Numerous studies have compared metal-backed components (MBTs) and all-polyethylene tibial components (APTs), but none of them specifically analysed the clinical results and the overall patient preference in patients who had undergone a staged bilateral knee replacement. The purpose of this study is to compare clinical results, perceived range of motion, and overall implant preference among patients who had undergone staged bilateral knee replacement with an APT and contralateral knee replacement with MBTs. A dataset of 62 patients from a single centre who underwent staged bilateral TKA between 2009 and 2022 was selected and retrospectively analysed. Tibial component removal was performed in three knees overall, all of which had MBTs. The mean measured Knee Score (KS) of knees with APTs was 78.37 and that of contralateral knees with MBTs was 77.4. The mean measured Function (FS) of knees with APTs was 78.22, and that of contralateral knees with MBs was 76.29. The mean flexion angle of knees with APTs was 103.8 and that for knees with MBTs was 101.04 degrees. A total of 54.8% of the patients preferred the knee that received APTs over contralateral MBTs. In our cohort, TKA with an APT in one knee and an MBT in the contralateral knee recorded similar clinical results and perceived ranges of motion. Patients in general preferred the knee that received an APT over contralateral knee with an MBT.

• Klíčová slova
• all-polyethylene tibia, bilateral knee replacement, metal-backed tibia, staged bilateral knee arthroplasty, total knee arthroplasty,
• Publikační typ
• časopisecké články 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.

• Klíčová slova
• All-polyethylene tibial component, Computational modeling, FEA, Finite element method, Knee replacement, Metal-backed tibial component, TKR, Total knee arthroplasty,
• MeSH
• analýza metodou konečných prvků MeSH
• kovy MeSH
• lidé MeSH
• polyethylen MeSH
• protézy - design MeSH
• protézy kolene * MeSH
• senioři MeSH
• tibie diagnostické zobrazování   chirurgie   MeSH
• totální endoprotéza kolene * MeSH
• Check Tag
• lidé MeSH
• senioři MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kovy MeSH
• polyethylen MeSH

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.

• Klíčová slova
• All-polyethylene knee replacement, Implant survival, Knee Society Score, Knee arthroplasty, NexGen,
• 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
• Názvy látek
• kovy MeSH
• polyethylen 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.

• MeSH
• lidé MeSH
• následné studie MeSH
• polyethylen MeSH
• protézy - design MeSH
• protézy kolene * MeSH
• reoperace MeSH
• selhání protézy MeSH
• senioři MeSH
• tibie chirurgie   MeSH
• totální endoprotéza kolene * škodlivé účinky   MeSH
• Check Tag
• lidé MeSH
• senioři MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• polyethylen 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.

• Klíčová slova
• All-polyethylene tibial component, Bone mechanics, Finite element model, Orthopaedic biomechanics, Total knee arthroplasty, von Mises strain,
• 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
• Názvy látek
• kovy MeSH
• polyethylen MeSH

PURPOSE OF THE STUDY: The aim of the study was: 1. statistical evaluation of the survival of the first Czech TKA of Walter-Motorlet type, 2. comparison of the outcomes of different types of tibial components and finding out of the difference, if any, in the survival of all-poly and metal-backed components. MATERIAL: The authors evaluated a group of patients treated by the Walter-Motorlet TKA in the period between September 1984 and December 1989. The cohort comprised 170 patients with 211 knees. Of this group, available to follow-up were 185 TKA in 148 patients on average 17.5 years after the operation (range, 15.0-20.1 years). One female patient who died of pulmonary embolism was not included in the study. The final cohort thus comprised 184 TKA in 147 patients. METHOD: The evaluation of the general outcomes was based on the method of the cumulative survival curve after Kaplan-Meier in dependence on the type of the implant its components and basic diagnosis. In addition, the authors carried out a comparison of different types of tibial components. OUTCOMES: After 20 years the curve shows 76% as the cumulative number of the survived implants. Eighteen TKA failed due to aseptic loosening and 12 TKA for infection. The comparison of survival curves in rheumatoid arthritis (RA) and osteoarthritis (OA) in case of the femoral components is in absolute terms slightly better in RA patients, however statistically this difference is insignificant (p = 0.34). Similar result was achieved in the tibial component, i. e. slightly better in RA patients, however only until the interval of 18 years after the surgery. After this interval the curve shows identical course in both diseases (p = 0.20). The comparison of individual all-poly tibial components revealed slightly better results in total plateau replacements (p = 0.13), the comparison of metal and total all-poly tibial components is slightly better in the metal-backed components (p = 0.07). However, the differences found out in all these cases are not statistically significant, either, and the outcomes of both types of components may be considered identical. DISCUSSION: Evaluation of the cohort at the interval of up to 20 years after the surgery only by means of usual health status documentation is highly demanding. The cumulative number of the survived implants evaluated by the Kaplan-Meier method after 20 years was 76%. There is no study following the cumulative survival of the TKA exceeding ten years in the Czech literature and these studies are not very frequent in other countries, either. Comparison of the outcomes of our study is difficult as the criteria used in different published studies are not uniform. Slightly more favourable results in RA patients may be ascribed to the fact that their demands for physical activity is not so high. Comparable outcomes of the all-poly and metal backed tibial components are rather surprising and their confirmation would require a more detailed examination in a randomized prospective study. CONCLUSION: Based on the comparison with similar articles published abroad, 76% as the outcome of the cumulative survival of the first type of the Walter-Motorlet TKA after more than 17 years may be considered satisfactory. The study has confirmed a good long-term survival of all-poly tibial components comparable with metal-backed components. It has indicated slightly better results in the survival of TKA in patients with RA as compared to those with OA, although the difference is not statistically significant. Evaluation of a greater cohort of patients at a longer interval after surgery would be considerably facilitated by the existence of a central TKA register.

• MeSH
• lidé MeSH
• následné studie MeSH
• protézy - design MeSH
• protézy kolene * MeSH
• reoperace MeSH
• selhání protézy MeSH
• totální endoprotéza kolene * MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH