Molecular mechanisms for the induction of chromosomal aberrations in CHO cells heated in S phase

During the past 20 years, 972 microvascular transplantations have been performed for 783 patients, with an overall failure rate of 6.2 percent. Fifty-four of the 60 failed transplantations were available for long-term follow-up and were retrospectively reviewed with respect to the original indications for transplantation, the number, and the type of salvage procedures performed following transplant failure. This study illustrates that the choice of salvage procedures performed following transplant failure depends on the original indications, the location, and the severity of the resultant wound. Failure following transplantation for coverage of contour defects or unstable wounds can often be managed by non-microsurgical methods. In contrast, when the indications for transplantation included the transfer of specialized tissues for thumb or digit reconstruction, the restoration of motor or sensory function, or the coverage of a limb-threatening wound, requirements for reconstruction could be satisfied only by a second successful tissue transplant. Eighteen of the 54 cases underwent an additional transplantation, with an 89 percent success rate.     

Use of 20 cm or longer interposition vein grafts in free flap reconstruction of the trunk

Between January of 1993 and September of 1995, six microsurgical free tissue transplants were performed using saphenous vein grafts ranging from 20 to 39 cm in length. All six free flaps survived. Two wounds were caused by radiation injury and two by tumor resection. The remaining two free flaps were performed for contour deformity and spinal cord coverage. All of the recipient sites were located on the trunk. In each case, an arteriovenous loop was created before the microvascular anastomosis to the free flap. There was one arterial thrombosis requiring thrombectomy and revision of the anastomosis. Three patients developed minor wound complications that responded to local wound care. Each of the flaps successfully provided wound coverage, and in two cases the flaps tolerated further radiation results. Long interposition vein grafts can be used for difficult microsurgical reconstructive procedures with reliable results when no local recipient vessels are available. Versatility is therefore afforded in placement of the flap and the choice of recipient vessels, making this option a useful one in the treatment of complex wounds of the trunk.     

Single versus double arterial anastomoses in combined second- and third-toe transplantation

Combined second and third toe transplantation is one good option for reconstruction of multiple digit amputation. However, the use of one or two arteries for pedicle anastomoses, which may influence the vascular complication and success rate, has never been addressed in the literature. This study includes a retrospective review of 57 combined second and third toe transplantation in 54 patients performed from February of 1983 through December of 1996. Group I, composed of 41 transplantations, underwent one arterial anastomosis, and group II, composed of 16 transplantations, underwent double arterial anastomoses during surgery if there were two recipient arteries available or whenever the second and third toes showed inadequate blood perfusion after one arterial anastomosis. In group I, 10 transplantations (24.4 percent) required re-exploration with a success rate of 92.7 percent (38 out of 41 transplantations). In group II, only one transplantation (6.2 percent) required re-exploration with successful flap salvage. The success rate was 100 percent for group II. Because the re-exploration and success rates between groups I and II were not statistically significant according to two-tailed Fisher's exact test, the combined second and third toe transplantation is a reliable procedure using either single or double arterial anastomoses.     

Microvascular soft-tissue coverage and distraction osteosynthesis for lower-extremity salvage

In our attempts to salvage massive lower-extremity injuries, even in the presence of severe peripheral vascular pathology, adequate soft-tissue coverage is no longer a limiting factor due to recent advances in microvascular composite tissue transfer. Restoration of tibial continuity without shortening has emerged as the last obstacle in the formidable task of salvaging lower extremities with grade III B and III C defects. Proposed solutions to this problem include conventional free cancellous bone-grafting applicable to small defects only, vascularized bone grafts, or shortening of the leg with subsequent elongation using the Ilizarov technique. We present our experience with 3 consecutive cases of lower-limb salvage, utilizing a new approach in which microsurgical soft-tissue reconstruction has been combined with bony reconstruction by distraction osteosynthesis. Bone transport by distraction osteosynthesis under a free flap performed while preserving the initial limb length throughout the treatment period proved to be superior to other methods in selected cases and is presented as a new technique for the management of problematic lower-limb injuries.     

Fate of free flap microanastomosis distal to the zone of injury in lower extremity trauma

The decision to perform free flap microanastomosis to clearly uninjured vessels proximal to the zone of injury for lower extremity reconstruction must be weighed against the anatomic and technical difficulties of performing such an anastomosis. Preserved blood flow through vessels traversing the zone of injury has been shown. The records of all patients who underwent lower extremity reconstruction with microvascular free flaps at NYU Medical Center and Bellevue Hospital Center from January 1979 through August 1995 were reviewed. Patients with free flap microanastomoses distal to the zone of injury were compared with those with proximally based anastomoses. The group of patients was subdivided further into acute (1-21 days), subacute (22-60 days), and chronic (greater than 60 days) reconstruction groups. Of 451 microvascular free flaps, 35 were performed with recipient vessels distal to the zone of injury. Time interval from injury to coverage ranged from 24 hours to 57 years. Of 35 distally based flaps, 33 (94 percent) were successful and 5 required reoperation (14 percent). There was a similar incidence of thrombotic complications throughout all after-injury phases. Of 416 free flaps performed with microanastomoses to vessels proximal to the zone of injury, 388 (93 percent) were successful and 62 (15 percent) required reoperation. There was no significant difference (p > 0.05) in outcome between distal and proximal anastomoses and no significant difference (p > 0.05) in rates of reoperation. Timing of operation after injury had no bearing on outcome. Distally based microvascular free flaps anastomoses may be technically less difficult with rates of survival equal to those of proximally based flaps. The consideration and use of microanastomoses distal to the zone of injury are encouraged in selected patients.     

Toe transplantation for isolated index finger amputations distal to the proximal interphalangeal joint

Functional deficit following single distal index finger amputations has been considered insignificant, and reconstruction is usually not recommended. Herein, 19 cases of second toe transplantation for reconstruction of isolated index finger amputation distal to the proximal interphalangeal joint are presented with long-term functional results. There are 14 men and 5 women. The average age was 26 years. The toe transplantations were performed either as a primary procedure (5 patients) while the wounds were still open or as a secondary procedure (14 patients) after the wounds healed. In 11 patients, the dominant hand was involved. All toes survived completely, although re-exploration was required in three cases (16 percent). The functional evaluation included (1) sensory recovery, where the average static and moving two-point discrimination were 8 mm (range 4 to 15 mm) and 6 mm (range 2 to 15 mm); (2) motor function, where the average of index-thumb pulp-to-pulp pinch compared with the normal hand was 67.5 percent (range 36 to 96 percent); (3) average range of motion in index finger joints (extension/flexion), where metacarpophalangeal joint was 14/90, proximal interphalangeal joint was 0/94, and distal interphalangeal joint was 19/38; and (4) functional and cosmetic results, where percentage of involvement in daily activities and functional capacity of the reconstructed index were 69 percent and 70.5 in average, respectively, over a total score of 100. Average scores of aesthetic appearance and acceptability of donor-site deformity were 74 and 87.5 over a total score of 100, respectively. Toe transplantation for distal index finger amputations improved hand function when performed in selected patients with specific job requirements or high motivation.     

MRI of the intracerebral lesions at 0.5 Tesla: comparison of fast spin-echo and conventional spin-echo sequences

The purpose of this study was to identify the angiosome of the medial saphenous artery and vein and to evaluate the use of this cutaneous angiosome as a free skin flap in the dog. In phase 1 of this study, selective angiography of the medial saphenous artery performed in six canine cadavers showed that the skin covering the entire medial femorotibial area, the distal half of the caudal head of the sartorius muscle, and the gracilis muscle were perfused by the medial saphenous artery. In phase 2, a medial saphenous fasciocutaneous island flap was raised and sutured back to the skin edges of the donor wound in three dogs. One hundred percent survival of all of the flaps occurred. In phase 3, a medial saphenous fasciocutaneous microvascular free flap was transferred to a wound that was created over the dorsal metacarpal (n = 3) or metatarsal region (n = 3). The mean length +/- SD of the medial saphenous vascular pedicle was 80 +/- 13 mm (n = 5); the mean diameter +/- SD of the medial saphenous artery was 2.8 +/- 0.2 mm (n = 5) and the mean diameter +/- SD of the medial saphenous vein was 4.2 +/- 0.2 mm (n = 5). One hundred percent of all flaps survived (n = 6). Selective angiography or the distal cranial tibial artery (metatarsal wounds, n = 3) and the median artery (metacarpal wound, n = 3) was performed 3 weeks after surgery. All of the vascular anastomoses were patent and neovascularization of the wound beds was present. This free flap was found to be acceptable for cosmetic reconstruction of wounds located on the distal extremity.     

The effect of tolerance to noninherited maternal HLA antigens on the survival of renal transplants from sibling donors

BACKGROUND: During pregnancy and nursing, a baby's developing immune system is intimately exposed to the mother's antigens. To determine whether this exposure is of clinical benefit to patients who later receive an allograft as an adult, we analyzed the outcome of primary renal transplantations from sibling donors. METHODS: We retrospectively studied graft survival and rejection episodes in 205 patients who had received renal transplants at nine centers between 1966 and 1996 from sibling donors bearing maternal or paternal HLA antigens not inherited by the recipient. The sibling donors were categorized by analysis of family HLA-typing data. RESULTS: In the multicenter analysis, graft survival was higher at 5 years and at 10 years after transplantation in recipients of kidneys from siblings expressing maternal HLA antigens not inherited by the recipient than in recipients of kidneys from siblings expressing paternal HLA antigens not inherited by the recipient (86 percent vs. 67 percent at 5 years and 77 percent vs. 49 percent at 10 years, P=0.006 for both). Paradoxically, there was a higher incidence of early rejection in the former group, suggesting that fetal and neonatal exposure to maternal antigens results in immunologic priming. Pretransplantation transfusions of donor blood reduced the incidence of acute rejection while preserving the beneficial effect of tolerance to noninherited maternal antigens on graft survival. Since 1986, new immunosuppressive drugs have lessened the short-term, but not the long-term, survival advantage of grafts expressing maternal HLA antigens not inherited by the recipient. CONCLUSIONS: In the transplantation of a kidney from a sibling donor who is mismatched with the recipient for one HLA haplotype, graft survival is higher when the donor has maternal HLA antigens not inherited by the recipient than when the donor has paternal HLA antigens not inherited by the recipient.     

The recipient splenic artery for arterialization in orthotopic liver transplantation

Adequate hepatic arterial reconstruction is essential for successful liver transplantation. In the case of insufficient recipient hepatic arterial flow, most surgeons recommend the use of the aorta for arterialization of the graft. We report here on a technique in which the recipient splenic artery is used in such a setting. The splenic artery is dissected from its origin on a 3-to-4 cm segment and divided. The proximal segment is flipped to the right and anastomosed to the graft's celiac axis in an end-to-end fashion. This technique was used in 7 of 79 orthotopic liver transplantations (9%) because the native hepatic artery was deemed to be inadequate for anastomosis. There were no complications related to the use of this technique and no arterial thromboses. Arterialization of hepatic grafts using the recipient proximal splenic artery is a simple, safe, and efficient technique that can be recommended in the presence of an inadequate recipient hepatic arterial flow.     

Aortic foreign body resulting in ischemic neuromyopathy and development of collateral circulation in a cat

A cat evaluated for paraplegia had firm pelvic limb musculature and did not have femoral pulses. External wounds were not evident, but abdominal radiography revealed a round metallic foreign body on the midline ventral to the sixth lumbar vertebra. Angiography indicated stenosis or thrombosis of the aorta in association with the foreign body; collateral circulation arose from the fifth lumbar artery. Arteriotomy was performed to extract the foreign body and associated thrombi. Six weeks after surgery, angiography revealed blood flow in the abdominal portion of the aorta, but no evidence of obstruction or additional collateral vessels. The cat regained function of the pelvic limbs within 1 year after surgery. Ischemic neuromyopathy and paraplegia in cats is commonly associated with aortic thromboembolism. A thrombus is necessary to cause typical clinical signs, and vasoactive substances released by platelets in the thrombus are believed to cause ischemic neuromyopathy. Progression of the collateral circulation may allow for clinical improvement without surgical intervention.     

A historical review of mental health services in Hong Kong (1841 to 1995)

OBJECTIVE: To review the experience of 1 microvascular surgeon during an 11-year period in performing 210 vascularized bone-containing free flaps for oromandibular reconstruction. DESIGN: Retrospective medical records review of patients who underwent primary and secondary oromandibular reconstruction with the use of vascularized bone free flaps. SETTING: Academic medical center. PATIENTS: A total of 201 patients underwent 210 composite free-flap reconstructions of the mandible for various disorders and with a range of bony and soft tissue defects. INTERVENTION: All patients underwent the microvascular transfer of vascularized bone flaps from the ilium, fibula, or scapula. In selected cases, 2 simultaneous free flaps were transferred to achieve an optimal bone and soft tissue reconstruction. Endosteal dental implants were used in 81 patients, with a total of 360 fixtures placed during these 11 years. MAIN OUTCOME MEASURES: The success of microvascular free tissue transfer, dental implant extrusion, and short- and long-term complications at the recipient and donor sites. RESULTS: Of the 210 mandibular reconstructions that were performed, 202 were successful in reestablishing mandibular continuity. Reexploration for vascular-related complications was done in 16 patients, 8 of whom were successfully treated, yielding an overall success rate of 96%. The overall success rate for endosteal dental implants was 92%. The implant success rate was 86% when the bone in which the fixtures were placed was irradiated postoperatively. The success rate was 64% in the 14 fixtures that were placed into previously irradiated bone. CONCLUSIONS: The success of the use of vascularized bone free flaps in restoring continuity to the mandible is clearly demonstrated in this series. There was an acceptable incidence of donor- and recipient-site complications that resulted in minimal long-term morbidity. The careful selection of a donor site(s) for oromandibular reconstruction allows for an optimal restoration of bony and soft tissue defects. Dental implants can be safely used in oromandibular reconstruction with a high level of success. Placing these implants during the initial surgery shortens the duration for achieving dental rehabilitation and enhances the success of the implants when postoperative radiotherapy is administered.     

Free tissue transfer in the management of burns

Although the majority of burn wounds undergoing surgical treatment require only excision with split-skin grafting, the introduction of free microvascular tissue transfer has allowed for the preservation of otherwise unsalvageable deep burn injuries and the resurfacing of burn scars in areas with no available local tissue. A total of 1699 patients with burn injuries were admitted to the Burns Unit in Newcastle upon Tyne in the 5 years 1989-1993. During this period 604 patients (35.5 per cent) required surgical treatment of their burns. Of these patients 582 (96.4 per cent) underwent excision of their burns with split-skin grafting, 13 (2.1 per cent) of the patients required local flap cover and nine patients (1.5 per cent) had free tissue transfer. Free flap loss in this study was 22 per cent in burns patients as compared to only 3 per cent in patients undergoing microsurgical reconstruction for other reasons.     

Remnant-like particle cholesterol levels in patients with dysbetalipoproteinemia or coronary artery disease

Fibula osteocutaneous free tissue transfer to reconstruct the oromandibular complex is a widely recommended technique following oncologic resection. Preoperative determination of adequate perfusion to the donor extremity is necessary to assure lower extremity viability after flap harvest. Vascular variations and/or peripheral arterial occlusive disease (PAOD) may exist whereby sacrifice of peroneal vessels can cause ischemia to the lower leg and foot. Additionally, variability of cutaneous perforators can make the fibula skin paddle viability unpredictable. Color flow Doppler (CFD) is a reliable modality to preoperatively assess the lower extremity in fibula osteocutaneous free tissue transfer patients. Prospective CFD examination of 38 consecutive patients (76 legs) considered for fibula free flap reconstruction was performed. A standard protocol was designed to evaluate the lower extremity vasculature and identify cutaneous perforators with CFD. Findings were studied with respect to flap choice, operative findings, and reconstruction outcomes. Number of cutaneous perforators and their impact on skin paddle design were also recorded. Color flow Doppler's ability to image peroneal vessels as well as determine collateral and distal perfusion were effective. CFD accurately identified bilateral vascular anomalies in one patient (2.6%), and significant arterial disease in three patients (7.9%). Cutaneous perforators were also accurately mapped and confirmed intraoperatively in 31 patients. In several instances, the information provided by the CFD examination altered flap selection, 4/38 patients (10.5%), or skin paddle design, 5/32 patients (15.6%). Color flow Doppler allowed successful fibula transfer in all the free flap candidates with normal exams. It has the advantages of low cost and no morbidity. CFD allows for accurate mapping of fibula cutaneous perforators which facilitates skin paddle design. We recommended the use of preoperative CFD in all patients being considered for fibular free flap surgery.     

Results later many years after TEA in femoro-popliteal segment (author's transl)

Our results later many years after 231 TEA in femoro-popliteal segment are based to examinate the indications of this reconstructive operation and to compare with other methods of arterial reconstruction. Resulted: the TEA is always a good method of biological worth without risk. This method authorized to indicate the reconstruction of chronical arterial occlusions. However the method is not to apply to all arterial occlusions without criticism only to selected patients.     

Restoring abdominal wall integrity in contaminated tissue-deficient wounds using autologous fascia grafts

Necrotizing abdominal wall infections, enteric fistulae, or exposed prosthetic material after ventral hernia repair often results in a loss of abdominal wall integrity. Further surgical reconstruction with prosthetic material is usually contraindicated in the contaminated wound because of the high infection rate necessitating prosthetic removal and further abdominal wall debridement. Consequently, for the past 9 years, we have been using free grafts of autologous fascia lata to replace deficient abdominal wall fascia and muscle in situations where prosthetic material is contraindicated and local tissue rearrangement (i.e., component separation) would be inadequate. Thirty-two patients (mean age 59 years) underwent abdominal wall reconstruction with autologous fascia lata grafts. Indications included exposed mesh (31 percent), enteric fistulae (28 percent), enteric contamination (22 percent), wound infection (13 percent), and immunosuppression alone (6 percent); 31 percent of all patients were immunosuppressed secondary to either a solid organ transplant or a systemic inflammatory disorder. Fascia grafts (mean size 10 x 17 cm) were sutured to the surrounding abdominal wall and covered by local skin flap advancement and/or myocutaneous flap rotation. All abdominal reconstructions were initially successful. Subsequent local abdominal wall complications included cellulitis (n = 3), seroma (n = 2), and skin dehiscence with exposed fascia grafts (n = 7). Five of seven patients with skin dehiscence healed by secondary intention, whereas two had split-thickness skin grafts successfully applied to the granulating fascia. Thigh donor site complications included hematoma (n = 1), skin dehiscence (n = 1), and seroma (n = 2). There have been no cases of lateral knee instability. The average follow-up period is 27 months (range 3 to 106 months). Recurrent hernia has been seen in three patients (9 percent). Interestingly, laparotomy has been performed through an intact fascia lata patch in three patients for unrelated intra-abdominal conditions. In each case, the graft was intact and revascularized, confirming experimental animal data performed in our laboratory. Recurrent hernia has not been observed through the laparotomy site. Our 9-year experience has demonstrated that in the face of large, contaminated abdominal wounds where prosthetic material is contraindicated and local tissue rearrangement would be inadequate, fascia lata autografts are a reliable adjuvant to abdominal wall reconstruction.     

Limited value of preoperative cervical vascular imaging in patients with velocardiofacial syndrome

The purpose of this two-part study was to evaluate the safety of surgical management of speech production disorders in patients with velocardiofacial syndrome without preoperative cervical vascular imaging studies. Anomalous internal carotid arteries have been shown to be a frequent feature of velocardiofacial syndrome. These vessels pose a potential risk for hemorrhage during velopharyngeal narrowing procedures. Magnetic resonance angiography, and other forms of cervical vascular imaging studies such as computerized tomography, have been advocated as aids to surgery by defining the preoperative vascular anatomy. However, it remains unclear whether these studies alter either the conduct or outcome of operations on the velopharynx. In the first part of this study, we reviewed the charts and videonasendoscopic evaluations of 39 consecutive patients with confirmed or suspected velocardiofacial syndrome who underwent sphincter pharyngoplasty or pharyngeal flap from 1978 to 1996. The charts were reviewed to determine (1) the frequency of identification of abnormal pharyngeal pulsations; (2) whether such pulsations affected the conduct of the operative procedure; and (3) whether the presence of pulsations affected surgical morbidity and/or surgical outcome. None of the patients underwent any type of cervical vascular imaging study. In the second part of this study, we surveyed plastic surgeons with numerous years of experience participating on cleft-craniofacial teams, to ascertain practice patterns relating to the management of patients with velocardiofacial syndrome. The questions related specifically to the surgeons' behavior in relation to angiography and their awareness of any cases of surgical morbidity related to the cervical vascular system in patients with velocardiofacial syndrome. We were interested in discerning both how commonly this situation arises clinically and the distribution of the various types of operative procedures in common use. Of our 39 patients, 10 patients (26 percent) had detectable pulsations on preoperative nasendoscopy. Of these, five patients underwent sphincter pharyngoplasty and five underwent pharyngeal flap procedures. Preoperative instrumental and intraoperative clinical assessment of pulsatile vessels allowed velopharyngeal reconstruction in all patients without surgical morbidity. Results of the questionnaire indicated that most cleft surgeons do not routinely order cervical vascular imaging studies for all of their patients with velocardiofacial syndrome. About half of the respondents indicated that their operative approach was influenced by information obtained from angiographic studies. None of the surgeons queried were aware of any cases of surgical morbidity related to the cervical vascular system in patients with velocardiofacial syndrome. Nearly 50 percent of surgeons use pharyngeal flap procedures most frequently, whereas 22 percent of surgeons use sphincter pharyngoplasty most frequently. Results of this study support the safety of sphincter pharyngoplasty or pharyngeal flap procedures in patients with velocardiofacial syndrome without preparatory angiography. These procedures can be performed safely, even in patients having aberrant velopharyngeal pulsations. Given the market cost of magnetic resonance angiography ($1600), one must question the cost-efficacy of magnetic resonance angiography for routine use in the velocardiofacial syndrome population.     

Effects of difructose anhydride III on calcium absorption in small and large intestines of rats

Patients with autosomal dominant polycystic kidney disease (ADPKD) have an increased risk of intracranial aneurysms. Reports on arterial aneurysms in other locations have not been conclusive. The present study was initiated to investigate the prevalence of coronary aneurysms. Thirty ADPKD patients who had undergone coronary angiography on clinical indication were identified, 15 after renal transplantation. For each ADPKD patient, a control patient was identified with end-stage renal disease, investigated by coronary angiography, and matched for age, sex, and time relation to transplantation. All angiograms were retrieved and reevaluated with respect to aneurysms, defined as an increase in artery diameter by 50% or more, as well as to pathologic ectasias not fulfilling this criterion. Aneurysms were detected in four ADPKD patients and two control subjects. Five more ADPKD patients, but none of the control subjects, had minor ectasias. One ADPKD patient had a dissecting aortic aneurysm, and another died of aortic dissection during bypass surgery. This study adds to the evidence of an increased risk of extracranial aneurysms in ADPKD patients.     

Muscle-flap coverage for infected peripheral vascular prostheses

Infection in a peripheral vascular prosthesis continues to be a serious complication in arterial reconstructive surgery and threatens the patient with loss of either limb or life. Infection rates at major centers are now low, ranging from 1 to 6 percent; however, limb loss and mortality rates for this complication range from 25 to 75 percent depending on the location of the graft and the extent of the infection. The use of muscle flaps in the management of acute wounds, infection-prone wounds, exposed orthopedic hardware, and osteomyelitis is now commonplace. Transposed muscle has been shown to be well-vascularized tissue that improves healing time and decreases local wound bacterial counts. After considering the preceding facts, we used muscle flaps for coverage of infected peripheral vascular prostheses in a highly select group of patients. These patients were "end of the line," and last-ditch efforts were made to salvage life or limb. Twenty-four infected vascular grafts in 20 patients have been analyzed. Ages ranged from 52 to 87 years. All patients had grade 3, stage I, II, or III peripheral graft infections, as previously defined by Szilagyi and modified by vonDongen. Aortofemoral reconstruction was the most common initial bypass procedure (14), followed by femoral popliteal (6), axillofemoral (2), iliofemoral (1), and subclavian/subclavian bypass (1). Staphylococcus aureus was the most common infecting organism. Muscles used for coverage were the rectus femoris (13), the sartorius (9), the rectus abdominis (1), and the pectoralis major (1). The graft material was composed of Dacron in 16 instances and polytetrafluoroethylene in 8.(ABSTRACT TRUNCATED AT 250 WORDS)     

Correction of asymmetric nostrils (alae) by columella transposition

A new method for correction of asymmetric alae is presented. Asymmetric alae frequently follow nasal, columellar, and alar reconstruction, and the resulting distortion can pose a reconstructive dilemma. Correction of these deformities can require complex composite grafting or tissue rearrangement procedures. By transposing the columella, we have equalized asymmetric nostrils without introducing new tissue to the region. Although not appropriate to all types of alar discrepancy, this novel method, where applicable, is safe, reliable, and does not produce significant visible scarring or donor site morbidity.