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Biomedical subjects

W W Shaw

Publications and source records attributed to W W Shaw.

At least 73 records · Page 4Linked to original sources
PubMed1991

Laser-assisted venous anastomosis: a comparison study.

A low-powered carbon dioxide laser was used to perform 25 vein grafts (50 anastomoses) on the femoral veins of Sprague-Dawley rats. The patency rate, clamp time, and bleeding time were compared with 50 conventional microvascular vein grafts (100 anastomoses). The patency of the laser-assisted anastomoses (LAVA) was 84 percent, while the conventional vein grafts yielded a 94 percent patency rate. The average clamp time and bleeding time for the LAVA were 47.2 min and 4.88 sec, respectively, while the conventional anastomoses required 57.6 min and had an average bleeding time of 9.44 sec. Histologically, both specimens healed at the same rate, but the laser-assisted anastomoses produced less inflammation and granulation tissue. These results suggest that the laser has potential as a tool for clinical application in microsurgery. In addition, the 94 percent patency rate achieved with the vein interposition graft would suggest that a decrease in the tension across the anastomosis can improve patency.

Anastomosis, Surgical↗
PubMed1991

The fasciovascular pedicle for revascularization of other tissues.

A fasciovascular pedicle based on the epigastric vessels was developed in a rat model to determine if it could be used as a "universal carrier" to revascularize a new composite flap. The effects of time course, carrier size, and flap ischemia on the revascularization process were studied. A 2.5 x 4-cm or 1 x 4-cm fascial patch pedicled on the vessels was transferred under bipedicled 2.5 x 4-, 6-, or 8-cm abdominal panniculocutaneous flaps. At different time intervals, the flap was raised as an island flap connected only by it vascular bundle and then sutured back in place. The skin perfusion by dermofluorometry and flap survival were both markedly increased on day 5 (p less than 0.001). The wide carrier had a 93% survival area, whereas the narrow carrier had only 71%. The wide carrier induced relatively faster and better revascularization (p less than 0.05). Moderate ischemia promoted revascularization (p less than 0.01). An india ink injection study and histological examination provided visual evidence of revascularization. This fasciovascular pedicle is a promising model for prefabrication of complex new composite flaps and for studying the process of revascularization between the layers. Based on these findings and further investigations, a thin, prefabricated abdominal free flap was successfully transferred for facial resurfacing in humans.

Abdomen↗
PubMed1991

The role of microvascular free flaps in salvaging below-knee amputation stumps: a review of 22 cases.

Twenty-two cases of traumatic below-knee amputation stumps with inadequate soft-tissue coverage salvaged with microvascular free flaps were reviewed retrospectively. All patients would have required an above-knee amputation for prosthesis fitting had microvascular free flaps not bee utilized. A total of 24 flaps were used in 22 patients; parascapular 11 (46%), foot filet six (25%), latissimus dorsi four (17%), lateral thigh, tensor fascia lata, and groin one (4%). Free flaps were performed immediately after injury in five (21%) cases, within the first week in two (8%), between 1 and 3 months in 12 (50%), and after 3 months in five (21%). Fifty per cent of the patients had significant other injuries. The patients had a total of 107 operations (mean, 4.9) related to their injury: 33 (mean, 1.5) of those operations were after the free flap, 27 (25%) of which were either performed because of a complication of the free flap or for revision of the free flap. Complications included partial necrosis in five (21%), neuroma in three (13%), hematoma in two (8%), donor site complication in two (8%), thrombosis requiring reoperation in one (4%), and flap failure in one (4%). Patient followup ranged from 12 to 116 months. All patients maintained a functional below-knee prosthetic level. The mean time to ambulation was 5.75 months, and was not significantly affected by flap complications. Most patients employed before their injury were employed after their injury. Despite a protracted course in these severe injured trauma patients, a functional below-knee amputation level was preserved in all cases utilizing microvascular free flaps.

Activities of Daily Living↗
PubMed1991

Prefabrication of composite free flaps through staged microvascular transfer: an experimental and clinical study.

The feasibility of prefabricating free flaps by inducing, through the process of staged reconstruction, an arteriovenous bundle and its surrounding fascia to perfuse a selected block of tissue was investigated experimentally and clinically. Sixteen rat knee joints were wrapped with their ipsilateral superficial inferior epigastric (SIE) fascia. In 8 joints, the composite flaps were resected en bloc and were immediately replaced orthotopically pedicled upon the superficial inferior epigastric vessels. In the remaining joints, the resection and orthotopic transfer were performed 2 weeks later. Only the joints in the latter group, which benefited from the staging period, were found to be perfused. The long finger proximal interphalangeal joint of a child was reconstructed by the staged microvascular transfer of his second toe proximal interphalangeal joint. At the first stage, a temporalis fascia flap was wrapped around the toe proximal interphalangeal joint and revascularized to the dorsalis pedis vessels. Six weeks later, the joint and its temporalis fascia envelope were dissected, and the "prefabricated" joint flap was transferred to the hand and revascularized to the wrist vessels. Bony union progressed uneventfully with excellent recovery of the range of motion. We conclude that regardless of the indigenous vascular anatomy, an unlimited array of composite free flaps can be constructed and transferred based on induced large vascular pedicles.

Animals↗
PubMed1989

Reconstruction of the lower extremity with microvascular free flaps: a 10-year experience with 304 consecutive cases.

A retrospective review of 304 consecutive microvascular free flaps to the lower extremity was done to identify the patterns of usage, results, and problems. The most common indication (91%) was for the replacement of extensive tissue loss caused by motor-vehicle injuries. Most of the defects were below the mid-tibia (73%). The associated compound fractures were predominantly gradable as Gustilo type IIIb&c. The latissimus dorsi, the rectus abdominus, and the scapular skin were the flaps used most commonly for coverage (77%). The overall flap failure rate was 8%, compared with 3% for our series of non-lower extremity cases, and 0% for the non-traumatic lower extremity cases. The magnitude of the traumatic insult was the most significant factor associated with anastomotic failure. The rate of anastomotic thrombosis doubled in the presence of vascular trauma, increased threefold in the presence of larger bony defects, and increased fivefold when vein grafts were needed. Experience was important in reducing the complications and improving the results. Fourteen patients (6%) underwent an amputation within the first 3 months, ten of them because of flap failure. Of 85 patients followed up for over one year, 91% had recovered good to excellent leg function. The ability to add healthy and well vascularized tissue to the traumatized limb is critical for the achievement of: 1) early definitive wound healing and restoration of function; 2) salvage of many impending amputations; 3) better prosthetic stump reconstructions; 4) better esthetic results.

Amputation, Surgical↗
PubMed1988

Vasoactive prostaglandins in the impending no-reflow state: evidence for a primary disturbance in microvascular tone.

The impending no-reflow (NRF) state was studied in the rat hindlimb to identify possible biochemical mediators producing the no-reflow phenomenon. After 5 hours of ischemia, the venous effluents draining the ischemic limb and the contralateral nonischemic limb were collected for three 30-minute time periods. Thromboxane B2 (TxB2), prostaglandin E2 (PGE2), and 6-ketoprostaglandin F1 alpha, the stable metabolite of prostacyclin (PGI2), were measured by radioimmunoassay. Venous outflow rate, distal skin perfusion assessed by dermofluorometry, and histology of muscle and skin were examined in control limbs, ischemic limbs, and limbs with impending no reflow. The no-reflow state was characterized by a significantly decreased venous outflow (less than 0.01 ml per minute), decreased skin perfusion (index of fluorescence of 15 percent in no-reflow limbs versus 70 percent in reflow limbs), and absence of thrombosis of the vasculature. The no-reflow state also was associated with 2.4 times more thromboxane B2 and 1.5 times more 6-ketoprostaglandin F1 alpha than that observed in ischemic limbs with reflow. The biosynthesis of vasodilating prostaglandin E2 in the no-reflow state, however, was only 40 percent of the prostaglandin E2 measured in limbs with reflow. We propose that the impending no-reflow state may reflect a state of global microcirculatory "agonal" vasoconstriction, most probably due to an overabundant release of the vasoconstrictor thromboxane relative to the vasodilating prostaglandin E2 and prostacyclin. The likelihood of specific biochemical mechanisms producing the no-reflow state suggests that pharmacologic agents may be able to reverse the impending no-reflow state to improve tissue survival.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

A historical perspective on the changing methods of management for major trauma of the lower extremity.

The quantity of severe injuries to the extremities challenging the modern, civilian surgeon cannot compare with that produced at Gettysburg or other battles of the Civil War. Nonetheless, the extent and severity of the trauma to the extremity generated on our "civilian battlefields" match and often surpass the wounds confronted by our predecessors. In the Civil War, as it had been for many preceeding years, amputation remained the dominant approach to managing a great variety of injuries to the extremities. However, constant surgical progress, as reflected by a gradual reduction in recourse to amputation, had enabled each succeeding generation of surgeons to surpass and distance themselves from their predecessors. Amputation of the traumatized extremity had always defined and continues to represent the prevalent abilities and limitations of conservative and reconstructive surgical efforts. Operative treatment, for much of its existence, represented a collection of dangerous ablative procedures which were used reluctantly when all other measures were exhausted. Its transformation into a successful reconstructive endeavor evolved primarily in this century. The understanding of bone healing and the functional importance of the knee joint led to a transformation in amputation and to changes in the management of fractures which are still evolving. The next revolution in operative treatment came with the ability to restore blood flow in injured extremities. Finally, the recent introduction of a variety of free flaps enables the reconstitution of extensive soft tissue and bony defects and further lowers the number of obligatory amputations. These innovations enabled the surgeon to reduce his or her recourse to amputation of severely injured extremities. Nonetheless, the significant number of amputations still performed constitute a reminder that there is still work to be done.

Amputation, Surgical↗
PubMed1987

Vascularized calvarial flaps.

Vascularized calvarial transfers offer many advantages. In this article the anatomic (soft tissue, vascular, osseous) basis of flap design is summarized, and the technical details of two calvarial flaps, the temporoparietal and the frontoparietal, are presented.

Adult↗
PubMed1986

Waveform analysis applied to laser Doppler flowmetry.

Laser Doppler flowmetry (LDF) has been found useful in monitoring free flaps. In the present study, waveform analysis has been applied to the LDF waveform. Waveform changes were investigated in the microcirculation during varying degrees of arterial or venous occlusion in the saphenous island and flap of the dog and the human digit. The quantitative analysis of laser Doppler flowmetry waveform allows for the diagnosis of arterial occlusion or venous occlusion and their differentiation.

Animals↗
PubMed1986

Dynamic computer tomography determining the patency of buried free flaps.

Numerous methods exist for monitoring the patency of cutaneous free flaps. Monitoring the patency of microvascular anastomosis in buried free flaps are limited. The present case report is of a 39-year-old female with Rhomberg's disease who underwent an abdominus rectus muscle free flap to correct the contour deformity of the right face. Dynamic CT scan was performed on the sixth postoperative day. Plots of the rate of change of density of the free flap were compared to an adjacent muscle of the face. Dynamic CT scanning provides a high degree of resolution of the free flap, the ability to examine the entire free flap, and the ability to determine the patency of buried free flap.

Adult↗
PubMed1986

Review of the morbidity of 300 free-flap donor sites.

Donor-site morbidity in 300 consecutive free flaps was reviewed to identify their etiologies and potentially prevent their recurrence in future cases. An overall morbidity rate of 20 percent was seen in this series. Secondary surgical procedures specific for donor-site problems were required in 7.7 percent of patients. Major complications occurred in 2.3 percent of the donor sites. From this review it is apparent that major donor-site morbidity is uncommon and most donor-site problems could probably have been avoided. Our recommendations are as follows: closure of the donor site to avoid excessive tension must be carefully planned preoperatively, donor-site anatomy and flap elevation techniques must be precisely understood, surgical retractors must be carefully placed to avoid injury to nearby structures, the donor site should be closed immediately following pedicle division, thus minimizing wound exposures, and complete surgical hemostasis is mandatory.

Abdominal Muscles↗
PubMed1986

Anatomic basis of plantar flap design: clinical applications.

Closure of plantar defects with local rotation flaps was studied in 10 patients with 11 plantar defects. Ages ranged from 15 to 66 years, and the average defect was 3.0 X 3.6 cm. Two patients were diabetics. Etiology was variable and included trauma, tumors, and breakdown in patients with anesthetic plantar surfaces. Plantar flaps were designed superficial to the plantar fascia based on the proximal plantar subcutaneous plexus blood supply. Sensation was provided by including the medial calcaneal nerve territory within the flap and by performing a limited intraneural dissection of the medial and lateral plantar nerves. Flaps were medially based, although laterally based designs are also possible when sensation is absent. The follow-up period averaged 20.8 months. Patients with normal sensation preoperatively had full sensation postoperatively and were able to bear weight on the flap without limitation. There was minor breakdown in one patient with incomplete sensation. One patient developed a hematoma. Sensate plantar flaps can be designed superficial to the plantar fascia. These flaps are durable and allow normal weight-bearing on the reconstructed surface.

Adolescent↗
PubMed1986

Management of acute lower extremity nerve injuries.

While repair of acute nerve injuries in the lower extremity has not been as aggressive as in the upper extremity, there should now be more effective early intervention. Newer microsurgical techniques can be used along with increased understanding of peripheral nerve internal anatomy to obtain more satisfactory repair and reconstruction of the injured nerves. The anatomy and vulnerability of the nerves in the leg are reviewed, and the decision process is analyzed in the context of the functional deficits following such injuries. A priority of goals in lower extremity nerve repair should be established to ensure salvage of the foot.

Acute Disease↗
PubMed1986

Reconstruction of foot injuries.

Foot injuries constitute a spectrum of problems that can be classified by severity. The development of successful techniques for the treatment of lower leg injuries has made the severity of a concomitant foot injury a key factor in determining the overall salvageability of the leg. A more complete classification of foot injuries is therefore needed and has been proposed. Preoperative assessment of foot injuries differs in the acute versus the delayed presentation. The acute case requires evaluation of wound conditions, exposed structures, and associated proximal injuries. The chronic injury requires gait analysis, study of weight-bearing patterns by Harris mat prints, skeletal evaluation, mapping of plantar sensation, and, in some cases, angiography. Thorough knowledge of foot anatomy is essential for developing a rational plan for treatment. The significance and course of the medial calcaneal nerve and the anatomy of the plantar nerves have not been fully appreciated in most reports on the treatment of foot injuries. The recognition of the proximal plantar subcutaneous plexus blood supply has modified the understanding of plantar flap design. It has simplified and improved the safety of dissection of sensate plantar flaps. A plethora of both local and distant flap options exist for the treatment of foot injuries. The foot is divided into four major areas based on different requirements for reconstruction and the types of flaps available. These areas are the proximal plantar area; the malleoli, Achilles tendon, and posterior (non-weight-bearing) heel area; the distal plantar area; and the dorsum. The options for coverage have been discussed in detail, and a summary of the reconstructive strategy by area has been presented in Table 3. Complex (type III) injuries are special injuries owing to their severity and multiple components. They require a careful initial evaluation for both feasibility and advisability of extremity salvage. Treatment of these injuries consists of bony stabilization and soft-tissue debridement followed by flap coverage.

Debridement↗
PubMed1986

The evolution of the surgical management of severe lower extremity trauma.

A hundred years ago, the question of whether to amputate a severely injured extremity could be answered rather easily and did not pose a serious dilemma. However, the increasing reconstructive capabilities have permitted the retreat to amputation to be made less frequently and occasionally create a dilemma concerning the best means of securing optimal function for the traumatized extremity. The surgeon must carefully balance the extent of trauma with the likelihood that his or her reconstructive efforts would surpass the functional results afforded by prompt amputation and prosthetic fitting. Although the mechanisms of limb destruction have changed in the past 2 centuries, the fundamental dilemma confronting the trauma surgeon has remained unchanged. In the words of Samuel D. Gross: "The cases which may reasonably require and those which may not require interference with the knife are not always so clearly and distinctly defined as not to give rise, in very many instances, to the most serious apprehension ... that, while the surgeon endeavors to avoid Scylla, he may not unwittingly run into Charybdis, mutilating a limb that might have been saved, and endangering life by the retention of one that should have been promptly amputated."

Amputation, Surgical↗
PubMed1986

Lower extremity nerve injuries.

The surgical and anatomic features pertinent to lower extremity nerve injury are reviewed. The common problems associated with specific nerve lesions are discussed and reparative recommendations are offered. A more informed, aggressive approach to lower extremity nerve repair is suggested.

Adult↗
PubMed1986

Aesthetic reconstructions of the leg after trauma.

Lower extremity trauma often results in significant skin or contour deformities as a result of the tissues destroyed. Such deformities are poorly tolerated by most patients, especially younger women. To achieve a satisfactory aesthetic reconstruction, the surgeon must be familiar with the special anatomy of the lower extremity as well all the different reconstructive options at his or her disposal. Minor scars or contour deformities can be corrected by traditional methods of scar revision or serial excision. Tissue expanders or silicone implants have a somewhat limited role in the lower extremity as compared with elsewhere in the body. Most major defects require free flaps to replace the surface or contour. Because of the importance of aesthetic results in the legs, free flaps should be utilized more often during the original trauma surgery if their use is deemed necessary for aesthetic reasons (Case 6).

Adult↗