Component In Knee Arthroplasty Research Articles

Tibial Baseplate Migration Is Not Associated with Change in Patient-Reported Outcome Measures and Clinical Scores After TKA: A Secondary Analysis of 5 Radiostereometric Analysis Studies with 10-Year Follow-up.

Radiostereometric analysis (RSA) provides highly accurate data about the migration of a total knee arthroplasty (TKA) component. However, patient-reported outcome measures (PROMs) reflect the patients' perspective of their functional status, pain, and overall health after TKA. The aim of this study was to evaluate the association between tibial implant migration and change in postoperative PROMs and clinical scores, using data pooled from long-term follow-up RSA studies. Individual implant migration data were collected from 5 randomized RSA studies, including a total of 300 patients with 6 distinct TKA implant designs (all Stryker). Tibial implant migration (maximum total point motion [MTPM]) was evaluated with RSA at 3 months, 1 year, and 2, 5, 7, and 10 years postoperatively. The Knee Society Score (KSS)-Knee and KSS-Function and Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales were collected in all studies at the same follow-up times. Linear mixed-effects models, with adjustment for TKA implant design and patient characteristics, were used to analyze the data. The 3-month follow-up visit was used as the baseline to assess the association between implant migration and PROMs across the 10-year follow-up. No association between tibial implant migration and change in KSS-Knee (p = 0.384), KSS-Function (p = 0.737), KOOS-Symptoms (p = 0.398), KOOS-Pain (p = 0.699), KOOS-Activities of Daily Living (p = 0.205), KOOS-Sport and Recreation (p = 0.702), or KOOS-Quality of Life (p = 0.368) was found across the entire follow-up. Similar results were found when using the 2-year follow-up as the baseline, after which both cemented and uncemented implants are expected to have stabilized. Tibial baseplate migration was not associated with postoperative worsening in PROMs or clinical scores in patients who underwent TKA. These findings suggest that implant migration, as measured with RSA, measures a different parameter (i.e., implant-bone fixation) than PROMs (i.e., patient perception) and clinical scores. Therefore, to assess the performance and safety of TKA implant designs, RSA and PROMs cannot be used interchangeably during the postoperative follow-up of patients and evaluation of the fixation of knee implants. Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Visible fluid motion on manipulation as the new threshold for intraoperatively determined knee arthroplasty component loosening: ADelphi study.

There is a lack of a clear, uniform definition for intraoperatively assessed component loosening of a knee arthroplasty component, complicating the interpretation and interchangeability of results of diagnostic studies using an intraoperative observation as the reference test. The purpose of this study was to establish a consensus among specialised knee revision surgeons regarding the definition of intraoperatively determined loosening of total or unicondylar knee arthroplasty components. Utilising the Delphi consensus method, an international panel of highly specialised knee revision surgeons was invited to participate in a three-round process. The initiation of the first round involved the exploration of possible criteria for intraoperatively determined loosening with open questions. The second round focused on rating these criteria importance on a five-point Likert scale. For the third round, criteria that reached consensus were summarised in consecutive definitions for intraoperatively determined loosening and proposed to the panel. Consensus was established when over 70% of participants agreed with a definition for intraoperatively determined loosening. The 34 responding panel members described in total 60 different criteria in the first round of which 34 criteria received consensus in the second round. Summarising these criteria resulted in four different definitions as minimal requirements for intraoperatively determined loosening. Eighty-eight percent of the panel members agreed on defining a component as loose if there is visible fluid motion at the interface observed during specific movements or when gently applying direct force. This study successfully established a consensus using a Delphi method among knee revision surgeons on the definition of intraoperatively determined component loosening. By agreeing on the visibility of fluid motion as new definition, this study provides a standardised reference for future diagnostic research. This definition will enhance the interpretability and interchangeability of future diagnostic studies evaluating knee arthroplasty component loosening. Level V.

Periprosthetic Transpatellar Fracture Replacement With Autogenous Iliac Graft: A Technical Note.

Periprosthetic fractures involving total knee arthroplasty (TKA) components, particularly involving the patella, can present a significant challenge regarding orthopedic surgery. This technical note outlines an approach for the reconstruction of complicated periprosthetic transpatellar fractures, with poor bone stock, utilizing autogenous iliac graft. This kind of procedure requires careful preoperative evaluation of imaging, precise intraoperative planning, and strict postoperative management to achieve adequate postoperative results. The inventive option of utilizing an autogenous iliac graft for reconstructionsuggests its potential benefits in addressing the unique biomechanical demands of patellar fractures in TKA patients with poor bone stock. Key technical aspects of this approach are highlighted and include graft harvest, graft preparation, and fixation techniques. Overall, this technique can provide a golden standard bailout for periprosthetic transpatellar fracture reconstruction and potentially offer orthopedic surgeons a comprehensive framework for addressing this challenging clinical scenario.

Titanium-Titanium Junctions in the Knee Corrode, Generating Damage Similar to the Hip

BackgroundPrevious studies identified corrosion between the modular tibial components of total knee arthroplasty devices. However, gaps persist. Compared to the hip, damage modes that occur within taper junctions in the knee remain poorly understood. In this study, we investigated corrosion on total knee arthroplasty components with titanium-titanium junctions. We asked the following question: under typical in vivo cyclic loading conditions, will the same alloy damage modes from total knee arthroplasty devices resemble those documented in the hip? MethodsA total of 50 paired titanium alloy tibial baseplates and stems were collected and semiquantitatively analyzed using Goldberg corrosion scoring. To characterize damage, a subsection of moderately and severely corroded components was sectioned and imaged using scanning electron and digital optical microscopy. ResultsOf the 100 device components, 95% showed visual evidence of corrosion. The initial contact area between the stem and bore generally occurred 3 mm from the stem taper base. Scanning electron microscopy revealed 4 damage modes, including oxide film formation, crevice corrosion, selective dissolution, and pitting. ConclusionsEach of the damage modes identified in modular titanium-titanium tibial junctions was previously reported by total hip arthroplasty retrieval studies. Cumulatively, our results suggest that mechanically assisted crevice corrosion promoted this damage in vivo.

Exploring consistent ratios in morphometry of the proximal tibia: insights for knee arthroplasty.

The current study, which delves into proximal tibia morphometric parameters in a Greek sample, not only analyzes whether specific linear distance ratios are consistent but also paves the way for a potential novel metric system for knee arthroplasty imaging studies using constant ratios. These findings could have significant implications for future enlarged research and clinical practice. A total of 38 dried tibiae were evaluated by two independent investigators. The following distances were measured with a digital Vernier sliding caliper: (1) the mediolateral distance of the proximal surface (A), (2) the anteroposterior distance of the proximal surface (B), (3) The longitudinal length of the bone (C), (4) the line connecting the anterior margin of the proximal surface with the highest peak of the tibia tuberosity (D), (5) the depth of the proximal margin of the medial articular facet (AF) (medial plateau) (E) and (6) the depth of the proximal margin of the lateral AF (lateral plateau) (F). The A, B, C, D, E, and F mean distances were 71.3mm, 47.4mm, 340.2mm, 37.1mm, 42mm, and 35.9mm. Reliability analysis for each observer on all measurements revealed an interclass correlation (ICC) score of 0.975 (observer 1) and 0.971 (observer 2). The ratio A/B was 1.5, A/C was a constant 0.2, and D/C was 0.1. The ratio E/F was 1.2. The six measurements (A-F) showed excellent inter-observer reliability (all ICC values > 0.990). The study established constant ratios of the studied linear distances around the proximal tibia. Considering these ratios, asymmetrical tibial components in knee arthroplasty seem to replicate the native anatomy more closely. Furthermore, the distance from the anterior margin of the proximal surface to the tibial tuberosity peak, constituting one-tenth of the longitudinal length of the tibia, shows promise as a metric system for imaging studies, especially in assessing lesions around tibial components.

Comparison of anatomic axes with a navigated functional rotation axis determined by ligament tension for rotational femoral component alignment in cadaver knee arthroplasty.

The malimplantation of the total knee arthroplasty (TKA) components is one of the main reasons for revision surgery. For determining the correct intraoperative femoral rotation several anatomic rotational axes were described in order to achieve a parallel, balanced flexion gap. In this cadaveric study prevalent used rotational femoral axes and a navigated functional rotational axis were compared to the flexion-extension axis defined as the gold standard in rotation for femoral TKA component rotation. Thirteen body donors with knee osteoarthritis (mean age: 78.85 ± 6.09; eight females and five males) were examined. Rotational computer tomography was performed on their lower extremities pre- and postoperatively. Knee joint arthroplasties were implanted and CT diagnostics were used to compare the preoperatively determined flexion-extension axis (FEA). The FEA is the axis determined by our surgical technique and serves as an internal reference. It was compared to other axes such as (i) the anatomical transepicondylar axis (aTEA), (ii) the surgical transepicondylar axis (sTEA), (iii) the posterior condylar axis (PCA) and (iv) the functional rotation axis (fRA). Examination of 26 knee joint arthroplasties revealed a significant angular deviation (p*** < 0.0001) for all axes when the individual axes and FEA were compared. aTEA show mean angular deviation of 5.2° (± 4.5), sTEA was 2.7° (± 2.2), PCA 2.9° (± 2.3) and the deviation of fRA was 4.3° (± 2.7). A tendency towards external rotation was observed for the relative and maximum axis deviations of the aTEA to the FEA, for the sTEA and the fRA. However, the rotation of the posterior condylar axis was towards inwards. All axes showed a significant angular deviation from the FEA. We conclude that the presented technique achieves comparable results in terms of FEA reconstruction when compared with the use of the known surrogate axes, with certain deviations in terms of outliers in the internal or external rotation.

MRI and SPECT/CT demonstrate, with low certainty of evidence, the highest diagnostic accuracy for aseptic knee arthroplasty loosening: A systematic comparative diagnostic test review and meta-analysis.

The purpose of this study was to evaluate and compare the diagnostic accuracy of modalities used to aid the diagnosis of aseptic knee arthroplasty loosening. A comparative diagnostic test accuracy systematic review and meta-analysis was conducted following the Cochrane and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. PubMed, EMBASEand Cochrane databases were searched for original articles evaluating diagnostic modalities up to March 2024. Included studies compared the modality (index test) to the intraoperative finding as reference test. The QUADAS-C (Quality Assessment of Diagnostic Accuracy Studies-Comparative)tool was used to assess the quality of the included studies. The GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach was used to evaluate the certainty of evidence. Level of evidence was evaluated using the Oxford Levels of Evidence tool. The primary outcome wasthe summary of diagnostic accuracy metrics for each modality as demonstrated by a summary receiver-operating characteristic (SROC) curve. The search yielded 467 articles. Of these, 14 articles were included. These 14 articles evaluated a total of five different diagnostic modalities: bone scintigraphy (three studies, 146 cases), 18-fluorodeoxyglucose positron emission tomography(two studies, 50 cases), single-photon emission computed tomography combined with computed tomography (SPECT/CT) (seven studies, 371 cases), radionuclide arthrogram (three studies, 196 cases)and magnetic resonance imaging (MRI) (one study, 116 cases). Nine studies exhibited a high risk of bias in patient selection, and all studies showed a high risk of bias related to the reference test. The majority of the included studies were classified as Level III evidence, leading to an overall low level of certainty in the evidence. The most accurate tests, as demonstrated by the SROC analysis, were MRI and SPECT/CT, with sensitivities ranging from 0.00 to 1.00 and 0.33 to 1.00 and specificities between 0.31-1.00 and 0.00-1.00, respectively. This review and meta-analysis evaluated available diagnostic modalities to aid the diagnosis of knee arthroplasty loosening and based on a low certainty of evidence suggests that MRI and SPECT/CT are currently the most accurate modalities available to aid the diagnosis of aseptic loosening of knee arthroplasty components. Level III.

High Rate of Unplanned Reoperation for Interprosthetic Femur Fractures After Total Hip and Knee Arthroplasty

BackgroundInterprosthetic femur fractures (IPFFs) are a rare, but devastating complication following total joint arthroplasty. There is limited evidence to help guide their management. The purpose of this study was to describe the features, treatment, and outcomes of surgically managed IPFFs. MethodsWe retrospectively identified 75 patients who had 76 IPFFs. The mean age at the time of IPFF was 75 years (range, 29 to 94), and 78% were women. The mean body mass index was 30 (range, 19 to 51), and the mean follow-up was 3 years (range, 0 to 14). There were 16 Vancouver B1 fractures, 28 Vancouver B2 fractures, 2 Vancouver B3 fractures, and 30 Vancouver C fractures. All B1 fractures underwent open reduction internal fixation (ORIF). All Vancouver B2 and B3 fractures underwent revision arthroplasty, including 1 proximal femur replacement and 1 total femur replacement. Vancouver C fractures were treated with ORIF (n = 20), distal femoral replacement (n = 9), and in 1 case, total femur replacement (n = 1). Kaplan-Meier survivorship was used to calculate 2-year survival free from all-cause reoperation and periprosthetic joint infection (PJI). ResultsThe 2-year survivorship-free rate from reoperation was 71%. There were 18 reoperations following initial surgical management of the IPFF, including 9 for infection, 3 for refracture, 3 for nonunion, 2 for hardware failure, and 1 for instability. An initial IPFF involving a stemmed femoral total knee arthroplasty component was associated with increased risk for reoperation (P = .007) and PJI (P = .044). There was no difference in survivorship free of reoperation between IPFFs managed with ORIF or revision arthroplasty (P = .72). ConclusionsAn IPFF is a devastating complication following total joint arthroplasty with high reoperation rates, most commonly secondary to PJI. Those IPFFs that occurred between 2 stemmed components were at the highest risk for reoperation.

Disengagement of Polyethylene Insert Locking Mechanism in Modular Tibial Components for Knee Arthroplasty: A Case Report

Background. Modular tibial components for knee arthroplasty are used in the majority of modern knee replacement systems. Despite a number of limitations, there are many aspects that make these types of implants indispensable for orthopedic surgeons.&#x0D; Aim — to demonstrate possible risks associated with a modular polyethylene liner with metal locking clip using a clinical case as an example.&#x0D; Case description. We present a case of primary total knee arthroplasty in a 70-year-old female patient. The surgery was performed by an experienced surgical team and resulted in good early radiologic and functional treatment outcome. After discharge, approximately 10 days after surgery, the patient developed knee pain. Control X-rays showed migration of the metal pin locking the polyethylene insert. The patient underwent an emergency revision surgery with replacement of the clip. The authors analyze possible causes of this complication and ways of its prevention.&#x0D; Conclusion. Migration of the insert locking element and dislocation of the insert in locked systems are quite rare complications of the knee arthroplasty. Their causes are soft tissue imbalance of the knee joint during arthroplasty and a number of technical errors. The very fact of using modular components of the joint is a predisposing factor for the disassociation of these modules.

Tibiofemoral Slip Velocity in Total Knee Arthroplasty is Design-Invariant but Activity-Dependent

Tibiofemoral slip velocity is a key contributor to total knee arthroplasty (TKA) component wear, yet few studies have evaluated this quantity in vivo. The aim of the present study was to measure and compare tibiofemoral slip velocities in 3 TKA designs for a range of daily activities. Mobile biplane X-ray imaging was used to measure 6-degree-of-freedom tibiofemoral kinematics and the locations of articular contact in 75 patients implanted with a posterior-stabilized, cruciate-retaining, or medial-stabilized design while each patient performed level walking, step up, step down, sit-to-stand, and stand-to-sit. Using these data, tibiofemoral slip velocity was calculated for the duration of each activity for each TKA design. The pattern of tibiofemoral slip velocity was similar for all 3 TKA designs within each activity but markedly different across the 5 activities tested, with the magnitude of peak slip velocity being significantly higher in level walking (range: 158–211 mm/s) than in all other activities (range: 43–75 mm/s). The pattern of tibiofemoral slip velocity in both the medial and lateral compartments closely resembled the pattern of tibiofemoral (knee) flexion angular velocity, with a strong linear relationship observed between slip velocity and flexion angular velocity (r = 0.81–0.97). Tibiofemoral slip velocity was invariant to TKA design but was significantly affected by activity type. Our measurements of slip velocity and articular contact locations for a wide range of daily activities may be used as inputs in joint simulator testing protocols and computational models developed to estimate TKA component wear.

The primary stability of a cementless PEEK femoral component is sensitive to BMI: A population-based FE study

The use of polyetheretherketone (PEEK) for cementless femoral total knee arthroplasty (TKA) components is of interest due to several potential advantages, e.g. the use in patients with metal hypersensitivity. Additionally, the stiffness of PEEK closer resembles the stiffness of bone, and therefore, peri-prosthetic stress-shielding may be avoided. When introducing a new implant material for cementless TKA designs, it is important to study its effect on the primary fixation, which is required for the long-term fixation. Finite element (FE) studies can be used to study the effect of PEEK as implant material on the primary fixation, which may be dependent on patient factors such as age, gender and body weight index (BMI). Therefore, the research objectives of this study were to investigate the effect of PEEK vs cobalt-chrome (CoCr) and patient characteristics on the primary fixation of a cementless femoral component. 280 FE models of 70 femora were created with varying implant material and gait and squat activity. Overall, the PEEK models generated larger peak micromotions than the CoCr models. Distinct differences were seen in the micromotion distributions between the PEEK and CoCr models for both the gait and squat models. The micromotions of all femoral models significantly increased with BMI. Neither gender nor age of the patients had a significant effect on the micromotions. This population study gives insights into the primary fixation of a cementless femoral component in a cohort of FE models with varying implant material and patient characteristics.

The Effect of Patient-Related Factors on the Primary Fixation of PEEK and Titanium Tibial Components: A Population-Based FE Study.

Polyetheretherketone (PEEK) is of interest as implant material for cementless tibial total knee arthroplasty (TKA) components due to its potential advantages. One main advantage is that the stiffness of PEEK closely resembles the stiffness of bone, potentially avoiding peri-prosthetic stress-shielding. When introducing a new implant material for cementless TKA designs, it is essential to study its effect on the primary fixation. The primary fixation may be influenced by patient factors such as age, gender, and body mass index (BMI). Therefore, the research objectives of this finite element (FE) study were to investigate the effect of material (PEEK vs. titanium) and patient characteristics on the primary fixation (i.e., micromotions) of a cementless tibial tray component. A total of 296 FE models of 74 tibiae were created with either PEEK or titanium material properties, under gait and squat loading conditions. Overall, the PEEK models generated larger peak micromotions than the titanium models. Differences were seen in the micromotion distributions between the PEEK and titanium models for both the gait and squat models. The micromotions of all tibial models significantly increased with BMI, while gender and age did not influence micromotions.

Undersizing of the tibial component in Oxford unicompartmental knee arthroplasty (UKA) increases the risk of periprosthetic fractures.

Tibial periprosthetic fractures (TPF) after unicompartmental knee arthroplasty (UKA) are a rare condition that affects about 1% of cases. Known risk factors include age, sex, body mass index (BMI), and bone density, as well as surgical technique and prosthesis design. The purpose of the study was to determine if undersizing of the tibial component in relation to the femoral component increases the risk of tibial periprosthetic fractures. Over a 6-year-period 1542 patients with cemented (n = 363) and uncemented (n = 1179) medial UKA were retrospectively evaluated. Tibial periprosthetic fractures were identified and classified, and epidemiologic data were documented at follow-up. Undersizing was defined as a smaller tibial component compared to the femoral implant. The association of potential risk factors for TPF with the incidence of TPF was investigated with binominal logistic regression. Fourteen patients (0.9%) suffered from TPF at a median of 1month after surgery. The mean follow-up period was 5.9 ± 1.7years. Fractures were more common in cases with undersized tibial components [odds ratio (OR) 3.2, p < 0.05]. Furthermore, older age (OR 1.1, p < 0.05) and female sex (OR 6.5, p < 0.05) were identified as significant risk factors, while BMI (p = 0.8) and cemented implantation (p = 0.2) had no effect on fracture rate. Revision surgery included open reduction and internal fixation or conversion to total knee arthroplasty. Undersizing of implant sizes in UKA increases the risk for TPF especially in patients with small tibial implants. Therefore, mismatched implants should be avoided for UKA particularly when risk factors like obesity, older age, or female gender are present. Tibial periprosthetic fractures were successfully treated by open reduction and internal fixation or conversion to total knee arthroplasty.

Cementless metal-backed patellar components in primary total knee arthroplasty using an implant of modern design.

The use of cementless total knee arthroplasty (TKA) components has increased during the past decade. The initial design of cementless metal-backed patellar components had shown high failure rates due to many factors. The aim of this study was to evaluate the clinical results of a second-generation cementless, metal-backed patellar component of a modern design. This was a retrospective review of 707 primary TKAs in 590 patients from a single institution, using a cementless, metal-backed patellar component with a mean follow-up of 6.9 years (2 to 12). A total of 409 TKAs were performed in 338 females and 298 TKAs in 252 males. The mean age of the patients was 63 years (34 to 87) and their mean BMI was 34.3 kg/m2 (18.8 to 64.5). The patients were chosen to undergo a cementless procedure based on age and preoperative radiological and intraoperative bone quality. Outcome was assessed using the Knee Society knee and function scores and range of motion (ROM), complications, and revisions. A total of 24 TKAs (3.4%) in 24 patients failed and required revision surgery, of which five were due to patellar complications (0.71%): one for aseptic patellar loosening (0.14%) and four for polyethylene dissociation (0.57%). A total of 19 revisions (2.7%) were undertaken in 19 patients for indications which did not relate to the patella: four for aseptic tibial loosening (0.57%), one for aseptic femoral loosening (0.14%), nine for periprosthetic infection (1.3%), one for popliteus impingement (0.14%), and four for instability (0.57%). Knee Society knee and function scores, and ROM, improved significantly when comparing pre- and postoperative values. Survival of the metal-backed patellar component for all-cause failure was 97.5% (95% confidence interval 94.9% to 100%) at 12 years. The second-generation cementless TKA design of metal-backed patellar components showed a 97.5% survival at 12 years, with polyethylene dissociation from the metal-backing being the most common cause of patellar failure. In view of the increased use of TKA, especially in younger, more active, or obese patients, these findings are encouraging at mean follow-up of seven years.

Artifact Reduction Proton Density Magnetic Resonance Imaging Can Better Visualize Unicompartmental Knee Arthroplasty Components but Does Not Improve Measurement Accuracy at 3T: An In Vitro Phantom Study.

Background There are no studies of the efficacy of slice encoding for metal artifact correction (SEMAC) magnetic resonance imaging (MRI) at 3T for patients following unicompartmental knee arthroplasty (UKA), although the artifact is expected to increase compared with 1.5T. Purpose To clarify whether SEMAC MRI can better visualize UKA components and improve measurement accuracy at 3T MRI. Materials and methods The phantom consisted of femoral and tibial standard UKA components embedded in agarose gel. The MR images were scanned on a 3T MR system including proton density (PD) MR images. Six orthopedic surgeons blinded to the size and details of the components independently scored the diagnostic value for measurement and measured the lengths of the femoral posterior condyle, femoral peg, anterior-posterior (AP) tibial component, medial-lateral (ML) tibial component, and tibial keel, with and without SEMAC. Visualization scores were stratified as 0 = definitely nondiagnostic, 1 = probably nondiagnostic, 2 = possibly diagnostic, 3 = probably diagnostic, and 4 = definitely diagnostic. In addition, the differences between actual length and 95% confidence intervals of five measurement points were analyzed. Results The diagnostic values of the posterior condyle (2.0; 1.5 vs. 0; 0) and femoral peg (1.5; 1.0 vs. 0; 0) were significantly better in SEMAC-PD MRI than in non-SEMAC-PD MRI (P<0.05). On the other hand, there were no significant differences in the visualizations of AP, ML, and keel of the tibial components. Measurements of the femoral posterior condyle and tibial keel approached the actual length, but were not involved within the 95% confidence interval(actual length, 19.4 mm vs. 95% CI, 15.7-19.1 mm). Conclusion A significant reduction of metal artifacts was observed only around the femoral component in SEMAC-PD MRI. Despite artifact reduction, this sequence did not result in better visualization for measurement.

Unicompartmental knee arthroplasties: does the type of tibial component selected influence implant survival?

Few information has been published on the survival of unicompartmental knee arthroplasty (UKA) and fixed-bearing tibial components. The aim of this study is to analyze if UKA survival varies according to UKA model used and to analyze the possible risk factors for UKA revision. A retrospective study analyzing 301 UKAs (ACCURIS, all-polyethylene tibial component, 152; Triathlon PKR, metal-backed tibial component, 149) was performed. Demographic parameters as well as implant survival and cause of prosthetic revision were analyzed. The Kaplan-Meier survival analysis, the log-rank test and the Cox multiple regression were used for the analysis. Average follow-up was 8.1 ± 3.08-years. Average age was 68.1 ± 8.6-years; 70.4% of subjects were women. The ACCURIS UKA group had a UKA revision rate higher compared to the Triathlon PKR group (16/152, 10.6% vs 5/149, 3.4%, respectively; p < 0.001). The main cause of prosthetic revision was aseptic loosening (5/21, 23.8%). All aseptic loosening cases and tibial component collapse were reported with the ACCURIS UKA group. Overall UKA survival was 98.01% (95% CI 95.62-99.1) at 1-year, 94.27% (95% CI 90.95-96.4) at 5-years and 92.38% (95% CI 88.48-94.99) at 10-years' follow-up. There were no differences in the Kaplan-Meier survival curves regarding operated side or affected tibiofemoral compartment (log-rank test = 0.614 and 0.763, respectively). However, Kaplan-Meier survival curve according to UKA model used was different (log-rank test = 0.033). The metal-backed component appeared to be a protector factor for UKA revision when adjusted for age, sex, operated side, and affected tibiofemoral compartment (Hazard Ratio 0.32, p = 0.031). Fixed-bearing UKAs showed excellent mid- and long-term survival rates. Aseptic loosening is the main cause of implant failure. PKR group (metal-backed component) seem to be a protector factor to UKA revision when it was compared with ACCURIS UKA group (all-polyethylene tibial component).

In Total Knee Arthroplasty, Cementless and Hybrid Tibial Components Did Not Differ from Cemented Components for Revision-Free Survival and Had No Aseptic Loosening at 10 Years.

In Total Knee Arthroplasty, Cementless and Hybrid Tibial Components Did Not Differ from Cemented Components for Revision-Free Survival and Had No Aseptic Loosening at 10 Years.

Preoperative predictors of implant size in patients undergoing total knee arthroplasty: a retrospective cohort study

BackgroundTraditionally, the size of total knee arthroplasty (TKA) components is predicted by preoperative radiographic templating, which is of limited accuracy. This study aimed to evaluate the role of demographic data and ankle volume in predicting implant size in TKA candidates.MethodsIn a retrospective study, 415 patients who underwent TKA at a single institution were included. The mean age of the patients was 67.5 ± 7.1 years. The mean BMI of the patients was 31.1 ± 4.7 kg/m2. TKA implants were Zimmer Biomet NexGen LPS-Flex Knee in all cases. The demographic data included age, sex, height, weight, BMI, ethnicity, and ankle volume. Ankle volume was assessed with the figure-of-eight method. Multivariate linear regression analysis was used for predicting factors of implant size.ResultsMultivariate linear regression analysis showed that the Sex (β:1.41, P < 0.001), height (β:0.058, P < 0.001), ankle volume (β:0.11, P < 0.001), and Age (β:0.017, P = 0.004) were significant predictors of tibial component size. Sex (β:0.89, P < 0.001), height (β:0.035, P < 0.001), and ankle volume(β:0.091, P < 0.001) were significant predictors of femoral component size in the multivariate analysis.ConclusionDemographic data, adjunct with the ankle volume, could provide a promising model for preoperative prediction of the size of tibial and femoral components in TKA candidates.

Musculoskeletal multibody dynamics investigation for the different medial-lateral installation position of the femoral component in unicompartmental knee arthroplasty

The surgical installation accuracy of the components in unicompartmental knee arthroplasty (UKA) is an important factor affecting the joint function and the implant life. Taking the ratio of the medial-lateral position of the femoral component relative to the tibial insert (a/A) as a parameter, and considering nine installation conditions of the femoral component, this study established the musculoskeletal multibody dynamics models of UKA to simulate the patients' walking gait, and investigated the influences of the medial-lateral installation positions of the femoral component in UKA on the contact force, joint motion and ligament force of the knee joint. The results showed that, with the increase of a/A ratio, the medial contact force of the UKA implant was decreased and the lateral contact force of the cartilage was increased; the varus rotation, external rotation and posterior translation of the knee joint were increased; and the anterior cruciate ligament force, posterior cruciate ligament force and medial collateral ligament force were decreased. The medial-lateral installation positions of the femoral component in UKA had little effect on knee flexion-extension movement and lateral collateral ligament force. When the a/A ratio was less than or equalled to 0.375, the femoral component collided with the tibia. In order to prevent the overload on the medial implant and lateral cartilage, the excessive ligament force, and the collision between the femoral component and the tibia, it is suggested that the a/A ratio should be controlled within the range of 0.427-0.688 when the femoral component is installed in UKA. This study provides a reference for the accurate installation of the femoral component in UKA.

Development of Multibundle Virtual Ligaments to Simulate Knee Mechanics After Total Knee Arthroplasty.

Preclinical evaluation of total knee arthroplasty (TKA) components is essential to understanding their mechanical behavior and developing strategies for improving joint stability. While preclinical testing of TKA components has been useful in quantifying their effectiveness, such testing can be criticized for lacking clinical relevance, as the important contributions of surrounding soft tissues are either neglected or greatly simplified. The purpose of our study was to develop and determine if subject-specific virtual ligaments reproduce a similar behavior as native ligaments surrounding TKA joints. Six TKA knees were mounted to a motion simulator. Each was subjected to tests of anterior-posterior (AP), internal-external (IE), and varus-valgus (VV) laxity. The forces transmitted through major ligaments were measured using a sequential resection technique. By tuning the measured ligament forces and elongations to a generic nonlinear elastic ligament model, virtual ligaments were designed and used to simulate the soft tissue envelope around isolated TKA components. The average root-mean-square error (RMSE) between the laxity results of TKA joints with native versus virtual ligaments was 3.5 ± 1.8 mm during AP translation, 7.5 ± 4.2 deg during IE rotations, and 2.0 ± 1.2 deg during VV rotations. Interclass correlation coefficients (ICCs) indicated a good level of reliability for AP and IE laxity (0.85 and 0.84). To conclude, the advancement of virtual ligament envelopes as a more realistic representation of soft tissue constraint around TKA joints is a valuable approach for obtaining clinically relevant kinematics when testing TKA components on joint motion simulators.