an intense vascular response associated with mandibular DO occurs primarily during the early stages of distraction. The authors hypothesize that as distraction continues, newly formed vessels likely undergo consolidation, thus forming more mature vessels capable of withstanding distraction forces. Future studies will assess the effects of therapeutic interventions designed to increase angiogenesis during DO on bony regenerate formation.

The application of distraction osteogenesis in craniofacial surgery has significantly altered the treatment of congenital mandibular deficiencies. However, evaluation of results in both animal studies and clinical cases has revealed deficiencies, particularly in two areas. First, distraction using a uniplanar device in an anteroposterior direction can result in a persistent anterior open bite. Second, the lateralization of the distracted hemimandible was often limited, with insufficient incremental gain in the bigonial distance. To overcome these shortcomings, a multiplanar distraction device was developed and tested in the canine model. This report details canine studies addressing the first problem: combined anteroposterior or sagittal (z-axis) and superoinferior or vertical (y-axis) movements. Six dogs underwent bilateral mandibular distraction with an external (extraoral), multiplanar device and completed sagittal plus vertical distraction. Evaluation included clinical examination (facial form, jaw position, and occlusion), photography, cephalograms (posteroanterior, basilar, and lateral), three-dimensional computed tomography reconstructions, and examination of dry skulls. The dogs averaged 18.5 mm (range, 15-20 mm) of sagittal distraction and 41.0 degrees (range, 21-50 degrees) of vertical distraction. Marked anterior open bites were produced after vertical distraction secondary to premature contact of the maxillary and mandibular molars. Distraction in the vertical direction also had the additive effect of increasing the sagittal gains by approximately 5% to 10%. In conclusion, a multiplanar distraction device (with the potential for distraction in three planes) was effective in increasing mandibular anteroposterior thrust (sagittal distraction) and also in creating an anterior open bite (vertical or superoinferior distraction). Vertical distraction probably requires bilateral osteotomies to obtain optimal results. The preliminary gains in sagittal length are modified (reduced or increased) after distraction in a second plane (vertical and horizontal). Specifically, vertical distraction in the inferior direction (creating an open bite) also leads to isolated increases in the anteroposterior plane. Conversely, vertical distraction in the superior direction (closing an open bite), as seen in a human malocclusion, may lead to isolated decreases in the anteroposterior plane, but this question remains to be investigated in the laboratory.

Distraction osteogenesis is a powerful technique capable of generating viable osseous tissue by the gradual separation of osteotomized bone edges. Although the histologic and ultrastructural changes associated with this process have been extensively delineated, the molecular events governing these changes remain essentially unknown. We have devised a rat model of mandibular distraction osteogenesis that facilitates molecular analysis of this process. Such information has significant clinical implications because it may enable targeted therapeutic manipulations designed to accelerate osseous regeneration. In this study, we have evaluated the expression of transforming growth factor beta-1, a major regulator of osteogenesis during endochondral bone formation and development, and osteocalcin, an abundant noncollagenous extracellular matrix protein implicated in the regulation of mineralization and bone turnover. The right hemimandible of 36 adult male rats was osteotomized, and a customized distraction device was applied. Animals were allowed to recover and, after a 3-day latency period, were distracted at a rate of 0.25 mm twice daily for 6 days followed by a 2- or 4-week consolidation period. Distraction regenerate was harvested after the latency period, days 2, 4, or 6 of distraction, and after 2 or 4 weeks of consolidation and processed for Northern analysis (n = 4 at each time point) and immunohistochemical localization of TGF-beta1 (n = 2 at each time point). Six sham-operated animals (i.e., skin incision without osteotomy) were also killed (immediately postoperatively), and the mandibles were harvested and prepared in a similar fashion. Equal loading and transfer of RNA for Northern analysis was ensured by stripping and probing membranes with a probe against GAPDH (a housekeeping gene). Our results demonstrate that the spatial and temporal patterns of TGF-beta1 mRNA expression and protein production coincide with osteoblast migration, differentiation, and extracellular matrix synthesis. In addition, we demonstrate that TGF-beta1 production may be an important regulator of vasculogenesis during mandibular distraction osteogenesis. Finally, we have shown that osteocalcin gene expression coincides temporally with mineralization during rat mandibular distraction osteogenesis.

The application of distraction osteogenesis to craniofacial surgery has altered the approach and treatment of congenital and acquired craniofacial defects. Although the histologic and ultrastructural changes associated with distraction osteogenesis have been described extensively, relatively little is known about the molecular regulation of this process. The elucidation of the molecular mechanisms of distraction osteogenesis has important clinical implications because it may facilitate the use of recombinant proteins or gene therapy to accelerate bone regeneration. Molecular analysis of distraction osteogenesis has bern n hindered by the use of large animal models in which only limited genetic information is available. In this study, a rat model of mandibular distraction osteogenesis is described. This report includes a pilot study (n = 50) to develop an appropriate distraction device and to determine the optimal placement of the osteotomy. The study subsequently included 80 animals, 35 of which were distracted at a rate of 0.25 mm per day for 6 days (1.5 mm total) and 35 that were distracted at a rate of 0.25 mm twice per day (3.0 mm total). These animals were killed at various time points (after latency and during the distraction and consolidation periods) and displayed histologic and radiographic findings of nembranous bone distraction osteogenesis that were consistent with those in large animal and clinical models, In addition, five animals each were acutely lengthened 1.5 mm and 3.0 mn and demonstrated a fibrous nonunion, Furthermore, the utility of this model is demonstrated in the analysis of the molecular mechanisms of distraction osteogenesis by applying the polymerase chain reaction to total cellular RNA isolated fron normal and distracted rat mandibles. In conclusion, it is believed that the rat model of distraction osteogenesis has significant advantages over traditional models, including decreased costs and facilitation of molecular analysis.