Orthopedic Joint Replacement Research Articles

Biocompatibility of $beta;-stabilizing elements of titanium alloys

In comparison to the presently used α + β titanium alloys for biomedical applications , β -titanium alloys have many advantageous mechanical properties, such as an improved wear resistance, a high elasticity and an excellent cold and hot formability . This will promote their future increased application as materials for orthopaedic joint replacements. Not all elements with β -stabilizing properties in titanium alloys are suitable for biomaterial applications—corrosion and wear processes cause a release of these alloying elements to the surrounding tissue. In this investigation, the biocompability of alloying elements for β - and near β -titanium alloys was tested in order to estimate their suitability for biomaterial components. Titanium (grade 2) and the implant steel X2CrNiMo18153 (AISI 316 L) were tested as reference materials. The investigation included the corrosion properties of the elements, proliferation, mitochondrial activity, cell morphology and the size of MC3T3-E1 cells and GM7373 cells after 7 days incubation in direct contact with polished slices of the metals. The statistical significance was considered by Weir-test and Lord-test ( α =0.05). The biocompatibility range of the investigated metals is (decreasing biocompatibility): niobium–tantalum, titanium, zirconium–aluminium–316 L–molybdenum.

Biocompatibility of β-stabilizing elements of titanium alloys

In comparison to the presently used α+ β titanium alloys for biomedical applications, β-titanium alloys have many advantageous mechanical properties, such as an improved wear resistance, a high elasticity and an excellent cold and hot formability. This will promote their future increased application as materials for orthopaedic joint replacements. Not all elements with β-stabilizing properties in titanium alloys are suitable for biomaterial applications—corrosion and wear processes cause a release of these alloying elements to the surrounding tissue. In this investigation, the biocompability of alloying elements for β- and near β-titanium alloys was tested in order to estimate their suitability for biomaterial components. Titanium (grade 2) and the implant steel X2CrNiMo18153 (AISI 316 L) were tested as reference materials. The investigation included the corrosion properties of the elements, proliferation, mitochondrial activity, cell morphology and the size of MC3T3-E1 cells and GM7373 cells after 7 days incubation in direct contact with polished slices of the metals. The statistical significance was considered by Weir-test and Lord-test ( α=0.05). The biocompatibility range of the investigated metals is (decreasing biocompatibility): niobium–tantalum, titanium, zirconium–aluminium–316 L–molybdenum.

Detection of biomaterial-associated infections in orthopaedic joint implants.

Biomaterial-associated infection of orthopaedic joint replacements is the second most common cause of implant failure. Yet, the microbiologic detection rate of infection is relatively low, probably because routine hospital cultures are made only of swabs or small pieces of excised tissue and not of the surfaces of potentially infected implants. Joint replacements from patients in whom infection was suspected, after clinical, radiologic, and biochemical examinations, were used in this study. The aim of the current study was to compare the detection rate of infection in total joint replacements based on cultures of the excised tissue and scrapings from the biomaterial surface. Joint prostheses were retrieved from 22 patients requiring orthopaedic revision surgery because of suspected infection of their prostheses. Routine hospital culturing of tissue only showed bacterial growth in nine patients (41%). However, after prolonged culturing, bacterial growth was observed in 14 patients (64%), whereas extensive culturing of scrapings from the biomaterial surface indicated bacterial growth in 19 of the 22 patients (86%). In addition, confocal laser scanning microscopy enabled observation of biofilm bacteria on the surfaces of the explanted prostheses. Diagnosis in orthopaedic revision surgery should consider using a microbial or microscopic analysis of the surface of an explanted prosthesis, where the biofilm mode of growth firmly anchors and protects the infecting organisms. Improved detection of infection by analysis of the implant surface is expected to yield ameliorated therapy and a reduced need for revision surgery.

Bone cements and fillers: a review.

Charnley [1] developed the first bone cement in the 1960s using poly(methyl methacrylate) (PMMA), which remains the most widely used material for fixation of orthopaedic joint replacements. In the field of dentistry, zinc polycarboxylate and glass polyalkenoate cements received major research interest from the 1970s to the present day. The discovery of a well-integrated intermediate layer between bone and many bioactive ceramic phases from the calcium-phosphate system, such as hydroxyapatite (HA), resulted in the development of new cements incorporating such phases. These investigations ranged from the development of castable bioactive materials to modified bioactive composites. This paper attempts to give a broad overview of the many different types of cements that have being developed in the past and those which are being researched at the present time. It has lead to a set of fundamental design criteria that should be considered prior to the development of a cement for use as a bone cement or in applications requiring a bone substitute.

Problems with Wear in Artificial Orthopaedic Joint Replacements: a Review

Problems with Wear in Artificial Orthopaedic Joint Replacements: a Review

Utility of Continuous Intrathecal Infusion of Bupivacaine and Fentanyl for Postoperative Pain Following Orthopedic Joint Replacement after Accidental Dural Puncture

Utility of Continuous Intrathecal Infusion of Bupivacaine and Fentanyl for Postoperative Pain Following Orthopedic Joint Replacement after Accidental Dural Puncture

Reduction of hemorrhage after knee arthroplasty using cryo-based fibrin sealant

The spray application of cryo-based fibrin sealant was evaluated for reducing hemorrhage in a complex, anticoagulated canine model of knee joint arthroplasty. Nine heparinized dogs underwent bilateral knee arthroplasty under tourniquet control with each animal having 3 mL of fibrin sealant sprayed onto one joint and the other joint serving as control. The fibrin sealant significantly reduced total and incremental bleeding as compared to the control side ( P < .05). In addition, the hemostatic effectiveness of the fibrin sealant increased as bleeding propensity increased ( P < .05). This study suggests that fibrin sealant may reduce bleeding from orthopedic joint replacement in human patients undergoing routine operations as well as those receiving forms of anticoagulation to reduce the incidence of deep venous thrombosis and pulmonary embolus.

Antimicrobial prophylaxis in orthopaedic surgery: the role of teicoplanin.

Orthopaedic joint replacement is generally considered 'clean' surgery characterized by a low incidence of infection. In recent years the use of a clean theatre environment, high local concentrations of antibiotic in the cement and systemic antibiotic prophylaxis have been recognized as important measures to reduce infection rates significantly, and this has been supported by clinical trials. Staphylococcus aureus and Staphylococcus epidermidis cause at least half of all orthopaedic surgical infections. Gram-negative bacilli are involved to a much lesser extent (10-30%). First- and second-generation cephalosporins are currently considered by most authors as standard prophylaxis in elective orthopaedic surgery. In the light of the increasing incidence of methicillin resistance in coagulase-positive and -negative staphylococci, it is becoming more important for antibiotics to act efficiently against such organisms if they are to be of value in prophylaxis in orthopaedic surgery. A combined, single-dose of vancomycin/gentamicin has been used successfully in an open, controlled study in patients undergoing total joint arthroplasty but, given the disadvantages associated with the use of vancomycin, teicoplanin may be an alternative choice in such procedures. This review analyses four comparative trials of the efficacy and safety of teicoplanin, two with cefamandole, one with cefuroxime and one with cephazolin, as prophylaxis in orthopaedic total joint replacement surgery.

Results of autologous blood donation in orthopedic hip and knee joint replacement

This study was undertaken to investigate the efficiency of autologous blood donation (ABD) with regard to saving of homologous transfusion, to determine the reasons for exclusion from donations and the rate of incidents during the procedure, and to investigate the quality of autologous fresh frozen plasma (AFFP). During an observation period of 4.5 years, all patients scheduled for elective orthopaedic hip and knee replacement were included. A period of 4 years was evaluated retrospectively, and the last half year was evaluated prospectively. Among a collective of 710 patients, 55 (8%) non-donors and 655 (92%) donors with a total number of 1592 ABD were found. Mean age of non-donors with hip surgery was significantly higher than that of donors (72 vs. 64 years), the same was observed in patients with knee surgery (71 vs. 68 years). In the hip surgery group, 11 of 338 patients were non-donors (3%), compared with 44 of 372 patients with knee surgery (12%). In the prospective part of the study, 7% of 121 patients were non-donors. Reasons for exclusion from donation were 5 times of medical and 4 times of organisational nature. In donors for hip surgery, a mean of 3.0 units was collected, compared with 1.9 units in donors for knee surgery. On the day before operation, mean haemoglobin concentrations were similar in donors and non-donors. During ABD, 11 incidents were observed, representing 0.69% of all ABD, 83.5% of 327 donors with hip surgery left the hospital without any transfusion of homologous blood, 16.5 of donors with hip surgery received one or more homologous transfusions, compared with 100% of non-donors (p < 0.001). In knee surgery, 93.3% of donors and 63.6% of non-donors required no homologous blood, whereas 6.7% of donors and 36.4% of non-donors received one or more homologous transfusions (p < 0.001). 529 of 2850 autologous blood units (19%) were not transfused, and 19 of these units were rejected due to technical or organisational problems. In 97 patients with 240 ABD and 240 AFFP, prothrombine time, fibrinogen concentration and AT III in defrosted AFFP exceeded 70% of the values determined before ABD. ABD is a safe procedure in almost all, even elderly, patients scheduled for elective orthopaedic hip or knee replacement in both types of operations, ABD reduces the risk of homologous transfusion significantly. A number of 3-4 units is necessary for total hip replacement, whereas 2 units are sufficient for partial or total knee replacement. Haemostatic quality of AFFP meets the requirements of fresh frozen homologous plasma.

Improving patient care and organizational health in good samaritan hospital's orthopedic unit

Identifying a framework to achieve quality improvements is essential for any business. This article describes a flexible yet practical approach used at Good Samaritan Hospital, a 500-bed acule care teaching institution in Dayton, Ohio. The case study tracks the hospital's efforts to improve performance in the processes used to care for orthopedic joint replacement patients before, during, and after surgery. The lessons learned at Good Samaritan can be applied to any organizational selling.

Antibiotic prophylaxis in peripheral vascular and orthopaedic prosthetic surgery.

Peripheral vascular by-pass and orthopaedic joint replacement surgery have much in common. The consequences of infection are serious and occasionally fatal. The incidence of infection varies from 0.5% to 3% depending on the anatomical site; the infecting organisms and distribution of organisms are similar. In orthopaedics a clean theatre environment, high local concentrations of antibiotic in the cement and systemic antibiotic prophylaxis are well established methods of reducing infection rates and are supported by clinical trials. In contrast, scientific evidence supporting these three tenets is lacking for peripheral vascular surgery. There are wide variations in the choice of prophylaxis cover for peripheral vascular surgery and the first clinical cases of antibiotic containing graft material have only recently been described. The choice of an ideal antibiotic for the prophylaxis of infections associated with vascular surgery is debatable; wound and graft infections in those receiving antibiotic prophylaxis range from 0.9% to 5.8% and 0.0 to 0.9%, respectively. For both forms of surgery whether single dose, short course or longer periods of prophylaxis is preferred, it is agreed that the antibiotic must achieve adequate concentrations at the time of potential bacterial contamination. One of the limiting factors of single dose prophylaxis is the ability of the antibiotic to penetrate bone, soft tissue or haematoma. However, single dose prophylactic antibiotic cover in prosthetic surgery will attract increasing support whenever the criteria of spectrum and 'risk period' cover is fulfilled. This may help to contain the increase in multi-resistant bacteria, particularly staphylococci within the hospital ecosystem. Prolonged systemic administration can now be replaced by high local antibacterial activity at the site of prosthesis insertion via a bonded sealant or an impregnated cement. This permits high activity which can last for several weeks until all the lines are removed and tissue incorporation has become established.

Fracture toughness of acrylic bone cements

Clinical experience has shown that fracture of PMMA-based bone cements is a significant factor in the failure of orthopaedic joint replacements. Earlier studies of the fracture toughness properties of bone cement have been limited to relatively large test specimens — ASTM standard test methods require the use of specimens with dimensions considerably larger that those associated with bone cement in clinical use. In this study, a miniature short-rod specimen was used to measure the fracture toughness (K IC) or two bone cements (Simplex-P and Zimmer LVC). The dimension of our mini specimens approaches the cross-section of bone cements as usedin vivo. The short-rod elastic-plastic fracture toughness test method introduced by Barker was utilized to ascertain the effect of specimen preparation and ageing in distilled water on fracture toughness. Our study indicated that slow hand-mixed specimens possess comparable fracture toughness to centrifuged specimens. After ageing in water, however, centrifuged and slow hand-mixed specimens are more fracture resistant than specimens prepared by mixing the cement quickly. An optimum void content for the bone cements studied was suggested by the experimental results; for Simplex-P bone cement it appeared to be less than 1.6% whereas it was between 1.6 and 3.6% for Zimmer LVC cement. Simplex-P bone cement also showed superior fracture toughness compared to Zimmer LVC cement after storage in water for 60 days at 37° C.

Medical applications of ion beam processes

The use of ions beams for treatment of surfaces in medical prostheses has gained increasing interest in the past few years. The application of ion beams has taken different forms: (1) ion implantation has been used for increasing the hardness and wear resistance of the new generation titanium based alloys, as well as reducing the wear of the mating polyethylene component used in orthopedic total joint replacement. Spire Corporation has been successful in commercializing ion implantation technology and is processing several thousand artificial knees and hips per year. (Spire uses the tradename IONGUARD™ for this application.) (2) Similarly, ion implantation has proven to be very effective for increasing the corrosion resistance of the Co-Cr based alloys that have traditionally been used in orthopedic prostheses. This application should be of particular interest in resolving the issues surrounding ion release problems associated with these alloys. (3) Ion beam etching/milling has been used for producing a highly textured surface for tissue ingrowth in applications ranging from porous orthopedic implants and percutaneous devices to artificial skin and the process should have a significant impact in this application. (4) There are indications that ion implantation is a useful process for increasing biocompatibility and tissue attachment on metallic samples. This subject deserves considerable attention in the coming years.

The Design and Utilization of Operating Theatres

The Design and Utilization of Operating Theatres , edited by Johnston and Hunter, is a primer for those interested in operating room construction or remodeling; however, it falls somewhat short of the flyleaf promise that the book will make planning simple. It is a chatty, easily read collection of observations made by a 22-member team assembled for a British symposium on design and utilization of operating theatres. The loosely integrated essays are frequently repetitious, but give a clear picture of some of the human frustrations that must be accommodated. The chapter on physical layout and air handling reflects the editors' long-term preoccupation with airborne bacterial cross-contamination and specific emphasis on orthopedic total joint replacement. Their attempts at air purification may or may not prove costeffective for ultraclean procedures, but curtains, air direction, and space suits are unlikely solutions for problems associated with the serious operations of the present and future involving

Carbon in medical devices

Abstract The variability of the crystalline structure of carbon allows a correspondingly wide range of possible properties. By controlling the structure of carbon through processing, as for example in the deposition of carbon in a fluidized bed, it is possible to produce deposits with unique combinations of properties. Certain of these carbons have been found to be extremely useful in prosthetic devices. The isotropic carbons deposited at relatively low temperatures (below about 1500°C), often called LTI carbons, are blocompatible in the broadest sense. They do not induce thrombosis or hemolysis or otherwise affect either the formed or molecular element of blood. They have exceptional wear and fatique properties which are not degraded by the body environment. Accordingly, these carbons are widely used in the construction of prosthetic heart valves. The modulus of elasticity of LTI carbon is unusually low for a material of such strength and falls within the limits reported for the elasticity of bone. This property, together with its ability to interface with both soft and hard tissue without eliciting a foreign body response, makes it possible to produce orthopedic joint replacements that can attach directly to bone without using polymethylmetacrylate bone cement. Using special vacuum deposition techniques, it is possible to deposit thin, impermeable isotropic carbons that mimic the structure and properties of the LTI carbon. Materials such as polymers and fabrics can be coated with such carbons and these coatings are finding use on vascular grafts, heart valve sewing rings, percutaneous access devices, and tendon and ligament replacements. Other forms of carbons, e.g. fibers and fiber composites, are currently being used clinically in orthopedic surgery. The impact of carbon on current replacement surgery and some possibilities for future applications will be described.