PURPOSE OF STUDY: Total joint replacements (TJR) have become the cornerstone of modern orthopedic surgery. A great majority of TJR employs ultrahigh molecular weight polyethylene (UHMWPE) liners. TJR manufacturers use many different types of UHMWPE, which are modified by various combinations of crosslinking, thermal treatment, sterilization and/or addition of biocompatible stabilizers. The UHMWPE modifications are expected to improve the polymer's resistance to oxidative degradation and wear (release of microparticles from the polymer surface). This manuscript provides an objective, non-commercial comparison of current UHMWPE formulations currently employed in total knee replacements. MATERIALS AND METHODS: UHMWPE liners from 21 total knee replacements (TKR) were collected which represent the most implanted liners in the Czech Republic in the period 2020-2021. The UHMWPEs were characterized using several methods: infrared microspectroscopy (IR), non-instrumented and instrumented microindentation hardness testing (MH and MHI), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and solubility measurements. The above-listed methods yielded quite complete information about the structure and properties of each UHMWPE type, including its potential long-term oxidation resistance. RESULTS: For each UHMWPE liner, IR yielded information about immediate oxidative degradation (in the form of oxidation index, OI), level of crosslinking (trans-vinylene index, VI) and crystallinity (CI). The MH and MHI testing gave information about the impact of structure changes on mechanical properties. The remaining methods (DSC, TGA, and solubility measurements) provided additional information regarding the structure changes and resistance to long-term oxidative degradation. Statistical evaluation showed significant differences among the samples as well as interesting correlations among the UHMWPE modifications, structural changes, and mechanical performance. DISCUSSION: Surprisingly enough, UHMWPE materials from different manufacturers showed quite different properties, including the resistance against the long-term oxidative degradation, which is regarded as one of the main reasons of TJR failures. The most promising UHMWPE types were crosslinked materials with biocompatible stabilizers. CONCLUSIONS: Current UHMWPE liners from different manufactures used in total knee replacements exhibit significantly different structure and properties. From the point of view of clinical practice, the traditional UHMWPE types, which contained residual radicals from irradiation and/or gamma sterilization, showed inferior resistance to oxidative degradation and should be avoided. The best properties were observed in modern UHMWPE types, which combined crosslinking, biocompatible stabilizers, and sterilization by ethylenoxide or gas plasma. KEY WORDS: UHMWPE; knee replacements; oxidative degradation; infrared spectroscopy; microhardness.
- MeSH
- biokompatibilní materiály chemie MeSH
- diferenciální skenovací kalorimetrie MeSH
- lidé MeSH
- polyethyleny * chemie MeSH
- protézy - design MeSH
- protézy kolene * MeSH
- termogravimetrie MeSH
- testování materiálů * metody MeSH
- totální endoprotéza kolene * přístrojové vybavení metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- srovnávací studie MeSH
BACKGROUND: Total knee arthroplasty (TKA) with all-polyethylene tibial (APT) components has shown comparable survivorship and clinical outcomes to that with metal-backed tibial (MBT). Although MBT is more frequently implanted, APT equivalents are considered a low-cost variant for elderly patients. A biomechanical analysis was assumed to be suitable to compare the response of the periprosthetic tibia after implantation of TKA NexGen APT and MBT equivalent. METHODS: A standardised load model was used representing the highest load achieved during level walking. The geometry and material models were created using computed tomography data. In the analysis, a material model was created that represents a patient with osteopenia. RESULTS: The equivalent strain distribution in the models of cancellous bone with an APT component showed values above 1000 με in the area below the medial tibial section, with MBT component were primarily localised in the stem tip area. For APT variants, the microstrain values in more than 80% of the volume were in the range from 300 to 1500 με, MBT only in less than 64% of the volume. CONCLUSION: The effect of APT implantation on the periprosthetic tibia was shown as equal or even superior to that of MBT despite maximum strain values occurring in different locations. On the basis of the strain distribution, the state of the bone tissue was analysed to determine whether bone tissue remodelling or remodelling would occur. Following clinical validation, outcomes could eventually modify the implant selection criteria and lead to more frequent implantation of APT components.
PURPOSE: This study aims to compare total knee replacement (TKA) with NexGen All-Poly (APT) and NexGen Metal-Backed (MBT) in terms of implant survivorship, reasons leading to implant failure and functional results of defined age categories. METHODS: A single-centre, retrospective evaluation of 812 patients who underwent knee replacement with NexGen CR between 2005 and 2021, comparing a modern congruent APT component to a modular MBT equivalent component using a similar surgical technique at a notable mean follow-up duration. Implant survival, functional outcomes using the Knee Society Score and range of motion were evaluated and compared in different age categories. RESULTS: Of the 812 NexGen CR TKAs performed at our institution, 410 (50.4%) used APT components and 402 (49.6%) MBT components. The survival rate of NexGen APT was 97.1% and that of NexGen MBT was 93.2% (p = 0.36). Removal of the implant occurred overall in 15 cases, for MBT in ten cases, and for APT in four cases. The FS was proved to be significantly higher when APT components were implanted in younger patients than for MBT (p = 0.005). A similar range of motion between the components was recorded (p = 0.1926). CONCLUSION: Under defined conditions, we measured the clinical results of implants from a single manufacturer implanted in a single department using a similar surgical technique. Considering the limitations, we suggest that all-polyethylene tibial components are equal or even superior to metal-backed ones across the examined age categories.
- MeSH
- kovy MeSH
- lidé MeSH
- polyethylen MeSH
- protézy - design MeSH
- protézy kolene * MeSH
- retrospektivní studie MeSH
- totální endoprotéza kolene * škodlivé účinky MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
PURPOSE OF THE STUDY Partial knee replacement appears to be an appropriate surgical solution of unicompartmental knee joint osteoarthritis in correctly indicated cases. The purpose of our study was to evaluate the mid-term outcomes of unicondylar knee replacement using the Oxford Phase III system in the group of patients treated by the First Department of Orthopaedic Surgery, St. Anne s University Hospital Brno. MATERIAL AND METHODS The prospective study evaluated 47 patients (in 4 patients bilaterally) after the Oxford unicompartmental knee replacement performed between 2011 and 2016. The patients were evaluated using the Knee Society Score (KSS), Oxford Knee Score (OKS) and radiological examination performed at 7.3 years after surgery on average. All the patients were operated on by the same surgeon. RESULTS Based on the questionnaires and the clinical examination, the clinical and functional status was assessed, using the Knee Society Score (KSS). The mean preoperative KSS and FS values were 59.8 and 56.5, respectively. The postoperative KSS and FS values were 91.2 and 83.4. The mean preoperative value of the Oxford Knee Score (OKS) was 27.3. Postoperatively the values reached 40.7 on average. Based on the radiological examination, the lower limb correction of axis in the frontal plane was assessed. The mean axis correction was 3.1°. The mean tibial component slope measured on lateral radiograph was 82.7°. The basic analysis of X-rays did not reveal any component malposition. The implant survival rate was calculated using the Kaplan-Meier cumulative survival curve. In our group of patients, the mean survival rate of Oxford Phase III unicondylar knee replacement at 7.3 years postoperatively is 98.0%. DISCUSSION Many studies have reported excellent results of unicondylar knee replacement and a long survival rate of over 90%. Still debated, however, are the indication criteria and also the importance of the surgeon s experience and mastery of the surgical technique. CONCLUSIONS The results of the study confirm our excellent clinical experience and the survival rate of 98% at the mean follow up of 7.3 years after surgery shows great promise for quality long-term results. Overall, crucial for the success of UKR continues to be the compliance with the indication criteria for surgery. The choice of the type of implant and, last but not least, the correct surgical technique and postoperative rehabilitation programme are also important. Key words: unicompartmental knee replacement, Oxford Phase III, osteoarthritis of the knee.
- MeSH
- artróza kolenních kloubů * chirurgie MeSH
- kolenní kloub diagnostické zobrazování chirurgie MeSH
- lidé MeSH
- prospektivní studie MeSH
- protézy kolene * MeSH
- retrospektivní studie MeSH
- totální endoprotéza kolene * škodlivé účinky MeSH
- výsledek terapie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
BACKGROUND AND OBJECTIVE: Total knee arthroplasty (TKA) with modern all-polyethylene tibial (APT) components has shown high long-term survival rates and comparable results to those with metal-backed tibial components. Nevertheless, APT components are primarily recommended for older and low-demand patients. There are no evidence-based biomechanical guidelines for orthopaedic surgeons to determine the appropriate lower age limit for implantation of APT components. A biomechanical analysis was assumed to be suitable to evaluate the clinical results in patients under 70 years. The scope of this study was to determine biomechanically the appropriate lower age limit for implantation of APT components. METHODS: To generate data of the highest possible quality, the geometry of the computational models was created based on computed tomography (CT) images of a representative patient. The cortical bone tissue model distinguishes the change in mechanical properties described in three parts from the tibial cut. The cancellous bone material model has a heterogeneous distribution of mechanical properties. The values used to determine the material properties of the tissues were obtained from measurements of a CT dataset comprising 45 patients. RESULTS: Computational modeling showed that in the majority of the periprosthetic volume, the von Mises strain equivalent ranges from 200 to 2700 με; these strain values induce bone modeling and remodeling. The highest measured deformation value was 2910 με. There was no significant difference in the induced mechanical response between bone models of the 60-year and 70-year age groups, and there was <3% difference from the 65-year age group. CONCLUSIONS: Considering in silico limitations, we suggest that APT components could be conveniently used on a bone with mechanical properties of the examined age categories. Under defined loading conditions, implantation of TKA with APT components is expected to induce modeling and remodeling of the periprosthetic tibia. Following clinical validation, the results of our study could modify the indication criteria of the procedure, and lead to more frequent implantation of all-polyethylene TKA in younger patients.
- MeSH
- analýza metodou konečných prvků MeSH
- biomechanika MeSH
- kovy MeSH
- lidé MeSH
- mechanický stres MeSH
- polyethylen MeSH
- protézy - design MeSH
- protézy kolene * MeSH
- tibie diagnostické zobrazování chirurgie MeSH
- totální endoprotéza kolene * metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
PURPOSE OF THE STUDY Laboratory methods are central to prosthetic joint infection (PJI) diagnosis. Most research teams focus on detection of specific inflammatory markers, causative pathogens, or on assessment of the tissue response. This study sought to determine the optimal cut-off values and diagnostic performance of selected synovial markers in relation to the diagnosis of hip or knee PJI. The studied markers were synovial level of glucose, lactate, coefficient of energy balance (CEB) and NGAL (neutrophil gelatinase-associated lipocalin). MATERIAL AND METHODS This prospective study includes 89 patients who underwent revision total knee or hip arthroplasty for septic or aseptic reasons in the period from 2014 to 2017. Among these 89 patients, there are 2 cases of prosthetic hip infection, 22 cases of prosthetic knee infection, 31 aseptic revision total hip arthroplasties and 34 aseptic revision total knee arthroplasties. The diagnostic characteristics of the studied methods were set in relation to the reference standard, the 2013 MSIS (Musculoskeletal Infection Society) criteria. The cut-off values were calculated using the ROC (receiver operating characteristic curve) analysis. RESULTS The synovial glucose test is considered positive if the glucose level drops below 2.65 mmol/L. The area under the curve is 0.813, sensitivity 75.0%, specificity 83.1%. The synovial lactate test is considered positive if lactate level rises above 8.87 mmol/L. The area under the curve is 0.882, sensitivity 70.8%, specificity 95.4%. Synovial NGAL is considered positive if its level exceeds 998 μg/L. The area under the curve is 1.000, sensitivity 100.0%, specificity 100.0%. CEB is considered positive if its value is lower than +4.665. The area under the curve is 0.883, sensitivity 91.7% and specificity 69.8%. Combining of these tests with other synovial markers does not improve the diagnostic performance of the studied tests. CONCLUSIONS The glucose and lactate levels and CEB undoubtedly reflect the presence of an inflammatory process in a prosthetic joint. However, the diagnostic characteristics of these tests are not better than those of other modern diagnostic techniques. As opposed to these tests, synovial NGAL shows excellent diagnostic performance. Nonetheless, the potential of this method shall be verified on larger cohorts of patients. Key words: prosthetic joint infection, periprosthetic infection, total knee arthroplasty, total hip arthroplasty, diagnosis, glucose, lactate, CEB, NGAL.
- MeSH
- biologické markery analýza MeSH
- C-reaktivní protein analýza MeSH
- glukosa MeSH
- infekce spojené s protézou * diagnóza etiologie MeSH
- kyselina mléčná MeSH
- lidé MeSH
- lipokalin-2 analýza MeSH
- náhrada kyčelního kloubu * škodlivé účinky MeSH
- prospektivní studie MeSH
- protézy kolene * škodlivé účinky MeSH
- senzitivita a specificita MeSH
- synoviální tekutina chemie MeSH
- totální endoprotéza kolene * škodlivé účinky MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
PURPOSE OF THE STUDY Use of an all-polyethylene (all-poly, AP) tibial component in primary total knee arthroplasty is still an attractive option considering the durability of replacement, the elimination of backside wear and the lower cost compared to modular metalbacked tibia. The purpose of the study was to evaluate the long-term results of the total knee replacement using the P.F.C. Sigma system with a monoblock all-polyethylene tibial component implanted at the 1st Orthopedic Department of the St. Anne's University Hospital and Masaryk University Brno in the period 1999-2010. MATERIAL AND METHODS In the monitored period, 911 total knee replacements using P.F.C. Sigma with an all-polyethylene tibial component were performed. This cohort of patients was evaluated at least 10 years after the primary replacement surgery. Altogether 323 knee replacements in 289 patients were evaluated. The clinical outcomes were assessed according to the Knee Society Clinical Rating System (KSS) and the Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System. The replacement survival was evaluated using the Kaplan-Meier survival analysis. RESULTS In the evaluated group, the average KS was 82.6 points and the average functional score was 74.7 points. Excellent results were recorded in 213 cases, good results in 78 and satisfactory in 23 replacements. Poor clinical results were reported in 9 patients. The average range of motion was 105.8°. In 5 knees (1.5%) revision surgery was performed for infection complications, 3 cases were complicated due to periprosthetic fractures, 4 replacements were revised due to anterior knee pain and 8 knees showed a limited range of motion. Only 1 replacement was revised for aseptic loosening, with no need for reimplantation of the component. The survivorship of the implant was 98.5 % at the follow-up of 12.8 years, including the reasons of reimplantation. DISCUSSION Total knee replacement with an all-polyethylene tibial component is not so popular as the metal-backed modular implants. The all-polyethylene tibial component has certain advantages: lower unit costs, no backside wear, no liner dislocation, possibility of conservative bone resection. On the other hand, this type of implant is not modular and augmentations or longer stems cannot be used. Even though this type of endoprosthesis is recommended exclusively for elderly patients with a lower level of activity, the current mid- and long-term results show that indications for all-poly implants are much broader. CONCLUSIONS The total knee replacement with an all-polyethylene tibial component shows very good long-term clinical outcomes with an excellent survival rate. The all-poly design is cost-effective and may be used not only in elderly patients. Key words: total knee replacement, all-polyethylene tibial component, long-term results.
PURPOSE OF THE STUDY The aim of this study was to evaluate and compare the functional outcomes and complication rates of patients in the midterm follow-up period when patients applied with medial unicondylar knee arthroplasty (UKA) were grouped according to Body Mass Index (BMI) values MATERIAL AND METHODS The study included 125 patients applied with medial UKA between December 2013 and December 2017 because of isolated medial compartment gonarthrosis and completed at least 2 years of follow-up. The patients were separated into three groups: non-obese with a BMI < 30 kg/m2, obese with BMI of 30-39 kg/m2, and morbidly obese (BMI ≥ 40 kg/m2). The implants used in all surgeries were cemented fixed-bearing implants. All patients were evaluated preoperatively with bilateral orthoroentgenograms, and weight-bearing anteroposterior and flexed lateral knee X-rays. Postoperatively, bilateral orthoroentgenograms and weight-bearing anteroposterior and flexed lateral knee X-rays were taken. Pre- and post-operative clinical outcomes were evaluated using the Knee Society Score (KSS), functional Knee Society Score (fKSS) Oxford Knee Score (OKS) and Visual Analogue Scale (VAS). RESULTS The 125 study patients comprised 83 females and 42 males with a mean age of 54 years (range, 42-71 years). No significant difference was determined between the three groups in respect of age, gender and side distribution (p > 0.05). In all three groups, the fKSS, KSS, OKS and VAS values at the final follow-up examination were statistically significantly improved compared to the preoperative values. No periprosthetic infection was determined in any patient throughout the follow-up period. Revision surgery was applied for various reasons to 5 patients; 2 in the non-obese group, 2 in the obese group, and 1 in the morbidly obese group. DISCUSSION In the last 20 years, a general increase has been seen in the number of obese patients with knee osteoarthritis requiring surgery. The increase in obesity represents an important worldwide public health problem. CONCLUSIONS The results of this study suggest that obesity does not influence the middle term outcomes of UKA. The functional outcome scores after surgery and improvement in these scores were comparable to patients with normal BMI. Key words: medial gonarthrosis, obesity, unicondylar knee arthroplasty.
- MeSH
- artróza kolenních kloubů * komplikace chirurgie MeSH
- dospělí MeSH
- kolenní kloub diagnostické zobrazování chirurgie MeSH
- lidé středního věku MeSH
- lidé MeSH
- morbidní obezita * MeSH
- protézy kolene * škodlivé účinky MeSH
- retrospektivní studie MeSH
- senioři MeSH
- totální endoprotéza kolene * škodlivé účinky MeSH
- výsledek terapie MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
PURPOSE OF THE STUDY The purpose of the study is to verify the correct alignment of components of the Oxford medial unicompartmental knee arthroplasty using the Zimmer Microplasty® instrumentation at the beginning of the learning curve. The implantation of prosthetic components of partial knee arthroplasty in proper alignment has an effect on long-term survival of the prosthesis and should eliminate the occurrence of frequent complications. MATERIAL AND METHODS The study group includes 20 patients, 9 men with the mean age of 68 years (range 62-78 years) and 11 women with the mean age of 69 years (range 52-81 years). 13 patients underwent surgery on the right knee and 7 patients on the left knee. The mean length of symptoms was 13 months (range 7-20 months), the mean varus knee deformity was 7° (range 4-12°). The selected patients met both the clinical and radiological criteria for enrolment in the study. In all of them medial unicompartmental knee arthroplasty was performed in 2019 by the same surgeon. After surgery, the parameters of accuracy of alignment of individual prosthetic components were measured on the full-length radiograph of the limb under load. The WOMAC score was recorded preoperatively and one year after surgery and subsequently compared. The knee joint flexion preoperatively and one year after surgery was evaluated. RESULTS The analysis of radiographs revealed that in 12 cases the femoral component was implanted in the mean valgus angle of 1.6° (range 1-3°) and in 8 cases in the mean varus angle of 3° (range 1-5°). All femoral components were implanted in the mean flexion of 7.3° (range 3-11°), no component was implanted in extension. As concerns the tibial component, 19 components were implanted in a neutral or minimum varus angle with the mean value of 1.1° (range 0.3-4°). One component only was implanted in the valgus angle of 1°. All tibial components were implanted with the mean dorsal slope of 6.5° (range 4-8°). The incision was 5 mm deep on average (range 3-6 mm). There was a slight divergence between the components, namely 2.8° on average (range 2-7°) and the distance between the components was 4mm on average (range 3-5 mm). The mean knee joint flexion achieved preoperatively by patients was 115° (range 110-123°), whereas postoperatively the mean flexion achieved was 126° (range 111-138°). The preoperative Womac score was 84.5 points on average (range 64-96 points), whereas postoperatively it was 26.4 points on average (range 7-52 points). None of the components was implanted outside the permitted range, no early complications of the partial replacement (luxation of polyethylene mobile bearing insert, early loosening of the prosthesis, tibial fracture) were observed. DISCUSSION Our radiographic measurements show that when Zimmer Microplasty® instrumentation is used correct alignment of the femoral and tibial component can be achieved and the individual components were correctly aligned within the recommended range. Every single component met the required criteria for alignment. When comparing the values obtained by us in measurements with those obtained by other authors from abroad, similar results regarding the alignment of components were achieved. CONCLUSIONS When using Zimmer Microplasty® instrumentation, excellent results can be achieved also at the beginning of the learning curve of partial knee replacement. Key words: medial gonarthrosis, unicompartmental arthroplasty, hemiarthroplasty, alignment of components.
- MeSH
- artróza kolenních kloubů * diagnostické zobrazování chirurgie MeSH
- femur diagnostické zobrazování chirurgie MeSH
- kolenní kloub diagnostické zobrazování chirurgie MeSH
- lidé středního věku MeSH
- lidé MeSH
- protézy kolene * MeSH
- senioři MeSH
- totální endoprotéza kolene * škodlivé účinky MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
The research aims to analyze the tibial component rotation using the finite element method by resecting the tibia in a transverse plane at an angle between 1.5° (external rotation) and -1.5° (internal rotation). We used a three-dimensional scanner to obtain the tibia's geometrical model of a cadaveric specimen. We then exported the surfaces of the tibial geometrical model through the Computer-Aided Three-dimensional Interactive Application (CATIA), which is a Computer-Aided Design (CAD) program. The CAD program three-dimensionally shaped the tibial component, polyethylene, and cement. Our analysis determined that the maximum equivalent stress is obtained in the case of proximal tibial resection at -1.5° angle in a transverse plane (internal rotation) with a value of 12.75 MPa, which is also obtained for the polyethylene (7.693 MPa) and cement (6.6 MPa). The results have shown that detrimental effects begin to occur at -1.5°. We propose the use of this finite element method to simulate the positioning of the tibial component at different tibial resection angles to appreciate the optimal rotation.
