Retinoids, 585-nm laser, and carbon dioxide laser: a numeric comparison of neocollagen formation in photoaged hairless mouse skin.

BACKGROUND: A variety of new methods for treating photoaging have been recently introduced. There has been increasing interest in comparing the relative efficacy of multiple methods for photoaging. However, the efficacy of a single method is difficult to assess from the data reported in the literature. METHODS: Photoaged hairless mice were randomly divided into seven treatment groups: control, retinoids (tretinoin and adapalene), lasers (585 nm and CO(2)), and combination groups (585 nm + adapalene and CO(2 )+ adapalene). Biopsies were taken from the treated regions, and the results were analyzed based on the repair zone. The repair zones of the various methods for photoaging were compared. RESULTS: Retinoids produced a wider repair zone than the control condition. The 585-nm and CO(2) laser resurfacing produced a result equivalent to that of the control condition. A combination of these lasers with adapalene produced a wider repair zone than the lasers alone, but the combination produced a result equivalent to that of adapalene alone. CONCLUSION: Retinoids are potent stimuli for neocollagen formation. The 585-nm or CO(2) laser alone did not induce more neocollagen than the control condition. In addition, no synergistic effect was observed with the combination treatments. The repair zone of the combination treatment is mainly attributable to adapalene.

Early passive mobilization after digital nerve repair and grafting in a fresh cadaver.

In the clinical management of combined tendon and nerve injuries, there are competing treatment strategies. Isolated tendon injuries should be rapidly mobilized after repair to prevent adhesion formation, whereas isolated nerve repairs are usually immobilized to prevent disruption and to allow axon regrowth. Recommendations in the published literature for the management of combined tendon and nerve injuries are vague and advise up to 3 weeks of immobilization. The goals of this study were to determine which length of nerve gap resulted in rupture of a repair following postoperative mobilization with the modified Duran protocol and with unrestricted motion and to determine whether nerve grafts are at risk of rupture after mobilization. A total of 100 digital nerves from 10 cadaver hands were tested with the modified Duran and the unsplinted protocols. Each digital nerve on each hand was sequentially resected and repaired at five progressively larger gap lengths after testing with both protocols. The mean nerve gaps at which disruption occurred were significantly different between the splinted (9.7 +/- 0.8 mm, n = 100) and unsplinted (7.3 +/- 1.9 mm, n = 100) protocols (t test, p < 0.001). One hundred percent of repairs remained intact, with up to 5 mm of resection with the modified Duran protocol (n = 100) and with up to 2.5 mm of resection with the unsplinted protocol (n = 100). All nerve grafts remained intact after mobilization within a dorsal-blocking splint (n = 100). Considering mechanical integrity of the nerve repair only, these data suggest that early mobilization with tendon protocols may be considered after a nerve injury to avoid the detrimental tendon sequelae that result from immobilization. The adequacy of functional recovery of mobilized nerves is yet to be determined.

Long-term outcome of embolotherapy and surgery for high-flow extremity arteriovenous malformations.

PURPOSE: To assess the long-term efficacy of embolotherapy in combination with surgery for management of symptomatic high-flow arteriovenous malformations (HFAVMs) of the lower and upper extremities. MATERIALS AND METHODS: Twenty consecutive patients with symptomatic high-flow lower extremity AVMs (LE-AVMs; n = 9) and upper extremity AVMs (UE-AVMs; n = 11) were treated from 1982 to 1999. All nine patients with LE-AVM had pain and seven had ulceration of the skin. All 11 patients with UE-AVM had debilitating pain, seven had weakness of the affected hand, and two had bony erosion. Embolization of the nidus beneath the site of maximum pain or ulceration was performed percutaneously from the femoral artery through coaxially placed microcatheters (n = 18) or surgical cutdown (n = 2). Cyanoacrylate (isobutyl or n-butyl) diluted with iophendylate or ethiodized oil was used in 19 of 20 patients. RESULTS: Follow-up was completed in eight of nine patients with LE-AVM (mean, 8.6 y) and nine of 11 patients with UE-AVM (mean, 7.4 y) after treatment. One patient with localized LE-AVM was functioning well 13 years after embolotherapy and another was functioning well 16 years after undergoing three embolotherapy procedures and two skin grafts. Five of nine patients with LE-AVM required below-the-knee (n = 4) or above-the-knee (n = 1) amputation 1-6 years after technically and clinically successful embolotherapy. All three trifurcation arteries were diffusely involved in HFAVM in patients requiring amputation. Healing of the two amputation sites, involved by AVM at the knee, was excellent after preoperative geniculate artery embolotherapy. All 11 patients with UE-AVM experienced marked symptomatic improvement; seven after embolotherapy alone and the other four after resection of AVM. One complication of digital spasm was reversed by administration of nerve blocks. CONCLUSIONS: LE-AVM with diffuse involvement of all three trifurcation arteries ultimately required amputation because of recurrence of symptoms after technically and clinically successful embolotherapy. Cyanoacrylate embolotherapy alone or in combination with surgical resection of the AVM provided excellent long-term palliation in patients with UE-AVM.

Pedal macrodactyly: coverage of a large defect with a rectus abdominus free flap.

The authors report a case of a unique reconstructive approach for an isolated macrodactyly of the lower extremity in an otherwise healthy African male. Surgical treatment included excision and local resection of the affected hypertrophied skin, soft tissue, and bone. A rectus abdominis free-tissue transfer and split-thickness skin graft were used for coverage of the defect. The foot healed without complication, and at 2-year follow-up, the patient had an aesthetically pleasing and fully functional result.

Salvage of the exposed irradiated knee joint with free tissue transfer.

Extremity radiation results in substantial complications in 6% to 10% of patients and includes fracture, edema, pain, fibrosis, neuropathy, arterial thrombosis, joint immobility, soft-tissue necrosis, and chronic infection. Chronic ulceration and infection of an irradiated joint is considered a particularly challenging problem for the reconstructive surgeon, and results of surgical management of these complications have not been reported previously in the medical literature. Two patients are presented with large ulcerated and necrotic radiation wounds of the knee, with chronic contamination, osteomyelitis, and involvement of the joint space. Both patients were treated successfully with debridement and coverage with free tissue transfer. They obtained stable, healed wounds, became pain free, and were able to ambulate on long-term follow-up. Adherence to principles established previously for the management of radiation-induced ulcers on other parts of the body not involving joint spaces (namely, thorough wound debridement and coverage with nonirradiated, well-vascularized tissue) can allow successful extremity salvage even in the presence of joint exposure, contamination, and osteomyelitis.

Patient satisfaction and outcomes of surgery for de Quervain's tenosynovitis.

A 3-part retrospective study was done to review the long-term results of surgery for de Quervain's tenosynovitis. Forty-three involved wrists in 43 consecutive patients who had surgery from 1991 to 1996 were followed by chart review, phone interview, and outpatient examination. At an average length of follow-up of 3 years there were 2 patients with recurrence of de Quervain's tenosynovitis (5%), 1 with radial sensory nerve injury (2%), and 1 with severe scar tenderness (2%). Complication was found to be significantly associated with patient dissatisfaction after surgery. A long duration of symptoms before surgery (> or = 10 months) was significantly associated with patient satisfaction. The cure rate of surgery, defined as the percentage of patients without postoperative complication, was 91%, with 88% of patients indicating full satisfaction. These findings suggest that (1) patient dissatisfaction is significantly associated with long-term complication after surgery, (2) surgery is more likely to be satisfactory for patients with a long duration of symptoms, and (3) surgical intervention is effective as definitive therapy for de Quervain's tenosynovitis.

Effects of nerve growth factor on nerve regeneration through a vein graft across a gap.

The limited availability of donor sites for nerve grafts and their inherent associated morbidity continue to stimulate research toward finding suitable alternatives. In the following study, the effect of direct administration of nerve growth factor (NGF) into a nerve conduit across a gap was tested in a rat sciatic nerve model. A 1-cm segment of the right sciatic nerve in Sprague-Dawley rats was resected, and the gap was then bridged using one of three methods: group I (NGF-treated group, n = 12), a vein graft filled with NGF (100 ng in 0.3-ml phosphate buffered saline); group II (control group, n = 12), a vein graft filled with phosphate buffered saline only; group III (standard nerve graft, n = 11), a resected segment of the sciatic nerve. All animals were evaluated at 3 and 5 weeks by behavioral testing and at 5 weeks by electrophysiologic testing. At 3 weeks, sensory testing showed that the latency to a noxious stimulus in group I animals (8.0 +/- 5.4 sec, mean +/- SD) was significantly lower than that of group II animals (13.2 +/- 6.5 sec), indicating that sensory recovery was superior in the animals receiving NGF. The mean latency of animals in group III was 12.9 +/- 6.5 sec, but the difference between the latencies of group I and group III did not reach statistical significance. At 5 weeks, there was no difference in sensory testing between groups. Motor function in groups I and III as measured by walk pattern analysis was superior to that of group II at 5 weeks (toe spread ratios 0.66 +/- 0.09, 0.48 +/- 0.07, and 0.69 +/- 0.09 for groups I, II, and III, respectively). Mean motor conduction velocities across the 1-cm gap were 8.6 +/- 4.7 m/sec, 2.5 +/- 0.7 m/sec, and 6.9 +/- 2.9 m/sec in groups I, II, and III respectively. The difference between groups I and III was not statistically significant, but the motor conduction velocity of group II was significantly slower than that of either group I or III (p < 0.002). The positive effects of NGF on regeneration of nerves across a gap seen in this study suggest that it may be useful for treating peripheral nerve injuries in combination with autogenous vein grafts.

Endothelial cell growth factor enhances musculocutaneous flap survival through the process of neovascularization.

The effect of an angiogenic growth factor-endothelial cell growth factor (ECGF)-was tested in the rat transverse rectus abdominis musculocutaneous (TRAM) flap model based on a single inferior vascular pedicle. The animals were divided into three groups (N = 8 per group) after flap elevation. In group A (control), each animal received both local and local intra-arterial injections of 1 ml saline. In group B (local), each received a 2-mg ECGF local injection and 1-ml saline local intra-arterial injection. In group C (local intra-arterial), each received a 1-ml saline local injection and a 2-mg ECGF local intra-arterial injection. All animals were evaluated on postoperative day 7. There was a significant increase in the percentage of the skin paddle survival area of the TRAM flap in both ECGF-treated groups when compared with the control group (group B vs. group A, p < 0.001; group C vs. group A, p < 0.001). This correlated with a significant increase in vascularity in both ECGF-treated groups compared with the control group (group B vs. group A, p = 0.007; group C vs. group A, p = 0.021). The results between groups B and C were not significant. ECGF, when administered via either local or local intra-arterial route, enhances musculocutaneous flap survival through the process of neovascularization.

The preconditioned TRAM flap: preliminary clinical experience.

The single-pedicled transverse rectus abdominis musculocutaneous (TRAM) flap is prone to partial flap loss and fat necrosis, especially in high-risk groups such as patients who smoke, irradiated patients, and obese patients. Possible methods to increase the reliability of the TRAM flap include the free TRAM, the double-pedicled TRAM, and the surgically delayed TRAM. When we traveled overseas to an underserved area we were largely unable to implement these options due to limitations in equipment, supplies, and the length of our trip. We encountered a combined fat necrosis and partial flap failure rate of 27% (3 of 11 patients) in a group of heavily irradiated patients. On subsequent trips we employed a technique of acute ischemic preconditioning of the TRAM flap in 5 high-risk patients and 1 low-risk patient with good results. Although this preliminary experience is too small to draw conclusions about clinical efficacy, it does demonstrate the feasibility of performing ischemic preconditioning in a musculocutaneous flap in a clinical situation.

Ischemic preconditioning improves the survival of skin and myocutaneous flaps in a rat model.

Inadequate blood supply of pedicle flaps results in partial necrosis, and prolonged ischemia during free-tissue transfer can result in partial or complete flap necrosis. Recent research in the field of cardiovascular surgery has shown that ischemic preconditioning (repeated brief episodes of coronary artery occlusion followed by reperfusion) improves myocardial muscle survival when the heart is subsequently subjected to prolonged ischemia. Preconditioning of skin or myocutaneous flaps as either pedicle or free flap models has never been studied. The goal of this investigation was to measure the effect of ischemic preconditioning on myocutaneous and skin flap survival areas and total necrosis rates after variable periods of global ischemia. In 220 rats, 100 transverse rectus abdominis myocutaneous flaps and 120 dorsal cutaneous flaps were randomized into treatment and control groups. The treatment flaps underwent preconditioning by three cycles of 10 minutes of pedicle clamping followed by 10 minutes of reperfusion for a total preconditioning period of 1 hour. The control flaps were perfused without clamping for 1 hour. Both control and treatment flaps then underwent global ischemia for 0, 2, 4, 6, 10, or 14 hours by pedicle clamping. Flap survival area was measured on the fifth postoperative day. Statistical analysis was performed with analysis of variance, student's t tests, and probit analysis. Preconditioning improved survival areas of pedicle myocutaneous flaps (0-hour group) from 47 +/- 16 percent (mean percent area surviving +/- SD) to 63 +/- 5 percent. This difference was statistically significant (t test, p < 0.04). There was no statistically significant improvement in pedicle skin flap survival. For free flap models (flaps undergoing global ischemia), preconditioning increased the survival areas of skin and myocutaneous flaps (analysis of variance, p < 10(-5)). For the skin flap model, statistical significance of the survival area difference was reached at 6, 10, and 14 hours of ischemia (t test, p < 10(-4)). The magnitude of this effect was higher in the myocutaneous flap model and reached statistical significance at 2, 4, 6, and 10 hours of ischemia (p < 10(-3)). Preconditioned flap survival areas were increased by two to five times that of non-preconditioned flaps at these ischemia times. Preconditioning lowered total necrosis rates at all ischemia times for both flap models. The critical ischemia time when 50 percent of skin flaps became totally necrotic (CIT50) improved from 6.9 to 12.4 hours by preconditioning. Similarly, preconditioning improved the CIT50 of myocutaneous flaps from 3.6 to 9.2 hours. For the first time, statistically significant improvements of partial necrosis areas and total necrosis rates have been demonstrated through intraoperative ischemic preconditioning of skin and myocutaneous flaps. In clinical practice, application of this technique may lead to improved survival during pedicled or free transfer of myocutaneous flaps and free transfer of skin flaps.

TRAM flap perforator ligation and the delay phenomenon: development of an endoscopic/laparoscopic delay procedure.

Despite its versatility in breast reconstruction, the TRAM flap is at times subject to ischemic compromise, especially in certain high risk populations. A preoperative delay procedure can decrease the likelihood of TRAM flap failure or fat necrosis, but the required extent of this delay procedure is not clearly defined. In an attempt to augment flap vascularity while reducing surgical dissection and morbidity, six distinct delay procedures and a nondelayed control were compared in a rat TRAM flap model (n = 8 for all groups). An important feature that was incorporated into several groups was the ligation of the contralateral rectus perforators through minimal skin incisions (endoscopic analogy, groups 4 to 7). The most effective delay procedure was the combination of contralateral rectus perforator ligation and ipsilateral dominant pedicle ligation (group 7), which was achieved with two minimal skin incisions and no significant flap undermining. This procedure reduced the flap necrosis from 63.2 +/- 5.8 percent (control) to 13.5 +/- 3.3 percent (p < 0.001). After completion of the animal studies, clinical application of a "minimally invasive" TRAM flap delay procedure was then undertaken in eight high risk patients with only modest ischemic compromise. Although the clinical experience is too early to draw definite conclusions, we feel that "endoscopic delay" has potential as a modality that will increase flap vascularity but minimize the morbidity of the preliminary procedure.

Comparison of the effects of ischemic preconditioning and surgical delay on pedicled musculocutaneous flap survival in a rat model.

Both surgical delay (SD) and ischemic preconditioning (IP) have been shown to be effective in improving the survival of pedicled musculocutaneous flaps. The goal of our study was to determine the effects of IP and SD, separately and together, on the survival of pedicled transverse rectus abdominis musculocutaneous (TRAM) flaps in a rat model. Thirty-two male Sprague-Dawley rats were divided into four groups of 8 rats each: (1) control, (2) 2-week SD, (3) IP, and (4) SD plus IP. A TRAM flap was elevated in each rat. Flap viability was assessed on the fifth postoperative day by computerized video planimetry. Mean area of flap survival was compared between the control, IP, SD, and SD plus IP groups using analysis of variance and Student's t-test. Improvement in surface area survival was seen in musculocutaneous flaps subjected to IP, SD, and SD plus IP compared with the control. IP and SD improved survival 1.3 and 1.4 times the control area respectively. Differences between treatment and control flaps were statistically significant (p < 0.04). In addition, the combination of SD plus IP improved survival by 1.8 times, which is statistically different from controls and from either technique individually (p < 0.002). IP and SD have similar efficacy in improving survival in this musculocutaneous flap model. The effects of IP and SD appear to be additive. The advantage of IP over SD is that IP can be performed during the same operative session as the flap elevation and only adds 1 hour to the surgical procedure.

Ischemic preconditioning of musculocutaneous flaps: effects of ischemia cycle length and number of cycles.

Previous work in our laboratory has indicated that ischemic preconditioning improves musculocutaneous flap survival 2.5 times that of the control flap area when the flaps are subsequently subjected to 4 hours of global ischemia. The preconditioning protocol used in this study was arbitrarily designed to be 10 minutes of pedicle clamping followed by 10 minutes of reperfusion. This sequence was repeated for three cycles with a total preconditioning time of 1 hour. There are no published works comparing different preconditioning protocols in musculocutaneous flaps. The goal of this study was to determine if the ischemic cycle time and the number of cycles influenced the effectiveness of ischemic preconditioning. Fifty-one male Sprague-Dawley rats were divided into one control and six treatment groups of 6 to 10 animals in each group. A transverse rectus abdominis musculocutaneous flap based on the inferior epigastric vessels was elevated in each animal. Flaps were preconditioned by pedicle clamping and reperfusion for either 5 or 10 minutes per cycle. This was repeated for one, two, or three cycles. Controls were simply perfused for 30 minutes. Each flap was then subjected to 4 hours of global ischemia. Flap surface survival area was calculated on the fifth postoperative day by computerized video planimetry. Differences in survival areas between control and preconditioned flaps were compared using analysis of variance and t-tests. There was an overall statistical significance in the comparison of flap survival of preconditioned flaps with that of controls. A single 5-minute cycle improved flap survival 2.5 times the mean control area. Two and three 5-minute cycles resulted in a reduction of the preconditioning effect, with flap survival no different than controls. Ten-minute preconditioning cycles increased flap survival 1.5 to 3 times the mean control area. Flap survival was improved by increasing the number of 10-minute cycles. Cycle time and number of cycles have definite effects on the survival areas of preconditioned musculocutaneous flaps. Ischemic preconditioning with 10-minute cycles is superior to 5-minute cycles. Three cycles of 10-minute preconditioning is statistically superior to one or two cycles. Future studies are planned to study four or more cycles and longer cycle times.

The effect of prolonged clamping and vascular stasis on the patency of arterial and venous microanastomoses.

During free tissue transfer, an artery and one or two veins must be sutured. Either the artery or the vein can be repaired first, but the optimal order of vascular repair has not been established. Maintaining a clamp on a vessel is associated with vessel injury, and releasing the clamp may cause bleeding and vascular stasis. The purpose of this study was to determine if the order of vessel repair and the length of vascular clamping affects surgical outcome. Free flaps were created on Sprague-Dawley rats (400-450 g) as follows: Bilateral abdominal skin flaps (3 x 3 cm) based on the superficial inferior epigastric vessels were elevated. The femoral artery and vein were tied and divided distal to the branching of the inferior epigastric vessels. Proximal to the branching, the artery and vein were divided. The animals were then randomized into four groups as follows: In group I (N=16), the artery was repaired and then the clamps were released to revascularize the flap. Venous stasis occurred as the vein was being repaired because of the venous clamp. In group II (N=15), the artery was repaired, but the clamp was maintained to prevent blood from coming in contact with the fresh arterial anastomosis and to prevent venous stasis. The vein was then repaired. In group III (N=15), the vein was repaired first but the venous clamp was not released until the artery was repaired. In group IV (N=15), the vein was repaired first and the clamps were released, allowing venous blood to contact the fresh anastomosis while the artery was being repaired. After final clamp removal, all anastomoses were assessed immediately for evidence of thrombosis. Five days postoperatively the skin flap was evaluated for evidence of necrosis and the anastomosis was inspected for evidence of late thrombosis. The anastomoses were resected for histopathological evaluation. Flap success was compared between groups using chi-squared analysis. Eleven of 16 flaps failed (69%) in group I, and 3 of 15 flaps failed (20%) in each of groups II, III, and IV. Statistical significance was reached in comparing group I with the other three groups (p < 0.01). All failures in group I were caused by immediate venous thrombosis. The other failures were secondary to arterial thrombosis. Histopathological analysis failed to demonstrate any differences between the groups. According to these results, arterial repair followed by clamp release prior to the completion of the venous repair results in a low success rate, probably secondary to venous stasis within the draining vein while the venous anastomosis is being completed. If the arterial repair is performed first, then it is recommended that the arterial clamp be maintained until the venous repair is completed. If the vein is repaired first, then it can be clamped or unclamped with similar results.

Trends in the incidence of upper extremity soft tissue malignancies: a 40-year review of the Connecticut State Tumor Registry.

BACKGROUND: Although soft tissue malignancies of the upper extremity are rare, the management of these lesions has been controversial and the etiologic factors associated with the occurrence of these tumors are not well understood. The purpose of this study was to identify possible epidemiologic factors related to a recently noted rise in the occurrence of these tumors in the state of Connecticut. METHODS: The occurrence of upper extremity soft tissue tumors over the past 40 years was reviewed in the Connecticut State Tumor Registry. Demographic data collected included occupational history, residence, and presence of concomitant malignancies. Tumor histology, the extent of resection, and the incidence of recurrences were also noted. Factors associated with recurrence were identified using linear regression analysis. RESULTS: During the 40-year study period, 359 patients having upper extremity soft tissue tumors were entered into the Connecticut State Tumor Registry. An increasing trend in the number of upper extremity soft tissue tumors was evident. Many patients were involved in heavy industry or related fields. Fibrosarcoma and liposarcoma were the most common tumor types, occurring in 111 (30.3%) and 48 patients (13.2%), respectively. Sixty-seven patients presented with a synchronous second primary malignancy of the breast (49 patients), lung (seven patients), or gastrointestinal tract (five patients). Most patients (69.9%) underwent local excision of the soft tissue tumors, with fewer undergoing wide excision (20.3%) or radical excision (9.7%). Recurrence, which occurred in 144 patients, was found to be associated with extent of resection, occupational history, and concomitant malignancy. Delineation of such risk factors may be helpful in identifying patients in whom aggressive management may decrease recurrence and improve survival.

A new experimental model: the vascular pedicled cutaneous flap over the mid-dorsum of the rat.

The cutaneous vascular anatomy of the mid-dorsum in the rat and its role in flap design was studied in the rat. The investigation consisted of anatomic dissection, methylene blue injection into the axial artery, and flap harvesting in live animals. Dissection and injection revealed that the mid-dorsum of the rat derives its blood supply largely from the 10th intercostal artery, here referred to as the middle dorsal artery, which originates from the lateral aspect of the thoracic aorta. The cutaneous vascular territory of the middle dorsal artery was defined as follows: the medial border, midline of the dorsum; the lateral border, midaxillary line; the cephalic border, a line joining the medial and lateral borders midway between the level of the axilla proximally and 1 cm above the base of the rib cage distally; and the caudal border, a line drawn midway between the latter point proximally and the anterior superior iliac spine distally. Both unilateral and bilateral vascular pedicled island cutaneous flaps were harvested in living rats based on and exceeding the vascular territory delimited by methylene blue injection. Flaps limited to this territory with intact middle dorsal arteries showed total survival, while oversized flaps underwent partial necrosis peripherally. Because of its simplicity, reliability, and consistent vascularity, this flap has potential applications in the study of flap hemodynamics.

Aneurysm of the radial artery following blunt trauma to the wrist.

Aneurysms involving the distal radial artery are rare lesions which are usually secondary to penetrating trauma or iatrogenic injury. Blunt trauma is an extremely uncommon cause. In the absence of a history of penetrating vascular injury, a radial artery aneurysm may easily be misdiagnosed as a nonvascular mass such as a synovial cyst. A diagnostic approach to these lesions is discussed emphasizing the role of noninvasive studies in uncomplicated cases. Excision of the aneurysm is recommended. The decision to ligate or reconstruct the radial artery remains controversial.

Timing, magnitude, and utility of surgical delay in the TRAM flap: I. Animal studies.

Surgical delay is an effective technique, but the precise timing of the delay effect and the required extent of the delay procedure are uncertain. We endeavored to study flap survival as a function of the duration of the delay period in a rat transverse rectus abdominis myocutaneous (TRAM) flap model. Two specific delay procedures (limited and extensive) were utilized, and flap survival was assessed after delay periods of 3, 7, 10, 14, 21, and 30 days (n > or = 7, all groups). A delay of 7 days or greater resulted in statistically significant improvement in flap survival in all groups. The delay effect appeared to be maximal at 14 days, and in the extensive delay group, a 14-day delay resulted in statistically greater flap survival than a 7-day delay. Improvement in flap survival was greater when an extensive delay procedure was used. Although the model system has limitations, the rat TRAM flap appears to be a suitable model for the study of the delay phenomenon. Possible clinical correlations are addressed in part II.