首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
The theory of epigenesis is the undisputed paradigm of embryology, and it is still based on the classical concept proposed by Aristotle: the idea that embryonic development is a generation of structures which takes place according to a design--today we say a set of instructions--already present in the fertilized egg. This is a doctrine which can be referred to as 'pre-information', since it claims the preexistence of information exactly as the old theory of preformation claimed the preexistence of form. Here, however, it is shown that a more general version of epigenesis can be held, because of a new principle which states that it is mathematically possible to obtain not only a convergent generation of form, or structure, but also a convergent generation of information.  相似文献   

2.
3.
4.
Intraoral reconstruction with a microvascular peritoneal flap   总被引:2,自引:0,他引:2  
The microvascular peritoneal flap offers a new reconstructive option for closure of intraoral defects. The flap is easy to raise, and donor-site morbidity is low. Unlike fascial flaps, in which the raw surface may take weeks to "mucosalize," the peritoneal surface heals primarily. Finally, the rectus muscle effectively covers all forms of mandibular reconstruction, and the reliable skin paddle makes possible the closure of substantial cutaneous defects.  相似文献   

5.
The subunit principle in nasal reconstruction   总被引:26,自引:0,他引:26  
The nasal surface is made up of several concave and convex surfaces separated from one another by ridges and valleys. Gonzalez-Ulloa has designated the nose an aesthetic unit of the face. These smaller parts (tip, dorsum, sidewalls, alar lobules, and soft triangles) may be called topographic subunits. When a large part of a subunit has been lost, replacing the entire subunit rather than simply patching the defect often gives a superior result. This subunit approach to nasal reconstruction causes unsatisfactory border scars of flaps to mimic the normal shadowed valleys and lighted ridges of the nasal surface. Furthermore, as trapdoor contraction occurs, the entire reconstructed subunit bulges in a way that simulates the normal contour of a nasal tip, dorsal hump, or alar lobule. Photographs show five patients in whom this principle was followed and one in whom it was not.  相似文献   

6.
Over the past 4 years at the Massachusetts General Hospital 18 patients have been treated for extensive defects (mean size 130 cm2) of the foot at or below the medial and lateral malleoli. These patients have been treated with free muscle flaps covered with thick split-thickness skin grafts. Full muscle flap survival has been seen in each patient, and all patients are currently ambulatory. A subgroup of nine patients are weight-bearing directly upon their skin grafts covering transferred muscle. All patients are walking without chronic breakdown over a mean follow-up of over 19 months with the exception of a single patient who has had breakdown in a region of redundant improperly tailored muscle flap. None of the skin grafted muscles has significant cutaneous sensibility. Detailed gait analysis of these patients has confirmed the weight-bearing capabilities of free muscle flaps with skin grafts and has proven to be an excellent method of foot reconstruction evaluation. It would appear from this study that cutaneous sensibility may not be necessary for successful reconstruction of the weight-bearing surface of the foot. This method of reconstruction should be considered when local tissues are not suitable for plantar foot reconstruction.  相似文献   

7.
The lack of adequate recipient vessels often complicates microvascular breast reconstruction in patients who have previously undergone mastectomy and irradiation. In addition, significant size mismatch, particularly in the outflow veins, is an important contributor to vessel thrombosis and flap failure. The purpose of this study was to review the authors' experience with alternative venous outflow vessels for microvascular breast reconstruction. In a retrospective analysis of 1278 microvascular breast reconstructions performed over a 10-year period, the authors identified all patients in whom the external jugular or cephalic veins were used as the outflow vessels. Patient demographics, flap choice, the reasons for the use of alternative venous drainage vessels, and the incidence of microsurgical complications were analyzed. The external jugular was used in 23 flaps performed in procedures with 22 patients. The superior gluteal and transverse rectus abdominis musculocutaneous (TRAM) flaps were used in the majority of the cases in which the external jugular vein was used (72 percent gluteal, 20 percent TRAM flap). The need for alternative venous outflow vessels was usually due to a significant vessel size mismatch between the superior gluteal and internal mammary veins (74 percent). For three of the external jugular vein flaps (13 percent), the vein was used for salvage after the primary draining vein thrombosed, and two of three flaps in these cases were eventually salvaged. In three patients, the external jugular vein thrombosed, resulting in two flap losses, while the third was salvaged using the cephalic vein. A total of two flaps were lost in the external jugular vein group. The cephalic vein was used in 11 flaps (TRAM, 64.3 percent; superior gluteal, 35.7 percent) performed in 11 patients. In five patients (54.5 percent), the cephalic vein was used to salvage a flap after the primary draining vein thrombosed; the procedure was successful in four cases. In three patients, the cephalic vein thrombosed, resulting in two flap losses. One patient suffered a thrombosis after the cephalic vein was used to salvage a flap in which the external jugular vein was initially used, leading to flap loss, while a second patient experienced cephalic vein thrombosis on postoperative day 7 while carrying a heavy package. There was only one minor complication attributable to the harvest of the external jugular or cephalic vein (small neck hematoma that was aspirated), and the resultant scars were excellent. The external jugular and cephalic veins are important ancillary veins available for microvascular breast reconstruction. The dissection of these vessels is straightforward, and their use is well tolerated and highly successful.  相似文献   

8.
9.
10.
11.
Reverse anterior tibial artery flap for reconstruction of foot donor site   总被引:2,自引:0,他引:2  
The foot offers numerous useful options for hand reconstruction. Hallux transfer, dorsalis pedis flap, second toe transfers, and toe joint transfers offer good functional results in reconstructed hands. However, when the donor site is repaired with skin grafts, delayed wound healing, scarring, and contractures often result. Poor cosmesis of the donor site and altered gait are the main drawbacks of the procedures. The authors propose a new concept of primary reconstruction of the donor foot using a reverse-flow anterior tibial flap from the same leg. Two flaps are raised from the same anterior tibial vessel system in continuity as a distal free flap for hand reconstruction and as a proximal reverse-flow pedicled flap to resurface the donor defect. This technique allows good flap reconstruction of the foot donor site, reducing morbidity and limiting the operation to the same limb. The authors report their experience of 33 cases. There were no failures. Primary wound healing was achieved in the foot donor site, with acceptable cosmesis and satisfactory function.  相似文献   

12.
Total and subtotal glossectomy: function after microvascular reconstruction   总被引:2,自引:0,他引:2  
Twelve patients with advanced carcinoma of the floor of the mouth and tongue were treated with total (five patients) or subtotal (seven patients) glossectomy, partial mandibulectomy, and immediate reconstruction with the microvascular composite groin flap. The osteomusculocutaneous groin flap was used in eleven patients, and the osteomuscular flap was used in one patient. The groin musculocutaneous or muscle flap was designed to resemble the shape of the tongue for dynamic food transport, improved swallowing, and acceptable speech. Eight of the 12 patients who survived more than 1 year were evaluated for speech and swallowing. Eight patients were able to speak intelligibly, six patients could tolerate a soft/pureed diet, and two patients were limited to fluids. Cinefluorographic swallow studies using semisolid contrast material showed voluntary active intraoral transport and propulsive pharyngeal emptying without aspiration in six patients with complete flap to palate contact; the remaining two patients were unable to move the intraoral contrast material effectively for swallowing because of poor palatal contact.  相似文献   

13.
Ten patients were reconstructed with the microvascular osteocutaneous groin flap for oromandibular defects with the objective of improving function. The flap was based on the superficial and deep circumflex iliac vessels for optimal positioning of the bone and contouring of the skin. Patients with major glossectomies and arch resections had intelligible speech and were able to eat a soft diet without aspirating. Cineradiographic studies to evaluate swallowing in selected patients showed that the shape of the intraoral flap and the location of the bone graft played an important role in swallowing and prevention of aspiration.  相似文献   

14.
The segmental rectus abdominis free flap for ankle and foot reconstruction.   总被引:1,自引:0,他引:1  
D B Reath  J W Taylor 《Plastic and reconstructive surgery》1991,88(5):824-8; discussion 829-30
The reconstruction of soft-tissue defects of the ankle and foot usually requires free-tissue transfer. Although certain local flaps have been described for the reconstruction of these injuries, their utility may be compromised by significant crush injury or the size and location of the defect. Part of the rectus abdominis muscle, the segmental rectus abdominis free flap, is ideally suited for this use because of the muscle's versatility, reliability, and negligible donor deformity when harvested through a low transverse abdominal incision. Seven patients reconstructed with this flap are presented, and the technique is discussed. All patients have been successfully reconstructed with preservation of the ankle and foot. At present, all patients are fully or partially weight-bearing. The segmental rectus abdominis free flap is recommended for the reconstruction of such wounds.  相似文献   

15.
16.
Thirteen patients with squamous cell carcinoma of the tongue underwent full-thickness longitudinal resection of the hemitongue and immediate microvascular reconstruction using a large, contoured ulnar forearm flap. Six of the 13 patients had a composite resection for which an additional vascularized iliac crest graft was used to reconstruct the mandible and to provide support to the overlying contoured flap. To increase tongue mobility, the skin flap was designed for independent reconstruction of the hemitongue and the floor of mouth. Twelve patients were evaluated for swallowing and speech, including dietary assessment, cineradiography, and voice spectrographic analysis. Contrast cineradiography was performed to determine oral tongue mobility during the first phase of swallow. Nine patients with a narrow reconstructed tongue root and a large surface area in the floor of the mouth had good tongue mobility, allowing them to transfer food dynamically from the mouth into the pharynx for swallowing. The remaining three patients, who had a wide tongue root and an ill-defined floor of the mouth, had decreased tongue mobility and poor oral transport. The functional outcome of swallowing and speech strongly correlated with the shape of the root of the tongue, the proximity of the reconstructed tongue to the palate, and the surface area of the floor of the mouth.  相似文献   

17.
18.
19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号