[Effect of sterilisation with formaldehyde, gamma irradiation and ethylene oxide on the properties of polyethylene joint replacement components]. / Vliv sterilizace formaldehydem, gama zárením a etylenoxidem na vlastnosti polyetylenových komponent kloubních náhrad.

PURPOSE OF THE STUDY: Each method of sterilisation has some effect on the structure and properties of UHMWPE and thus also on joint replacement longevity. This study was designed to compare, using objective methods of measurement, several kinds of sterilisation and to recommend the one which has the best prospect for making joint replacements last longer. MATERIAL AND METHODS: Two groups of UHMWPE samples were tested. Group 1 included virgin GUR 1020 polyethylene, non-modified and non-sterilised (Meditech, Germany). Group 2 comprised of three sets of samples sterilised with formaldehyde, gamma irradiation and ethylene oxide, respectively. In both groups, physicochemical properties were assessed by infrared spectroscopy (IR), and the oxidation (OI) and trans-vinyl (VI) indices, which show the degree of oxidation of a material, were determined. Free-radical concentrations were measured by the method of electron spin resonance (ESR). The mechanical properties of each sample were studied using small punch tests (SPT) and testing microhardness (MH). Any change in mechanical properties can affect, to various degrees, the quality and longevity of a prosthetic joint. RESULTS: The samples sterilised by gamma irradiation showed higher values of both the OI (0.37) and the VI index (0.038) than the other samples (OI, 0.02 to 0.05 and VI, 0). Also, the free-radical concentration was detectable only in the gamma-sterilised sample. Values obtained for mechanical properties were as follows: peak load in the range of 58.48 N (gamma irradiation) to 59.60 N (ethylene oxide); ultimate load in the range of 46.69 N (gamma irradiation) to 57.50 N (ethylene oxide); ultimate displacement in the range of 4.29 mm (gamma irradiation) to 4.58 mm (virgin polyethylene and formaldehyde); and work to failure in the range of 185.18 mJ (gamma irradiation) to 205.89 mJ (virgin polyethylene). Microhardness values were obtained in the following ranges: 41.2 to 44.6 MPa (virgin polyethylene); 40.2 to 44.1 MPa (formaldehyde); 46.1 to 49.3 MPa (gamma irradiation); and 40.3 to 44.2 MPa (ethylene oxide). DISCUSSION: The samples sterilised with formaldehyde and ethylene oxide have mechanical properties very similar to virgin polyethylene, they are not damaged by oxidation and do not contain free radicals. Owing to these characteristics, the immediate and long-term oxidation stability of the three samples is higher. The sample sterilised by gamma irradiation showed the presence of free radicals and immediate and long-term oxidative degradation. This results in the deterioration of mechanical properties and the growth of crystallinity due to enhanced oxidation and leads to higher polyethylene microhardness. CONCLUSIONS: Sterilisation with gamma irradiation results in oxidative degradation and mechanical property deterioration, which is one of the potential risks of a shorter life span of joint replacements. The use of ethylene oxide or formaldehyde does not change polymer properties nor has any effect on oxidation of materials. Therefore, a longer life expectancy of the joint replacements sterilised with ethylene oxide can be expected. The life span of their joint replacements is a key issue for the patients. Prosthetic joint loosening is painful and the patient often requires re-implantation. A higher number of re-implantations is associated with higher costs for the institution involved and, consequently, for the whole health care system. Although this study basically deals with chemical issues, it informs the surgeon of the latest developments leading to the improvement of implanted materials, which can increase the life expectancy of joint replacements and patients' satisfaction.

[Cement-within-cement femoral stem reimplantation technique]. / Reimplantace náhrady kycelního kloubu metodou docementování dríku do puvodního cementového luzka.

PURPOSE OF THE STUDY: The reimplantation of a cemented femoral component at revision is always a challenge for the orthopaedic surgeon, particularly when the cement mantle is intact. The aim of this study was to provide evidence that the recementing of a femoral stem into the original cement mantle can be included in routine surgical procedures. MATERIAL AND METHODS: A group of 104 patients with femoral stem revision, followed-up for an average of 50.2 months, were retrospectively reviewed. The outcome evaluation was focused, in the first place, on survivorship of the femoral component, acetabular migration, and dislocation and infection after revision arthroplasty. Hip function evaluation was based on the Harris hip scores before surgery and at the latest follow-up. On radiographs Gruen zones were assessed pre-operatively and at the latest follow-up. The results were statistically evaluated using the Kaplan-Meier survival analysis (Statistica 8.0). RESULTS: Of the 104 patients, only three (2.9 %) had stem re-revision due to its loosening. Further 16 patients underwent revision for other post-operative complications. The success rate of reimplantation in our group including all post-operative complications was 81.7 %. The average Harris scores were 56 before surgery and 87 at the latest follow-up. Radiolucent lines in Gruen zones were on average 0.45 mm in width before revision and 0.15 mm at the latest follow-up. Fourteen patients had second revision within 20 months of the first and only five were revised after a long period. DISCUSSION: The cement-within-cement exchange of a femoral component is a relatively frequent orthopaedic procedure. Despite this frequency, however, there have not been enough literature reports based on large patient groups to give support to its routine use. The aim of this study was to demonstrate on a large patient group that recementing a femoral stem into the original intact cement mantle can be considered an established operative technique. Our results suggest that the list of indications for this technique, as described by Lieberman and Nelson, can be extended by the following: broken stem with an intact distal cement mantle, replacement of a monoblock femoral component due to severe head damage, loosening of the femoral component without impairment of the distal cement mantle, conversion of a cervico-capital to a total hip replacement and the need of removing all bone cement. No risk is associated with reimplantation of the original component if there is no need for a different implant to correct angle or length stability. A new implant is always used when any part of the femoral component has been damaged mechanically. If only the proximal stem requires recementing, the use of the original component is preferred because of absolute cement/stem cohesion. The number of our patients in which the technique failed was generally in agreement with the results of other authors. CONCLUSIONS: Utilisation of the original cement mantle of a femoral component is one of the options at revision arthroplasty. It requires rational considerations based on the type of surgery, state of the cement mantle, and type of material used for the femoral stem. The method is indicated preferably in the hips with an intact cement mantle treated for loosening of the acetabular component, recurrent dislocation or unequal leg-length in monoblock femoral components. In such situations the removal of well-fixed cement would also involve a considerable loss of bone tissue. The follow-up outcomes showed that the involvement of the cement-within-cement technique in routinely used surgical procedures is fully justified.

[Polyetheretherketone (PEEK). Part I: prospects for use in orthopaedics and traumatology]. / Polyetheretherketon (PEEK) - I. cást: Perspektivní materiál pro ortopedickou a traumatologickou praxi.

On the basis of current studies, polyaryletherketone (PAEK) polymers appear to be materials with great prospects for medical application. The most important member of this family of semi-crystalline thermoplastics is polyetheretherketone (PEEK) with its composites. The excellent properties of this material find their use in the treatment of various disorders of the skeletal system. At present they are used with advantage to construct spinal implants, and replacements for other orthopaedic applications and for dental and trauma medicine are at advanced stages of clinical testing.

[Polyetheretherketone (PEEK). Part II: application in clinical practice]. / Polyetheretherketon (PEEK)--II. cást: Poznatky o vyuzití v klinické praxi.

Polyetheretherketone (PEEK) is one of the up-to-date organic polymer thermoplastics with applications in orthopaedics and trauma medicine. This study presents a detailed analysis of its tests and applications in clinical medicine. A wide range of PEEK modifications and composites are commercially available, e.g., PEEK-Classix, PEEK-Optima, Endolign and Motis. They differ in their physical properties, which makes them suitable for different applications. Other forms, so-called PEEK bioactive composites, contain beta-tricalcium phosphate and hydroxyapatite. Research in this field is also concerned with the surface finish of this polymer thermoplastic and involves macroporous titanium and hydroxyapatite layers, or treatment with laser for an exactly defined surface structure. The clinical applications of PEEK and its composites include, in addition to components for spinal surgery, osteosynthesis plates, screws, intramedullary nails or external fixators, which are implants still at the stage of prototypes. In this review, attention is paid to the use of PEEK thermoplastics for joint replacement. Mid-term studies involving hundreds of patients have shown that, for instance, the VerSys Epoch Fullcoat Hip System (Zimmer) has a markedly lower stress-shielding effect. Carbon fibre-reinforced (CFR-PEEK) composites are used to make articulating components for total hip replacement. Their convenient properties allow for production of much thinner liners and an enlargement of the femoral head diameter, thus reducing the wear of joint implants. CFR-PEEK composites are particularly effective for hip resurfacing in which the Mitch PCR (Stryker) acetabular component has been used with good results. The MOTIS polymer acetabular cup (Invibio Ltd.) is another example. Further PEEK applications include the construction of finger-joint prostheses (Mathys AG), suture anchors (Stryker) and various kinds of augmentations (Medin). Based on the information obtained, the authors suggest further use for CFR-PEEK composites, such as the construction of articulating liners for total shoulder joint replacement, particularly in reverse shoulder arthroplasty.

[Distribution of UHMWPE wear particles in periprosthetic tissues of total hip replacements]. / Distribuce oterových cástic UHMWPE v periprotetických tkáních u TEP kycelního kloubu.

INTRODUCTION: Information on the distribution of UHMWPE wear particles around joint replacements is essential for the understanding of aseptic loosening of implants. MATERIAL AND METHODS: Samples of soft tissue from around total hip arthroplasty (THA), which had a typical appearance of polyethylene granuloma, were collected from the places corresponding to the radiological zones of Gruen and DeLee. The samples were taken from 45 patients (group N1). Since the samples varied in macroscopic appearance and/or the technique of processing, a sub-group of 15 more uniform samples (group N2) were collected by the first author in order to ensure the maxi- mum reliability. The samples were examined for the extent of tissue damage and the amount of particles in each zone. The comprehensive orthopaedic evaluation of tissue damage was carried out as follows: the first author studied the joint replacement revision protocol and pre-operative radiograph in each patient. He evaluated the degree of damage in each zone and wrote down the results in the form of an ordered series according to increasing damage (relational statement). This ordered series was called orthopaedist's statement (OS). The amount of particles in each zone around THA was assessed by the IRc method developed in the laboratory of the second author. IRc method yielded numbers that were proportional to the volume of biologically active particles with size 0.1-10 microm in given zones. The set of numbers from IRc method for each individual case of THA was ordered in a series (relational statement). This ordered series was called a measurement statement (MS) and could be directly compared with orthopaedist's statement (OS). The OS's and MS's for each patient were statistically evaluated, independently for each group (N1=45, N2=15), and two hypotheses were tested: a) distribution of particles in various zones around THA is uniform, b) there is an agreement between OS and MS. RESULTS: The number of UHMWPE wear particles in different periprosthetic zones within each patient was significantly different in both groups (N1 and N2) at the significance level of P=0.001. The OS's and MS's were identical at the significance level P=0.05. Moreover, maximum amount of particles was found in zones III and 7 in 40 patients out of 45. DISCUSSION: Polyethylene wear debris is considered one of the major causes of THR failures. However, neither national nor international literature has provided a study that would show a statistically significant relationship between the numbers of wear particles in individual zones and the extent of tissue damage in these zones. This is most probably due to the fact that four independent methods had to be developed in order to compare OS's and MS's: 1) accurate technique of tissue sampling during THA revisions, 2) accurate method of isolating wear particles from the tissues collected, 3) efficient, reliable and reproducible quantification of UHMWPE particles and 4) correct method of statistical analysis for comparison of the orthopaedist's statements and the measurement statements for all patients involved. CONCLUSION: The distribution of wear particles in the periprosthetic tissues of THA is not uniform, i.e. the amount of wear particles of each patient varies from zone to zone. The extent of tissue damage in each zone, as assessed by the orthopaedic surgeon (OS), was in a good agreement with the volume of 0.1-10 microm particles obtained by IRc measurement (MS) of the zone. We have provided conclusive evidence that the highest number of particles is accumulated in zone III and zone 7. As the number of particles the zones varies and the greatest damage is repeatedly found in areas with the highest particle numbers, it can be concluded with certainly that wear particles are one of the main causes of aseptic joint implant failure.

[Heterotopic excessive wear granuloma mistaken for an aneurysm of the external iliac artery]. / Zámena masivního heterotopického oterového granulomu s aneuryzmatem arteria iliaca externa.

Reimplantation of a total hip arthroplasty (THA) with excessive heterotopic polyethylene granuloma is reported. An 84- year-old woman, who had undergone THA reimplantation on the right side 4.5 years previously, was indicated for revision surgery due to aseptic failure of the acetabular component. Pre-operative examination revealed a pulsating mass below the right inguinal ligament that raised the suspicion of a pseudoaneurysm of the external iliac artery. Because of this suspected late complication of the first revision arthroplasty, surgical exploration was indicated by the vascular surgeon prior the second reimplantation. A CT-scan showed a large mass attached to a preserved lumen of the external iliac artery, and this was diagnosed by the vascular surgeon as a pseudoaneurysm. However, no pseudoaneurysm was found by a vascular surgery procedure, and the large mass ventrally extending the external iliac artery appeared to be a large polyethylene granuloma well enveloped in a fibrous pseudocapsula. The granuloma was removed and the wound sutured. Twelve days later, revision total hip arthroplasty and acetabular reconstruction were successfully carried out.

[Long-term experience with the combined ARBOND hydroxyapatite coating in implant osteointegration]. / Dlouhodobé zkusenosti s kombinovaným hydroxyapatitovým povrchem ARBOND v osteointegraci implantátu.

PURPOSE OF THE STUDY: The hydroxyapatite coating of an implant surface provides osteoactive conditions that can support osteointegration of cementless joint arthroplasties. However, the possibilities of hydroxyapatite degradation, resorption and delamination that may become responsible for failure of total hip arthroplasty (THA) have been reported. The aim of the study was to assess the properties of Arbond hydroxyapatite coating by comparing the long-term survival of implants identical in construction but different in surface coating. MATERIAL: One group (HA) comprised 86 patients (100 THAs) with an average age of 45.14 years (range, 22.3 to 77.4 years) at the time of surgery who received a femoral stem (Walter) with a coating of Arbond sprayed over the proximal half. The other group (control) included 92 patients (100 THAs) with an average age of 49.7 years (range, 33 to 68.7) who had an identical femoral component without coating. In both groups the conical-shaped acetabular cup (Walter) and femoral head made of sintered ceramics were used. The patients in whom one or both components were replaced or extracted were not included in the final clinical evaluation (Harris Hip Score). For the statistical analysis of survival, a stable component still in place at the date of the revision procedure was regarded as surviving; a lose component at the same date was considered a failure. Finally, 71 hips of the HA group followed up for an average of 15.51 (range, 5.6 to 18.56) years and 39 control hips at an average follow-up of 14.19 (range, 6.24 to 18.48) years were clinically evaluated. The data of patients who died in the course of study (HA group, 11; control group, 14) were included in the clinical evaluation with the date of their last follow-up. METHODS: For both groups, the Kaplan-Meier survival curves were constructed for overall survival and for the survival of acetabular and femoral components separately. Differences in survival curves were evaluated with the use of Gehan's Wilcoxon test. Component survival was also calculated using 15-year life-table survivorship analysis. Differences in variables under study were assessed with the use of the two-tailed Student's t-test. A p value of less than 0.05 was considered significant. RESULTS: A total of 29% hips were revised in the HA group, 27% for aseptic loosening of the acetabular cup, in 2% both components were removed because of deep infection. In the control group revision procedures were performed in 61% of the hips. Except for one case of deep infection (1%), the reason was cup loosening in 30%, stem loosening in 12% and both components loosening in 18% of the hips. The HA group showed a significantly longer survival of both total hip prostheses and individual components. The final HHS was significantly better than the initial score in both groups. There was no difference in the degree of improvement between the two groups. The radiographic data showed full osteointegration of stems in the HA group. The control group, on the other hand, had 87% of the stems with translucent lines in zone I and zone VII according to Gruen's classification. DISCUSSION: The significantly longer survival of hips in the HA group gives support to the use of hydroxyapatite coating in total hip arthroplasty. The poorer results in grit-blasted implants, as compared with the literature data, can be explained by allow degree of roughness of the Walter implant surfaces. CONCLUSIONS: The combined Arbond hydroxyapatite coating improves conditions for implant osteointegration in the bone.

[New metod for quantification of UHMWPE wear particles around joint replacements]. / Nová metoda kvantifikace oterových cástic UHMWPE v okolí kloubních náhrad.

PURPOSE OF THE STUDY: The orthopaedic community has unanimously adopted the view that ultra high molecular weight polyethylene (UHMWPE) wear particles are a very frequent cause of aseptic implant loosening. Some studies have tried to provide objective evidence for this.We have found descriptions of particle distribution or morphology, but no report that would objectively cor- relate the number of particles in zones surrounding an implant with the extent of damage to these zones. The aim of this study was to develop a method allowing us to evaluate a number of samples with polyethylene abrasive wear large enough to find association between the extent of damage around a THA and the number of biologically active UHMWPE wear particles, 0.1 to 10 microm in size. MATERIAL AND METHODS: In 28 patients undergoing revision total hip arthroplasty (THA) at the 1st Orthopaedic Clinic, 1st Faculty of Medicine, Char- les University, we took samples of typical osteoaggressive granuloma from defined zones around the implant; the zones corresponded to those described by Gruen and DeLee. The extent of tissue damage in each zone was evaluated on the basis of pre-operative radiographs and by the extent of osteolysis and damage to soft tissues actually observed during revision THA. The volume of wear particles in each zone was assessed by the IRc method developed by us; this is based on a quantitative evaluation of infrared spectra. To verify the methodology, a comparison between tissue damage and the number of particles in each zone was made in three randomly selected patients. RESULTS: We introduced a method of detailed orthopaedic evaluation which enabled us to categorize zones around a revised THA according to the extent of damaged tissue. As a result, a series of zones ranked by the extent of damaged tissue, or an "orthopaedist's statement" (OS), was obtained. At the same time we adopted a method, based on infrared spectroscopy and termed IRc, by which the number of particles in the samples of damaged tissues and osteoaggressive granulomas collected from the area around a revised THA was determined.The results of evaluation were presented as numerical data that, in a defined way, were converted into a series of zones ranked according to the number of wear particles, i.e., the "result of measurement" (RM). In this study we verified the methods described above and made a comparison of OSs and RMs for three randomly selected patients. The very good agreement found confirmed the reliability of both methods which will soon be used to evaluate a group of patients large enough to provide statistically significant results. DISCUSSION: The IRc method determines a total volume of UHMWPE wear particles, 0.1 to 10 microm in size, which are generally considered to be most biologically active. This study suggests that the distribution of particles around a THA is uneven and that relation between tissue damage and the number of wear particles in individual zones surrounding a THA does exist. The major conclusion from the orthopaedic point of view is a confirmation of the assumption that UHMWPE wear particles are one of the chief causes of THA failure. Although this fact is generally accepted, studies correlating the number of particles with tissue damage and osteolysis in individual zones are very scarce. CONCLUSIONS: The quick and simple IRc method offers a possibility to quantify polyethylene wear particles in soft tissues. The number of 0.1 to 10 microm wear polyethylene particles correlated with pre-operative radiographic findings and orthopaedic evaluation of revision THAs in three randomly selected patients. The confirmed correlation between the extent of tissue damage in individual zones surrounding a THA and the volume of wear particles detected in these zones supports the view that UHMWPE wear particles are one of the main causes of THA failure.

[Late hematogenous infection of prosthetic joint]. / Pozdní hematogenní infekce kloubních náhrad.

The importance of prevention in late hematogenous infection is well understood but, because responsibility lies with general practitioners and other specialists, the orthopedic surgeon is usually not much interested. In both our and other countries, discussions are taking place on whether and to what extent antibiotic prevention should be carried out. Antibiotic prophylaxis of hematogenous infection is not indicated for all patients with joint arthroplasty, but only for a limited, defined group of patients at high risk. In these, however, the present state of knowledge suggests that prevention is necessary. A preventive treatment of late hematogenous infection is used for a procedure or a disease associated with risks in all the patients involved within two years of prosthetic joint implantation and, after this period, only in immunosuppressed patients. Surgery on the urogenital tract associated with the risk of bacteremia includes prostate gland surgery, operations for urinary bladder tumors, nephrolithotomy, extracorporeal lithotripsy and prostate biopsy. Certain conditions, such as urinary catheter presence, intermittent catheterization, urethral stent presence, urine retention and a history of urinary tract infection or prostate inflammation, pose an increased risk of bacterial colonization for the urogenital system. Dental procedures associated with a risk of bacteremia include tooth extraction, surgery on the parodontium, surgical extraction of an impacted tooth, dental implant treatment, procedures in a tooth's apical region, initial application of an orthodontic apparatus, intraligamentous blocks and also cleaning teeth and implants expected to bleed. Gynecological surgery with a risk of bacteremia are abdominal, vaginal and laparoscopic hysterectomies, surgery for cancer contaminated with vaginal bacteria, reconstruction surgery, operations on the pelvic floor for defects associated with urinary incontinence and use of xenotransplants. In obstetrics, a cesarean section carries some risks. In general surgery, the preventive administration of antibiotics is indicated, apart from situations always requiring antibiotic therapy, also for advanced forms of acute appendicitis, perirectal abscess, invasive endoscopy procedures on the colon, soft tissue phlegmona or abscess, surgical treatment of venous ulceration and pressure sores, and limb amputation. When inserting any piercing in patients with joint replacement at risk, it is recommended to do it with antibiotic administration; also, it is necessary to responsibly treat any inflammatory complication. The system of prevention for the late hematogenous infections of prosthetic joints is not developed as thoroughly as, for instance, it is in cardiology for patients with valve reconstruction. Because of the reasons given above, it is advisable to set up unambiguous guidelines for the prevention of late hematogenous infection in patients with joint replacement.

[Late hematogenous infection of prosthetic joints in our patients and proposal for a system of prevention]. / Výskyt pozdní hematogenní infekce kloubních náhrad v nasem souboru a návrh systému prevence.

PURPOSE OF THE STUDY: To design a prophylactic strategy for late hematogenous infection is not an easy task. It requires the assessment of risk factors for the patient as well as of a potential source of bacteremia. Cost effectiveness, efficacy of the antibiotic selected and complications associated with antibiotic treatment, such as allergic reactions and development of resistance to the antibiotic given, should also be considered. The aim of this retrospective study is to evaluate the occurrence of late hematogenous infection in our large group of patients, to analyze risk factors and to suggest an optimal system of antibiotic prophylaxis in order to prevent the development of this unwelcome complication. MATERIAL AND METHODS: Since our objective was to include a large number of patients, a retrospective study was chosen as the method used. The patients treated for infectious complications of total joint replacement at the 1st Department of Orthopaedics, Teaching Hospital in Motol, 1st Faculty of Medicine, Charles University, in the years 1991 through 2004, were evaluated with the use of a targeted questionnaire and complete medical records. The group comprised 229 patients, 149 women and 80 men. Of these, 123 were treated for infection of total hip replacement, 102 for total knee replacement, two had infection of prosthetic shoulder joints and two had infection of elbow joint alloplasty. RESULTS: Medical history of 37 patients (16.3 %) included infection of or a risk-associated procedure on the urogenital system (endoscopic or open surgery, prostate gland biopsy, extracorporeal lithotripsy). Six patients (2.6 %) underwent surgery with possible bacteremia (intestine resection for tumor, 2x; surgery for paronychium, 2x; cholecystectomy, 1x; and appendectomy, 1x). Dental surgery or mouth disease was recorded in 11 patients (4.8 %). DISCUSSION: The authors suggest that the orthopedic surgeons performing joint replacement should assume their deal of responsibility and should provide relevant, comprehensive information to both the patient and the attending physician. These surgeons should be ready to remain involved in their patients' further therapies and, after assessing all risks, should be able to recommend an optimal prophylactic treatment. The introduction of a new preventive approach requires a simple and uncomplicated scheme. Any complicated and expensive system of preventive antibiotic administration will only meet with lack of understanding and with trivialization. The requirement that antibiotic treatment should be selected according to the site and type of risk-associated disease is logical, but, in our opinion, rather formal and unrealistic. The authors prefer a simple system permitting a rapid and overall introduction of preventive measures. CONCLUSIONS: The groups of patients indicated for prevention of late hematogenous infection of prosthetic joints are clearly defined and, by no means, do they involve all patients with total joint replacement. Key words: prosthetic joint, infection, prevention, antibiotics, complication.

[Method for assessment of distribution of UHMWPE wear particles in periprosthetic tissues in total hip arthroplasty]. / Metodika sledování distribuce oterových cástic UHMWPE v okolních tkáních u TEP kycelního kloubu.

PURPOSE OF THE STUDY: Aseptic loosening of implants is the main complication affecting the longevity of joint prostheses. The highest proportion of loosening occurs due to osteolysis produced by the presence of ultra-high molecular weight polyethylene (UHMWPE) wear particles smaller than 1 microm. These can be identified by microscopic, spectroscopic or light-scattering methods. Here we describe our method for counting wear particles, based on the principle of light scattering. MATERIAL AND METHODS: Between 2002 and 2004, we collected samples of polyethylene granuloma in 19 patients who underwent revision total hip arthroplasty (THA) for aseptic loosening. The samples were obtained from strictly defined areas corresponding to the radiographic presentation of periprosthetic zones describes by Gruen and DeLee in THA. The frozen samples were lyophilized and subjected to delipidation and hydrolyzation procedures in 65 % HNO3. The top part of solution containing wear particles was blended with isopropanol, and the mixture was filtered through a 10-microm polycarbon membrane. Subsequently, the filtrate was filtered through a 0.1-microm membrane. Membranes with trapped particles, 0.1 to 1.0 microm in size, were sent for particle characterization and quantification. The number of wear particles was measured by the method based on light scattering with calibration (LSC), using a Beckman Coulter LS230 analyzer that can express particle size distribution in a given volume in percent. The method was based on the fact that each particle reflects rays that can be measured. The medium measured contained an unknown number of UHMWPE particles and a known number of calibration glass beads varying in size. The number of UHMWPE particles was calculated from the known number of calibration beads. RESULTS: Because the collected samples were also used to develop the method, comprehensive data was obtained in six patients only. Particle distribution recorded in the periprosthetic zones in THA varied greatly; up to a five-fold difference in particle concentration was observed between the zones. In five of the six patients, the highest particle concentration was found in zone III. DISCUSSION: Seeking a method that would be exact, quick and cheap and would eliminate particle aggregation remains the subject of study for researchers cooperating with clinical practice. At present methods based on weighing isolated particles are used most frequently. We developed the LSC method that, for quantification, utilizes the ability of particles to disperse light, and allows us to calculate the real numbers of UHMWPE wear particles in a medium containing a known number of calibration particles. Although this is an indirect method, it gives more accurate results than the direct weighing of particles. The advantages of the LSC method involve less demand on sample purity, greater speed and low limits of detection. The method is useful for statistical evaluation of a larger number of samples. The variation in particle distribution in THA found in this study is in agreement with the relevant literature data; it is also in agreement with our assumptions and clinical findings. CONCLUSIONS: The authors developed an original method for assessment of UHMWPE wear particles in tissue samples, which is quicker than the methods so far used. In the periprosthetic tissues studied, particles about 1 microm in size were detected; their numbers (about 1010 particles per gram dry tissue) are in agreement with the literature data. The distribution of particles in periprosthetic zones in THA was uneven. The highest number of particles was found in the neighboring zone III and zone 7, as described by Gruen and DeLee. Key words: wear, polyethylene, total hip arthroplasty, light scattering, aseptic loosening, wear particles.

[Seven-year clinical experience with the SVL/Beznoska implant for total knee arthroplasty]. / Sedmileté klinické zkusenosti s náhradou kolenního kloubu SVL / Beznoska.

PURPOSE OF THE STUDY: The aim of the study was to evaluate our seven-year experience with the anatomic, non-constrained SVL/Beznoska implant for total knee replacement. MATERIAL: A total of 374 cemented total knee replacements, using the SVL/Beznoska implant, were evaluated in 333 patients treated at the First Orthopedic Clinic Charles University in Prague, during a seven-year period. In addition, a patellar replacement was used in five of these patients. Included in the evaluation were also eight non-cemented and hybrid SVL/Beznoska implants used 6 years ago. METHODS: The aim of the study was to evaluate the results in terms of implant function. Therefore, the longevity of implants was assessed by Kaplan-Meier's survival analysis. Another criterion was the flexion achieved. To be able to compare our clinical results involving the SVL/Beznoska implant with other, foreign types of implants, the patients were evaluated on the basis of the New Jersey Orthopaedics Hospital Knee Evaluation System. RESULTS: The Kaplan-Meier's survival score was evaluated. The mean maximum flexion achieved in the patients with SVL implants was 107 degrees . The evaluation by the New Jersey Orthopaedics Hospital Knee Evaluation System showed excellent outcomes in 269 (72 %) patients, good outcomes in 79 (21 %) patients, satisfactory in 19 (5 %) and poor in 7 (2 %) patients. There was no mechanical failure of the implant, such as break of an implant or dislocation of a PE component. Six infected implants and four aseptic loosenings were recorded. Three patients diagnosed with an infected total knee replacement had been treated for rheumatoid arthritis for a long time. One patient was on dialysis for renal insufficiency and one had erysipelas. DISCUSSION: The results of our group with the SVL/Beznoska implant were compared with those obtained from the group of 63 patients who underwent total knee arthroplasty with the LCS implant. In these patients, the mean maximum flexion achieved was 105 degrees , and the criteria of the Knee Evaluation System showed excellent outcomes in 81 %, good in 16 % and satisfactory in 3 % of the patients. No unsatisfactory outcome was recorded. Considering the fact that the LCS implant was used only in younger and active patients, the outcomes achieved with the SVL/Beznoska system can be regarded as very good. Of the six patients with infectious complications, three were treated with immunosuppressive therapy for rheumatoid arthritis, one was on dialysis for renal insufficiency and one experienced a flare-up of erysipelas. CONCLUSIONS: The most important outcome of the evaluation of 374 total knee replacements, using the SVL implant carried out at the First Orthopedic Department of the First Faculty of Medicine, Charles University, was the finding of a perfect function of all components in all patients treated. None of the complications occurring in our group was associated with the use of this implant.

[Non-cemented alloplasty of the hip joint]. / Necementovaná aloplastika kycelního kloubu.

The authors present a review of the contemporary problem of non-cemented alloplasty of the hip joint. They compare the advantages and disadvantages of cemented and non-cemented endoprostheses of the hip joint in relation to possible loosening and possible re-operation and with regard to the surgical technique. The negative action of bone cement is divided into two groups: 1. immediate effects which act on surrounding tissues and the patient's organism during operation. 2. late effects which involve abrasion and the phagocytic response to small cement fragments and the formation of osteoaggressive granulations. These late effects are demonstrated on histological material. The authors emphasize that non-cemented alloplasty has also some pitfalls which involve in particular higher demands on the accuracy of the surgical technique and, no doubt, more severe haemorrhage. The main advantages are according to the authors the elimination of negative effects of bone cement, in particular late effects. The authors tried to classify the contemporary spectrum of available non-cemented implants with regard to their design, materials and surface finish.

[Shoulder arthroplasty in traumatological indications, surgical technique]. / Endoprotéza ramenního kloubu v traumatických indikacích--operacní technika.

PURPOSE OF THE STUDY: Shoulder arthroplasty in traumatological indications has a considerably worse prognosis than when the indication is osteoarthritis or rheumatoid arthritis. The problem lies in the technique of rotator cuff reconstruction and the restoration of adequate bio-mechanical properties of the shoulder joint. In this study, the difficult reconstruction of four-part fractures of the proximal end of the humerus was improved by the development of a new type of shoulder joint endoprosthesis. MATERIAL AND METHODS: Our endoprosthesis permits fixation of bone fragments of the greater and lesser tubercles to the shaft and to the diaphyseal fragment by using screws or a toothed plate designed for this purpose and produced in various shapes. In addition to the modularity of the head, the endoprosthesis has a component facilitating better recovery of biomechanical properties of the proximal end of the humerus, and this is a variable neck of the prosthesis. The modularity of the neck makes it possible to adjust the colodiaphysal angle and to adjust the head in relation to the stem in eight different positions. The shoulder replacement described, produced in two modifications by ProSpon (Czech Republic) and MIL (France), was used in surgical treatment of 43 acute fractures and 33 cases of post-traumatic destruction. The clinical outcome was assessed using the Constant rating score. RESULTS: In patients with acute trauma of a shoulder, an average of 59 points (range, 23-82) was achieved. The average maximal elevation was 88 degrees, with a range of 40 to 140 degrees. In 25% of the patients, no postoperative pain was present; mild pain at strain was reported by 73% of the patients and pain limiting the arm's activity by 3%. In patients with post-traumatic destruction of a shoulder, the average value vas 53.5 points (range, 20-88) and the average maximal elevation was 85 degrees (range, 30-130). No postoperative pain was reported by 36%, mild pain at strain was recorded in 52% and activity-limiting pain in 12% of the patients. DISCUSSION: The currently reported views are in agreement with our opinion that, at present, every method of shoulder replacement should enable the surgeon to achieve, as easy and reliably as possible, the reconstruction of fragments with the attachments of the rotator cuff. With our system, shoulder arthroplasty for the reconstruction of the proximal humerus, using the supplementary fixation components described, allowed us to treat even the most serious cases of traumatic destruction of the proximal humerus. CONCLUSIONS: To facilitate the treatment of trauma in displaced, three- or four-part fractures of the proximal end of the humerus, a new technique of reconstruction with the use of an endoprosthesis designed by us was developed. Fixation and reconstruction of fragments of the greater and lesser tubercles are carried out with screws and a special toothed plate that provides good fixation of the fragments to the stem. Compared with the current method of fragment fixation with simple suture, this technique offers an easy way of restoring the biomechanical properties in the region of the proximal end of the humerus and improves the stability of osteosynthesis. This aids in early mobilization and functional therapy of the patient, which results in a better overall outcome of the treatment.

[Shoulder arthroplasty in traumatological indications, long-term results]. / Endoprotéza ramenního kloubu v traumatických indikacích--dlouhodobé výsledky.

PURPOSE OF THE STUDY: To evaluate the long-term results of shoulder arthroplasty in trauma cases, using ProSpon and MMS-M.I.L. novel systems. MATERIAL AND METHODS: The shoulder endorosthesis designed by the authors, and manufactured as two products by ProSpon (Czech Republic) and MIL (France) companies, was used in surgical treatment of 43 cases of acute fractures and 33 cases of post-traumatic conditions. The Constant score was used to evaluate the clinical outcome. RESULT: In patients with acute trauma, the average Constant score was 59 points (range, 23-82). The average maximal elevation was 88 degrees (range, 40-140). No postoperative pain, mild pain at strain and arm activity-limiting pain were recorded in 25%, 72% and 3% of the patients, respectively. In patients with post-traumatic destruction of the shoulder, the average Constant score was 53.5 points (range, 20-88) and the average maximal elevation was 85 degrees (range, 30-130). No pain, mild pain and activity-limiting pain were present in 36%, 52% and 12% of the patients, respectively. The patients in whom the reconstruction of the proximal humerus and rotator cuff was performed with the use of a special toothed plate and screws, as designed by the authors, the overall average Constant score was higher by 12 and 11 points for acute trauma and post-traumatic destruction, respectively, when compared with the conventional technique of reconstruction by suture. Two serious complications were recorded, namely, a failure of the reconstruction due to splitting of the greater tubercle fragment at the site of plate fixation and an instability of the shoulder. In patients who were indicated for shoulder arthroplasty due to post-traumatic destruction, the average increase in the Constant score was 12 points in comparison with the pre-operative status. DISCUSSION: Our results of shoulder arthroplasty in acute injury to the proximal humerus are in agreement with the results published in the literature. In reconstruction of the tubercles, there was a considerable difference in results between our screws-and-plate technique and the conventional suture method. With the former, the average Constant score was higher by 12 and 11 points and the average active elevation was better by 15 and 10 degrees for acute trauma and post-traumatic destruction, respectively. Clinical observations also show that osteosynthesis of the tubercle, particularly of the greater one, has better stability with the use of screws and plate, rehabilitation is associated with less pain and shoulder motion improves more rapidly. CONCLUSIONS: The results presented here are comparable with those reported in the literature. In the group treated by the technique designed by the authors, the outcomes are markedly better. This technique of shoulder reconstruction provides better stability for attachment fixation of the rotator cuff, facilitates reconstruction of the proximal humerus in acute trauma and restoration of biomechanical properties of the shoulder joint.

[A cannulated articulating spacer--a functional implant for treatment of infected hip joint prostheses]. / Kanalizovaný artikulovaný spacer--funkcní implantát pro resení infekce náhrady kycelního kloubu.

PURPOSE OF THE STUDY: Two-stage revision arthroplasty with the use of a spacer is generally accepted as a reliable method for treating infected hip replacements. Spacers made from antibiotic-loaded bone cement give good results in treatment of deep infections, but this technique is demanding in terms of spacer shaping. In addition, the conventional spacer may dislocate or fracture during patient mobilization. We attempted to avoid the disadvantages of conventional spacers by the construction of a cannulated articulating spacer. This is a special implant consisting of a polyethylene acetabulum, a stem, a modular neck and a head. Both the acetabulum and stem are covered with antibiotic-impregnated bone cement. They are subsequently pressed into the bone bed to make impression in the cement. The union of the bone bed with cement, which occurs in conventional implantation, must be avoided. This is achieved by making movements with the implant attached to an insertion handle, and by irrigating the operative field with large volumes of saline. A drain inserted in the canal running along the stem long axis facilitates continuous lavage of the medullary cavity. MATERIAL AND METHODS: A total of 11 patients with deep infection of a hip replacement were treated with the use of a cannulated articulating spacer in the years 2002 and 2003. Seven patients had late hematogenous infections and four had chronic delayed infections. The drains providing lavage stayed in place for about 10 to 12 days or less when three consecutive cultivations of drainage discharge were negative. Antibiotics were administered for at least 6 weeks according to the results of CRP and FW assessment. The reimplantation was planned on the basis of laboratory and clinical findings. The outcome was evaluated using the Harris hip score. RESULTS: Infection was successfully eradicated in all cases. The average time during which the cannulated articulating spacer was in place was 9.4 weeks. The results, as rated by the Harris hip score, were very good; after reimplantation, the average score was 95.1 points (range, 92 to 99). Even better evidence of the advantages of this method was provided by the increase in the average Harris hip score, which was 35.3 points (range, 26 to 69). No spacer dislocation or any other mechanical complication associated with the implant were recorded. DISCUSSION: Our results achieved with the cannulated articulating spacers developed in our department, as compared with conventional ones, show that the articulating spacer provides the patient with greater comfort and, therefore, improved quality of life for the period between the removal of a loose prosthesis and reimplantation of a definitive one. This method markedly reduces the risk of failure or dislocation of the temporary implant. In comparison with the PROSTALAC system, which is difficult to obtain and which requires complicated instrumentation, our method is simpler and less expensive. Our results show that the presence of an articulating spacer as a foreign body has no effect on the efficacy of treatment for deep infection. CONCLUSIONS: The procedure for preparing a cannulated articulating spacer described here is a modification of the method used to treat deep infection at the site of a total hip arthroplasty; it is inexpensive and provides markedly greater comfort for the patient. The technique combines the advantages of a two-stage revision involving spacer insertion with the use of lavage. Because patient have no major complaint and there is low risk of implant failure, the method allows us to adjust the reimplantation timing to the course of infection eradication and patients' overall health status.

[Effect of ultrasonic shock waves on the bone-bone cement interface]. / Pusobení ultrazvukové rázové vlny na spojení kostního cementu s kostí.

PURPOSE OF THE STUDY: Identification of the impact of ultrasound shock wave on the integration of bone cement in the bone and the examination of a potential application of this method in order to facilitate the extraction of cemented implants, mainly femoral component of total hip arthroplasty. MATERIAL: We used pig proximal femurs from which we made fragments involving approximately one third to one half of the profile of the bone and Palacos bone cement. METHOD: We made a groove in the cancellous bone, pressed bone cement with a wire loop in the cavity and let it harden. The samples were divided by random selection into two groups. Samples from A group were exposed to ultrasound shock waves and group B served as a control group. Then we measured the force needed for the extraction of the cement plug from the bone. RESULTS: Our measuring has shown an evident decrease of the force necessary for the extraction of the bone cement after the application of ultrasound shock wave. We did not find out any macroscopically evident damage of the bone cement or of the surrounding cortical bone. DISCUSSION: The results of our measuring are influenced by a different shape and size of the examined samples which also substantially differ from the situation when a stem of the endoprosthesis is implanted in the femoral canal and is surrounded by a cement mantle. As concerns risks associated with the application of the shock wave in this indication there is a risk of a fracture of the cortical bone around THR stem (the literature does not mention this complication) and a risk of the increase of pressure in the medullary cavity of the femur combined with a risk of fat embolism. In our view this increase of pressure is comparable with the effect of the implantation of femoral component. This method cannot be used for releasing cementless implants as the surrounding cortical bone gets damaged before the implant is released. CONCLUSION: Ultrasound shock wave is still used rarely in orthopaedics, however, the existing results are promising in many aspects. Of great importance is the fact that it is a non-invasive method. The field dealt with by this work covers only experiments in vitro but the results provide hope for a future clinical use.

[Polyethylene disease]. / Polyetylenová choroba.

PURPOSE OF THE STUDY: The experience obtained during revision surgery and findings of polyethylene granulomas in surrounding tissues of replacement as well as marked differences in the viability of implants resulted in the study of polyethylene disease and its basic mechanisms producing the development of osteoaggressive granulomas. We investigated the morphology of particles and their number in tissues surrounding the implant. The aim of our study was to develop a method for the detection of polyethylene particles in tissues, to identify different types of wear and to assess factors that may influence the viability of joint arthroplasty in general. MATERIAL: Every revizion of joint arthroplasty performed during the last five years was evaluated in terms of the presence of polyethylene granules and the viability state of articular polyethylene inserts. A total of 55 samples were taken from tissues around loosened endoprostheses. The location of each sample was exactly determined. METHOD: A technique was developed to identify wear particles and to visualize them after all organic structures of a polyethylene granuloma were dissolved with nitrogenic acid. RESULTS: The viability of articular polyethylene implants showed extreme differences in relation to different periods of manufacture and probably also to different methods of sterilization. Articular inserts sterilized with formaldehyde (the method used at the beginning of arthroplasty in our country) showed the highest viability and the lowest wear. The polyethylene particles present in tissues surrounding the implant were characterized in terms of morphology and size. DISCUSSION: The comparison of literature data and our results has revealed that there are many unknown facts about the quality and structure of polyethylene. The method of sterilization also appears to play a role. Because the issue is complex, we were not able to identify all factors leading, in some cases, to an early and unexpected failure of the implant and we consider further investigation to be necessary. CONCLUSIONS: Polyethylene disease is an important factor limiting the viability of joint arthroplasty. It results from a complex interaction of polyethylene particles arising by wear with surrounding tissues. The particles, less than 0.5 micron in size, are phagocytized by macrophages and, by complex mechanism of expression of inflammation mediators, they result in the inhibition of osteogenesis and activation of osteoclastic processes. The previous methods of sterilization with formaldehyde vapors apparently reduced wear influenced the resistance of polyethylene to wear to a lesser degree. A method was developed to detect these particles and to characterize their morphology in the tissues of a polyethylene granuloma.

Distribution of polyethylene wear particles and bone fragments in periprosthetic tissue around total hip joint replacements.

Ultra-high molecular weight polyethylene (UHMWPE) wear particles play a significant role in failures of total joint replacements (TJRs). In this work, we investigated the distribution of these wear particles in periprosthetic tissues obtained from nine revisions of hip TJR. In the first step, all periprosthetic tissues were combined and mechanically separated into granuloma tissue (containing hard granules visible to the naked eye) and surrounding tissue (without visible granules). In the second step, the tissues were hydrolyzed by protease from Streptomyces griseus and granules were separated by filtration; this divided the sample into four groups: (i) lyzate and (ii) non-degraded large granules from the granuloma tissue plus (iii) lyzate and (iv) non-degraded small granules from the surrounding tissue. In the third step, the large as well as small granules were hydrolyzed by collagenase from Clostridium histolyticum. In the last step, the UHMWPE wear particles from all four groups were purified by HNO3 digestion and weighed. The purity of the isolated particles was verified by scanning electron microscopy, infrared spectroscopy and energy-dispersive X-ray analysis. Of the total amount of polyethylene particles in the whole granuloma tissue, 72% of particles in the size range 0.1-10 microm and 68% of those larger than 10 microm were found in granules. Therefore, the formation of granules significantly lowers the effective amount of wear particles available for interaction with reactive cells and seems to be a natural defense mechanism.

A new technique for reconstruction of the proximal humerus after three- and four-part fractures.

The results of proximal humeral replacement following trauma are substantially worse than for osteoarthritis or rheumatoid arthritis. The stable reattachment of the lesser and greater tuberosity fragments to the rotator cuff and the restoration of shoulder biomechanics are difficult. In 1992 we developed a prosthesis designed to improve fixation of the tuberosity fragments in comminuted fractures of the proximal humerus. The implant enables fixation of the fragments to the shaft of the prosthesis and the diaphyseal fragment using screws, washers and a special toothed plate. Between 1992 and 2003 we used this technique in 50 of 76 patients referred to our institution for shoulder reconstruction after trauma. In the remaining 26, reconstruction with a prosthesis and nonabsorbable sutures was performed, as the tuberosity fragments were too small and too severely damaged to allow the use of screws and the toothed plate. The Constant score two years post-operatively was a mean of 12 points better in the acute trauma group and 11 points better in the late post-traumatic group than in the classical suture group. We recommend this technique in patients where the tuberosity fragments are large enough to allow fixation with screws, washers and a toothed plate.