Pre-implantation apposition grafts for edentuous anterior maxillary. Retrospective study of 36 patients

INTRODUCTION: Apposition grafting is a method of choice for reconstruction of the anterior maxillary. The purpose of this work was to evaluate the success rate, the degree of bone resorption and the osteointegration of these grafts. MATERIAL AND METHODS: We reviewed retrospectively 36 cases of pre-maxillary bone apposition in patients operated from 1998 to 2002. Autografts were used for all patients. The harvesting site was parietal for 24 patients, intraoral for 8 and iliac for 4. RESULTS: There was two graft failures. The success rate was 94.5%. Partial resorption with effect on implantation was noted in 3 patients. Eighty implants were inserted successfully in 234 grafted sites with on average 2.4 implants per graft. Three implants were removed. Implant survival was 96.2%. DISCUSSION: This study demonstrated that the premaxillary apposition technique using autologous grafts provides sufficient bone volume to enable optimal implant insertion and stability.     

Complications in high tibial (medial opening wedge) osteotomy

Introduction The high tibial (medial opening wedge) osteotomy (HTO) is a standard procedure in the treatment of varus gonarthrosis. This is potentially associated with various complications. The aim of this study was an analysis of complications and potential technical mistakes.Materials and methods A total of 85 patients (49 male and 36 female) suffering from varus gonarthrosis underwent a medial opening wedge HTO. The osteotomy was fixed in 55 patients by a spacer plate (Puddu plate; group A). In group B (n=30), the osteotomies were fixed by C-plate.Results The rate of complications was 43.6% in group A and 16.7% in group B (p<0.05). Infraction of the lateral tibial head is a possible intraoperative complication. This was seen in 11.7%. An additional osteosynthesis was required in group A. In contrast, the C-plate can solve this problem without additional measures. General complications of the HTO were seen: infection (4.7%), hematoma (4.7%), and thrombosis (2.3%). In every case of a severe deep infection, the osteotomy space was filled with synthetic bone graft. These grafts were used only in group A. Failure of the implants is a potential cause of loss of correction. This complication was seen nine times in group A but never in group B.Conclusion A diligent surgical technique and a convenient implant are obligatory in (medial opening wedge) HTO.     

Gellan-based scleral implants of indomethacin: in vitro and in vivo evaluation

Film-type scleral implants of indomethacin with gellan gum were prepared by solvent casting and evaluated for uniformities of thickness, weight, drug content, and surface pH. The effect of plasticizers like glycerol, propylene glycol (PG), and polyethylene glycol 200, and 400 on the void volume of free gellan films (placebo) was calculated from the water content of the films. The drug release from the prepared implants was determined using a static dissolution set-up developed and optimized in our laboratory. Based on the results of the void volume and initial drug release studies, glycerol and PG were selected as the plasticizers for the gellan-based implants. The morphology of the drug-free films (containing 10% and 40% of PG) and the drug-loaded films (before and after dissolution and crosslinked) was studied using scanning electron microscopy. Further, the effect of plasticizer concentration, gellan concentration, effect of crosslinking technique, and duration of crosslinking using calcium chloride on in vitro drug release characteristics were evaluated. Selected batches of the implants were subjected to pharmacodynamic studies, after scleral placement, in uveitis-induced (intravitreal injection of bovine serum albumin 50 μg/ml) rabbit eyes. The release of indomethacin from the prepared implants followed matrix diffusion kinetics with diffusion co-efficient (n) values ranging between 0.358 to 0.708 and seemed to depend on both gellan and plasticizer concentration. Surface crosslinking with 10% calcium chloride for 8 hr retarded drug release (1.42 times less than noncrosslinked implant) and was optimum. The pharmacodynamic studies showed a marked improvement in the various clinical parameters (congestion, keratitis, flare, clot, aqueous cells, and synechias) in the implanted eye compared with the control eye in the rabbits. The scleral implants survived up to 3 weeks in vivo.     

Immediate reconstruction of extruded alloplastic nasal implants with irradiated homograft costal cartilage

OBJECTIVE: To describe a novel surgical protocol for the management of patients presenting with extruded nasal implants. STUDY DESIGN: Retrospective chart review. METHODS: Analysis of consecutive patients presenting with extruded nasal implants from 1986 to 2000. Patients were selected from a large database of revision rhinoplasty cases. Inclusion criteria were: 1) at least one previous rhinoplasty procedure, 2) an extruded nasal implant that was documented preoperatively, 3) immediate reconstruction that was carried out with irradiated homograft costal cartilage (IHCC), and 4) at least 1 year of follow-up recorded, including standard postoperative rhinoplasty photographs. A total of 18 patients met the inclusion criteria and form the basis of this study. Data gathered from the charts included date of surgery, last date of follow-up, location of implant extrusion, alloplastic material, specific use of IHCC for reconstruction, percent of clinical IHCC resorption at last follow-up, and presence of warping of the IHCC. RESULTS: All 18 patients were satisfied with the cosmetic outcomes of their nasal reconstructions. The most common extruded alloplast was Silastic, followed by Gore-Tex (W.L. Gore & Associates, Inc., Flagstaff, AZ). There were no cases of extrusion or infection of the IHCC implant subsequent to immediate reconstruction of the extruded alloplast. Clinical resorption of the IHCC was minimal, with a mean follow-up of 26 months. Only one patient had a complication, warpage, resulting in removal of the IHCC. In that patient, the IHCC still had carving markings on the implant after 2 years in vivo. CONCLUSIONS: In this series of patients, a novel surgical protocol was used. The extruded implant was removed and immediate reconstruction with irradiated rib cartilage was done. All patients were evaluated for postoperative infection, graft extrusion, and satisfaction with cosmetic result. There was one major complication in this series of 18 patients, warping of the IHCC, which necessitated removal and replacement. This approach appears to be a reasonable method for reconstruction of extruded nasal alloplasts.     

羟基磷灰石涂层牙种植体骨内种植的临床研究

142颗羟基磷灰石涂层牙种植体被植入73例患者，临床观察18－48个月，累积成功率为92．3％，生命表分析显示成功率随临床观察时间延长而下降。在本组资料，羟基磷灰石涂层剥脱和基桩中央螺栓折断是失败的主要原因，这可能与种植体羟基磷灰石涂层质量和机械设计不合理有关。在牙槽骨高度和宽度不足的病例，植入种植体时同期植骨是可行的。     

血管内支架结合电解可脱弹簧圈治疗颅内动脉瘤

目的 初步总结使用血管内支架结合电解可脱卸弹簧圈（GDC）治疗颅内梭形及宽颈动脉瘤的体会,探讨其适应证、方法、疗效及并发症。方法 5例颅内梭形动脉瘤及12例宽颈动脉瘤,首先将冠脉支架跨动脉瘤颈放置,通过支架的网孔将微导管送入动脉瘤腔,继续填塞GDC。结果 13例动脉瘤致密填塞,3例大部分填塞,1例支架未能送入颅内而单用弹簧圈部分栓塞,载瘤动脉通畅,临床效果优良。结论 联合使用支架及微弹簧圈是治疗颅内梭形及宽颈动脉瘤的有效方法,远期疗效需进一步随访。     

Aging Adversely Impacts Biological Properties of Human Bone Marrow‐derived Mesenchymal Stem Cells: Implications for Tissue Engineering Heart Valve Construction

Our aim was to study the aging effects on the in vitro biological properties of bone marrow‐derived mesenchymal stem cells (BMSCs) for construction of tissue‐engineered heart valves. BMSCs were taken from teenagers with congenital heart diseases, and middle‐aged and elderly patients with valvular diseases. Proliferative abilities were compared among the three groups by using colony‐forming unit counting and growth curves (5‐bromo‐2′‐deoxyuridine assay). Cell differentiation, vascular endothelial growth factor (VEGF) release under hypoxic condition, and migratory abilities were compared as well. Colony‐forming units in the teenage group were significantly greater than those in the other two groups (P < 0.05), and significantly higher counts were observed in the middle age group than in the aged group (P < 0.05). Growth curves presented similar trends in which cells' proliferative abilities in the aged group decreased significantly (P < 0.05), while no differences were noted between the two nonaged groups. The differentiation potential to endothelial cells, osteoblasts and adipocytes, VEGF releases, and migratory abilities differed significantly between the aged group and nonaged groups (P < 0.05). However, no differences were noted between the two nonaged groups. BMSCs from older patients with heart valve diseases could be harvested and expanded successfully, and the phenotype and morphology were uniform as nonaged groups. However, the proliferative and differentiation properties of aged cells, as well as cytokine release and migratory abilities, are significantly impaired.     

四种螺纹截面形态对种植体初期稳定性影响的三维有限元研究

目的 利用即刻负载有限元模型研究种植体不同螺纹截面类型因素对初期稳定性的影响.方法 利用Pro/E软件、Hypermesh 7.0软件及ABAQUS 6.5有限元软件,建立4类种植体即刻负载的三维有限元模型,比较4种螺纹截面形态(V型,支撑型, 矩型和反支撑型)在分别垂直和水平加载时对种植体初期稳定性的影响.结果 对不同螺纹截面形态种植体的微动程,垂直加载时支撑型螺纹种植体微动最小,反支撑型螺纹种植体微动最大,水平加载时反支撑型螺纹种植体微动最小,支撑型螺纹种植体微动最大.结论 螺纹截面的形态和强度对垂直相对位移有影响, 对颊舌相对位移影响不大,螺纹顶边和底边与种植体体部的角度越大,抵抗垂直向的能力越强,但强度差,因此在螺纹种植体设计时,要兼顾螺纹截面角度和强度.     

Regulating human implant technologies in Europe--understanding the new era in medical device regulation

It has been suggested that we are entering a new era in medical device regulation in Europe. This paper discusses the implementation of the European Medical Devices Directive (EMDD) in EU member states with a particular focus on the UK. Case studies are then presented of two models of implant technologies--Trilucent breast implants and the 3M Capital hip prosthesis. Both have been withdrawn from the marketplace recently in controversial circumstances. Different aspects of regulatory activity are outlined with a bearing upon benefits and safety from national health services' and consumers' perspectives, and a number of issues concerned with the ability of regulatory mechanisms and practices to serve public health and safety are identified. Our analysis of the case studies draws parallels with studies of drug regulation, and explores the construction of risk and public participation in policy making. We argue that there are weaknesses in the regulation of medical devices and that commercial interests have dominated regulatory policy. Our case studies, however, suggest a shift towards a more user-oriented shaping of regulation.