Vascular complications in orthopaedic patients treated by orthopaedic microsurgeons

Over a 20 year period, five patients experienced serious vascular complications involving major arterial insult during various routine orthopaedic procedures. The nature of the vascular damage necessitated immediate surgical repair which was performed successfully by an orthopaedic microsurgeon who was either a member of the initial surgical team or the hospital's Orthopaedic Unit. The purpose of this study is to illustrate not only the severity of these limb and/or life-threatening complications, but also to focus attention on the importance of the orthopaedic surgeon's ability to manage these serious injuries promptly. This suggests the need for Orthopaedic Units to have surgeons with adequate training in microvascular techniques, so as to be able to successfully manage these unexpected and serious complications. We conclude that the presence of a vascular surgeon or an orthopaedic surgeon trained in microvascular surgery represents an invaluable attribute to the orthopaedic team, and minimizes, if not eliminates the potentially disastrous outcome from these serious intraoperative vascular complications.     

Difficult orthopaedic infections

Three difficult orthopaedic infections, infected non-union, MRSA infection and postoperative infection after joint replacement are presented. The Papineau method and continuous irrigation method are useful for infected nonunion. The choice of antibiotics for MRSA infection is described. The present state and treatment for post-operative infection after joint replacement are discussed.     

Internet resources for orthopaedic surgeons

PURPOSE: Using polarized bovine brain microvessel endothelial cells (BBMEC) monolayers as in vitro model of the blood brain barrier and Caco-2 monolayers as a model of the intestinal epithelium, the present work investigates the effects of Pluronic P85 block copolymer (P85) on the transport of the P-gycoprotein (P-gp)- dependent probe, rhodamine 123 (R123). METHODS: The permeability and cell efflux studies are performed with the confluent cell monolayers using Side-Bi-Side diffusion cells. RESULTS: At concentrations below the critical micelle concentration, P85 inhibits P-gp efflux systems of the BBMEC and Caco-2 cell monolayers resulting in an increase in the apical to basolateral permeability of R123. In contrast, at high concentrations of P85 the drug incorporates into the micelles, enters the cells and is then recycled back out to the apical side resulting in decrease in R123 transport across the cell monolayers. Apical to basolateral permeability of micelle-incorporated R123 in BBMEC monolayers was increased by prior conjugation of P85 with insulin, suggesting that modified micelles undergo receptor-mediated transcytosis. CONCLUSIONS: Pluronic block copolymers can increase membrane transport and transcellular permeability in brain microvessel endothelial cells and intestinal epithelium cells. This suggests that these block copolymers may be useful in designing formulations to increase brain and oral absorption of select drugs.     

Rapid prototyping for orthopaedic surgery

During pregnancy, mouse uterine epithelial cells produce and secrete a large amount of macrophage colony-stimulating factor (M-CSF/CSF-1). Macrophages accumulate and proliferate in the undecidualized endometrium of the pregnant uterus. Observations showed that macrophages expressed scavenger receptor class A (type I and type II) and class C (macrosialin). Scavenger receptors appeared to be involved in the removal of apoptotic cells in the degenerated decidual tissue. The expression of class A and class C scavenger receptor mRNAs in the uterus of pregnant mice was elevated but the expression of class B scavenger receptor (CD36) mRNA was similar to that of non-pregnant mice. The expression of various cytokines and chemokines, including M-CSF, monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein 1-alpha (MIP1-alpha), was enhanced in the uterus of pregnant mice, suggesting that these molecules regulate macrophage chemotaxis and immunological function in the uterus. These findings imply that the pregnant uterus provides a microenvironment for the recruitment, differentiation, and proliferation of macrophages and the regulation of scavenger receptor and cytokine expression for a successful pregnancy.     

Global blood management in orthopaedic surgery

Blood loss tends to be significant in many orthopaedic procedures because of the nature of the tissues and the inability to cauterize or coagulate bleeding bony surfaces. Regional hypotensive anesthesia has been useful in reducing blood loss particularly for joint replacement. A spectrum of measures is available to retrieve autologous blood and reinfuse it. The loop consists of predeposit autologous blood, preoperative hemodilution, intraoperative and postoperative red cell retrieval, and reinfusion. The safety of autologous blood has been accepted universally, but the measures to preserve it must be used judiciously to avoid excessive cost and, most importantly, ensure patient safety.     

Post-operative pyrexia in an orthopaedic unit

The causes of post operative pyrexia in an orthopaedic unit was studied prospectively in 520 patients who underwent surgery. Two hundred patients (38.4%) developed postoperative pyrexia as defined by having recorded high temperatures of over 38 degrees C on two occasions within 24 hours (excluding the first 24 hours post-operatively). The commonest causes of post-operative pyrexia were wound infection in 70 (13.4%), respiratory tract infections in 40 (7.6%) and malaria in 30 (5.7%) patients, while other causes were urinary tract infection in 20 (3.8%), thrombophlebitis in 15 (2.8%) and deep vein thrombosis in 15 (2.8%) of the patients; while ten (1.9%) patients had pyrexia of undetermined cause despite exhaustive clinical and laboratory workup. The other associated conditions in patients who developed pyrexia were diabetes mellitus in 20 (3.8%), HIV seropositivity and malignancy in 30 (5.7%) and six (1.1%) patients, respectively.     

Composite technology in load-bearing orthopaedic implants

Composite materials have been widely promoted as possible orthopaedic biomaterials but to date have found few successful commercial applications, due to the many challenging problems presented by their design, fabrication and testing. The range of possible composite biomaterials is reviewed, together with the possible methods of fabrication and the limitations that these place on the design of composite components. The use of composite materials allows many new design possibilities, but this freedom of design requires a clearer understanding of the objectives and constraints on the design process. The testing of composite components also presents many challenging problems, which are not adequately addressed by existing standards developed for testing conventional monolithic materials. The interaction of composite materials with the body is more complex than that of the component materials, and the prediction of their long-term mechanical performance also presents many intractable difficulties. However, despite these challenges composite materials are likely to prove invaluable in the future development of orthopaedics.     

New fibreglass casting system in orthopaedic practice

The composition, manufacture and application of a new fibreglass casting system for use in orthopaedic practice are described. The performance of the first 51 fibreglass casts used in routine fracture work is reviewed. The advantages (the cast is waterprof, extremely light and strong) and the disadvantages (an ultraviolet light source is required to cure the cast and the fiberglass tape is rather expensive) are evaluated.     

Teaching medical ethics to orthopaedic surgery residents

Orthopaedic surgery residents will be faced with a variety of ethical issues when they enter clinical practice. A previous survey suggested that they lack knowledge about how to approach several types of medical ethics dilemmas. We developed a medical ethics curriculum for orthopaedic surgery residents and presented it over a one-year period to the residents in one training program. The effect of the educational intervention on the residents' knowledge of medical ethics and their ability to handle hypothetical situations was measured by comparing their responses to a questionnaire, administered before and after the intervention, with those of residents in a training program in which the intervention was not provided. The twenty-five residents at the site of the educational intervention had a mean improvement of 0.10 in the overall score, from a mean score of 0.71 on the baseline survey to a mean score of 0.81 on the follow-up survey. This improvement was significantly greater than the mean improvement of 0.02 for the thirty residents at the control site, who had a mean score of 0.72 on the baseline survey and a mean score of 0.74 on the follow-up survey (p = 0.002). Six residents who participated in the medical ethics curriculum rated it as very useful; seventeen, as somewhat useful; one, as slightly useful; and one, as not at all useful. A medical ethics curriculum can increase orthopaedic residents' knowledge of medical ethics. Whether this curriculum also will lead to behavioral changes requires additional evaluation.     

Applications of computer modelling for the design of orthopaedic, dental and cardiovascular biomaterials

The antigen-presenting capacity of dendritic cells (DCs) makes them attractive potential cellular adjuvants for vaccination strategies. Currently, most in vitro culture systems for the production of these DCs include serum. However, this is undesirable because serum contains growth factors that vary between individuals and could affect DC development. Unless the patient's own serum is used, foreign antigens and the risk of infection will detract from the usefulness of these cells in clinical strategies. In this study we investigated the production of DCs from CD34+ progenitor cells of cancer patients or normal donors under serum-free conditions. We have established a model system for the investigation of DC development and maturation. Dendritic cells that developed from myeloid precursors accumulated after 2 weeks in an intermediate CD1a , CD80-, CD83-, CD86- stage. Intermediate DCs adhered to plastic surfaces, expressed Birbeck granules, and were negative for CD2 and CD14. In the presence of granulocyte-macrophage colony-stimulating factor and tumor necrosis factor-alpha, interleukin-4 promoted the development of these stages. Spontaneous maturation of intermediate DCs into fully activated DCs expressing CD83 and costimulatory molecules occurred asynchronously over the ensuing 2 to 3 weeks. This maturation involved increased expression of CD80, CD83, CD86, CMRF-44, HLA-A, -B, -C, and -DR as well as downregulation of CD1a and CD11b. Activated DCs are characterized by the lack of adherence to plastic surfaces and the absence of Birbeck granules. By day 28, these cells were nonphagocytic, potent antigen-presenting cells with an irreversible phenotype. This serum-free system offers advantages in that the process of differentiation and maturation of committed DCs is extended over a period of more than 28 days, allowing investigators to study the effects of individual cytokines or other supplements during distinct phases of DC development in a defined environment.     

Prophylaxis for thromboembolism in elective orthopaedic surgery

Thromboembolism is a major complication for patients undergoing elective hip and knee surgery. It can delay full recovery and increase the cost of treatment. This review article focuses on the pathophysiology, risk factors, and methods of prophylaxis in this select patient group. Emphasis is placed on the role of the nurse in the ongoing assessment of the patient's risk for thromboembolism.     

Further uses of polymethylmethacrylate in orthopaedic surgery

The Esophageal-Tracheal Combitube is a new alternative airway device. Few complications of its use have been reported. This article reports a case of a 71-year-old female with angioedema of the tongue and airway obstruction who suffered piriform sinus rupture during Combitube placement by prehospital personnel, resulting in massive subcutaneous emphysema. Caution is required when using this device in all but the most controlled situations.