Michael F. Angel

Vascular endothelial growth factor (VEGF) expression and the effect of exogenous VEGF on survival of a random flap in the rat

The induction of endogenous vascular endothelial growth factor (VEGF) production in the skin flap with ischemic injury and the effect of exogenous VEGF on survival of the ischemic skin flap were studied in rats. A dorsal flap model (3x10 cm(2)) was used in this study. In Part I, biopsies were taken from the flap at 2.5, 5.5, and 8.5 cm distances from the distal edge at 0, 6, 12, and 24 h after the flaps were sutured. Malonyldialdehyde (MDA) and VEGF(165) protein level were measured. In Part II, exogenous VEGF (1 microg/ml) was injected subdermally into the flaps in 14 rats before the flaps were replaced. Flaps that received a saline injection were used as the controls. The skin paddle survival was measured on postoperative day five. The results showed that the MDA level in the distal part of the flap significantly increased at 24 h postoperatively when compared to MDA in other parts of the flap. However, VEGF levels in the distal part of the flap significantly decreased when compared to the middle part of the flap. Subdermal injection of exogenous VEGF to the distal area of the flap could significantly improve survival of the distal flap (89% of total skin paddle) when compared to the control, which had a 64% mean percent survival. We conclude that production of endogenous VEGF protein is significantly increased in the skin flap with mild ischemia, but decreased in the flap with severe ischemia. Administration of exogenous VEGF could significantly enhance survival of ischemic flaps.

Clinical applications of venous flaps in the reconstruction of hands and fingers

In recent years, the venous flap has been highly regarded in microsurgical and reconstructive surgeries, especially in the reconstruction of hand and digit injuries. It is easily designed and harvested with good quality. It is thin and pliable, without the need of sacrificing a major artery at the donor site, and has no limitation on the donor site. It can be transferred not only as a pure skin flap, but also as a composite flap including tendons and nerves as well as vein grafts. All these advantages make it an optimal candidate for hand and digit reconstruction when conventional flaps are limited or unavailable. In this article, we review its classifications and the selection of donor sites, update its clinical applications, and summarize its indications for all types of venous flaps in hand and digit reconstruction.

The effect of postconditioning on the muscle flap survival after ischemia-reperfusion injury in rats.

ABSTRACT Background: Timely recognition of vascular compromise of free flaps is crucial to salvaging failing flaps due to the vulnerability of muscle tissues to ischemia. The concept of postconditioning (post-con) that has been introduced as an “after injury” strategy may be beneficial to salvage the failing muscle flaps. We aim to investigate the effect of post-con on the muscle flap survival after ischemia-reperfusion (I/R) injury in rats. Materials and methods: The gracilis muscle flap model was used and a complete 4 hr of ischemia was generated by occlusion of the pedicle of dissected flap. The post-con procedure was started at the end of ischemia with six cycles of 15 s of reperfusion, followed by 15 s of complete reocclusion prior to the unlimited reperfusion. Muscle edema, malondialdehyde (MDA) level, muscle viability, and different time intervals (0, 3, 6, 18 hr) of gene expression of VEGF post-perfusion were assessed. Results: Significant difference in muscle viability was noted between the post-con group and the control group (4 hr of ischemia followed by full reperfusion without intervention) in spite of being noncomparable with the sham group (no ischemic exposure) 3 days postoperatively. Statistically decreased muscle edema and MDA level were observed in the post-con group compared with the control group. Histological study also showed that attenuated inflammatory reaction was observed in the post-con group compared with the control group. A relatively higher level of VEGF since 3-hr post-reperfusion in the post-con group compared with the control and sham groups was recorded. Conclusions: Our results indicate that post-con procedure effectively reduces I/R injury and improves the survival of muscle flaps after ischemia. The consistent expression of VEGF in a high level may play an important role in the physiological effects of post-con.

Secondary ischemic tolerance improved by administration of L‐NAME in rat flaps

Nitric oxide (NO) under basal conditions is an important regulator of vascular tone. Under ischemic conditions, however, NO can combine with superoxide anion to produce the damaging hydroxyl free radical. The current project observes the effect of inhibiting NO production (L‐Nitro‐amino‐methyl‐arginine, L‐NAME) on flaps rendered ischemic by secondary (2°) venous obstruction.

Extensor Tendon Reconstruction for Zones II and IV Using Local Tendon Flap: A Cadaver Study

PURPOSE To assess the feasibility of reconstructing extensor tendon segmental defects in zones II (over the middle phalanx) and IV (over the proximal phalanx) using local tendon flaps (LTFs), explore in these 2 zones the anatomical constraints that limit the use of the LTF as regards the maximum defect that could be reconstructed, and compare this flap with distant tendon grafts (DTG) reconstruction for similar size defects. METHODS We dissected 33 fresh-frozen cadaver extensor tendons from the fingers of 9 fresh-frozen cadaver forearms. A 0.5-cm defect was created in each extensor tendon of 21 fingers: 12 in zone II and 9 in zone IV. In each of 12 additional fingers, we created a 1.0-cm defect in zone IV. In 25 fingers, LTFs measuring 0.5 and 1.0 cm in length were harvested from the extensor tendon proximal to each defect and were turned distally to reconstruct the respective 0.5- and 1.0-cm defects. In 8 fingers, palmaris longus tendon grafts measuring 0.5 and 1.0 cm in length were used to reconstruct the respective 0.5- and 1.0-cm defects. Limited kinematic analysis was performed on the repaired fingers by maximally flexing the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints in sequential fashion. RESULTS In zone II, repair was technically feasible using LTFs in all 9 of the 0.5-cm extensor tendon defects. Likewise, LTFs were feasible for zone IV to repair 6 of 8 and all 9 of the respective 0.5- and 1.0-cm extensor tendon defects. Two failed repairs occurred early in the study by suture gapping following LTF of 0.5 cm to repair extensor tendon defects in zone IV of a long and small finger during maximal flexion. We determined the anatomical constraints for the use of the LTFs. The maximum length of repairable defect using the LTF was 0.5 cm in zone II of the index, long, ring, and small fingers, and zone IV of the small finger. In zone IV of the index, long, and ring fingers, the largest defect that could be repaired was 1.0 cm. Similarly, DTGs were feasible in zone II to repair all 4 of the 0.5-cm defects and in zone IV to repair all 4 of the 0.5- and 1.0-cm extensor tendon defects. CONCLUSIONS In a cadaver model, both the LTF and the DTG are anatomically feasible and technically easy to perform. However, the LTF avoids a distant donor site, provides morphologically similar donor tendon that is readily accessible, and avoids morbidity that may be associated with the use of DTG. In this study, however, the LTF was limited in its use to zones II and IV of the extensor tendon.

Chronic Headache As A Sequela of Rigid Fixation for Craniosynostosis

Rigid fixation has been used over the past 20 years for the long-lasting correction of traumatic and congenital craniofacial defects. It has been noted that the use of plates and screws can result in the migration of the hardware through the skull to the inner cerebral cortex where it embeds in the dura. In addition, there is controversy concerning the safety of using titanium plates in the pediatric population. We report here on an 8-year-old boy who presented to our clinic with a chronic headache after rigid craniofacial fixation using titanium plates 7 years before.

Distraction osteogenesis as a treatment for retrognathia and obstructive sleep apnea resulting from temporomandibular joint septic arthritis: A case report

t e Septic arthritis is a rare but serious infective process that is characterized by pain, swelling, and possible loss of function of the affected joint. Knees and hips are the most commonly affected joints, but the temporomandibular joint (TMJ) is among the other joints that are infrequently affected. Reports of septic arthritis of the TMJ are relatively rare, with only approximately 80 cases reported in the previous 70 years. Of these cases, most have been in adults, with only 11 cases reported in children younger than 12 years. Septic arthritis of the TMJ can have diferent complications, including ankylosis, condylar esorption, and altered mandibular growth. In ases where condylar resorption occurs, this can lead o the development of significant complications, inluding obstructive sleep apnea (OSA). The authors resent a case of a pediatric patient who developed SA as a sequela of septic arthritis of the TMJ and iscuss the patient’s surgical treatment with mandiblar distraction osteogenesis (DO).

Contemporary postnatal plastic surgical management of meningomyelocele

BACKGROUND The goals of this study were to review the outcome of the surgical procedure and hospitalization associated with meningomyelocele repair, and to examine the results of different closure strategies. METHODS Eighty-three consecutive patients having surgery for meningomyelocele over a ten year period form the basis of this study. Thirty-two closures with a mean defect size preoperatively of 11.5 cm(2) were performed by the neurosurgeon (ADP), and fifty-one closures with a mean defect size of 28.4 cm(2) by the plastic surgeon (MFA). RESULTS Defects up to 12 cm(2) were closed with local advancement fasciocutaneous flaps. As defect size increased, latissimus muscle flaps were added in 30 (36%) and gluteus muscle in 16 (19%). In recent years, 18 patients (21.6%) with a mean defect of 29 cm(2) were treated with overlapping of deepithelialized fasciocutaneous flaps to add an additional layer of coverage to the dural closure. There were 9 major complications, 6 requiring reoperation. There were 10 minor wound failures managed conservatively. Mean hospital stay was 24.2 days. Re-operation increased length of stay to 45 days (p < 0.0001). Minor wound problems added 6 days to mean hospital stay. Wound failure did not correlate with either defect size or closure technique. Thoracic location was associated with increased wound failure (p < 0.05). Use of a shunt did not increase morbidity. All closures remained durable after discharge. CONCLUSIONS Location in the thoracic area predicts major wound failure and need for reoperation. Wound complications significantly increase hospital stay. The use of a variety of techniques to achieve multi-layered closures leads to durable coverage for defects of all sizes.

Encephalocele as a late complication of cranial vault reconstruction in a patient with Crouzon's syndrome.

Encephalocele is a rare late complication of craniosynostosis repair. An undiagnosed nick to the dura is the etiology of this complication. It usually presents within a few months to years after repair. This case report describes a patient with Crouzons Disease who had a craniosynostosis repair as an infant and presents 22 years later with an encephalocele. The patient had a thorough physical exam, 2D, and 3D CT Scans as a preoperative workup. Surgical intervention included repair of the encephalocele, cranialization of the frontal sinus with bone grafting, and Lefort III osteomies for mid face advancement. The patient benefited from a two-team simultaneous approach between Neurosurgery and Plastic Surgery. The patient also benefited from an aggressive one-stage repair of all her defects and deformities.

The role of fructose-1,6-diphosphate in cell migration and proliferation in an in vitro xenograft blood vessel model of vascular wound healing.

SummaryBoth smooth muscle cells and endothelial cells play an important role in vascular wound healing. To elucidate the role of fructose-1, 6-diphosphate, cell proliferation and cell migration studies were performed with human endothelial cells and rat smooth muscle cells. To mimic blood vessels, endothelial and smooth muscle cells were used in 1:10, 1:5, and 1:1 concentrations, respectively, mimicking large-, mid-, and capillary-sized blood vessels. Cell migration was studied with fetal bovine serum-starved cells. For cell proliferation assay, cells were plated at 30–50% confluency and then starved. The cells were incubated for 48 h with fructose-1, 6-diphosphate at (per ml) 10 mg, 1 mg, 500 µg, 250 µg, 100 µg, and 10 µg, pulsed with tritiated-thymidine and incubated with 1 N NaOH for 30 min at room temperature, harvested, and counted. For migration assay, confluent cells were starved, wounded, and incubated for 24 h with same concentrations of fructose-1, 6-diphosphate as in proliferation assay. The cells were fixed and counted. Smooth muscle cell proliferation was inhibited by fructose-1, 6-diphosphate at 10 mg/ml. In the xenograft models of 1:10, 1:5, and 1:1 fructose-1, 6-diphosphate inhibited proliferation at 10 mg/ml. In migration studies 10 mg fructose-1, 6-diphosphate per ml was inhibitory to both cell types. In large-, mid-, and capillary-sized blood vessels, fructose-1, 6-diphosphate inhibited proliferation of both cell types at 10 mg/ml. At the individual cell level, fructose-1, 6-diphosphate is nonstimulatory to proliferation of endothelial cells while inhibiting migration, and it acts on smooth muscle cells by inhibiting both proliferation and migration.