Total Knee Arthroplasty Implants Research Articles

Do Patients With Hypoallergenic Total Knee Arthroplasty Implants for Metal Allergy Do Worse? An Analysis of Health Care Utilizations and Patient-Reported Outcome Measures

BackgroundMetal allergy is a rare and controversial cause of implant failure and poor outcomes following total knee arthroplasty (TKA). Few studies have investigated clinical and patient-reported outcome measures (PROMs) in patients treated with hypoallergenic implants. This investigation aimed to compare: (1) health care utilizations (eg, hospital length of stay, 90-day readmission rate, and incidence of nonhome discharge) and (2) 1-year PROMs between patients who received hypoallergenic and standard TKA implants. MethodsThis was a retrospective review of prospectively collected data from patients who underwent primary TKA between 2018 and 2019. Propensity score matching (3:1) was used to compare standard TKA patients with those who received hypoallergenic TKA implants, respectively. Knee injury and Osteoarthritis Outcome Score (KOOS) pain, KOOS Physical function Shortform (PS), and Veterans RAND 12-Item Health Survey Mental Component Score were collected preoperatively and at 1-year. After matching, 190 hypoallergenic and 570 standard TKAs were analyzed. ResultsNo differences were observed in length of stay (P = .98), 90-day readmission (P = .89), and nonhome discharge (P = .82). Additionally, there was no significant difference in change from preoperative to 1-year PROMs (KOOS pain, P = .97; KOOS PS, P = .88; Veterans RAND 12-Item Health Survey Mental Component Score, P = .28). Patient-reported satisfaction was similar at 1-year (P = .23). Patients achieved similar rates of Patient Acceptable Symptom State (PASS) and minimal clinically important difference (MCID) for KOOS pain (PASS, P = .77; MCID, P = .33) and KOOS PS (PASS, P = .44; MCID, P = .65). ConclusionPatients treated with hypoallergenic TKA implants for suspected metal allergy had similar outcomes compared to patients who had standard implants and no metal allergy.

Patellofemoral Arthroplasty.

Patellofemoral arthroplasty (PFA) as a treatment option for isolated patellofemoral disease continues to evolve. Enhancement in patient selection, surgical technique, implant design, and technology has led to improved short-term and midterm outcomes. Furthermore, in the setting of a younger patient with isolated patellofemoral arthritis, PFA represents an option for improved function with faster recovery times, bone preservation, maintenance of ligamentous proprioception, and the ability to delay total knee arthroplasty (TKA). The most common reason for revising PFA to a TKA is progression of tibiofemoral arthritis. In general, conversion of PFA to TKA leads to successful outcomes with minimal bone loss and the ability to use primary TKA implants and instrumentation. PFA seems to be a cost-effective alternative to TKA in appropriately selected patients with 5-, 10-PFA survivorships of 91.7% and 83.3%, respectively, and an annual revision rate of 2.18%; however, more long-term clinical studies are needed to determine how new designs and technologies affect patient outcomes and implant performance.

Short-term clinical and radiological comparisons between two Medial Pivot Total Knee Arthroplasty implants with different geometries.

Different total knee arthroplasty (TKA) implants were created for the treatment of severe symptomatic gonarthrosis and Medial Pivot TKA (MP TKA) seem to reproduce the normal kinematics of the knee. We compare two different prosthetic designs of MP TKA in order to identify whether there is a difference between the two in terms of degree of patient satisfaction. Methods: A total of 89 patients were analyzed. A group of 46 patients who benefited from a TKA with the Evolution® prosthesis and one of 43 patients who received a TKA with the Persona® prosthesis. KSS, OKS, FJS and the ROM were analyzed at follow up. The values of KSS and OKS were similar between the two groups (p>0,05). Our statistical analysis revealed a statistically significant increase (p <0.05) in ROM in the Persona® group and in FJS in the Evolution® group. No radiolucent lines were observed in both groups at the radiological final follow-up. Conclusions: MP TKA models analysed are a valuable tool to achieve satisfactory clinical outcomes. This study demonstrates that the FJS is an important score for the evaluation of patient's satisfaction: a ROM's limitation can be accepted by the patient in exchange for a more natural perceived knee.

Restoring Anatomical Features in Primary Total Knee Arthroplasty.

Today, the number of people affected by gonarthrosis symptoms is increasing proportionally. Total knee arthroplasty (TKA) is a successful intervention that aims to reduce pain and restore knee function. However, studies have shown that active young patients still have limitations in performing activities such as skiing, golfing, surfing, and dancing. Over the last few years, total knee arthroplasty has undergone significant changes. Most of the modern TKA implants are designed to reproduce the normal biomechanics of the knee joint, mimicking the physiological pattern with greater compliance in the medial compartment between the tibial insert and femoral condyle and less congruence on the lateral side. Unfortunately, functional outcomes are compromised in approximately half of TKA patients. This loss may be caused by the abnormal kinematics and inherent instability of many contemporary implants. The proper alignment of the femoral component during TKA is a crucial step that influences postoperative results. The position of the femoral component in the axial plane is responsible for flexion stability, knee joint kinematics, flexion alignment, and patellar tracking. The main goal when choosing a type of prosthesis is to achieve an adequate recovery that leads to an improvement in mobility and an increase in the efficiency of the quadriceps.

RWD68 Early Optimal Recovery As a Composite Outcome to Measure Value of Care in Patients Undergoing Primary Total Knee Arthroplasty with a New Implant Design

Many adjustments have been made to the design of Total Knee Arthroplasty (TKA) implants to improve outcomes. This study aims to investigate the impact of an innovative TKA implant design on a new composite outcome “early optimal recovery (EOR)”, an overall measure for value of care which combines early clinical outcomes and healthcare resource utilizations (HRU).

Machine Learning for Detecting Total Knee Arthroplasty Implant Loosening on Plain Radiographs.

(1) Background: The purpose of this study was to investigate whether the loosening of total knee arthroplasty (TKA) implants could be detected accurately on plain radiographs using a deep convolution neural network (CNN). (2) Methods: We analyzed data for 100 patients who underwent revision TKA due to prosthetic loosening at a single institution from 2012 to 2020. We extracted 100 patients who underwent primary TKA without loosening through a propensity score, matching for age, gender, body mass index, operation side, and American Society of Anesthesiologists class. Transfer learning was used to prepare a detection model using a pre-trained Visual Geometry Group (VGG) 19. For transfer learning, two methods were used. First, the fully connected layer was removed, and a new fully connected layer was added to construct a new model. The convolutional layer was frozen without training, and only the fully connected layer was trained (transfer learning model 1). Second, a new model was constructed by adding a fully connected layer and varying the range of freezing for the convolutional layer (transfer learning model 2). (3) Results: The transfer learning model 1 gradually increased in accuracy and ultimately reached 87.5%. After processing through the confusion matrix, the sensitivity was 90% and the specificity was 100%. Transfer learning model 2, which was trained on the convolutional layer, gradually increased in accuracy and ultimately reached 97.5%, which represented a better improvement than for model 1. Processing through the confusion matrix affirmed that the sensitivity was 100% and the specificity was 97.5%. (4) Conclusions: The CNN algorithm, through transfer learning, shows high accuracy for detecting the loosening of TKA implants on plain radiographs.

Patellar dimensions in south Indian population-An aid to implant design in total knee arthroplasty

For a successful knee arthroplasty it is imperative to measure patellar thickness intraoperatively to guide the depth of resection. Width thickness ratio of patella is a useful indicator for assessing premorbid patellar thickness. Patellar implants for total knee arthroplasty rely mostly on data from Western population as data from Indian population is sparse. To study the dimensions of patella in South Indian population and to compare it with the previous literature. To estimate the commonest variant of patella in Indian population as per the Weibergs classification.: 101 dry patella from the Department of Anatomy of MVJ Medical College and Research Hospital were used for this study following approval from Instutional ethical committee . The dimensions of patella i.e Patellar height, width, thickness, width of medial and lateral articular facet were measured using Digital Vernier calipers. The results of various statistical parameters (Length, Width, Thickness, MAF and LAF) on the right and left side and combined were expressed in terms of mean and standard deviations along with minimum and maximum values.() The mean height, width and thickness of patella was 39.07mm, 42.56mm and 22.7mm respectively. The values of all the variables of both sides were compared. There was no statistical difference between the variables on right and left sides. Width of MAF in the present study was 19.8 ±2.82 mm while Width of LAF was 24.6±1.88mm. Ratio of width to thickness of patella was 1.8mm. There was no correlation between the two variables.Patella was classified according to Wiberg classification on the basis of dimensions of the width of medial articular and lateral articular facet as well as curvature of the facets. The most common variant observed was Type 2.The knowledge of patellar morphometry will aid the orthopedic surgeons in designing prosthesis. Morphometric data of patella on Indian population will also act as guide for forensic experts and anthropologists in sex determination.

Modern implants in total knee arthroplasty are more patellofemoral joint friendly compared to their traditional design: a systematic review and meta-analysis.

Implant designs for total knee arthroplasties (TKA) are continuously evolving to improve outcomes and satisfaction rates after TKA. The present systematic review and meta-analysis aimed to explore the evidence in the literature regarding the outcomes of the Attune knee system over the PFC Sigma knee design and investigate the advantage of one over the other. A systematic review and meta-analysis of published studies till August 2021 was performed using the defined eligibility criteria. This was a systematic review of the literature published in the Cochrane Central Register of Controlled Trials (CENTRAL) Library, PUBMED, and EMBASE. The analysis included prospective and retrospective comparative trials comparing TKA by PFC sigma or Attune posterior stabilized (PS) or cruciate-retaining (CR), fixed bearing, or rotating platform systems. Patient-reported outcome measures (PROM) and postoperative patellar complications were analysed in the studies utilizing attune knee system (modern implants) to its counterpart PFC sigma (traditional implants) for TKA. Quality assessment was conducted using NIH Quality Assessment Tool for controlled intervention studies (RCTs and case-control studies). This review included 3 RCTs and the rest, 10 of which were non-RCT, including 5852 patients. ATTUNE designs suggested a statistically significant improvement in KSS over PFC Sigma designs. Other PROMs such as OKS and WOMAC scores yielded comparable results between the two groups. ATTUNE knee prosthesis did not result in better knee range of motion, patient satisfaction, or radiological outcomes than the PFC design. Regarding the complications, attune knee prosthesis demonstrated favourable results over PFC Sigma for anterior knee pain and patellofemoral (PF) crepitus. The present systematic review highlights better KSS and lesser chances of PF complications favouring a modern implant design over its traditional counterpart. Other patient-reported outcome analyses at a short-term follow-up period were comparable among patients undergoing total knee replacements with two different implant designs. Radiological outcomes for component positioning also suggested similar results among the two groups.

Does design change in total knee arthroplasty implants affect patient-reported outcomes?

PurposeThe purpose of this study is to compare the early results of patient-reported outcomes between two generations of a total knee system.MethodsBetween June 2018 and April 2020, 121 first-generation, cemented TKAs (89 patients) and 123 s-generation, cemented TKAs (98 patients) were performed by a single surgeon. Demographic and surgical data were collected from all patients. Starting at the 6-month follow-up, patient-reported outcome measures Knee Injury and Osteoarthritis Outcome Score, Joint Reconstruction (KOOS-JR) and Knee Society (KS) clinical and radiographic scores were prospectively recorded. This study represents a retrospective review of these prospectively collected data.ResultsThere were no statistically significant differences between the two groups in terms of demographic variables such as age, body mass index, gender and race. KOOS-JR and Knee Society (KS) scores improved significantly (p < 0.001) from their preoperative values in both device generations. There were no differences, pre-operatively, between the two groups in terms of KOOS-JR, KS functional, KS objective, patient satisfaction, and expectation scores; however, there were statistically significant (p < 0.001) lower values of KOOS-JR and KS functional scores for first versus second generation at 6 months (81 vs. 89 and 69 vs. 74, respectively).ConclusionWhile significant improvement in KS objective, subjective, and patient satisfaction scores were noted with both knee systems, KOOS-JR and KS function scores were significantly higher at the early (6-month) follow-up in the second-generation group. Patients responded acutely to the design change as evidenced by significantly improved patient-reported outcome scores for the second generation.

Comparison between passive knee kinematics during surgery and active knee kinematics during walking: A preliminary study.

Recovery of function is among a patient's main expectations when undergoing total knee arthroplasty (TKA). However, normal gait knee function is not always completely restored, which can affect patient satisfaction and quality of life. Computer-assisted surgery (CAS) allows surgeons to evaluate passive knee kinematics intra-operatively. Understanding associations between knee kinematics measured during surgery and during daily activities, such as walking, could help define criteria for success based on knee function and not only on the correct alignment of the implant or the leg. This preliminary study compared passive knee kinematics measured during surgery with active kinematics measured during walking. Eight patients underwent a treadmill gait analysis using the KneeKG™ system both before surgery and three months afterwards. Knee kinematics were measured during CAS both before and after TKA implantation. The anatomical axes of the KneeKG™ and CAS systems were homogenised using a two-level, multi-body kinematics optimisation with a kinematic chain based on the calibration measured during CAS. A Bland-Altman analysis was performed before and after TKA for adduction-abduction angle, internal-external rotation, and anterior-posterior displacement over the whole gait cycle, at the single stance phase and at the swing phase. Homogenising the anatomical axes between CAS and treadmill gait led to limited median bias and limits of agreement (post-surgery -0.6 ± 3.6 deg, -2.7 ± 3.6 deg, and -0.2 ± 2.4 mm for adduction-abduction, internal-external rotation and anterior-posterior displacement, respectively). At the individual level, correlations between the two systems were mostly weak (R2 < 0.3) over the whole gait cycle, indicating low kinematic consistency between the two measurements. However, correlations were better at the phase level, especially the swing phase. The multiple sources of differences did not enable us to conclude whether they came from anatomical and biomechanical differences or from measurement system errors.

Estudio de la malrotación del componente femoral como causa de dolor tras la implantación de una artroplastia total de rodilla

IntroductionThe total knee arthroplasty (TKA) has been shown to be a successful and cost-benefit procedure in terms of pain improvement in patient with symptomatic knee osteoarthritis. However, almost a 20% of the patients are not satisfied with the result of the surgery. Material and methodWe have carried out a transversal unicentric cases controls study with clinical cases of the own hospital, obtained by a clinical records revision. A total of 160 patients with a TKA with at least 1year of follow-up were selected. Demographic variables, functional scales (WOMAC and VAS) and rotation of the femoral component through the analysis of the images obtained by CT scan were collected. ResultsThe total was 133 patients that was divided in two groups. A control group and pain group. The control group was made up of 70 patients with a mean age of 69.59years (23 men and 47 women) and the pain group was made up of 63 patients with a mean age of 69.48years (13 men and 50 women). We did not found difference regarding the analysis of the rotation of the femoral component. In addition, we were not found significant differences when applying a stratification by sex. The analysis of the malrotation of the femoral component, previously defining limits of value rotation considered as extreme, in any of the case did not show significant differences. ConclusionThe results of the study confirm that malrotation of the femoral component had no influence on the presence of pain at a minimum of one year of follow-up after TKA implantation.

High Rate of Intramedullary Canal Culture Positivity in Total Knee Arthroplasty Resection for Prosthetic Joint Infection

BackgroundPeriprosthetic infection is a devastating complication following total knee arthroplasty. A 2-stage protocol often includes an interim antibiotic spacer with intramedullary (IM) dowels. However, the necessity of IM dowels has recently been challenged. Specifically, the data supporting bacterial colonization of the IM canal are limited and controversial. The purpose of this study was to identify the rate of positive IM cultures during resection arthroplasty in periprosthetic knee infection. MethodsA total of 66 IM diaphyseal cultures were taken during resection arthroplasty from 34 patients diagnosed with periprosthetic knee infection. These IM cultures were taken from the femoral and tibial canals using separate sterile instruments. All patients had infected primary total knee arthroplasty implants at the time of resection. ResultsThirty one percent (n = 21) of IM canal cultures in this study were positive from either the tibial or the femoral diaphysis at the time of resection arthroplasty. There were 18 of 21 (86%) of the positive IM canal cultures with concordant intraoperative joint cultures where the IM cultures matched the intraarticular cultures. ConclusionWith a 31% positive IM canal culture rate, this study confirms the logic of using IM dowels with an antibiotic spacer to treat periprosthetic knee infection. Since the failure of a 2-stage reimplantation is catastrophic, any attempt to provide additional local antibiotic delivery seems warranted. Since nearly one-third of our patients had positive IM cultures, this simple addition to an antibiotic spacer has the potential to improve 2-stage results. Claims supporting the elimination of IM dowels during resection arthroplasty seem ill-advised.

Correlation between tibial valgus deformity and aspect ratio of resected tibial surface in female Chinese patients undergoing total knee arthroplasty.

Morphology of the resected tibial surface is the reference for tibial component design, selection, and implantation in total knee arthroplasty (TKA). This comparative study sought to answer whether valgus deformity of the tibia would affect the morphology of the resected tibial surface in TKA. Thirty-one female Chinese patients with valgus tibias were retrospectively and consecutively identified from a single-center registration database. Thirty-one patients with well-aligned tibias were matched in terms of gender, height, and weight. Weight-bearing full-length radiographs and computed tomography images of the whole lower limb were obtained for every case. Tibial resection was mimicked perpendicular to the mechanical axis of the tibia in the frontal plane with 3° of posterior slope and a cut level individualized by the actual intraoperative cut. On the resected surface, mediolateral dimension (MLD), medial anteroposterior dimensions (mAPD), and lateral anteroposterior dimensions (lAPD) were measured, and aspect ratios (AR) were calculated. We compared the AR between the two groups. The aspect ratio of resected tibial surface positively correlated with tibial valgus alignment. Patients with valgus tibias had significantly smaller AR (MLD/mAPD) for the medial plateau (1.50 ± 0.06 vs. 1.54 ± 0.07, P = 0.032). However, the AR for the lateral plateau was similar between the two groups (1.63 ± 0.08 vs. 1.65 ± 0.07, P = 0.328). This difference in morphology of resected tibial surface between valgus and well-aligned tibias should be considered in tibial component design, as well as in the selection and placement of TKA implants for knees with valgus tibias.

The use of an individualized intraoperative video shows no impact on the early postoperative clinical outcome after total knee arthroplasty: a prospective, randomized, controlled trial

PurposeThe purpose of the study was to evaluate the potential of an intraoperatively recorded video shown to patients immediately postoperatively on early outcome after total knee arthroplasty (TKA). The hypothesis was that there is a beneficial outcome concerning range of motion (ROM) and patient-reported outcome due to enhanced trust into the artificial joint.MethodsSeventy-three patients were randomly assigned 1:1 to two study groups in which they were either shown a video of their own postoperative range of motion or they were not. Clinically, the New Knee Society Score (nKSS) and ROM were evaluated and compared between the groups 6 weeks after surgery. Chi-square exact test, Kolmogorov–Smirnov test, Mann–Whitney U test, and the Wilcoxon signed rank test were used. Inter- and intra-class correlations were calculated for measurements of ROM.ResultsNo clinically relevant differences were observed preoperatively and 6 weeks postoperatively between both groups in range of motion (ROM). All patients were showing a significantly improved clinical outcome 6 weeks after the procedure. Clinical scores showed statistically significant differences with respect to preoperative nKSS for satisfaction and statistically significant differences with respect to postoperative nKSS for function.ConclusionShowing a video filmed immediately after implantation of primary TKA had no significant effect on ROM and clinical outcome at 6 weeks. We believe that face-to-face verbal communication in combination with video-assisted education ensures that patients understand their artificial joint in the best possible way and will continue to use intraoperatively filmed videos to enhance patient engagement during postoperative rehabilitation.Level of evidenceI.

Customized-individually-made origin® implants in total knee arthroplasty allow a reliable solution for accurate reproduction of planned implant positioning.

To evaluate the accuracy and reproducibility of a patient-specific, customized individually made (CIM) total knee replacement (TKR) using the ORIGIN® prosthesis. This was a prospective study conducted at a University Hospital from January 15, 2019, to April 30, 2021. The study included patients planned for an ORIGIN® CIM TKR procedure. Exclusion criteria included revision surgery, severe deformity, stiffness, or laxity. Evaluations were carried out using computed tomography scans performed 8 weeks preoperatively and 6 weeks postoperatively. The primary outcome measurements were the preoperative, planned, and postoperative CT scan alignment measurements including the Hip-Knee-Ankle (HKA) angle, mechanical Medial Distal Femoral articular surface Angle (mMDFA, distal alpha angle), Posterior Distal femoral articular surface angle (PDFA, posterior alpha angle), mechanical Medial Proximal Tibial articular surface Angle (mMPTA, beta angle) and posterior proximal tibial angle (PPTA). Secondary outcomes included the accuracy of implant positioning with percentage of outliers at 2° and 3° RESULTS: The study encompassed 51 knees from 50 patients with mean age of 68.1 (SD = 8.89). The overall HKA angle deviated by -0.93° [95% CI: -1.45; -0.43], and the PDFA angle by -0.61° [95% CI: -1.07; -0.15], while the mMPTA exceeded planned values by 1.00° [95% CI: 0.57; 1.43]. The 3° outliers rate ranged from 3.9% for the mMPTA to 7.8% for the HKA alignment, with no outliers in mMDFA and PPTA. Similarly, the 2° outliers rate ranged from 15.7% for both the PDFA angle and mMPTA to 19.6% for the HKA alignment. The Bland-Altman plots further emphasized the precision of planned and post-operative angles across all measurements. The CIM TKR showed high accuracy and reproducibility, closely matching preoperative planning. The weakest accuracy at 3°-outliers is in the reproduction of the HKA alignment at 92.2% (range for all angle: 92.2-100%). Similarly, the weakest accuracy at 2°-outliers is in the reproduction of the HKA alignment at 80.4% (range for all angles: 80.4-92.2%).

Trends in characterization and analysis of TKA implants for 3D printing

In almost every country, knee joint problems are common among humans. As per American Academy of Orthopedic Surgeons, it is estimated that 3.5 million individuals in the world will undergo knee replacement surgery by 2030. People with advanced rheumatoid arthritis, or long-standing osteoarthritis are usually affected by this deformity due to changes in lifestyle. These conditions mainly affect middle-aged and elderly individuals with osteoarthritis or severe knee injuries. These problems can be overcome with the help of total knee implants by undergoing surgical procedures for providing relaxation &amp; comfort to the knee joint. These procedures are also known as total knee arthroplasty (TKA). TKA is an ancient surgical process employed for treating intracapsular knee joint arthritis. It is promising technique greatly augmenting a patient’s standard of life. The main components of TKA are femoral and tibial components, spacer, and patellar components respectively. Materials often used in these components include titanium, Ti6Al4V, cobalt-chromium alloys, polyethylene and bio compatible materials. 3D printing of TKA implants is a recent avenue being explored by researchers in an attempt to develop a better replacement for the conventional implants for providing comfort to the patients. This paper presents thorough assessment of research trends in mechanical characterization and finite element analysis of knee joint prosthetics, especially TKA implants for 3D printing.

Robotic-assisted revision total joint arthroplasty: a state-of-the-art scoping review.

During the past decades, robotic-assisted technology has experienced an incredible advancement in the field of total joint arthroplasty (TJA), which demonstrated promise in improving the accuracy and precision of implantation and alignment in both primary total hip arthroplasty (THA) and total knee arthroplasty (TKA). However, revision TJA remains a technically challenging procedure with issues of large-scale bone defects and damage to nearby anatomical structures. Thus, surgeons are trying to harness the abilities of robotic-assisted technology for revision TJA surgery. PubMed, Embase, Cochrane Library, and Google Scholar were comprehensively searched to identify relevant publications that reported the application of robotic-assisted technology in revision TJA. Overall, ten studies reported the use of the robotic system in revision TJA, including active (ROBODOC) and semi-active (MAKO and NAVIO) systems. One clinical case reported conversion from hip fusion to THA, and three studies reported revision from primary THA to revision THA. Moreover, four studies reported that robotic-assisted technology is helpful in revising unicompartmental knee arthroplasty (UKA) to TKA, and two case reports converted primary TKA to revision TKA. In this study, we present the latest evolvements, applications, and technical obstacles of robotic-assisted technology in the revision of TJA and the current state-of-the-art. Current available evidence suggests that robotic-assisted technology may help surgeons to reproducibly perform preoperative plans and accurately achieve operative targets during revision TJA. However, concerns remain regarding preoperative metal artifacts, registration techniques, closed software platforms, further bone loss after implant removal, and whether robotic-assisted surgery will improve implant positioning and long-term survivorship.

Inconsistent Surgical Implant Documentation: A Case Study in Total Knee and Hip Arthroplasty

Value-based care initiatives require accurate quantification of resource utilization. This study explores hospital resource documentation performance for total knee and hip arthroplasty (TKA, THA) implants and how this may differ between hospitals. This retrospective study utilized the Premier discharge database, years 2006 to 2020. TKA/THA cases were categorized into 5 tiers based upon the completeness of implant component documentation: Platinum, Gold, Silver, Bronze, Poor. Correlation between TKA and THA documentation performance (per-hospital percentage of Platinum cases) was assessed. Logistic regression analyses measured the association between hospital characteristics (region, teaching status, bed size, urban/rural) and satisfactory documentation. TKA/THA implant documentation performance was compared to documentation for endovascular stent procedures. Individual hospitals tended to have very complete (Platinum) or very incomplete (Poor) documentation for both TKA and THA. TKA and THA documentation performance were correlated (correlation coefficient = .70). Teaching hospitals were less likely to have satisfactory documentation for both TKA (P = .002) and THA (P = .029). Documentation for endovascular stent procedures was superior compared to TKA/THA. Hospitals' TKA and THA-related implant documentation performance is generally either very proficient or very poor, in contrast with often well-documented endovascular stent procedures. Hospital characteristics, other than teaching status, do not appear to impact TKA/THA documentation completeness.

Influencia de los trastornos del movimiento en la necesidad de recambio de prótesis total de rodilla primaria.

Introduction: We assess how Movement disorders influence the survival of primary Total Knee Arthroplasty implants. Methods: Retrospective observational study analyzing patients who underwent primary total knee replacement in our center who required revision surgery. Results: We found a higher prevalence than expected by age of Movement disorders in the primary total knee replacement group that required revision due to aseptic loosening. Conclusion: Movement Disorders seem to influence the survival of primary total knee replacement implants.

Validation of a novel finite-element model for evaluating patellofemoral forces and stress during squatting after posterior-stabilized total knee arthroplasty

IntroductionSeveral studies have documented the relationship between patellofemoral pain and patient dissatisfaction after total knee arthroplasty (TKA). However, few computer simulations have been designed to evaluate the patellofemoral joint during flexion. The aim of this study was to validate a new computational simulation, driven by forces and moments, and to analyze patellofemoral reaction forces and stress under squat loading conditions after TKA implantation. HypothesisThis computational simulation of a squat using a model driven by forces and moments is comparable to in vitro and in silico data from the literature. Material and methodsWe developed a finite element model of the lower limb after implantation of a fixed-bearing posterior-stabilized TKA. To simulate squat loading conditions when standing on both legs, an initial load of 130N was applied to the center of the femoral head. Quadriceps force, patellofemoral contact force and Von Mises stress on the patellar implant, tibiofemoral contact forces and pressure on the tibial insert, and post-cam contact force were evaluated from 0° to 100° of knee flexion. ResultsQuadriceps force increased during flexion, up to 6 times the applied load. Von Mises stress on patellar implant increased up to 16MPa at 100° flexion. Tibiofemoral contact forces increased up to 415 N medially and 339 N laterally, with 64% distributed medially on the tibial insert. Post-cam contact started slightly before 70° of flexion. DiscussionIn this simulation, tibiofemoral, patellofemoral and post-cam contact forces, and pressure distribution on the tibial insert were consistent with various published studies. This agreement suggests that computational simulation driven by forces and moments can reproduce squat loading conditions during knee flexion after TKA, without experimental kinematic data used to drive the simulation. ConclusionThis study represents an initial step towards validating tibiofemoral and patellofemoral mechanical behavior under squat conditions, from this computational simulation driven by forces and moments. This model will help us better understand the influence of various implantation techniques on patellofemoral forces and stress during flexion. Level of evidenceIV, biomechanical computational study.