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Biomedical subjects

Gregory R D Evans

Publications and source records attributed to Gregory R D Evans.

At least 19 recordsLinked to original sources
PubMed2007

Microvascular surgery.

LEARNING OBJECTIVES: After reading this article, the participant should be able to: 1. Describe the common room set-up, medical considerations, and technical equipment necessary to perform microvascular surgery. 2. Describe the common arterial and venous techniques in performing microvascular surgery. 3. Recognize the common flap types along with their vascular supply and innervation used for microvascular surgery. 4. Describe common techniques for flap monitoring. 5. Describe techniques and medications for thrombolytic therapy. 6. Describe common medical conditions that may preclude an optimal result in microvascular surgery. SUMMARY: This article will explore common approaches to microsurgery. It is anticipated that the readers can utilize this article for maintenance of certification educational components and take the principles outlined and apply them to their daily practice.

Anastomosis, Surgical↗
PubMed2006

Free flap reconstruction for infection of ankle fracture hardware: case report and review of the literature.

BACKGROUND: Clinical management of orthopedic hardware infections related to ankle fracture fixation may present difficult therapeutic dilemmas. Typically, management includes removal of the hardware, debridement of necrotic tissue, and eventual placement of an alternative method of stabilization, usually, an external fixator or cast. However, problems arise when the fracture cannot be managed adequately with an external method. Such is the case with supination external rotation (SER) fractures, yet maintaining the hardware in the setting of infection typically is not considered an option. METHODS: Case report and review of pertinent English-language literature. RESULTS: The patient was a 47-year-old man with diabetes mellitus who sustained a type IV SER fracture that was treated with plate and screw fixation. Six weeks postoperatively, he presented with infection of the lateral ankle incision and the hardware. This was treated with debridement of the wound and dressing changes while leaving the hardware in place. It was decided to use a free muscle flap in an effort to preserve the ankle for a functional outcome versus the alternative of a below-knee amputation. With a free rectus abdominis flap, the lower extremity was preserved, and after four months, the patient was able to walk. One year postoperatively, the patient was ambulating without difficulty, and the hardware was still in place. CONCLUSIONS: This report examines the dilemma of SER ankle fractures and how management strategies must be tailored to the individual situation. In some cases, the hardware must be considered essential to avoid below-knee amputation.

Ankle Injuries↗
PubMed2006

Survival of diced cartilage grafts: an experimental study.

BACKGROUND: Use of diced cartilage grafts in rhinoplasty surgery has recently undergone a dramatic resurgence. Some authors recommend wrapping diced cartilage with oxidized methylcellulose (i.e., Surgicel). Others prefer wrapping diced cartilage with autogenous deep temporal fascia. This study was designed to compare the behavior of diced cartilage grafts as an isolated entity or when wrapped with either Surgicel or deep temporal fascia. METHODS: Septal cartilage and deep temporal fascia were obtained from five patients in this institutional review board-approved study. The cartilage was diced into 0.5-mm pieces and implanted into subcutaneous dorsal skin pockets of Rowlett nude rats as isolated diced cartilage grafts, or wrapped in Surgicel or deep temporal fascia. Pieces of Surgicel and fascia were implanted alone as controls. The specimens were harvested at 8 weeks; processed by thin-section histology; stained with hematoxylin and eosin, Masson's trichrome, glial fibrillary acidic protein, safranin-O, and Evans van Gieson; and evaluated to determine cartilage viability and architectural characteristics. RESULTS: Diced cartilage wrapped in Surgicel yielded the lowest percentage viability and minimal staining with hematoxylin and eosin, trichrome tissue, safranin-O, and Evans van Gieson stains. Diced cartilage grafts wrapped in fascia had the greatest percentage of viable cartilage. The grafts wrapped in deep temporal fascia also demonstrated the strongest staining with the aforementioned stains. Differences in uptake of glial fibrillary acidic protein were not noticeable between the three groups. However, absolute numbers of nucleated lacunae and basophilic lacunae were significantly higher for grafts wrapped in deep temporal fascia. CONCLUSIONS: Diced cartilage grafts have reemerged as a viable method for nasal reconstruction in both primary and secondary rhinoplasty. Wrapping diced cartilage specimens contains the individual pieces and facilitates graft placement. Surgicel wraps appear to incite an inflammatory response and subsequent absorption of the cartilage. Fascia wraps appear to minimize inflammatory responses to the cartilage, thereby preserving healthy cartilage. This study demonstrates that deep temporal fascia is the preferred envelope with which to facilitate graft containment and maintain chondrocyte viability of diced cartilage grafts.

Animals↗
PubMed2006

The evolution of the midface lift in aesthetic plastic surgery.

The midface lift has recently gained significant popularity with many surgeons. It allows the surgeon an opportunity to achieve greater facial harmony with facial rejuvenation procedures by correcting midfacial atrophy, addressing the tear trough deformity, and correcting the perceived malposition of the malar fat pad. This article examines the history of midfacial procedures. Surgical attempts at improving the aging face have evolved from minimal excisions and skin closure to aggressive dissections at multiple planes. The midface target area is peripheral to classic approaches, and its correction has required further anterior dissection from a distance or direct access centrally. Ultimately, conquering the stigmata of midface aging is entirely related to vectors and volume.

Aging↗
PubMed2006

Histological analysis of human diced cartilage grafts.

BACKGROUND: Grafting the radix and dorsum of the nose has been controversial and the plastic surgery community has recently revisited diced cartilage grafts. Previous articles by the authors reported clinical failures of diced cartilage-Surgicel-wrapped grafts and the successful implementation of diced cartilage-fascia-wrapped grafts for rhinoplasty procedures. This article investigates four means of radix and dorsum augmentation, including banked and fresh septum. METHODS: Twenty-seven human specimens were taken from rhinoplasty patients: six failed diced cartilage-Surgicel-wrapped grafts, eight diced cartilage-fascia-wrapped grafts, and 13 specimens of fresh cartilage or previously placed cartilage grafts. All were stained with hematoxylin and eosin, Masson's trichrome, safranin-O, glial fibrillary acidic protein, and Evans' van Gieson stains and analyzed for chondrocyte viability, matrix proteins, and regenerative potential of the cartilage. RESULTS: The diced cartilage-Surgicel-wrapped grafts showed disorganized fibrosis, loss of nuclei in chondrocyte lacunae, and negative glial fibrillary acidic protein staining. All specimens contained remnants of Surgicel and evidence of foreign body reaction. The diced cartilage-fascia-wrapped grafts showed normal histologic characteristics, healthy cartilage pieces with viable chondrocytes in their lacunae, positive glial fibrillary acidic protein staining, and organized capsule of fibrosis surrounding the cartilage pieces. The fascia was viable and showed an organized architecture distinctly different from the disorganized scar tissue of the diced cartilage-Surgicel-wrapped grafts. CONCLUSIONS: Given the histologic findings, diced cartilage-Surgicel-wrapped grafts absorbed due to foreign body reaction. Diced cartilage-fascia wrapped grafts survived and demonstrated normal cartilage viability. According to the clinical performance and analysis of these grafts, diced cartilage-fascia is the most reliable way to augment the nasal dorsum and radix with autologous diced cartilage.

Cartilage↗
PubMed2006

Current options in head and neck reconstruction.

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Understand current trends in the treatment of head and neck cancer. 2. Discuss the challenges of reconstructing head and neck defects 3. Understand the different reconstructive options available for specific anatomical regions of the head and neck. BACKGROUND: Reconstructive surgery of the head and neck is both technically challenging and rewarding. In the past 20 years, significant advances in this field have improved surgical outcomes and patient function. The development and subsequent refinement of microvascular techniques, in particular, have been a major reason for this progression. METHODS: In this article, the authors review the current options available in head and neck reconstruction. Because a large number of major craniocervicofacial defects result from oncologic resection, the authors have focused their review on this particular subject. By dividing their discussion into different anatomical sites, the authors hope to cover all major aspects of this broad topic. RESULTS: Free tissue transfer has revolutionized head and neck reconstruction. The most widely used free flaps include the fibula, radial forearm, anterolateral thigh, and rectus abdominis. Restoration of both form and function is the ultimate goal. CONCLUSIONS: Although defects of the head and neck region present a challenge, successful cosmetic and functional results have been achieved with both local and free tissue flaps. The flexibility of free tissue transfer, however, has dominated this area and continues to be the method of choice for reconstruction of sizable defects.

Forecasting↗
PubMed2006

A novel technique for the prophylactic plating of the osteocutaneous radial forearm flap donor site.

The osteocutaneous radial forearm free flap (ORFFF) provides a suitable composite construct for reconstruction of head and neck defects. Initial acceptance of the ORFFF during the 1980s waned significantly as long-term outcome studies demonstrated a high incidence of donor-site fractures associated with harvesting a segment of the cortical radius. Biomechanical and clinical studies have demonstrated a significant improvement in the mechanical strength of ostectomized long bones after prophylactic plating. Our case report identifies a novel technique for rigid fixation using a low-contact, locking-screw plating system (LCP, Synthes USA). The system provides a fixed-angle construct using a locking-screw system that provides appropriate axial load transfer using unicortical screw fixation.

Adult↗
PubMed2006

Institutional review of free TRAM flap breast reconstruction.

INTRODUCTION: A 10-year experience with breast reconstruction in a university hospital was recently reviewed. The purpose of this study was to determine the subtypes of breast reconstructive procedures and to evaluate the frequency and change in technique over time of free TRAM (transverse rectus abdominis muscle) flap breast reconstruction performed at one institution. Trends in the development of the procedure over this period were also reviewed. MATERIALS & METHODS: Between November 1994 and September 2004, a 10-year retrospective chart review was conducted. The indications for mastectomy and reconstruction were determined. The median age was 48 (range 31-66). The range of follow-up was 2 to 71 months, with a median of 19.5 months. The mean follow-up was 23.5 months. Outcome data were grouped into 2 consecutive 5-year periods (period 1: 1994-1998; period 2: 1999-2004) and evaluated for changes over time in techniques and outcome. Statistical analysis (Decision Analyst, Inc., STATS Statistics software, version 1.1, 1998) was performed using the difference between 2 proportions module to assess the probability of a significant difference in the data for period 1 and period 2 parameters. RESULTS: Over a 10-year period, 117 patients underwent breast reconstruction. This consisted of 12 pedicle procedures (11.3%), including 1 bipedicle flap (0.9%) and 2 bilateral pedicle procedures (1.8%). There were 3 latissimus dorsi pedicle flaps (2.8%). Sixteen patients (15.1%) received tissue expander or implant reconstructions. Of the 117 patients, 79 underwent free flap breast reconstruction. Of the 79 free-flap patients, 22 (27.8%) had bilateral procedures, for a total of 101 free flaps performed in these 79 patients. Fifty-two patients underwent immediate reconstruction (65.8%) and 25 were delayed (31.6%) reconstructions using either deep inferior epigastric artery perforator (DIEP) flaps (4 = 3.9%) or free TRAM flaps (97 = 96.0%). A muscle-sparing technique was used in 43 of the 97 free TRAM flaps (44.3%). The preferred vascular inflow was the internal mammary artery, which was used in 66 out of 101 flaps (65.3%). The rate of anastomotic revision (arterial and venous) was 4.9%. The majority of cases used a 2.5-mm venous coupler (65.3%). In 2 of the free TRAM cases, there was insufficient volume to establish the patients preexisting volume. Therefore, at the patient's request, immediate implants were used to augment the reconstruction. The average hospital stay was 8.13 days, and the average intensive care stay was 4.59 days. When assessed for trends over time, we noted a reduction in our hospital length of stay and our ICU length of stay. CONCLUSION: The experience with free tissue breast reconstruction reveals predominant use of the TRAM flap. This is justified by the reliability of this flap and the advances in achieving esthetic breast reconstruction. Additionally, we have begun performing DIEP free-flap reconstructions. Our clinical practice has evolved concurrent with standards of care, as noted by the increase in use of muscle-sparing techniques and the reduction in the use of dextran. We do not routinely use therapeutic anticoagulation in our cases. Our hospital length of stay and average intensive care length of stay have also decreased over time, consistent with a system-wide effort to increase the efficiency of healthcare delivery.

Adult↗
PubMed2006

Managing extracavitary prosthetic vascular graft infections: a pathway to success.

Prosthetic vascular graft infections portend grave consequences if not treated expediently. Despite the low incidence of infection, the potential for limb loss or death greatly magnifies this complication. The surgical management of prosthetic graft infections has evolved over the last 2 decades. With the myriad therapeutic options now available, an algorithm is necessary to provide the optimal surgical treatment of Samson groups 1 through 5 extracavitary infected vascular prostheses. An extensive review of the literature was undertaken to evaluate the most effective management schemes. The authors found that 3 factors--Samson classification, bacteriology, and patient vascular anatomy--are vital to the surgical strategy. These 3 criteria were examined, and an algorithm was developed based on successful clinical and experimental results. This review provides a step-by-step rationale for the surgical management of extracavitary prosthetic graft infections according to the most successful reported outcomes.

Algorithms↗
PubMed2006

Transfer of training in robotic-assisted microvascular surgery.

BACKGROUND: Transfer of training refers to the ability to transfer acquired skills from one discipline to another. This study aims to determine whether experience in traditional freehand microsurgery facilitates mastery of robotic microsurgery. METHODS: Microsurgical anastomoses of coronary arteries harvested from explanted pig models were used to demonstrate whether prior experience with microsurgery is required in learning robot-assisted microsuturing. Eighty microsurgical anastomoses were performed. Three fully trained vascular surgeons (n = 3) (Group A) and 5 midlevel surgical residents (n = 5) (Group B) performed the anastomoses. Each subject performed 5 freehand and 5 robotic-assisted (Zeus robotic system) anastomoses. Anastomosis time and integrity of anastomoses were recorded, including errors of management (EOM) (breaking suture, breaking knots, breaking or damaging needles). RESULTS: For fully trained surgeons, all anastomoses in the robotic-assisted group were mechanically intact. There was significantly increased anastomosis time with the robot (Robot: 14 minutes, versus freehand: 7.2 minutes, P < 0.01). The robotic-assisted anastomoses were associated with a higher EOM (Robot: 1.2, versus freehand: 0.3, P < 0.01). Surgical trainees had longer anastomosis times with robotic assistance (Robot: 14.8 minutes, versus freehand, 12.7 minutes; P < 0.01) and increased EOM (Robot: 1.6, versus freehand: 1.0; P < 0.05).Overall, surgical trainees and fully trained vascular surgeons had longer anastomotic times with robotic assistance [Robot: 14.0 versus 14.8 minutes; P = not significant (NS)], and EOM (Robot: 1.6, versus freehand: 1.2; P = NS) were not significantly different. CONCLUSION: The technical feasibility of performing a safe and efficient robotic-assisted microsurgical anastomosis in explanted vessels was repeatedly tested and demonstrated in this study within reasonable time required for the anastomosis. Compared with conventional microanastomosis, both fully trained surgeons and residents demonstrated an ability to master the robotically assisted procedure with similarly longer anastomosis times and EOM. This study indicates that robotically assisted microanastomosis can be mastered equally well by surgical trainees and fully trained vascular surgeons.

Anastomosis, Surgical↗
PubMed2006

The effects of restricted work hours on clinical training.

Resident education has changed dramatically over the past 10 years. With the implementation of restricted work hours on clinical training, questions have arisen whether these restricted hours will affect clinical competency. This manuscript attempts to answer this question through a survey performed to assess the perception of residents about duty-hour restrictions and the potential effect on residents' clinical exposure. In this study, a majority of the respondents did believe that work-week restrictions significantly affected patient care and clinical exposure. However, few respondents were willing to accept an additional year of training to compensate for the loss of this clinical exposure. Regardless, work-hour restrictions are here to stay and will probably be further limited in the future. Training programs will have to adjust to provide the necessary clinical exposure while complying with these new ACGME guidelines.

Humans↗
PubMed2005

Effects of irradiation on nerve graft vasculature.

Increasing doses of therapeutic irradiation are known to impair nerve regeneration after grafting. One possible factor is the effect of irradiation on the endoneurial vasculature. This study investigates the effects of postoperative irradiation on the size, number, and cross-sectional area of endoneurial vessels in the rat posterior tibial nerve graft model. Sixty-five Sprague-Dawley rats underwent 1.5-cm interposition grafts to the tibial nerve. Postoperatively, they were assigned to one of five groups. The animals in Group 1 were unirradiated controls. Groups 2 to 5 received postoperative irradiation in the amounts of 46, 66, 86, and 106 Gy, respectively. One hundred and twenty days after grafting, sections of the proximal, grafted, and distal nerve were harvested and analyzed with digital morphometry. Statistical analysis of the average vessel area, number of vessels, and total vascular area was performed. The grafted segments of Groups 4 and 5 and the distal segments of all irradiated groups showed a statistically significant decrease in the number of vessels, compared to controls. The average size of the vessel was smaller in the proximal segment of the irradiated groups, compared to controls. There was no difference in size in either the grafted or distal segments of the irradiated groups, compared to controls. The observed changes in the endoneurial vasculature resulted from both the action of regeneration and the effects of irradiation. The irradiation effects appear to be dose-dependent.

Animals↗
PubMed2005

Nerve growth factor expression response to induction agent booster dosing in transfected human embryonic kidney cells.

To assess whether nerve growth factor (NGF) expression would respond to booster dosing with the inducing agent ponasterone A, human embryonic kidney cells (HEK-293) were transfected with human NGF cDNA. Cells were cultured for 5 days in media with or without ponasterone A. On day 5, controls received a ponasterone A media replacement, whereas experimental groups received ponasterone A booster media replacement. NGF protein expression bioactivity was assessed using a PC-12 cell bioassay and the concentration of secreted NGF was quantified using NGF enzyme-linked immunosorbent assay. Cells with and without ponasterone A were left for 5 days without changing the medium. On day 5, the supernatants were collected and flash-frozen for enzyme-linked immunosorbent assay. The ponasterone A-positive and -negative booster medium was replaced in the appropriate wells. Supernatants were collected from the wells at 2, 4, and 6 days after the booster dose and removal of original supernatant. The medium was flash-frozen for enzyme-linked immunosorbent assay (1.5 ml), and the remaining 500 mul was transferred to PC-12 cells seeded onto 12-well plates to determine NGF bioactivity. All experiments were performed in quadruplicate. NGF production was measured daily by enzyme-linked immunosorbent assay over a 6-day period after the ponasterone A booster to a maximal release of 1233 +/- 130 pg/ml at day 6 (11 days after original induction). Maximal NGF production per 10(3) cells was 2.5 +/- 0.61 pg at day 6. Bioactivity was determined by percentage differentiation (per 100 cells counted) at 26, 52, and 98 percent for ponasterone A-treated wells on 2, 4, and 6 days after booster dosing (7, 9, and 11 days after induction), respectively. PC-12 cell differentiation was not visualized in the ponasterone A-negative control wells. Human NGF-EcR-293 cells can inducibly secrete bioactive NGF when exposed to the induction agent ponasterone A. Furthermore, repeated bioactive NGF expression peaks beyond that previously demonstrated can be achieved using induction agent booster dosing, indicating the ability to regulate the system over an extended period.

Cell Differentiation↗
PubMed2005

Some dusty old books.

Explore the source record for details and available documents.

Academic Medical Centers↗
PubMed2005

Osteoblastic phenotype expression of MC3T3-E1 cells cultured on polymer surfaces.

BACKGROUND: Current efforts in bone tissue engineering have as one focus the search for a scaffold material that will support osteoblast proliferation, matrix mineralization, and, ultimately, bone formation. The goal is to develop a bone substitute that is functionally equivalent to autograft bone. Previously published reports have shown that osteoblasts exhibit varying rates and degrees of proliferation and mineralization when grown on different surfaces. METHODS: This study presents a histologic and biomolecular analysis of MC3T3-E1 murine preosteoblast cells grown on poly(lactide-co-glycolide) (PLGA) versus poly(-caprolactone) (PCL), two commonly studied scaffold polymers. MC3T3-E1 cells were cultured on slides coated with either PLGA or PCL, and on uncoated glass slides as control, with six slides in each group. After 6 weeks in culture, the cells were stained for osteocalcin, alkaline phosphatase activity, and matrix mineralization. In addition, to assess the effects of the surface material on phenotypic expression at the molecular level, MC3T3-E1 cells were cultured on polymer-coated 24-well plates for 4 days, and analyzed by reverse transcription polymerase chain reaction for the expression of osteocalcin and alkaline phosphatase. RESULTS: The results showed that three groups of slides stained positively for osteocalcin at 6 weeks. However, markedly less alkaline phosphatase activity and mineralization were observed on the cells grown on PCL. Real-time polymerase chain reaction assays subsequently revealed decreased expression of both markers by cells cultured on PCL compared with PLGA. CONCLUSIONS: These results suggest that PCL does not support the full expression of an osteoblastic phenotype by MC3T3-E1 cells. PCL, therefore, is less desirable as a scaffold polymer in bone tissue engineering in so far as supporting bone formation is concerned. However, because PCL has favorable handling characteristics and strength, modifications of PCL may prompt further investigation.

3T3 Cells↗