Feng Zhang

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.

Vascularized fibular grafts in patients with avascular necrosis of femoral head: a systematic review and meta-analysis

BackgroundVascularized fibular grafting (VFG) has been initiated to treat avascular necrosis of the femoral head (ANFH) since the late 1970s. There are a number of review articles updating the use of VFG to treat the ANFH. None of them applied statistical analysis for combining results from different studies to obtain a quantitative estimate of the overall effect and potential harm of VFG in comparison to other treatment.MethodsSeveral electronic databases were searched to find studies using VFG to treat ANFH. The outcomes sought included Harris Score, failure rate (conversion to total hip arthroplasty (THA) and/or femoral head collapse), and complications rate. Included studies were assessed for methodological bias and estimates of effect were calculated. Potential reasons for heterogeneity were explored.ResultsThe clinical results of 69.0xa0% of VFG-treated patients and 25.0xa0% of non-VFG-treated patients were good to excellent (OR 0.13; pxa0<xa00.01). The conversion rate to THA of VFG-treated and that of other methods treated hips was 16.5xa0% and 42.6xa0% (OR 0.19; pxa0<xa00.001). Collapse rate of VFG-treated and that of non-VFG-treated hips was 16.7xa0% and 63.6xa0% (OR 0.09; pxa0<xa00.05). The complication rate of VFG-treated and that of other methods treated patients was 23.8xa0% and 8.9xa0% (OR 3.44; pxa0=xa00.09). For Steinberg stage I, II ANFH, failure rate of VFG-treated and that of non-VFG-treated hips was 9.8xa0% and 40.2xa0% (OR 0.17; pxa0<xa00.001). For Steinberg stage II, III ANFH, failure rate of VFG-treated and that of non-VFG-treated hips was 16.5xa0% and 42.8xa0%, respectively (OR 0.17; pxa0<xa00.001).ConclusionsVFG is a justified method that can prevent the ANFH from progressing to collapse, and that can retard or avoid hip replacement, especially in the hips of Steinberg stage I, II, and III.

Chapter 10: Conduit luminal additives for peripheral nerve repair.

The use of nerve conduits as an alternative for nerve grafting has a long experimental and clinical history. Luminal additives, factors introduced into these nerve conduits, were later developed to enhance the nerve regeneration through conduits. This chapter generalizes the types of additives used, and the reported performance of luminal additives in conduits to present a preference list for the most effective additives to use over specific distances of nerve defect.

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.

Effects of vascular endothelial growth factor on survival of surgical flaps: a review of experimental studies.

Partial or complete necrosis of skin flaps remains a significant problem in plastic and reconstructive surgery. Growth factors have shown promise in improving flap survival through increased angiogenesis and blood supply to the flap. Vascular endothelial growth factor (VEGF) is the most widely investigated and successful one. But the mechanisms of the effects are still not very clear. In the course of a series of experiments, we indicated that tissue survival of surgical flaps could be improved by both preoperative (sustained phase effect) and intraoperative (acute phase effect) application of VEGF. We reviewed both experimental and clinical investigations on the use of VEGF with surgical flaps to summarize the evidence of both phases of VEGF activity in promotion of flaps survival in detail. With the combinations of acute and sustained phases of effects, VEGF protein and gene, VEGF morphologic actions, and VEGF histochemical modulations suggest a pattern of VEGF activity that can be superimposed on classic descriptive mechanisms of tissue survival of flaps.

Minimally invasive pedicle screw fixation combined with percutaneous vertebroplasty in the surgical treatment of thoracolumbar osteoporosis fracture.

OBJECTnThe purpose of this study was to evaluate the feasibility and safety of minimally invasive pedicle screw fixation combined with percutaneous vertebroplasty (PVP) for treating acute thoracolumbar osteoporotic vertebral compression fracture (VCF) and preventing secondary VCF after PVP.nnnMETHODSnTwenty patients with a mean age of 73.6 years (range 65-85 years) who sustained fresh thoracic or lumbar osteoporotic VCFs without neurological deficits underwent minimally invasive pedicle screw fixation combined with PVP. Visual analog scale pain scores were recorded, and the Cobb angles and the central and anterior vertebral body (VB) heights were measured on the lateral radiographs before surgery and immediately, 1 month, 2 months, 3 months, 6 months, 1 year, and 2 years after surgery.nnnRESULTSnThe patients were followed up for an average of 26 months (range 24-30 months) after sugery. The visual analog scale score was found to be significantly decreased; from 7.3 ± 1.3 before surgery to 1.2 ± 0.7 immediately after surgery and to 0.7 ± 0.7 (p < 0.001) at the end of follow-up. The Cobb angle was 17.0° ± 4.3° before surgery and 6.4° ± 3.6° immediately after surgery. The central VB height that was 44.5% ± 7.6% before surgery increased to 74.6% ± 6.4% of the estimated intact central height immediately after surgery (p < 0.001). The anterior VB height increased from 50.7% ± 7.4% before surgery to 82.5% ± 6.7% of the estimated intact anterior height immediately after surgery (p < 0.001). There were no significant changes in the results obtained over the follow-up time period. There was no occurrence of new fracture in surgically treated or adjacent vertebrae in these patients.nnnCONCLUSIONSnMinimally invasive pedicle screw fixation combined with PVP is a good choice for the treatment of acute thoracolumbar osteoporotic VCF and can prevent the occurrence of new VCFs after PVP.

A comparative study of finger pulp reconstruction using arterialised venous sensate flap and insensate flap from forearm

OBJECTIVEnThe aim of this study was to investigate the feasibility of finger pulp reconstruction using arterialised venous flaps from forearm and compare the outcomes of arterialised venous sensate flap and insensate flap.nnnMETHODSnTwenty-seven arterialised venous flaps were reviewed retrospectively in the reconstruction of finger pulp defects in 23 patients, including 15 sensate flaps (sensate group) and 12 insensate flaps (insensate group). Nine flaps in this series were harvested from the dorsal aspect of the forearm and the other 18 were harvested from the volar aspect. Standardised assessment of outcomes in terms of objective sensory recovery, pinch power of the reconstructed digits, cold intolerance and time of returning to work was completed.nnnRESULTSnAll flaps survived completely. Twenty-six flaps were available for follow-up of more than 9 months (mean, 15.4 months). Almost all the flaps in the sensate group obtained normal sensation, while most cases of the insensate group only achieved protective sensation. Cold intolerance was present in most cases of the insensate group in comparison with the sensate group with only one case suffering from slight cold intolerance. There was no significant difference of pinch power between the two groups. All the patients were contented with the aesthetic outcomes of the surgery.nnnCONCLUSIONnThe arterialised venous sensate flap from forearm is a practical alternative for finger pulp reconstruction with satisfactory functional and aesthetic outcomes. The forearm region can be an acceptable donor site for arterialised venous sensate flap in the reconstruction of larger finger pulp defect.

Effects of taurine on reperfusion injury

Taurine is an organic acid, which has a very important function in the human body. Recently, the antioxidant property of taurine has been much emphasised. In this study, the gracilis muscle flap model was used to investigate the effect of taurine in ischaemia/reperfusion injury in rats. Totally 32 Sprague-Dawley rats were divided into two groups: control group (nxa0=xa016) and the treatment group with taurine (nxa0=xa016). After elevation of the gracilis muscle flap, 4xa0h of ischaemia was performed in both groups. Thirty min before the reperfusion, taurine (200xa0mgxa0kg(-1)) was injected intravenously. After 24xa0h of reperfusion, the amount of malondialdehyde (MDA), tissue water content and flap viability were evaluated. After 72xa0h of reperfusion, histological findings were evaluated. Amount of MDA and tissue water content were significantly lower (pxa0<xa00.005), and the flap viability was significantly higher (pxa0<xa00.005) in the treatment group 24xa0h after reperfusion. On comparing the outcomes of histological analysis between control and treatment groups, the amounts of collagen, fibroblast and angiogenesis in treatment group were significantly higher than those in the control group. However, the amount of polymorphonuclear leucocyte and tissue necrosis in the treatment group were significantly lower than in the control group. Our results showed that taurine played an important role in the process of ischaemia/reperfusion injury and presented certain protective effects with the improvement in flap survival after ischaemia/reperfusion injury.

The free dorsoradial forearm perforator flap: anatomical study and clinical application in finger reconstruction.

The perforator flaps are characterized by their thinness and the adjustable length of their vascular pedicle. The purpose of this investigation is to refine the anatomy of the perforators in the middorsoradial forearm and present our clinical experience using this free perforator flap in the reconstruction of finger defects. Anatomic study was conducted on 46 cadaver forearms. It was noted that a perforator was consistently observed in the midforearm exhibiting 4 patterns, in which a dorsoradial perforator was present with 37 cases (80.4%) originating from the interosseous artery system (patterns 1–3) and 9 cases (19.6%) from the descending branch of the radial recurrent artery (pattern 4). This perforator consistently emerged in the intermuscular septum between the extensor carpi radialis longus and extensor digitorum communis. Twenty free flaps based on this middorsoradial cutaneous perforator were elevated for the coverage of soft tissue defects of fingers (range: 3 cm × 2.0 cm to 5 cm × 2.5 cm) in 17 patients. All the flaps survived with satisfactory outcomes. Clinical findings on this perforator in terms of its origins and courses coincided with the anatomic results (&khgr;2 = 0.287, P = 0.962). The free flap based on this perforator is a reliable perforator flap in spite of varied origins.