Kevin O'Grady

Use of octyl-2-cyanoacrylate for skin closure in facial plastic surgery

Octyl-2-cyanoacrylate is a long carbon chain cyanoacrylate derivative that is stronger and more pliable than its shorter chain derivatives. One hundred and eleven patients underwent elective surgical procedures by the same surgeon using either octyl-2-cyanoacrylate or sutures for skin closure at the University of Illinois at Chicago. Most patients underwent excision of benign skin lesions with a mean wound size of 112 mm3. Patients were randomized into either control (vertical mattress suture closure) or test groups (closure with octyl-2-cyanoacrylate). Surgical judgment was used to determine which wounds in each group required application of subcutaneous sutures to relieve tension and aid in skin edge eversion. Generally, full-thickness (through dermis) wounds larger than 1 cm3 required the use of subcutaneous sutures. The time required to close the epidermis with suture (mean, 3 minutes and 47 seconds) was about four times that of octyl-2-cyanoacrylate (mean, 55 seconds). Wounds were evaluated at 5 to 7 days for infection, wound dehiscence, or tissue reaction, and at 90 days using the modified Hollander wound evaluation scale. At 1 year, photographs of the wounds were evaluated by two facial plastic surgeons that graded the cosmetic outcome using a previously validated visual analog scale. There were no instances of wound dehiscence, hematoma, or infection in either group. Results of wound evaluation at 90 days determined by the modified Hollander scal revealed equivalent cosmetic results in both groups. Results of the visual analog scale ratings showed scores of 21.7 +/- 16.3 for the 49 patients treated with octyl-2-cyanoacrylate and 29.2 +/- 17.7 for the 51 control patients treated with sutures. The lower visual analog scale score represented a superior cosmetic outcome at 1 year with the octyl-2-cyanoacrylate as compared with sutures. This difference is statistically significant at p = 0.03. Additionally, patient satisfaction was very high in the group treated with octyl-2-cyanoacrylate.

Mandibular reconstruction using bone morphogenetic protein 2: long-term follow-up in a canine model.

Objective: To determine the degree of bone resorption and stability of 3‐cm, full‐thickness canine mandibular defects reconstructed with recombinant human bone morphogenetic protein 2 (rhBMP‐2) and a bioerodible particle carrier followed for 30 months after reconstruction.

The effect of recombinant human bone morphogenetic protein-2 on the integration of porous hydroxyapatite implants with bone.

To determine if recombinant human bone morphogenetic protein-2 (rhBMP-2) can be adsorbed onto porous ceramic hydroxyapatite (HA) and promote the integration of HA to host bone, 54 subperiosteal pockets were created on the skulls of 19 adult Pasteurella-free white rabbits. Fourteen HA implants were saturated with saline and placed in subperiosteal pockets (control), 22 HA implants were saturated with saline and placed into subperiosteal pockets after burring 1-2 mm of calvarium to expose bleeding cancellous bone, and 18 HA implants were saturated with rhBMP-2 and placed into subperiosteal pockets. The animals were sacrificed at 1 month with examination to determine implant mobility. Histology was used to determine the amount of bone growth into the implant. Of the 14 control sites, 10 implants were found to be freely mobile, five demonstrated host bone resorption, and only one exhibited bone growth into the implant. Of the 22 burred sites, eight were freely mobile and 10 demonstrated bone growth into the implant (p = 0.04). Of the 18 rhBMP-2 sites, only two were freely mobile, none demonstrated host bone resorption, and 16 exhibited bone growth into the implant (p = 0.00002). This study supports the use of porous ceramic HA as a biocompatible, osteoconductive implant material for use in craniomaxillofacial augmentation and reconstruction. It also provides evidence that rhBMP-2 enhances osseointegration, thereby fixing the implant in position against the host-bone interface. In the clinical setting, osseous fixation of the implant should aid in preventing displacement, minimizing host bone resorption, and decreasing the incidence of extrusion.

An evaluation of fibrin tissue adhesive concentration and application thickness on skin graft survival

Objectives To e‐amine the effects of fibrinogen concentration and application thickness of fibrin tissue adhesive on skin graft survival.

Peripheral nerve regeneration: Comparison of laminin and acidic fibroblast growth factor

PURPOSE In an effort to show the differences between neurotrophic factors, laminin and acidic fibroblast growth factor (aFGF) were compared in terms of their abilities to regenerate axons in vivo over an extended distance. MATERIALS AND METHODS The sciatic nerve was transected in 15 Sprague-Dawley rats. A 15-mm Silastic tube (Dow Corning, Midland, MI) was placed between the ends of the cut nerve and filled with either laminin, aFGF, or buffer applied to collagen sponges. RESULTS Ten weeks postimplantation, mean axon counts showed that both laminin (2432) and aFGF (1612) produced significantly higher numbers of axons than controls (1009) (P < .05) and that laminin showed significantly more nerve regeneration than aFGF (P < .05). CONCLUSION These results indicate that laminin and aFGF enhance peripheral nerve regeneration across a large gap, presumably through their neurotrophic effects and mitogenic properties on supporting cells. Furthermore, it is concluded that the transient nature of aFGFs effect on the regenerative environment limits its effectiveness at regenerating axons over a prolonged period of time.

Biomechanical Strength of Human Nasal Septal Lining: Comparison of the Constituent Layers

Objective/Hypothesis: Nasal septal perforation is a common complication following surgery involving the nasal septum. Septoplasty, septorhinoplasty, and submucosal resection may result in the inadvertent resection of perichondrium, which may predispose the patient to septal perforations.

Modulation of mechanical properties in multiple-component tissue adhesives

In vitro, ex vivo, and in vivo studies were performed to investigate the effect of mixing upon the mechanical properties of a two-component tissue adhesive. The hypothesis investigated was that a more complete mixing of the two components would yield an increase in the mechanical performance of the adhesive. This in turn would be demonstrated by improved outcomes in models of clinical sealant application. In vitro stereological analysis of tissue adhesive mixed and delivered by several different applicators demonstrated variation in the amount of mixing provided by each type of delivery system. Ex vivo tensile adhesive strength showed that there was a correlation between the amount of mixing and bonding strength; that is, more thorough mixing demonstrated higher adhesive strength. No significant difference was seen, however, between the different applicator types and impact on in vivo dermal incisional closure strength. There was a correlation, though, in amount of mixing and in vivo hemostasis. In a rabbit spleen incision model, a more thoroughly mixed sealant corresponded with a decrease in time to obtain complete hemostasis, as well as less sealant used. The effects of mixing on tissue-adhesive mechanical performance were influenced somewhat by the amount of mixing provided by the applicator. This effect, however, was dependent upon the sealant formulation and the type of in vivo application.

A Histologic Analysis of Three-Dimensional Versus Two-Dimensional Tissue Expansion in the Porcine Model†

Objective Recently, a two‐dimensional Silastic Dacron stretching skin device has been developed for scalp reduction surgery. Attached subgaleally, this device stretches skin over time, while avoiding the visible volumetric distention that is typical of three‐dimensional tissue expanders. Unlike three‐dimensional expanders, the histological changes observed with a two‐dimensional stretching device have not been described in the literature. The present study compares the histological effects of two‐dimensional and three‐dimensional skin tissue expansion in the porcine model.

Combined use of fibrin tissue adhesive and acellular dermis in dural repair.

Background The management of cerebrospinal fluid (CSF) leaks can be challenging. Acellular dermal grafts derived from human cadavers can be used as a replacement material when autogenous materials are unavailable. Fibrin tissue adhesive (FTA) is a wound support product that has been used for hemostatic and tissue fixation purposes. The combined use of acellular dermis in conjunction with FTA for dural repair remains a subject of study. The aim of this study was to evaluate wound healing and tissue compatibility characteristics of acellular dermal substitute material when used both with and without FTA, for repair of a dural tear in a chinchilla model. Methods Forty-nine chinchillas were included in this randomized case-control study. The squamous portion of the temporal bone was removed to expose the tegmen. A 2 X 2 mm dural defect was removed to create an iatrogenic CSF leak. Then, animals were randomly assigned to one of three treatment groups: group 1, acellular dermis alone; group 2, acellular dermis with FTA; group 3, fibrinogen, acellular dermis, and FTA. Surgical sites were examined grossly at 1- and 2-week intervals. Temporal bones were examined histologically. Results Grossly, groups 2 and 3 had significantly less visible CSF leak and brain herniation noted at both 1- and 2-week intervals when compared with group 1. Histological results confirmed the gross results showing the best seal in group 2 and 3. Conclusion Acellular dermis combined with FTA provided superior support compared with acellular dermis alone in repair of induced dural defects.

Expression of in vivo mechanical strain upon different wave forms of exogenous forces in rabbit craniofacial sutures.

AbstractSutures are fibrous joints between craniofacial bones, providing an interesting model for studying the biomechanics of the interface between soft and mineralized tissues. To explore whether different wave forms of exogenous forces induce corresponding sutural strain wave forms, sutural strain of the premaxillomaxillary suture (PMS) and nasofrontal suture (NFS) of New Zealand White rabbits (N=8) was recorded upon application of static, sine- and square-wave forces against the maxilla from 1 N to 5 N in 1 N increments. The PMS demonstrated compressive strain, whereas the NFS tensile strain. Despite a tenfold difference in peak PMS strain (-1451 ± 512 μ ∈ ) and NFS strain (141 ± 39 μ ∈ ) in response to 5 N cyclic forces, wave forms of exogenous forces were expressed as corresponding wave forms of sutural strain in both the PMS and NFS. Peak sutural strain was similar upon static and sine-wave cyclic loading. Thus, cells and matrix components of fibrous sutural tissue experience different wave forms of exogenous forces as corresponding wave forms of tissue-borne mechanical strain. Current craniofacial orthopedic therapies exclusively utilize static forces to change the shape of craniofacial bones via mechanically induced bone apposition and resorption. The present data provide room for exploring whether cyclic forces capable of inducing different sutural strain wave forms may accelerate sutural anabolic or catabolic responses.