Hubert Weinberg

Functional evaluation following microvascular oromandibular reconstruction of the oral cancer patient: A comparative study of reconstructed and nonreconstructed patients

Over the past decade, the use of free flap transfers in head and neck surgery has led to remarkable advances in the reliability and the ultimate results of oromandibular reconstruction. Stable and retentive dental restorations have been achieved using enosseous implants placed directly into the vascularized bone flaps. However, the functional assessment of patients who underwent primary mandibular reconstruction with these techniques has not been previously reported. A group of 10 reconstructed and 10 nonreconstructed segmental hemimandibulectomy patients were compared using a battery of tests to assess their overall well‐being, cosmesis, deglutition, oral competence, speech, length of hospitalization, and dental rehabilitation. In addition, objective measures of the masticatory apparatus (interincisal opening, bite force, chewing performance, and chewing stroke) were used to compare these two groups as well as normal healthy subjects and edentulous patients restored with conventional and implant‐borne dentures. The results show a clear advantage for the reconstructed patients in almost all categories. Persistent problems and future directions in oromandibular reconstruction are discussed.

The neurofasciocutaneous radial forearm flap in head and neck reconstruction: A preliminary report

The radial forearm free flap has achieved considerable popularity as a reconstructive technique due to its thin, pliable tissue and long vascular pedicle. The successful use of this flap as a carrier of a vascularized nerve to bridge motor nerve gaps and as a sensate flap has not been previously reported in head and neck reconstruction. The superficial branch of the radial nerve was used as a vascularized nerve graft to bridge a facial nerve defect following radical parotidectomy. The medial and lateral antebrachial cutaneous nerves were used to re‐establish sensation in a reconstructed pharyngeal mucosal defect. The published clinical and experimental studies on vascularized nerves and sen‐sate flaps are reviewed in detail.

Primary Placement of Osseointegrated Implants in Microvascular Mandibular Reconstruction

The goal of mandibular reconstruction is to rehabilitate the patient by restoring occlusal relationships, lower facial contour, oral continence, and a denture-bearing surface. One of the major advantages of the use of vascularized bone over all other methods of mandibular reconstruction is its ability to achieve dental rehabilitation rapidly. The use of osseointegrated dental implants is a valuable adjunct in oral rehabilitation. It provides the most rigid form of stabilization to withstand the forces of mastication. In situations In which soft tissue reconstruction or the height of the alveolar ridge is not sufficient for a tissue-borne denture, implants offer the most suitable alternative. Mandibular reconstruction with free tissue transfer techniques is Ideally suited for the placement of implants. These can be inserted at the time of mandibular reconstruction. Four months after surgery, when the integration process has occurred, the implants are unroofed, loaded, and ready for prosthetic placement. We will present several representative patients who underwent mandibular reconstruction with microvascular free bone transfer who have been successfully rehabilitated by osseointegrated implants. The process of osseointegration, different types of dental implants, and issues regarding radiation and Implants are discussed. This is the first report of dental rehabilitation by primary placement of dental implants in patients undergoing microvascular mandibular reconstruction.

The combined sensate radial forearm and iliac crest free flaps for reconstruction of significant glossectomy‐mandibulectomy defects

The loss of motor and sensory function of the tongue following ablative surgery has a devastating effect on oral function. At the present time, there is no way to restore lost tongue musculature following partial glossectomy. The use of sensate cutaneous flaps has been shown to restore sensory feedback to reconstructed areas of the oral cavity. No single composite flap supplies a sensate soft‐tissue component together with an osseous component of sufficient bone stock for functional mastication. In this article, the combination of the radial forearm free flap with the iliac crest osteocutaneous or osteomyocutaneous free flap is reported. The radial forearm free flap was used to resurface the resected portion of the tongue to provide maximum mobility and sensation. The lingual nerve was the recipient nerve for anastomosis to the antebrachial cutaneous nerves in all but one case. The iliac bone was used to reconstruct the mandible, with the iliac skin paddle or the internal oblique muscle used to reconstruct the neoridge. This combination of flaps was used in 10 patients. There was one flap failure due to vascular kinking from“piggybacking” the iliac crest to the distal end of the radial forearm flap. As a result, the use of two separate sets of recipient vessels is now advocated.

Locally Administered Vascular Endothelial Growth Factor cDNA Increases Survival of Ischemic Experimental Skin Flaps

&NA; Microvascular surgery has emerged as an attractive area for recent advances in the field of gene therapy. The present study investigated the survival of ischemic, experimental skin flaps after treatment with the gene encoding vascular endothelial growth factor (VEGF). In 30 Sprague‐Dawley rats, anterior abdominal skin flaps supplied by the epigastric artery and vein were created. Ten animals were treated with a mixture of liposomes and the cDNA encoding the 121‐amino acid isoform of VEGF. Another 10 animals were treated with control plasmid DNA and liposome transfection medium; a third group of 10 animals was given physiologic saline. Each solution was injected directly into the femoral artery distal to the origin of the epigastric pedicle supplying the flap. Four days after injection, the pedicle was ligated and blood flow in the flap was approximated using dye fluorescence. Seven days later, the amount of viable tissue within the flap was measured by planimetry. After the animals were killed, specimens from both the operated and nonoperated sides of the abdomen were harvested for immunohistologic evidence of VEGF protein expression. Average dye fluorescence indices of the three groups (VEGF cDNA, control plasmid, and saline) 2 hours after pedicle ligation were 35.9, 23.9, and 53.9 percent, respectively (p < 0.05). Compared with the two control groups, flaps receiving VEGF cDNA had significantly greater tissue viability at the end of 7 days: 93.9 versus 28.1 percent for the control plasmid DNA group and 31.9 percent for the saline group (p < 0.05). Immunohistochemical staining documented increased deposition of VEGF protein in flaps that were infused with the VEGF cDNA versus saline alone (p < 0.05). The results indicated that the survival of ischemic tissues can be enhanced by administration of a cDNA encoding VEGF, a protein known to be important in the process of angiogenesis and wound healing. (Plast. Reconstr. Surg. 102: 2033, 1998.)

Experimental studies in the survival of venous island flaps without arterial inflow

The authors have studied the effects of various circulatory settings on flap survival. The dog model was used to study the survival of venous flaps without arterial inflow both as island and free flaps. Venous flaps were compared with arterial flaps without venous outflow and standard island flaps with arterial inflow and venous outflow. Attempts were made to study their vascular morphology and blood gas changes. The venous flaps without arterial inflow survived with normal hair growth and wound healing, as did the standard island flaps. These observations suggest that capillary diffusion can occur without the continuous flow of blood through a capillary. Several possible mechanisms to explain survival of the venous flaps without arterial inflow were discussed. These observations could be important in providing an animal model to study microcirculation and a possible new area for microsurgical transfer of a skin flap.

The internal oblique-iliac crest free flap in composite defects of the oral cavity involving bone, skin, and mucosa

The reconstruction of oromandibular defects following ablative surgery is a challenging undertaking. When the defect involves skin as well as mucosa, the challenge becomes even greater. The internal oblique iliac crest osteomyocutaneous free flap is particularly useful for reconstruction of through-and-through composite defects due to the inclusion of two separate soft-tissue flaps on the same vascular pedicle. We report our experience with this flap in the reconstruction of 10 patients with such defects. The utility, and the limitations of this form of reconstruction are discussed in detail.

Plastic surgical perspectives on vascular endothelial growth factor as gene therapy for angiogenesis.

The practice of plastic surgery has always remained at the frontier of medical science. Over the past few decades, this frontier has been marked by significant developments in the field of gene therapy. Gene therapy serves to replace, supplement, or manipulate a patients genetic makeup to restore function that has been lost or to correct function that is aberrant. Recent technology may allow surgeons to augment the processes of wound healing and angiogenesis by transfecting genes encoding desirable proteins, such as vascular endothelial factor (VEGF), into ischemic tissues. VEGF is a vital growth factor in the development of blood vessels. Although its mechanisms of action are numerous, its sole function seems to be the augmentation of angiogenesis. VEGF is active in growth and development, in wound healing, and in various pathologic conditions, such as psoriasis and rheumatoid arthritis. The role of VEGF in the field of plastic surgery is just beginning to be explored; it may someday prove to be very rewarding.

Continuous tissue oxygen tension measurement as a monitor of free-flap viability

&NA; Early recognition of vascular compromise within microvascular free‐tissue transfers is essential if reexploration is to prove successful. Tissue oxygen tension is increasingly recognized to be a sensitive and reliable index of tissue perfusion, and preliminary studies suggest that it may be of value in the assessment of free‐flap viability. We describe our investigation into the application of an implantable microcatheter oxygen sensor in the monitoring of free flaps used in head and neck and extremity reconstruction. In a preliminary study using the rabbit model, we sought to evaluate the response of oxygen tension as an index of tissue perfusion in myocutaneous (n = 20) and osteomyocutaneous flaps (n = 5) under conditions of arterial and venous occlusion. A clinical study was then undertaken to evaluate the role of this method in the monitoring of surface and buried free flaps. In 30 heterogeneous free‐tissue transfers, sensors placed intraoperatively were used to provide continuous information about flap oxygen tension (mean monitoring period 3.2 ± 0.8 days). The data generated were correlated with changes in clinical parameters and routine flap observations. Results for experimental and clinical data have confirmed the efficacy of continuous tissue oxygen measurements using this device as a method that provides an objective, recordable index of free‐tissue transfer viability in a variety of circumstances and vascular events. Tissue oxygen tension is a suitable index by which to evaluate flap viability with the probe placed in muscle or bone but is unreliable when used for the monitoring of revascularized cutaneous flaps. (Plast. Reconstr. Surg. 99: 763, 1997.)

Beneficial Effects of Ibuprofen on Experimental Microvascular Free Flaps: Pharmacologic Alteration of the No-Reflow Phenomenon

Pharmacologic alteration of the no-reflow phenomenon was determined based on increased tolerance to ischemia in ibuprofen-treated free flaps. Sprague-Dawley rats (N = 60) were divided into control (lactated Ringers) and treated (ibuprofen) groups and subdivided into six groups of ischemia: 1 hour, 6 hours, 8 hours, 10 hours, 12 hours, and 14 hours of ischemia. Fluorescein uptake was measured after 10, 30, and 60 minutes following microrevascularization. Dye elimination studies were done for each ischemia group that demonstrated good fluorescein uptake. All free flaps in the 1-, 6-, and 8-hour groups survived. The ibuprofen-treated 10- and 12-hour flaps all survived, whereas the 10-hour control and 14-hour ibuprofen-treated free flaps failed to survive. Despite high fluorescein uptake, the 14-hour ibuprofen-treated flaps did not eliminate the fluorescein, whereas all surviving free flaps adequately eliminated the fluorescein. Failure to eliminate dye despite adequate uptake suggested a deranged microcirculation with increasing ischemia time. By inhibiting cyclo-oxygenase, nonsteroidal anti-inflammatory agents such as ibuprofen may block the untoward effects mediated by thromboxane A2, such as vasoconstriction, microvasculature thrombus formation, and intravascular sludging. These effects are theorized in part to be responsible for the failure of a free flap to survive despite revascularization.