Implantation Of Joint Prosthesis Research Articles

Effect of various admixtures on selected mechanical properties of medium viscosity bone cements: Part 2 – Hydroxyapatite

Poly methyl-methacrylate (PMMA) is one of the most widely used polymer composite materials in orthopaedic and trauma surgery. However, this material can change its mechanical properties when exposed to the highly aggressive environment of the human body, which may result in joint implant loosening and thus in a need for revision surgery. Therefore, in recent years, numerous researchers have investigated the effect of adding various particles to PMMA in order to obtain a composite bone cement with enhanced mechanical properties. In our study, we examined the effect of adding different grain sizes of hydroxyapatite (HA) to the commercially available PMMA (Palamed, Heraeus) on the mechanical properties of the fabricated PMMA/HA bone cement composite. Samples were subjected to compressive loading, as this type of load reflects typical conditions in the human body after joint prosthesis implantation. Hydroxyapatite of two different grain sizes was used: 5 µm (HA5) and 10 µm (HA10). Being a naturally occurring bone mineral, hydroxyapatite can improve the biocompatibility of bone cements, which would prolong the total joint replacement (TJR) survival rate. However, when added to PMMA, HA can affect its mechanical properties. In this study, the effects of adding HA was added in 0, 1, 2, 3, 5, 8, 10 % of dry mass were analysed. Obtained results demonstrated that only the addition of 2 % HA had a significant impact on the mechanical properties of PMMA. The other percentage concentrations had no effect on PMMA properties.

Effect of various admixtures on selected mechanical properties of medium viscosity bone cements: Part 1 – α/β tricalcium phosphate (TCP)

Every year millions of people around the world suffer from joint and bone diseases and require orthopaedic surgery. Owing to its unique properties such as biocompatibility and ability to bond bones with orthopaedic implants, poly methyl-methacrylate (PMMA) is among the most widely used polymer composites for bone cements in orthopaedic and trauma surgery. On the other hand, this material is characterized by low mechanical properties, which can lead to accelerated implant loosening in aggressive environments, such as the human body. Over the years, researchers have studied PMMA, especially its failure mechanism. Various additives to PMMA have been proposed to enhance the mechanical properties of this material. This study investigated the effect of mixing PMMA with α-TCP (PMMA/α-TCP bone cement composite) and β-TCP (PMMA/β-TCP bone cement composite) on its mechanical properties. The study was conducted on commercially available PMMA (Haraeus Palamed) mixed with α-TCP and β-TCP in different concentrations. TCP has bacteriostatic properties and, as a bone compatible material, it stimulates bone regeneration and bone ingrowth, which highly increases the survival rate of PMMA bonding. However, the addition of particles to PMMA can affect mechanical properties of bone cements. In this study, the effects of 0, 1, 2, 3, 5, 8 and 10% dry mass concentration of TCP in bone cement on the mechanical properties of PMMA were investigated. Samples were subjected to compressive loading. This loading mode is typical of the human body after joint prosthesis implantation. The analysis involved comparing selected mechanical parameters of samples prepared according to manufacturer’s instructions and of samples prepared with the addition of α-TCP and β-TCP. Results demonstrated that the addition of β-TCP, whose crystals are triangular, did not affect the mechanical properties of PMMA. On the other hand, the addition of more than 3% dry mass α-TCP, the inner structure of which is hexagonal, led to a slight yet significant decrease in the compressive strength of PMMA.

Swing-torsion composite friction behavior of CoCrMo/UHMWPE contact interface of artificial knee joint prosthesis implantation materials

Artificial knee replacement has been widely used in clinical medicine, but the motion of the artificial knee prosthesis is very complicated in the human body. The prosthesis suffers wear which further lead to osteolysis and aseptic loosening. Therefore, the artificial knee joint prosthesis material CoCrMo and UHMWPE were studied in this paper, and the swing-torsion composite friction behavior between CoCrMo/UHMWPE contact interfaces is carried out on the artificial knee joint simulator. The tribological behavior and damage mechanism of the CoCrMo/UHMWPE contact interface were studied during the swing-torsion composite motion friction experiment. The changed trend of swing and torsion component friction coefficients in the swing-torsion composite motion are the same as that in the single swing and torsion. UHMWPE is worn more seriously in the swing-torsion composite motion. The main damage mechanism of CoCrMo in the swing-torsion composite motion is abrasive wear and the main damage mechanisms of UHMWPE is abrasive wear and fatigue wear.

Effect of bacteriophage lysin on infection around rabbits’ knee joint prosthesis

Objective To investigate the effect of local injection of bacteriophage lysin LysGH15 into rabbits’ knee joint on the staphylococcus aureus infection after implantation of knee prosthesis. Methods Models of Staphylococcus aureus infection in rabbits’ knee after joint prosthesis implantation were built and divided into experimental group for intra-articular injection with LysGH15 and control group for injection with saline into their joints cavity. On the day before and the 1st, 3rd, 7th, 14th day after the injection of LysGH15 or saline, knee joint fluid samples were collected from the infected knee cavity to make bacterial culture and intercellular adhesion gene A (icaA) reverse transcription polymerase chain reaction (RT-PCR) detection. After the last time of sample collection, these joint prosthesis were freed and taken out. The biofilm formation was evaluated with observation of biofilm under scanning electron microscope (SEM). Results On the 1st and 3rd day after LysGH15 was injected, the concentration of bacteria in the synovial fluid of experimental group decreased rapidly to (105.3±53.8) cfu/ml and (37.9±22.5) cfu/ml, which was significantly different from that 255.7±103.4 cfu/ml ahead of injection (t=5.771, P=0.000; t=9.205, P=0.000), while there was no significant difference for the control group (t=0.388, P=0.700). On the 1st and 3rd day after LysGH15 was injected, the relative gray ratio of icaA gene expression in experimental group decreased rapidly to 0.848±0.412 and 0.156±0.071, which was significantly different from that 2.371±0.940 ahead of injection (t=6.636, P=0.000; t=10.508, P=0.000), while there was no significant difference for the control group (t=0.709, P=0.483). Scanning electron microscopic observation of biofilm showed that the damage was more serious in the experimental group than in the control group, as the Rank sum test result showed that there was significant difference between the two groups (U=2.254, P=0.024). Conclusion Local injection of bacteriophage lysin LysGH15 into the infected joint cavity can rapidly reduce the Staphylococcus aureus bacteria concentration, lower the expression of icaA gene and destroy the biofilm synthesized by bacteria on the surface of the prosthesis implanted in rabbits’ knees. Key words: Joint; Prosthesis; Biofilm; Bacteriophage lysin

Effect of phage lysin on infection and biofilm formation in rabbit after knee joint prosthesis implantation

Objective To investigate the effect of local injection of phage lyase LysGH15 into rabbits’knee joint on the systemic inflammation, local infection around knee joint prosthesis and biofilm formation on the prosthesis surface after their knee joint prosthesis implantation surgeries. Methods Models of Staphylococcus aureus infection on rabbits’ knee joint prosthesis after prosthesis implantation were built and divided into experimental group for intra-articular injection with lyase and control group for injection with saline into their joint cavity. The phage lysin LysGH15 was synthesized and purified. On the 1st, 2nd and 3rd day after the inoculation with Staphylococcus aureus bacteria into the rabbits’ knee joint cavity of the prosthesis implanted side, 0.5 ml diluted solution of LysGH15 was injected into the knee joint cavity with infection around the prosthesis for the experimental group rabbits and 0.5 ml saline was injected into the corresponding joint cavity for control group rabbits as blank contrast. On the 1st, 3rd, 7th and 14th day, blood samples were collected from their ear vein to make plasma procalcitonin test for evaluation of rabbits’ systemic infection. After the last time for collection of venous blood samples, these rabbits were killed instantly and their knee joints of prosthesis implantation side were dissociated. Tissue around the prosthesis was processed with HE staining to observe and evaluate the local infection and tissue necrosis around the prosthesis. The biofilm formation on the prosthesis surface was evaluated with semi quantitative method after the observation of samples under scanning electron microscope (SEM). Results After the injection of LysGH15 in experimental group, their serum procalcitonin level, which worked as the systemic inflammatory marker, decreased rapidly especially on the 3rd day after lysin injection. Compared with the control group, the infection degree of experimental group significantly decreased. In the experimental group, the infection and necrosis degree of the tissue surrounding the prosthesis were significantly lower in the experimental group than those in the control group. The semi quantitative scores were conducted for these samples and graded to make rank sum test. The difference between the two groups was statistically significant (U=2.4948, P=0.0126). There was a statistically significant difference in the rank sum test between the two groups in the quality of biofilm formation (U=2.2539, P=0.0242). Conclusion Phage lysin LysGH15 can alleviate the rabbits' systemic inflammation caused by Staphylococcus aureus bacteria after their knee joint prosthesis implantation, reduce the extent of damage caused by infection and inflammation to the tissue around the prosthesis, and inhibit the formation of bacterial biofilm on the surface of implanted prosthesis. Key words: Rabbits; Knee joint; Bacteriophages; Biofilms; Prosthesis-related infections; Staphylococcus aureus

Non-linearly viscoelastic constitutive equation of cancellous bone tissue and identification of material constants

In the paper a new constitutive equation for human cancellous bone tissue was formulated. A strain energy function was postulate, which describes the elastic response of the tissue to the load. The nonlinear viscoelasticity was also taken into account in the constitutive model. The material constants in the constitutive equation were identified on the basis of the results of stress relaxation tests and monotonic compression tests using the curve fitting method. The Levenberg-Marquardt algorithm of the least square method was used here. On the basis of the relaxation tests, the values of relaxation times were identified, while the elastic and viscoelastic constants were determined on the basis of monotonic compression tests. The tests were performed at room temperature. On the cuboidal samples of cancellous bone obtained from femoral heads during the surgeries of hip joint prosthesis implantation.

Swing Friction Behavior of the Contact Interface Between CoCrMo and UHMWPE Under Dynamic Loading

CoCrMo alloy and UHMWPE have been widely used in knee joint prosthesis implantation materials. In this paper, swing friction behavior of the contact interface between CoCrMo alloy and UHMWPE is studied under dynamic loading. Swing friction characteristic and damage mechanism are discussed. The results show that swing friction coefficients increase with the rising of maximum normal load and swing angular amplitude. Unloading-standing could play alleviative roles in friction and wear to a large degree. As the cycle number gradually increases, the surface roughness of UHMWPE decreases, while the roughness of CoCrMo increases. During the swing friction, the main damage mechanism of CoCrMo is abrasive wear and the main damage mechanisms of UHMWPE are abrasive wear, fatigue wear and plastic deformation. Besides, it is easier to generate surface damages with small angle and heavy load.

Variations in ESR and CRP in total knee arthroplasty and total hip arthroplasty in Iranian patients from 2009 to 2011.

Background:Implantation of joint prosthesis, either in the knee or in the hip, may cause some problems such as an infection, so that a timely treatment is essential. In this respect, discovering a marker detecting the incidence of an infection is one of the requirements of arthroplasty. The present study was conducted to determine variations of two markers in arthroplasty and infection incidence in Iranian patients.Materials and Methods:This prospective study was carried out in Isfahan’s educational treatment centers from 2009 to 2011 on patients undergoing total knee arthroplasty (TKA) and total hip arthroplasty (THA) surgical operations. The erythrocyte sedimentation rate (ESR) was measured by Sed rate device (Lena) and C-reactive protein (CRP) by autoanalyzer device (Erba) with the unit of ng/dL. The patients underwent ESR and CRP tests the day before operation, the day of operation, and 1, 2, 5, and 15 days and 1, 3, 6, and 12 months after operation.Results:Mean ESR increased during the first 5 days then decreased gradually lasting for 3 months. After 1 year it increased to a level higher than before the operation. The variations in ESR values were 19.1 ± 12.9 before the operation and 21.14 ± 10.8 after 1 year with significant difference (P < 0.001). The level of CRP had an upward trend from the first day after operation and reached its maximum on the second day, then had a downward trend up to 1 month after the operation; however, it did not reach its preoperative level during 1 year.Conclusion:ESR and CRP and their variations can be suitable factors to detect probable infections in patients undergoing TKA and THA operations.

Periprosthetic Joint Infections

Implantation of joint prostheses is becoming increasingly common, especially for the hip and knee. Infection is considered to be the most devastating of prosthesis-related complications, leading to prolonged hospitalization, repeated surgical intervention, and even definitive loss of the implant. The main risk factors to periprosthetic joint infections (PJIs) are advanced age, malnutrition, obesity, diabetes mellitus, HIV infection at an advanced stage, presence of distant infectious foci, and antecedents of arthroscopy or infection in previous arthroplasty. Joint prostheses can become infected through three different routes: direct implantation, hematogenic infection, and reactivation of latent infection. Gram-positive bacteria predominate in cases of PJI, mainly Staphylococcus aureus and Staphylococcus epidermidis. PJIs present characteristic signs that can be divided into acute and chronic manifestations. The main imaging method used in diagnosing joint prosthesis infections is X-ray. Computed tomography (CT) scan may assist in distinguishing between septic and aseptic loosening. Three-phase bone scintigraphy using technetium has high sensitivity, but low specificity. Positron emission tomography using fluorodeoxyglucose (FDG-PET) presents very divergent results in the literature. Definitive diagnosis of infection should be made by isolating the microorganism through cultures on material obtained from joint fluid puncturing, surgical wound secretions, surgical debridement procedures, or sonication fluid. Success in treating PJI depends on extensive surgical debridement and adequate and effective antibiotic therapy. Treatment in two stages using a spacer is recommended for most chronic infections in arthroplasty cases. Treatment in a single procedure is appropriate in carefully selected cases.

Expression profile of Toll-like receptors in monocytes of peripheral blood from osteoarthritic patients undergoing arthroplasty

To investigate the difference in the expression of TLRs in monocytes from patients with/without implants. Blood samples from 21 osteoarthritic patients undergoing joint replacement (11 cases) or arthroscopy (10 cases) were tested. Blood samples were obtained within 24 h before surgery and the third postoperative day to measure cell-associated TLRs by FCM. The results showed that in the absence of clinical infection, implantation of joint prosthesis seems to be associated with a significant decrease in circulating TLR2- and TLR7-positive cells, whereas the decrease in TLR4- and TLR9-positive cells was not statistically significant. A small intervention in the form of knee arthroscopy was without effect. TLRs seem to be affected by the implantation of joint prosthesis, perhaps by migration to and entrapment in peri-implant tissues. Due to their role in innate and adaptive immunity, TLRs may have consequences for the postoperative inflammation and infection.

Metal sensitivity in patients with orthopaedic implants: a prospective study

Sensitization to orthopaedic implant materials is an unpredictable event that might affect implant performance. In candidates for hip or knee joint prosthesis implantation, to evaluate preoperative assessments for identifying patients with metal sensitivity, to determine the percentage of patients who developed metal sensitivity at 1 year after prosthesis implantation, and to examine the clinical relevance of patch tests and lymphocyte transformation tests (LTT-MELISA®) for the evaluation of metal sensitization. A total of 100 patients referred for total hip or total knee arthroplasty were assessed preoperatively and then at 1 year post-implantation by means of patch tests with the metals present in the implant alloys. In a pilot study, 20 patients also underwent both patch testing and a lymphocyte transformation test (LTT-MELISA®) for the same metals. Only 72 of 100 patients were patch tested both before and after surgery, and 12 of 20 also underwent LTT-MELISA® before and after surgery. Of 31/100 patients with an apparent history of nickel sensitivity determined during preoperative assessment of subjects, 12 tested negative on both tests, and 4 with a negative history of nickel sensitivity tested positive. One year post-implantation (72 patients), 5 patients who had initially tested negative for a metal allergy became positive for at least one or more metal constituents of the prosthesis on at least one or the other test. Given the discrepancies between the information obtained while taking patient histories and test results, preoperative history-taking alone appears to be insufficient for identifying patients with metal sensitivity. Moreover, the increase in the percentage of patients who tested positive for metal sensitivity 1 year post-implantation suggests the possibility of prosthesis-induced sensitization. Therefore, objective determination of metal sensitivity at preoperative assessment should be considered in planning arthroplasty intervention, as it would help the surgeon in selecting the most appropriate prosthesis for the patient and could benefit implant performance.

UPDATE ON INFECTIONS IN ARTICULAR PROSTHESIS

The implantation of joint prostheses, especially for the hip and knee, is becoming increasingly common. This provides a significant reduction in discomfort and an immeasurable improvement in patient mobility. Reviews of the worldwide literature indicate that 1 to 5% of these prostheses become infected, although it is important to remember that as the number of operations performed to implant these prosthesis increases, so will the number of cases of this type of infection. Gram-positive bacteria predominate in contaminations of joint prostheses, in particular Staphylococcus aureus and Staphylococcus epidermidis. Infections caused by gram-negative bacilli and fungi such as Candida sp have been reported with increased frequency throughout the world. Infections of joint prostheses present characteristic signs that can be divided into acute manifestations (severe pain, high fever, toxemia, heat, redness and wound secretions) and chronic manifestations (progressive pain, cutaneous fistula formation and pus drainage, without fever). The definitive diagnosis of the infection should be made through cultures to isolate the microorganism, using material collected from joint fluid puncture, surgical wound secretions, and surgical debridement. It is essential to cover for methicillin-resistant Staphylococcus aureus, given the epidemiological importance of this agent in these infections. The total duration of antibiotic therapy ranges from six weeks to six months, and this treatment should be adjusted as needed, based on the results from culturing.

The First Case of a Staphylococcus pseudintermedius Infection after Joint Prosthesis Implantation in a Dog

We have reported a bacterial infection in a dog with progressive dysplasia of the hips. Orthopedic surgery was performed. Seven weeks prior to the surgery, the patient was bitten by another dog. The postimplantation wound exuded for four days after the surgery. Microbiological analysis performed by standard identification techniques showed the presence of Staphylococcus intermedius, but an additional molecular analysis indicated S. pseudintermedius. This was followed by an evaluation of antibiotic susceptibility of the strain which showed cefoxitin, ciprofloxacin, clindamycin, trimethoprim/sulfamethoxazole, doksycycline, erythromycin, and gentamicin resistance. Minimal inhibitory concentration (MIC) values for selected antibiotics were reported. Resistance for cefoxitin indicates that methicillin resistant S. pseudintermedius (MRSP) strains were present in individual macroorganisms, but they can expand and persist the colonization of other hosts.

Polymères bactériostatiques : une nouvelle approche pour les ciments orthopédiques

The implantation of joint prostheses may lead to infection (about 2% of the cases) with more or less dramatic consequences as morbidity or even death. Several clinical and experimental studies showed the high interest of antibiotic prophylaxis to prevent such infections but also its relative inefficiency when the infection is established. Bioactive polymers bearing anionic groups have synthesized and showed to be able to inhibit bacterial adhesion. In this study, the bioactive polymers were mixed with commercial acrylic orthopaedic cement used in the surgery of total hip prosthesis. We demonstrated that mixtures cement/bioactive polymers may inhibit adhesion of Staphylococcus aureus ( S. aureus) – strain resistant MRSA 88244) by diffusion process. Kinetics of diffusion of the bioactive polymers can be controlled by addition of hydrophobic units as methymethacrylate in the macromolecular chains of the polymers.

Osteomyelitis: clinical update for practical guidelines

Bone infections represent a diagnostic or therapeutic challenge for the infectivologist, orthopaedic surgeon, radiologist and nuclear medicine physician. Staphylococcus aureus is the major bacterium responsible for bone infections although Mycobacterium tuberculosis is emerging as an infectious agent in Italy because of immigration from Africa and Asia. Osteomyelitis requires long and expensive antibiotic treatment, including rifampicin administered parenterally for several weeks and the use of antimicrobial-impregnated cement in prosthesis substitution. Sometimes it is necessary to carry out surgical debridement of a necrotic bone or the consolidation of compromised bones and joint prosthesis implants. Radiographs and bone cultures are mainstays for the diagnosis of bone infections but are often useless in the lengthy management of these patients. Diagnosis of skeletal infections still includes conventional radiography but magnetic resonance imaging is essential in haematogenous and spinal infections. Bone scans are still useful in acute osteomyelitis whereas scintigraphy using labelled white blood cells is preferred in infections of peripheral bone segments or joint prosthesis. In the axial skeleton a combination of an agent for detecting inflammation ((67)Ga citrate) and a metabolic agent ((99m)Tc-methylene diphosphonate) enables an infection and an area of increased metabolic activity to be distinguished. [(18)F]Fluorodeoxyglucose positron emission tomography, where available, has a significant impact in the study of infections using radionuclides: high-resolution tomographic images represent an effective alternative to gallium in the assessment of inflammation of spine lesions but a comparison with morphological examinations (computed tomography or magnetic resonance imaging) is essential.

Biomechanical considerations on shoulder joint prosthesis implantation

The biomechanical goals of prosthetic reconstruction of the shoulder are to restore the normal anatomy and range of motion, and to recreate the normal soft tissue balance of the static and dynamic stabilizers of the glenohumeral joint. An unconstrained prosthesis design best reproduces the physiological articulation and original anatomy of the shoulder. Humeral head components have been recently developed, which are adaptable to the variable anatomy of the proximal humerus (third generation design). A precise reconstruction of the three dimensional structure of the proximal humerus may lead to an improved functional outcome. However, there is still a lack of biomechanical data to support this concept. The optimal design of the glenoid component remains a challenge for future research. Specific issues including the choice of biomaterials, the optimum shape, radius of curvature, surface area of the articulation, component height and stem design remain under investigation. Although the prosthetic design represents an important factor in the success of glenohumeral arthroplasty, the surgical reconstruction of the soft tissues to recreate the normal soft tissue balance as well as postoperative rehabilitation determine the functional outcome.

Phenotypic and genomic variation among Staphylococcus epidermidis strains infecting joint prostheses.

We studied the SmaI and SstII macrorestriction patterns of 54 Staphylococcus epidermidis strains isolated from 14 patients infected following the implantation of joint prostheses. Multiple strains from pus and infected tissue specimens of each patient were selected on the basis of different colony morphologies and drug resistance patterns. The same criteria were used to select 23 S. epidermidis strains from hand swabs of eight healthy individuals. For 10 of the 14 patients, all the intrapatient strains appeared to be closely or possibly related, whereas related strains were detected in the skin flora of only one of the eight healthy individuals. This observation suggests that, in most cases, the patients were infected by a single S. epidermidis clone which subsequently underwent rearrangements that yielded derivatives with divergent phenotypes and, occasionally, divergent macrorestriction patterns. The four patients whose specimens contained unrelated S. epidermidis strains were probably infected with several polyclonal strains.