Aims. Loosening of components after total knee arthroplasty (TKA) can be associated with the development of radiolucent lines (RLLs). The aim of this study was to assess the rate of formation of RLLs in the cemented original design of the ATTUNE TKA and their relationship to loosening. Methods. A systematic search was undertaken using the Cochrane methodology in three online databases: MEDLINE, Embase, and CINAHL. Studies were screened against predetermined criteria, and data were extracted. Available National Joint Registries in the Network of Orthopaedic Registries of Europe were also screened. A random effects model meta-analysis was undertaken. Results. Of 263 studies, 12 were included with a total of 3,861 TKAs. Meta-analysis of ten studies showed high rates of overall tibial or femoral RLLs for the cemented original design of the ATTUNE TKA. The overall rate was 21.4% (95% confidence interval (CI) 12.7% to 33.7%) for all types of design but was higher for certain subgroups: 27.4% (95% CI 13.4% to 47.9%) for the cruciate-retaining type, and 29.9% (95% CI 15.6% to 49.6%) for the fixed-bearing type. Meta-analysis of five studies comparing the ATTUNE TKA with other implants showed a significantly higher risk of overall tibial or femoral RLLs (odds ratio (OR) 2.841 (95% CI 1.219 to 6.623); p = 0.016) for the ATTUNE. The rates of loosening or revision for loosening were lower, at 1.2% and 0.9% respectively, but the rates varied from 0% to 16.3%. The registry data did not report specifically on the original ATTUNE TKA or on revision due to loosening, but ‘all-cause’ five-year revision rates for the cemented ATTUNE varied from 2.6% to 5.9%. Conclusion. The original cemented ATTUNE TKA has high rates of RLLs, but their clinical significance is uncertain given the overall low associated rates of loosening and revision. However, in view of the high rates of RLLs and the variation in the rates of loosening and revision between studies and registries, close surveillance of patients who have undergone TKA with the original ATTUNE system is recommended. Cite this article: Bone Joint J 2023;105-B(6):610–621

Aims. Conflicting clinical results are reported for the ATTUNE Total Knee Arthroplasty (TKA). This randomized controlled trial (RCT) evaluated five-year follow-up results comparing cemented ATTUNE and PFC-Sigma cruciate retaining TKAs, analyzing component migration as measured by radiostereometric analysis (RSA), clinical outcomes, patient-reported outcome measures (PROMs), and radiological outcomes. Methods. A total of 74 primary TKAs were included in this single-blind RCT. RSA examinations were performed, and PROMs and clinical outcomes were collected immediate postoperatively, and at three, six, 12, 24, and 60 months’ follow-up. Radiolucent lines (RLLs) were measured in standard anteroposterior radiographs at six weeks, and 12 and 60 months postoperatively. Results. At five-year follow-up, RSA data from 61 patients were available and the mean maximum total point motion (MTPM) of the femoral components were: ATTUNE: 0.96 mm (95% confidence interval (CI) 0.79 to 1.14) and PFC-Sigma 1.37 mm (95% CI 1.18 to 1.59) (p < 0.001). The PFC-Sigma femoral component migrated more in the first postoperative year, but stabilized thereafter. MPTM of the tibial components were comparable at five-year follow-up: ATTUNE 1.12 mm (95% CI 0.95 to 1.31) and PFC-Sigma 1.25 mm (95% CI 1.07 to 1.44) (p = 0.438). RLL at the medial tibial implant-cement interface remained more prevalent for the ATTUNE at five-year follow-up compared to the PFC-Sigma (20% vs 3%). RLL did not progress over time, and varied between patients at different timepoints for both TKA systems. Clinical outcomes and PROMs improved compared with preoperative scores, and were not different between groups. Conclusion. MTPM migration at five-year follow-up of the femoral and tibial component of the ATTUNE were similar and as low as that of the PFC-Sigma. MTPM migration of both knee implants did not significantly change from one year post-surgery, indicating stable fixation. Long-term ATTUNE performance may be expected to be comparable to the clinically well-performing PFC-Sigma. We have not found evidence of increased tibial component migration as measured by RSA to support concerns about cement debonding and a higher risk of aseptic loosening with the ATTUNE TKA. Cite this article: Bone Joint J 2023;105-B(11):1168–1176

Objectives. The Attune total knee arthroplasty (TKA) has been used in over 600 000 patients worldwide. Registry data show good clinical outcome; however, concerns over the cement-tibial interface have been reported. We used retrieval analysis to give further insight into this controversial topic. Methods. We examined 12 titanium (Ti) PFC Sigma implants, eight cobalt-chromium (CoCr) PFC Sigma implants, eight cobalt-chromium PFC Sigma rotating platform (RP) implants, and 11 Attune implants. We used a peer-reviewed digital imaging method to quantify the amount of cement attached to the backside of each tibial tray. We then measured: 1) the size of tibial tray thickness, tray projections, peripheral lips, and undercuts; and 2) surface roughness (Ra) on the backside and keel of the trays. Statistical analyses were performed to investigate differences between the two designs. Results. There was no evidence of cement attachment on any of the 11 Attune trays examined. There were significant differences between Ti and CoCr PFC Sigma implants and Attune designs (p < 0.05); however, there was no significant difference between CoCr PFC Sigma RP and Attune designs (p > 0.05). There were significant differences in the design features between the investigated designs (p < 0.05). Conclusion. The majority of the earliest PFC Sigma designs showed evidence of cement, while all of the retrieved Attune trays and the majority of the RP PFC trays in this study had no cement attached. This may be attributable to the design differences of these implants, in particular in relation to the cement pockets. Our results may help explain a controversial aspect related to cement attachment in a recently introduced TKA design. Cite this article: A. Cerquiglini, J. Henckel, H. Hothi, P. Allen, J. Lewis, A. Eskelinen, J. Skinner, M. T. Hirschmann, A. J. Hart. Analysis of the Attune tibial tray backside: A comparative retrieval study. Bone Joint Res 2019;8:136–145. DOI: 10.1302/2046-3758.83.BJJ-2018-0102.R2

Aims. The primary objective of this study was to compare migration of the cemented ATTUNE fixed bearing cruciate retaining tibial component with the cemented Press-Fit Condylar (PFC)-sigma fixed bearing cruciate retaining tibial component. The secondary objectives included comparing clinical and radiological outcomes and Patient Reported Outcome Measures (PROMs). Methods. A single blinded randomized, non-inferiority study was conducted including 74 patients. Radiostereometry examinations were made after weight bearing, but before hospital discharge, and at three, six, 12, and 24 months postoperatively. PROMS were collected preoperatively and at three, six, 12, and 24 months postoperatively. Radiographs for measuring radiolucencies were collected at two weeks and two years postoperatively. Results. The overall migration (mean maximum total point motion (MPTM)) at two years was comparable: mean 1.13 mm (95% confidence interval (CI), 0.97 to 1.30) for the ATTUNE and 1.16 mm (95% CI, 0.99 to 1.35) for the PFC-sigma. At two years, the mean backward tilting was -0.43° (95% CI, -0.65 to -0.21) for the ATTUNE and 0.08° (95% CI -0.16 to 0.31), for the PFC-sigma. Overall migration between the first and second postoperative year was negligible for both components. The clinical outcomes and PROMs improved compared with preoperative scores and were not different between groups. Radiolucencies at the implant-cement interface were mainly seen below the medial baseplate: 17% in the ATTUNE and 3% in the PFC-sigma at two weeks, and at two years 42% and 9% respectively (p = 0.001). Conclusion. In the first two postoperative years the initial version of the ATTUNE tibial component was not inferior with respect to overall migration, although it showed relatively more backwards tilting and radiolucent lines at the implant-cement interface than the PFC-sigma. The version of the ATTUNE tibial component examined in this study has subsequently undergone modification by the manufacturer. Level of Evidence: 1 (randomized controlled clinical trial). Cite this article: Bone Joint J 2020;102-B(9):1158–1166

Abstract. Objective. Up to 20% of patients can remain dissatisfied following TKR. A proportion of TKRs will need early revision with aseptic loosening the most common. The ATTUNE TKR was introduced in 2011 as successor to its predicate design The PFC Sigma (DePuy Synthes, Warsaw, In). However, following reports of early failures of the tibial component there have been ongoing concerns of increased loosening rates with the ATTUNE TKR. In 2017 a redesigned tibial baseplate (S+) was introduced, which included cement pockets and an increased surface roughness to improve cement bonding. Given the concerns of early tibial loosening with the ATTUNE knee system, this study aimed to compare revision rates and those specific to aseptic loosening of the ATTUNE implant in comparison to an established predicate as well as other implant designs used in a high-volume arthroplasty centre. Methods. The Attune TKR was introduced to our unit in December 2011. Prior to this we routinely used a predicate design with an excellent long-term track record (PFC Sigma) which remains in use. In addition, other designs were available and used as per surgeon preference. Using a prospectively maintained database, we identified 10,202 patients who underwent primary cemented TKR at our institution between 01/04/2003–31/03/2022 with a minimum of 1 year follow-up (Mean 8.4years, range 1–20years): 1) 2406 with ATTUNE TKR (of which 557 were S+) 2) 4652 with PFC TKR 3) 3154 with other cemented designs. All implants were cemented using high viscosity cement. The primary outcome measures were all-cause revision, revision for aseptic loosening, and revision for tibial loosening. Kaplan-Meier survival analysis and Cox regression models were used to compare the primary outcomes between groups. Matched cohorts were selected from the ATTUNE subsets (original and S+) and PFC groups using the nearest neighbor method for radiographic analysis. Radiographs were assessed to compare the presence of radiolucent lines in the Attune S+, standard Attune, and PFC implants. Results. At a mean of 8.4 years follow-up, 308 implants underwent revision equating to 3.58 revisions per 1000 implant-years. The lowest risk of revision was noted in the ATTUNE cohort with 2.98 per 1000-implant-years where the PFC and All Other Implant groups were 3.15 and 4.4 respectively. Aseptic loosing was the most common cause for revision across all cemented implants with 76% (65/88) of involving loosening of the tibia. Survival analysis comparing the ATTUNE cohort to the PFC and All Other Cemented Implant cohorts showed no significant differences for: all-cause revision, aseptic loosening, or tibial loosening (p=0.15,0.77,0.47). Radiolucent lines were detected in 4.6%, 5.8%, and 5.0% of the ATTUNE S+, standard ATTUNE, and PFC groups respectively. These differences were not significant. Conclusion. This study represents the largest non-registry review of the original and S+ ATTUNE TKR in comparison to its predicate design as well as other cemented implants. There appears to be no significant increased revision rate for all-cause revision or aseptic loosening. Radiographic analysis also showed no significant difference in peri-implant radiolucency. It appears that concerns of early loosening may be unfounded. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Introduction. Despite improvement in implants and surgical techniques up to 20% of Total Knee Arthroplasty TKA patients continue to report dissatisfaction. The ATTUNE Knee System was designed to provide better patellar tracking and stability through the mid-range of flexion and therefore improve patient outcomes and satisfaction. Aims. The aims of this study were to assess patient outcomes in a consecutive series of ATTUNE TKA and ensure early results were comparable to other TKA systems in Australia. Methods. Between September 2014 and December 2015, 332 ATTUNE TKR's were implanted locally. All patients in our learning curve from case 1 were included. Mean follow-up was 2.6 years (range: 2.0–3.2). Revision, complications and postoperative ROM was collected. Patient reported outcome was measured using the Multi-Attribute Arthritis Prioritization Tool (MAPT) questionnaire. Revision rates were cross checked with an AOANJRR Ad Hoc report. Results. Revision rate of the ATTUNE TKR was lower than national rates, however not statistically different (1.6% vs. 2.1%) (p=0.508). Postoperative MAPT scores were significantly lower after TKR (median 63.4 vs. 0.0) (p<0.001). A total of 86.7% patients had a good outcome postoperative TKR (MAPT≤ 20). Conclusion. Our findings suggest the ATTUNE TKR has comparable revision rates to other TKRs currently available in Australia. Furthermore, patient reported outcome was high 2.8 years postoperatively, with 85% patient satisfaction

Abstract. Introduction. Higher than expected rates of tibial loosening with the ATTUNE® total knee arthroplasty (TKA) implant has been reported. Component loosening can be associated with the development of radiolucency lines (RLL) and our study aim was to systematically assess the reported rates of these. Methodology. A systematic search was undertaken using the Cochrane methodology in four online databases. Identified studies were assessed and screened against predetermined inclusion criteria. Meta-analysis was conducted using a random-effects model. Results. Nine studies (n=2,727 TKAs) from 6,590 titles met the inclusion criteria: 1 Randomised Controlled Trial (n=74), 1 prospective cohort (n=200), 4 retrospective cohort (n=1,639), and 3 case-series (n=814). All used the 2013 ATTUNE® design. In meta-analysis: 8 studies (n=1,440 ATTUNE TKAs) reported an overall prevalence of 11% (95%CI: 6.4-18.3%) for medial tibia RLL; 7 studies (n=940) a 12.3% (95%CI: 4.0-32%) rate of any tibia RLL.; 5 studies (n=736) femoral RLL in 11% (95%CI: 7.2-106.5%) and 7 studies (n=896) any RLL in 20.7% (95%CI: 13.4-30.6%). Meta-analysis of 4 studies (n=1,036) comparing the ATTUNE® with another implant (PFC Sigma®, LCS®, or PERSONA®) showed a higher risk of medial tibia RLL (OR: 2.538; 95%CI: 1.397-4.611, P=0.002) and any RLL (OR: 2.725; 95%CI: 1.302-5.703, P=0.008) in the ATTUNE® group. Conclusions. The 2013 ATTUNE® TKA system is associated with high rates of radiolucency around the tibial and femoral components. Comparative studies suggesting these rates are more than double those of other systems. Radiolucency may be a herald of component loosening, therefore, close surveillance of this implant is recommended

Introduction

In an effort to provide a TKA bearing material that balances resistance to wear, mechanical failure and oxidation, manufacturers introduced antioxidant polyethylene. In many designs, this is accomplished through pre-blending the polymer with the antioxidant before consolidation and radiation crosslinking. This study reports the wear performance (in terms of thickness change) of a hindered phenol (PBHP) UHMWPE from analysis of an early series of knee retrievals and explores these questions: 1) What is early-time performance of this new bearing material? 2) Is there a difference in performance between fixed and mobile bearings in this design? 3) How does quantitative surface analysis help understand performance at the insert-tray modular interface?

Aims. The primary aim of this study was to compare the migration of the femoral and tibial components of the cementless rotating platform Attune and Low Contact Stress (LCS) total knee arthroplasty (TKA) designs, two years postoperatively, using radiostereometric analysis (RSA) in order to assess the risk of the development of aseptic loosening. A secondary aim was to compare clinical and patient-reported outcome measures (PROMs) between the designs. Methods. A total of 61 TKAs were analyzed in this randomized clinical RSA trial. RSA examinations were performed one day and three, six, 12, and 24 months postoperatively. The maximal total point motion (MPTM), translations, and rotations of the components were analyzed. PROMs and clinical data were collected preoperatively and at six weeks and three, six, 12, and 24 months postoperatively. Linear mixed effect modelling was used for statistical analyses. Results. The mean MTPM two years postoperatively (95% confidence interval (CI)) of the Attune femoral component (0.92 mm (0.75 to 1.11)) differed significantly from that of the LCS TKA (1.72 mm (1.47 to 2.00), p < 0.001). The Attune femoral component subsided, tilted (anteroposteriorly), and rotated (internal-external) significantly less. The mean tibial MTPM two years postoperatively did not differ significantly, being 1.11 mm (0.94 to 1.30) and 1.17 mm (0.99 to 1.36, p = 0.447) for the Attune and LCS components, respectively. The rate of migration in the second postoperative year was negligible for the femoral and tibial components of both designs. The mean pain-at-rest (numerical rating scale (NRS)-rest) in the Attune group was significantly less compared with that in the LCS group during the entire follow-up period. At three months postoperatively, the Knee injury and Osteoarthritis Outcome Physical Function Shortform score, the Oxford Knee Score, and the NRS-activity scores were significantly better in the Attune group. Conclusion. The mean MTPM of the femoral components of the cementless rotating platform Attune was significantly less compared with that of the LCS design. This was reflected mainly in significantly less subsidence, posterior tilting, and internal rotation. The mean tibial MTPMs were not significantly different. During the second postoperative year, the components of both designs stabilized and low risks for the development of aseptic loosening are expected. Cite this article: Bone Joint J 2023;105-B(2):148–157

Aims. The aim of this study was to investigate whether wear and backside deformation of polyethylene (PE) tibial inserts may influence the cement cover of tibial trays of explanted total knee arthroplasties (TKAs). Methods. At our retrieval centre, we measured changes in the wear and deformation of PE inserts using coordinate measuring machines and light microscopy. The amount of cement cover on the backside of tibial trays was quantified as a percentage of the total surface. The study involved data from the explanted fixed-bearing components of four widely used contemporary designs of TKA (Attune, NexGen, Press Fit Condylar (PFC), and Triathlon), revised for any indication, and we compared them with components that used previous generations of PE. Regression modelling was used to identify variables related to the amount of cement cover on the retrieved trays. Results. A total of 114 explanted fixed-bearing TKAs were examined. This included 76 used with contemporary PE inserts which were compared with 15 used with older generation PEs. The Attune and NexGen (central locking) trays were found to have significantly less cement cover than Triathlon and PFC trays (peripheral locking group) (p = 0.001). The median planicity values of the PE inserts used with central locking trays were significantly greater than of those with peripheral locking inserts (205 vs 85 microns; p < 0.001). Attune and NexGen inserts had a characteristic pattern of backside deformation, with the outer edges of the PE deviating inferiorly, leaving the PE margins as the primary areas of articulation. Conclusion. Explanted TKAs with central locking mechanisms were significantly more likely to debond from the cement mantle. The PE inserts of these designs showed characteristic patterns of deformation, which appeared to relate to the manufacturing process and may be exacerbated in vivo. This pattern of deformation was associated with PE wear occurring at the outer edges of the articulation, potentially increasing the frictional torque generated at this interface. Cite this article: Bone Joint J 2021;103-B(12):1791–1801

Aims. To establish our early clinical results of a new total knee arthroplasty (TKA) tibial component introduced in 2013 and compare it to other designs in use at our hospital during the same period. Methods. This is a retrospective study of 166 (154 patients) consecutive cemented, fixed bearing, posterior-stabilized (PS) TKAs (ATTUNE) at one hospital performed by five surgeons. These were compared with a reference cohort of 511 knees (470 patients) of other designs (seven manufacturers) performed at the same hospital by the same surgeons. There were no significant differences in age, sex, BMI, or follow-up times between the two cohorts. The primary outcome was revision performed or pending. Results. In total, 19 (11.5%) ATTUNE study TKAs have been revised at a mean 30.3 months (SD 15), and loosening of the tibial component was seen in 17 of these (90%). Revision is pending in 12 (7%) knees. There was no difference between the 31 knees revised or with revision pending and the remaining 135 study knees in terms of patient characteristics, type of bone cement (p = 0.988), or individual surgeon (p = 0.550). In the reference cohort, there were significantly fewer knees revised (n = 13, 2.6%) and with revision pending (n = 8, 1.5%) (both p < 0.001), and only two had loosening of the tibial component as the reason for revision. Conclusion. This new TKA design had an unexpectedly high early rate of revision compared with our reference cohort of TKAs. Debonding of the tibial component was the most common reason for failure. Additional longer-term follow-up studies of this specific component and techniques for implantation are warranted. The version of the ATTUNE tibial component implanted in this study has undergone modifications by the manufacturer. Cite this article: Bone Joint J 2021;103-B(6 Supple A):137–144

Introduction. Bone mineral density (BMD) is correlated with component migration and aseptic loosening after total knee arthroplasty (TKA). Older implant designs have demonstrated BMD loss up to 23% in the first 6 months after TKA, and continued to BMD decline at an average of 5% per year for as long as 2 years after TKA. The impact of component design and fixation method on BMD loss after TKA in modern implant designs has not been fully elucidated. The purpose of this study is to determine the effect of tibial tray thickness and fixation method (cemented versus cementless) on BMD loss patterns of the proximal tibia in two different modern TKA implant systems. Methods. A prospective, nonrandomized, single center study of patients undergoing primary TKA by one of two surgeons was performed with four study cohorts: cemented DePuy Attune, cementless DePuy Attune, cemented Stryker Triathlon, cementless Stryker Triathlon. Target sample size was 80, with 20 per cohort based on adhoc power analysis. Exclusion criteria included: age over 75, BMI >40, inflammatory arthritis, previous knee surgery involving the femur, tibia or tibial bone, and diagnosis of osteopenia/osteoporosis. Implant fixation type was based on surgeon intraoperative assessment of patient bone quality. Demographic data was collected preoperatively. Dual Energy X-ray Absorptiometry (DEXA) Bone Density Monitoring was performed at 6 weeks and one year postoperatively. Bone mineral density was calculated from the DEXA scans for 4 zones for the tibia relative to the keel or central peg: anterior, posterior, medial and lateral. Results were reported as BMD at 1 year postoperatively as a percentage of BMD at 6 weeks postoperatively. Results. 81 knees with complete DEXA studies at 6 weeks and 1 year postoperatively were available for analysis. The mean (SD) age at the time of surgery was 65.4 years (6.1), with 39 men and 42 women and a mean (SD) BMI of 31.2 kg/m. 2. (4.7). The patients who received cementless implants were significantly younger with a mean (SD) age of 62.1 (6.0) than those who received cemented implants with a mean age of 69.1 (3.7) (p < 0.05). There was no difference in age between implant type (p > 0.05). There was no difference in BMI or gender distribution between implant types or fixation type (p > 0.05). There was no significant difference in mean BMD loss between 6 weeks and 1 year postoperatively between the cemented and cementless Triathlon in any zone, between the cemented Triathlon and Attune in any zone, the cementless Triathlon and Attune in any zone, and the cemented and cementless attune in the lateral, anterior and posterior proximal tibia (p > 0.05). There was significantly more BMD loss seen in the medial tibia in the cemented (BMD at 1 year 88% of BMD at 6 weeks) than cementless (BMD at 1 year 103% of BMD at 6 weeks) Attune (p = 0.043). Conclusion. BMD loss at 1 year postoperatively versus 6 weeks postoperatively after TKA with two modern implant designs is not significantly affected by tibial tray thickness. BMD loss was unaffected by fixation type for the Stryker Triathlon, but was significant less for the cementless DePuy Attune than the cemented version

Aims. A novel enhanced cement fixation (EF) tibial implant with deeper cement pockets and a more roughened bonding surface was released to market for an existing total knee arthroplasty (TKA) system.This randomized controlled trial assessed fixation of the both the EF (ATTUNE S+) and standard (Std; ATTUNE S) using radiostereometric analysis. Methods. Overall, 50 subjects were randomized (21 EF-TKA and 23 Std-TKA in the final analysis), and had follow-up visits at six weeks, and six, 12, and 24 months to assess migration of the tibial component. Low viscosity bone cement with tobramycin was used in a standardized fashion for all subjects. Patient-reported outcome measure data was captured at preoperative and all postoperative visits. Results. The patient cohort mean age was 66 years (SD seven years), 59% were female, and the mean BMI was 32 kg/m. 2. (SD 6 kg/m. 2. ). Mean two-year subsidence of the EF-TKA was 0.056 mm (95% confidence interval (CI) 0.025 to 0.086) versus 0.006 mm (95% CI -0.029 to 0.040) for the Std-TKA, and the two-year maximum total point motion (MTPM) was 0.285 mm (95% upper confidence limit (UCL) ≤ 0.363) versus 0.346 mm (95% UCL ≤ 0.432), respectively, for a mean difference of -0.061 mm (95% CI -0.196 to 0.074). Inducible displacement also did not differ between groups. The MTPMs between 12 and 24 months for each group was below the published threshold of 0.2 mm for predicting early aseptic loosening (p < 0.001 and p = 0.001, respectively). Conclusion. Both the enhanced fixation and the standard tibial implant design showed fixation with a predicted low risk of long-term aseptic loosening. Cite this article: Bone Jt Open 2024;5(1):20–27

The June 2023 Knee Roundup. 360. looks at: Cementless total knee arthroplasty is associated with early aseptic loosening in a large national database; Is cementless total knee arthroplasty safe in females aged over 75 years?; Could novel radiological findings help identify aseptic tibial loosening?; The Attune cementless versus LCS arthroplasty at introduction; Return to work following total knee arthroplasty and unicompartmental knee arthroplasty; Complications and downsides of the robotic total knee arthroplasty; Mid-flexion instability in kinematic alignment better with posterior-stabilized and medial-stabilized implants?; Patellar resurfacing does not improve outcomes in modern knees

Aims. One of the main causes of tibial revision surgery for total knee arthroplasty is aseptic loosening. Therefore, stable fixation between the tibial component and the cement, and between the tibial component and the bone, is essential. A factor that could influence the implant stability is the implant design, with its different variations. In an existing implant system, the tibial component was modified by adding cement pockets. The aim of this experimental in vitro study was to investigate whether additional cement pockets on the underside of the tibial component could improve implant stability. The relative motion between implant and bone, the maximum pull-out force, the tibial cement mantle, and a possible path from the bone marrow to the metal-cement interface were determined. Methods. A tibial component with (group S: Attune S+) and without (group A: Attune) additional cement pockets was implanted in 15 fresh-frozen human leg pairs. The relative motion was determined under dynamic loading (extension-flexion 20° to 50°, load-level 1,200 to 2,100 N) with subsequent determination of the maximum pull-out force. In addition, the cement mantle was analyzed radiologically for possible defects, the tibia base cement adhesion, and preoperative bone mineral density (BMD). Results. The BMD showed no statistically significant difference between both groups. Group A showed for all load levels significantly higher maximum relative motion compared to group S for 20° and 50° flexion. Group S improved the maximum failure load significantly compared to group A without additional cement pockets. Group S showed a significantly increased cement adhesion compared to group A. The cement penetration and cement mantle defect analysis showed no significant differences between both groups. Conclusion. From a biomechanical point of view, the additional cement pockets of the component have improved the fixation performance of the implant. Cite this article: Bone Joint Res 2022;11(4):229–238

Introduction. With the introduction of new technology in orthopaedics, surgeons must balance anticipated benefits in patient outcomes with challenges or complications associated with surgical learning curve for the technology. The purpose of this study was to determine whether the surgeon learning curve with a new multi-radius primary TKA system (primary TKA implant and instruments) designed for surgical team ease would impact clinical outcomes, surgical time and complications. Materials & Methods. From November 2012 to July 2015, 2369 primary TKAs were prospectively enrolled in two multicenter studies across 50 sites in 14 countries with a new knee system (ATTUNE®) evenly balanced across four configurations: cruciate retaining or posterior stabilised with either fixed bearing or rotating platform (CRFB, CRRP, PSFB, PSRP). 2261 knees had a <1 year visit and 1628 had a greater than 1 year visit. These knees were compared to a reference dataset of 845 primary TKAs from three manufacturers in the same four configurations with currently available products (CURRENT-TKA). Demographics for ATTUNE and CURRENT-TKA were similar and typical for primary TKA. Operative times, clinical outcomes and a series of five patient reported outcomes were compared for ATTUNE vs. CURRENT-TKA. The first 10 ATTUNE subjects for each surgeon were defined as learning curve cases (N=520) and were compared to all later subjects (N=1849) and also with the CURRENT-TKA cases (N=845). Patient reported outcome measures and clinical outcome analyses were adjusted for covariates including patient demographics, pre-op assessment and days post-op. Results. Mean (SD) surgical time for ATTUNE learning curve cases was 79.3 (24.7) minutes, which reduced thereafter to 73.6 (24.3) (p<0.001). Beyond 10 cases, there was a continued reduction in ATTUNE surgical time (R-Squared = 0.031). After 10 cases, surgical time was on par with the mean (SD) 72.0 (21.7) for CURRENT-TKA (p=0.097). PROM outcomes of the first 10 learning curve cases for ATTUNE were not statistically different from later cases at less than 1 year or later when adjusted for relevant covariates including configuration, patient demographics, pre-op functional status, and time post-op (p-values > 0.01). PROM outcomes for ATTUNE vs. CURRENT-TKA under the same covariate adjustments showed a trend favoring KOOS ADL, Symptoms, and Sport and Recreation subscores at minimum 1 year (p-values < 0.05). The incidence of intraoperative operative site (knee) complications was 1.3% (7/520) for the ATTUNE learning curve cases which was similar to both the 0.6% (5/845) rate for historical CURRENT-TKA (p=0.230) and the 0.8% (14/1849) intraoperative complication rate for the ATTUNE later cases (p=0.195). Discussion. The introduction of new implants into the market place needs to have adequate data to support that they are safe and effective. Except for a minor increase in surgical time during the first 10 patients, this study found that surgeon learning curve with the new ATTUNE primary TKA system does not adversely affect patient short term outcomes and complication rates

To achieve a long-lasting fixation of uncemented femoral knee implants, an adequate primary stability is required. Several factors, including the applied load, bone quality, surgical preparation, and implant characteristics affect the primary fixation. Recently, novel Attune® cementless femoral component has been proposed by DePuy Synthes (Warsaw, IN, USA). We aimed to compare the primary stability of this novel high-flex design against the conventional LCS® under different loading conditions (gait, deep knee bend (DKB), and high-flex loading), while accounting for the effect of bone quality and cut accuracy. Six pairs of femora were prepared following the normal surgical procedure. Calibrated CT-scans and 3D-optical scans of the bones were obtained to measure bone mineral density (BMD) and bone cut accuracy, respectively. After implantation of the appropriate size implants (Left legs: Attune; right: LCS), a black-and-white speckle pattern was applied to each specimen (Fig.1B). The micromotion measurement was repeated three times in nine regions of interest (ROIs): the medial and lateral condyles from the posterior view; anterior, distal, and posterior regions from the medial and lateral views; the proximal tip of the anterior flange. The reconstructions were subjected to a gait load and a portion (around 50%) of the peak force of a DKB to prevent fracture of the proximal femur (Fig. 1A and Table. 1). The loads were derived from the Orthoload database using implant-specific inverse dynamics [1]. In addition, a sequence of DIC-images synchronized with the applied load was captured to find the relationship between micromotion and load. Afterwards, implants were pushed-off simulating 150° of flexion, while force-displacement graph was recorded. BMD and bone cut accuracy were not significantly different between the groups. Under both loading conditions, Attune had a significantly lower micromotion (Table. 1). Cut accuracy was not a significant factor, and BMD was only significant for the comparison under the gait loading (not under DKB conditions). High-flex push-off force was not significantly different. However, Attune required a significantly higher load to reach a micromotion of 50 or 150 µm during the push-off test. Different relations between micromotion and applied load, depending on the loading configuration and implant design, were found (Fig. 2). Our study has shown a clearly lower range of micromotion for the novel implant. Potential factors to explain the higher micromotion of LCS are parallel anterior and posterior bone cuts in the LCS versus the tapered bone cuts of the Attune. In addition, LCS has a less surface area in contact with bone due to the presence of a rim at the borders of the implant, which may have resulted in lower pre-stresses at the bone-implant interface. Taking to account, the promising clinical outcome of LCS and also the lower range of micromotion of Attune, we suggest that the Attune has a potential to be at least as successful as the LCS system from a bone fixation point of view. However, further clinical evaluation of the Attune is necessary to assess its performance on the longer term

Introduction. Tibiofemoral constraint in patients with total knee replacements (TKR) is dependent on both implant geometry and the surrounding soft tissue structures. Choosing more highly constrained geometries can reduce the contribution of soft tissue necessary to maintain joint stability [1]. Often when knee revision surgeries are required, the soft tissue and bone are compromised leading to the use of more constrained implants to ensure knee stability [2]. The current study quantifies the differences in varus-valgus (VV) and internal-external (IE) constraint between two types of total knee revision systems: SIGMA® TC3© and ATTUNE® REVISION. Methods. Nine cadaveric knees (7 male, age 64.0 ± 9.8 years, BMI 26.28 ± 4.92) were implanted with both fixed-bearing SIGMA TC3 and ATTUNE REVISION knee systems. Five knees received the TC3 implant first, while the remaining 4 received the ATTUNE implant first. The knees were mounted in an inverted position, and a six degree-of-freedom force-torque sensor (JR3, Woodland, CA) was rigidly secured to the distal tibia (Fig. 1). A series of manual manipulations applying IE and VV torques was performed through the flexion range [3]. Each specimen was then revised to the alternate revision system, and the manual manipulations were repeated. Joint loads were calculated, and tibiofemoral kinematics were described according to the Grood-Suntay definition [4]. VV and IE kinematics were calculated as a function of flexion angle, VV torque, and IE torque as has been described previously [3]. The knees were analysed at ±6 Nm VV and ±4 Nm IE, and the kinematics were normalized to the zero load path. A paired t-test (p < .05) was employed to identify significant differences between the kinematics of the two knee systems at 10º flexion increments. Results. Less VV motion was observed in the ATTUNE REVISION system compared to the TC3 system reaching statistical significance in mid-flexion. (Fig. 2). No significant differences were observed in IE rotation between the two designs, except in full extension where the SIGMA TC3 provided increased constraint (Fig. 3). Discussion. The ATTUNE REVISION System provided increased VV constraint compared to the TC3 design. The ATTUNE tibial post was more conforming to the femoral box throughout flexion, which contributed to the increased constraint. However, this increase was not concurrent with a reduction in IE rotational freedom as has been common with more constrained revision systems [5]. ATTUNE REVISION provides additional VV stability while retaining knee IE freedom and, therefore, may enable more natural knee kinematics for patients with MCL deficiency in need of a revision TKR. Future work will focus on how the increased levels of VV constraint affect weight-bearing knee kinematics in the presence of ligament deficiency. Acknowledgements. This work was supported by DePuy Synthes Joint Reconstruction, Warsaw, Indiana, a Johnson and Johnson Company. For figures and references – please contact authors directly

Introduction. Aseptic loosening of total knee replacements is a leading cause for revision. It is known that micromotion has an influence on the loosening of cemented implants though it is not yet well understood what the effect of repeated physiological loading has on the micromotion between implants and cement mantle. This study aims to investigate effect of physiological loading on the stability of tibial implants previously subjected to simulated intra-operative lipid/marrow infiltration. Methods. Three commercially available fixed bearing tibial implant designs were investigated in this study: ATTUNE. ®. , PFC SIGMA. ®. CoCr, ATTUNE. ®. S+. The implant designs were first prepared using a LMI implantation process. Following the method described by Maag et al tibial implants were cemented in a bone analog with 2 mL of bone marrow in the distal cavity and an additional reservoir of lipid adjacent to the posterior edge of the implant. The samples were subjected to intra- operative range of motion (ROM)/stability evaluation using an AMTI VIVO simulator, then a hyperextension activity until 15 minutes of cement cure time, and finally 3 additional ROM/stability evaluations were performed. Implant specific physiological loading was determined using telemetric tibial implant data from Orthoload and applying it to a validated FE lower limb model developed by the University of Denver. Two high demand activities were selected for the loading section of this study: step down (SD) and deep knee bend (DKB). Using the above model, 6 degree of freedom kinetics and kinematics for each activity was determined for each posterior stabilized implant design. Prior to loading, the 3-D motion between tibial implant and bone analog (micromotion) was measured using an ARAMIS Digital Image Correlation (DIC) system. Measurement was taken during the simulated DKB at 0.25Hz using an AMTI VIVO simulator while the DIC system captured images at a frame rate of 10Hz. The GOM software calculated the distance between reference point markers applied to the posterior implant and foam bone. A Matlab program calculated maximum micromotion within each DKB cycle and averaged that value across five cycles. The implant specific loading parameters were then applied to the three tibial implant designs. Using an AMTI VIVO simulator each sample was subjected to 50,000 DKB and 120,000 SD cycles at 0.8Hz in series; equating to approximately 2 years of physiological activity. Following loading, micromotion was measured using the same method as above. Results. Initial micomotion measurements during DKB activity for ATTUNE. ®. , PFC SIGMA. ®. CoCr, ATTUNE. ®. S+ were 155µm, 246µm, and 104µm, respectively, and following physiological loading were 159µm, 264µm, and 112µm, respectively. While there was statistical significance between the micromotion of implant designs (p<0.05), there was no significance between before and after loading. Conclusion. This study shows there is no significant change in micromotion after approximately 2 years of physiological loading. However, there is a significant difference in micromotion between implant designs

Introduction. Aseptic loosening is one of the highest causes for revision in total knee arthroplasty (TKA). With growing interest in anatomically aligned (AA) TKA, it is important to understand if this surgical technique affects cemented tibial fixation any differently than mechanical alignment (MA). Previous studies have shown that lipid/marrow infiltration (LMI) during implantation may significantly reduce fixation of tibial implants to bone analogs [1]. This study aims to investigate the effect of surgical alignment on fixation failure load after physiological loading. Methods. Alignment specific physiological loading was determined using telemetric tibial implant data from Orthoload [2] and applying it to a validated finite element lower limb model developed by the University of Denver [3]. Two high demand activities were selected for the loading section of this study: step down (SD) and deep knee bend (DKB). Using the lower limb model, hip and ankle external boundary conditions were applied to the ATTUNE. ®. knee system for both MA and AA techniques. The 6 degree of freedom kinetics and kinematics for each activity were then extracted from the model for each alignment type. Mechanical alignment (MA) was considered to be neutral alignment (0° Hip Knee Ankle Angle (HKA), 0° Joint Line (JL)) and AA was chosen to be 3° varus HKA, 5° JL. It is important not to exceed the limits of safety when using AA as such it is noted that DePuy Synthes recommends staying within 3º varus HKA and 3º JL. The use of 5º JL was used in this study to account for surgical variation [Depuy-Synthes surgical technique DSUS/JRC/0617/2179]. Following a similar method described by Maag et al [1] ATTUNE tibial implants were cemented into a bone analog with 2 mL of bone marrow in the distal cavity and an additional reservoir of lipid adjacent to the posterior edge of the implant. Tibial implant constructs were then subjected to intra-operative ROM/stability evaluation, followed by a hyperextension activity until 15 minutes of cement curing time, and finally 3 additional ROM/stability evaluations were performed using an AMTI VIVO simulator. The alignment specific loading parameters were then applied to the tibial implants using an AMTI VIVO simulator. Each sample was subjected to 50,000 DKB cycles and 120,000 SD cycles at 0.8 Hz in series; approximating 2 years of physiological activity. After physiological loading the samples were tested for fixation failure load by axial pull off. Results. Following alignment specific physiological loading the average fixation pull-off load for MA was 3289 ± 400 N and for AA was 3378 ± 133 N (Figure 1). There was no statistically significant difference fixation failure load by axial pull-off between the two alignment types (p=0.740). Conclusion. This study indicated that anatomic alignment, as defined with the alignment limits of this study, does not adversely affect the fixation failure load of ATTUNE tibial implants. For any figures or tables, please contact the authors directly

Introduction. Patella implant research is often overlooked despite its importance as the third compartment in a total knee replacement. Wear and fracture of resurfaced patellae can lead to implant failure and revision surgeries. New simulation techniques have been developed to analyze the performance of patella designs as they interact with the trochlear groove in total knee components, and clinical validation is sought to ensure that these simulations are appropriate. The objective of this work was to subject several patellar designs to patient-derived deep knee bend (DKB) inputs on a 6 degree of freedom (DOF) simulator and compare the resultant wear scars to clinical retrievals. Materials and Methods. Previously reported DKB profiles were developed based on in vivo patellofemoral data and include a wide range of patient variability. The profiles chosen for this body of work were based on the stress in the patellar lateral facet; maximizing this stress whilst maintaining the ability to run the profile stably on the simulator. Load/kinematic profiles were run on three patellar designs (n=3 per group) for 220,000 cycles at 0.8Hz on an AMTI VIVO joint simulator. A comparison cohort of clinically retrieved devices of the same design was identified in an IRB-approved database. Exclusion criteria included gross delamination, cracking secondary to oxidation, and surgeon-reported evidence of malalignment leading to mal-tracking. 29 Patellae were included for analysis: PFC. ®. All Poly (n=14), ATTUNE. ®. Anatomic (n=6), and ATTUNE. ®. Medialized Dome (n=9). Mean in vivo duration was 70.1 months. Patellae were analyzed under optical microscope in large-depth-of-field mode to map the surface damage profile. Burnishing ‘heat-maps’ were generated for retrievals and simulated patellae by normalizing the patellar size and overlaying silhouettes from each component of the same type using a custom-developed MatLAB code. Results. Burnishing heat-map comparisons between retrievals and simulator specimens for each of the three designs were compared. Retrievals show more variation than simulator devices, however the general loci and relative area of burnished regions is closely aligned for each of the three designs. The retrieved and simulated burnishing scar heat-maps on all-poly PFC. ®. patellae are centered medio-laterally with a wider profile on the lateral aspect. The burnishing marks are continuous. A similar observation may be made of the ATTUNE. ®. medialized dome, retrievals and simulator specimens, though the contact areas appear to be more concentrated away from the apex. The anatomic patellae show two primary regions of contact, and minimal burnishing at the apex. The simulator specimens likewise show two principal regions of contact. Discussion. Wear scar analysis shows that joint simulation on AMTI VIVO yields clinically relevant wear patterns across a variety of device types. Clinically relevant damage provides insight that load and motion inputs to the simulator deliver results that may be used to interpret in vivo performance or analyze future designs and/or materials. This qualitative surface contact analysis will help to inform future quantitative mass loss and fatigue failure studies. For any figures or tables, please contact authors directly

Total Knee Arthroplasty (TKA) is an effective surgery performed for knee osteoarthritis. Despite this success up to 20% of patients are less than fully satisfied. Rotating platform (RP) bearings have demonstrated significant reduction in rates of wear in laboratory studies but thus far have failed to demonstrate a clinical difference compared to fixed bearing (FB) arthroplasty in patients. This may be due to studies limited by small sample size and single centre design. Additionally, no studies have utilised modern patient-reported outcome measures (PROMs) such as PKIP to investigate differences between these bearings. A non-randomised, prospective, multi-centre study was conducted across centres in Australia, United Kingdom and the United States from November 2012 to May 2015. Knee prosthesis included were the RP and FB models of the PFC Sigma Knee (Depuy, Synthes) and the ATTUNE Knee (Depuy, Synthes). Data was collected on pre-arthroplasty interventions, demographics and PROMs. PROMs included were the KOOS, OKS, EQ53DL and PKIP. Participants were followed-up for 2 years. A total of 1,718 patients were recruited across 27 centres. 959 participants underwent a FB TKA, 759 participants underwent a RP TKA. No significant difference was found between RP and FB in change from baseline at 2 years across any parameter in all PROMs investigated at 2 years. Body Mass Index pre-operatively was the biggest indicator of change from baseline at 2 years. Our data demonstrates similar improvements in the short-term in both RP and TKA across all PROMs. Patients reported similar scores in satisfaction, confidence, mobility and stability in the PKIP PROM for both RP and FB groups. We have not found any evidence to suggest that RP TKA is disadvantageous at 2 years, and this is reassuring for any surgeon looking to utilise this bearing type in practice. Our data does not demonstrate a clinical advantage in RP TKA over FB TKA at 2 years in any PROM

Introduction. Wear of polyethylene continues to be a significant factor in the longevity of total knee replacement (TKR). Moderately cross-linked polyethylene has been employed to reduce the wear of knee prostheses, and more recently anti-oxidants have been introduced to improve the long-term stability of the polyethylene material. This is the initial study of the wear of a new anti-oxidant polyethylene and a new TKR design, which has modified femoral condylar geometry. Materials and Methods. The wear of a new TKR the Attune knee was investigated using a physiological six station Prosim knee wear simulator (Simulator Solutions, UK). Six mid-size Attune fixed bearing cruciate retaining TKRs (DePuy Inc, Warsaw, USA) were tested for a period of 6 million cycles. The inserts were manufactured from AOX™, a compression moulded GUR1020 polyethylene incorporating Covernox™ solid anti-oxidant. The AOX polymer was irradiated to 8M Rad, to give a moderately cross-linked material. High and intermediate kinematics, under anterior-posterior displacement control were used for this study (McEwen et al 2005). The maximum femoral axial loading was 2600N, with flexion-extension of 0 to 58°, an anterior-posterior displacement of 0–10 mm for high kinematics and 0–5 mm for intermediate, and an internal-external rotation of ±5°. The lubricant was 25% (v/v) calf serum supplemented with 0.03% (v/v) sodium azide solution in deionised water, as an antibacterial agent, and was changed approximately every 0.33 Mc. Wear was assessed gravimetrically and moisture uptake was assessed using unloaded soak controls. Volumetric wear was calculated using a density of 0.94 mg/mm. 3. , and compared with a previous study examining the Sigma XLK TKR design which uses moderately crosslinked polyethylene which is in current clinical use (Brockett et al 2012). Results. The mean wear as a function of cycles, under high and intermediate kinematics is indicated in Figure 1. There was a significant reduction in wear rate with intermediate kinematics. The mean wear rate for the Attune TKR under high kinematics (0–3 Mc) was 6.27±1.03 mm. 3. /Mc, and during the intermediate kinematics (3–6 Mc) was 4.63 ±1.01 mm. 3. /Mc. These wear rates were comparable to previously reported data for a moderately cross-linked UHMWPE Sigma TKR (Figure 2, Brockett et al 2012) under high kinematics. Under intermediate kinematics there was a small but significant difference between the wear rates (ANOVA, p<0.05). Discussion. A new Attune design TKR has a new bearing material and a new femoral geometry was examined through experimental wear simulator studies, and compared with a previously reported study conducted under the same test conditions. The wear performance of the new Attune TKR was comparable with the Sigma XLK bearing under high kinematics, but higher under intermediate kinematics. This study has examined the short term wear performance of the implant, and found it to be a low wear option for TKR. The longer-term potential advantages offered by a more oxidatively stable material will be investigated in the future

Abstract. Objectives. Obesity is prevalent with nearly one third of the world's population being classified as obese. Total knee arthroplasty (TKA) is an effective treatment option for high BMI patients achieving similar outcomes to non-obese patients. However, increased rates of aseptic loosening in patients with a high BMI have been reported. In patients with high BMI/body mass there is an increase in strain placed on the implant fixation interfaces. As such component fixation is a potential concern when performing TKA in the obese patient. To address this concern the use of extended tibial stems in cemented implants or cementless fixation have been advocated. Extend tibial stems are thought to improve implant stability reducing the micromotion between interfaces and consequently the risk of aseptic loosening. Cementless implants, once biologic fixation is achieved, effectively integrate into bone eliminating an interface. This retrospective study compared the use of extended tibial stems and cementless implants to conventional cemented implants in high BMI patients. Methods. From a prospectively maintained database of 3239 primary Attune TKA (Depuy, Warsaw, Indiana), obese patients (body mass index (BMI) >30 kg/m²) were retrospectively reviewed. Two groups of patients 1) using a tibial stem extension [n=162] and 2) cementless fixation [n=163] were compared to 3) a control group (n=1426) with a standard tibial stem cemented implant. All operations were performed by or under the direct supervision of specialist arthroplasty surgeons. Analysis compared the groups with respect to class I, II, and III (BMI >30kg/m², >35 kg/m², >40 kg/m²) obesity. The primary outcome measures were all-cause revision, revision for aseptic loosening, and revision for tibial loosening. Kaplan-Meier survival analysis and Cox regression models were used to compare the primary outcomes between groups. Where radiographic images at greater than 3 months post-operatively were available, radiographs were examined to compare the presence of peri-implant radiolucent lines. Results. The mean follow-up of 4.8, 3.4, and 2.5 years for cemented, stemmed, and cementless groups respectively. In total there were 34 all-cause revisions across all the groups with revision rates of 4.55, 5.50, and 0.00 per 1000-implant-years for cemented, stemmed, and cementless groups respectively. Survival Analysis did not show any significant differences between the three groups for all-all cause revision. There were 6 revisions for aseptic loosening (5 tibial and 1 femoral); all of which were in the standard cemented implant group. In contrast there were no revisions in the stemmed or cementless implant groups, however, this was not significant on survival analysis. Analysis looking at class I, II, and III obesity also did not show any significant differences in survival for all cause revision or aseptic loosening. Conclusion. This retrospective analysis showed that there were no revisions required for aseptic loosening when either a cemented stemmed or cementless implant were used in obese patients. These findings are in line with other studies showing that cementless fixation or extended stem implants are a reasonable option in obese patients who represent an increasing cohort of patients requiring TKR. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction. Anterior knee pain (AKP) is a recognized cause of patient's dissatisfaction after total knee arthroplasty. Potential implant/technique related contributors to AKP are patellofemoral maltracking, trochlear geometry, femoral malrotation, patellar tilt and overstuffing. The primary aim of this prospective, matched pair study was to assess the safety, efficacy and performance of an anatomic patella and its effect on AKP in in a matched pair analysis. Material and Methods. Between July 2012 and May 2013, 55 consecutive posterior stabilized cemented Attune TKAs (Depuy) were matched to the PFC Sigma group based on age, gender, and body mass index (BMI). All surgeries were performed via medial parapatellar approach with patellar resurfacing. Clinical and radiographic analysis was performed prospectively with minimum 6 month follow-up. Radiographic measurements included overall limb alignment, anterior offset, posterior offset, joint line, patellar thickness, patellar tilt and patellar displacement by two independent observers. Results. The mean functional outcomes were similar in both groups. AKP incidence between Attune and PFC was statistically insignificant (3.6% and 3.8%). Radiographic analysis revealed no mal-alignment, or osteolysis. No complications such as infection, patellar fracture, subluxation or dislocations were observed. Discussion. Attune knee design demonstrates excellent short-term safety and efficacy. At minimum 6-month follow-up, anatomical patella with shows less AKP than single radius patella design. Longer follow-up is required to assess functional outcome this design

Introduction. For many patients, total knee replacement (TKR) provides pain relief and restores motion for many years [1]. Some patients, however, experience early failures and require revision surgery. One of the suggested contributors to early failure has been excessive wear due to malalignment [2]. Previous work has shown that varus-valgus malalignment results in extreme condylar loading and could lead to high wear [3]. The purpose of this experiment, therefore, was to evaluate medial/lateral load sharing in an in vitro wear simulation. Methods. Wear testing was conducted on midsized Attune and Sigma fixed bearing cruciate substituting TKR components (DePuy Synthes). The two systems differ in many aspects; notably, Attune employs antioxidant-stabilized moderately-crosslinked polyethylene and a gradually changing sagittal femoral curvature while Sigma uses remelted moderately-crosslinked polyethylene and a mulit-radius femoral design. Wear was evaluated across a wide range of medial/lateral (M/L) load splits: 10/90, 60/40, and 90/10 using an AMTI six-station knee simulator (Figure 1). Simulation was conducted for 3 million cycles using at 1 Hz using previously described methods [4] with ‘High Kinematic’ displacement controlled inputs in 25% bovine calf serum (Hyclone) at 37 ± 2°C supplemented with sodium azide and EDTA. Polyethylene wear was determined gravimetrically with load soak compensation every 0.5 Mcyc. Results. The wear of Attune and Sigma components were consistently low across all load splits (Figure 2). The standard 60/40 load split was the lowest wearing condition for both designs, but the extreme lateralized and medialized loadings were not appreciably higher (Figure 3). No statistics are available due to the small sample size. Conclusion. The medial/lateral load sharing did not affect wear for Attune and Sigma designs in this displacement controlled in vitro wear simulation. For each group, the inserts subjected to extreme load splits wore comparably to those with a standard 60/40 load split. It is important to note that all samples experienced similar motions with similar cross-shear and differed primarily in the condylar load sharing. With this in mind, the relationship of the results is supported by research in fundamental polyethylene behavior that suggests cross-shear may dominate loading effects [5]. Clinically, however, patients will likely experience altered motions and other effects due to malalignment that were not investigated in this study. While this study showed limited variation in wear across a wide range of condylar load ratios, surgeons and device manufacturers should continue to explore the full implications of malalignment

Introduction. Potential implant and technique related factors to improve patellofemoral (PF) kinematics in total knee arthroplasty (TKA) are design of trochlear geometry and patella, restoration of posterior offset, patellar tilt and avoid overstuffing. The primary aim of this prospective, matched pair study was to assess the radiographic features of PF kinematics with an anatomic patella. Material and Methods. Between July 2012 and May 2013, 49 consecutive posterior stabilized cemented Attune TKAs (Depuy Synthes Warsaw Indiana) were matched to the 49 PFC Sigma (Depuy) based on age, gender, and body mass index (BMI). All surgeries were performed via medial parapatellar approach with patellar resurfacing. Radiographic analysis was performed prospectively with minimum 1-year follow-up and included overall limb alignment, anterior offset, posterior offset, joint line, patellar thickness, patellar tilt and patellar displacement by two independent observers. Results. We found significant improvement in all post-operative radiographies parameters from prior to surgery, however, there was no significance between the two groups (Table 1). Posterior offset and joint line were restored in all cases and no overstuffing of the PF joint was seen. Discussion. At minimum one-year follow-up, anatomical patella has excellent safety and efficacy with restoration of the PF kinematics. Metalized design of the Attune anatomic patella component allows better contact with trochlear groove and improves tilt with lateralization of the patella

Background. Revision total knee arthroplasty (rTKA) is a high stakes procedure with complex equipment and multiple steps. For rTKA using the ATTUNE system revising femoral and tibial components with sleeves and stems, there are over 240 pieces of equipment that require correct assembly at the appropriate time. Due to changing teams, work rotas, and the infrequency of rTKR, scrub nurses may encounter these operations infrequently and often rely heavily on company representatives to guide them. In turn, this delays and interrupts surgical efficiency and can result in error. This study investigates the impact of a fully immersive virtual reality (VR) curriculum on training scrub nurses in technical skills and knowledge of performing a complex rTKA, to improve efficiency and reduce error. Method. Ten orthopaedic scrub nurses were recruited and trained in four VR sessions over a 4-week period. Each VR session involved a guided mode, where participants were taught the steps of rTKA surgery by the simulator in a simulated operating theatre. The latter 3 sessions involved a guided mode followed by an unguided VR assessment. Outcome measures in the unguided assessment were related to procedural sequence, duration of surgery and efficiency of movement. Transfer of skills was assessed during a pre-training and post-training assessment, where participants completed multi-step instrument selection and assembly using the real equipment. A pre and post-training questionnaire assessed the participants knowledge, confidence and anxiety. Results. All participants reported orthopaedics as their primary speciality with mean of 6-years experience. 80% reported they are ‘sometimes’ required to scrub for operations in which they do not feel comfortable with the equipment. All participants improved across the 3 unguided sessions reducing their operative time by 47%, assistive prompts by 75%, dominant hand motion by 28% and head motion by 36%. This transferred into the real-world: Participants completed 11.3% of tasks correctly in pre-training compared to 83.5% correct in the timely selection and assembly of rTKA equipment, post-training. All participants reported increased confidence and reduced anxiety after the training. Conclusion. Unfamiliarity with orthopaedic procedures or equipment is common for scrub nurses and can impact surgical performance. VR training improves their understanding, technical skills and efficiency in complex rTKA. These VR-learnt skills translate into the physical environment. This has important implications on how scrub nurses can be trained remotely, asynchronously and safely to perform complex orthopaedic surgery

INTRODUCTION. Implant wear testing is traditionally undertaken using standardized inputs set out by ISO or ASTM. These inputs are based on a single individual performing a single activity with a specific implant. Standardization helps ensure that implants are tested to a known set of parameters from which comparisons may be drawn but it has limitations as patients perform varied activities, with different implant sizes and designs that produce different kinematics/kinetics. In this study, wear performance has been evaluated using gait implant specific loading/kinematics and comparing to a combination deep knee bend (DKB), step down (SD) and gait implant specific loading on cruciate retaining (CR) rotating platform (RP) total knee replacements (TKR). This combination activity profile better replicates patient activities of daily living (ADL). METHODS. Two sets of three ATTUNE. ®. size 5 right leg CR RP TKRs (DePuy Synthes, Warsaw, IN) were used in a study to evaluate ADL implant wear. Implant specific loading profiles were produced via a validated finite element lower limb model [1] that uses activity data such as gait (K1L_110108_1_86p), SD (K1L_240309_2_144p), and DKB (K9P_2239_0_9_I1) from the Orthoload database [2] to produce external boundary conditions. Each set of components were tested using a VIVO joint simulator (AMTI, Watertown, MA, Figure 1) for a total of 4.5 million cycles (Mcyc). All cycles were conducted at 0.8Hz in force-control with flexion driven in displacement control. Bovine calf serum lubricant was prepared to a total protein concentration of 18g/L and maintained at 37°±2°C. Wear of the tibial inserts was quantified via gravimetric methods per ISO14243–2:2009(E). Polyethylene tibial insert weights were taken prior to testing and every 0.5Mcyc there after which corresponded to serum exchange intervals. The multi-activity test intervals were split into10 loops of 1,250 DKB, 3,000 SD, and 45,750 gait cycles in series. Based on activity data presented by Wimmer et al. the number of cycles per activity and activities used is sufficient for a person that is considered active [3]. A loaded soak control was used to compensate for fluid absorption in wear rate calculations. Wear rates were calculated using linear regression. RESULTS SECTION. The wear rate for the gait-only activity test was calculated to be 0.20±0.04mg/Mcyc conversely the wear rate for the multi-activity test was 2.65±0.67mg/Mcyc (Figure 2). Wear scars can be found in Figure 3. Using a two-sided t-test of unequal variance, it was found that there was a significant difference between the two wear rates (p=0.004). DISCUSSION. Adding activities to the wear simulation test significantly increased the average wear rate of the test samples, confirming that changes in cross shear from different activities will tend to increase the wear of an implant. The results of this study prove that single activity wear testing may not be the most clinically severe wear testing that can be used for pre-clinical wear assessment. For any figures or tables, please contact the authors directly

The study aimed to compare trochlear profiles in recent total knee arthroplasty (TKA) models and to determine whether they feature improvements compared to their predecessors. The hypothesis was that recent TKA models have more anatomic trochlear compartments and would display no signs of trochlear dysplasia. The authors analyzed the geometry of the 6 following TKA models using engineering software: PFC and Attune (DePuy), NexGen and Persona (Zimmer), Noetos and KneeTec (Tornier). The mediolateral trochlear profiles were plotted at various flexion angles (0°, 15°, 30° and 45°) to deduce the sulcus angle. Analysis of sulcus angles reveals general convergence of recent designs towards anatomic values. At 0° of flexion, sulcus angles of recent implant models were between 156.0–157.4°, while those of previous generation models between 154.5–165.5°. At 30° of flexion, sulcus angles of recent models also lie within 145.7–148.6°, but those of previous models are between 149.5–152.0°. All three manufacturers deepened their trochlear profile at 30° of flexion in recent models compared to earlier designs. Sulcus angles converge towards anatomic values but still exceed radiologic signs of dysplasia by 2–5°. Recent TKA designs have more anatomic trochlear geometries than earlier TKA models by the same manufacturers, but trochlear compartments still exceed radiologic signs of trochlear dysplasia by 2° to 5°. The hypothesis that recent TKA models display no signs of trochlear dysplasia is therefore refuted. Surgeons should be aware of design limitations to optimize choice of implant and extensor mechanisms alignment. Level of evidence: IV geometric implant analysis

Objectives. The purpose of this study was to evaluate the impact of multi-radius (MR, n=20) versus gradually reducing radius (GR, n=18) knee design on the kinematics and kinetics of the knee during level ground walking one year after total knee arthroplasty. Materials and Methods. Thirty-eight knees with end-stage knee osteoarthritis were examined before and one year after total knee arthroplasty. The groups consisted of subjects who had undergone total knee arthroplasty with a representative MR designed implant (B Braun-Aesculap Vega. ®. Knee System) and a representative GR designed implant (Depuy Attune. ®. Knee System) (Figure 1). The kinematic and kinetic parameters of knee varus angle, first peak knee adduction moment, sagittal plane knee excursion and extensor moment were evaluated during gait, as well as the spatiotemporal gait outcomes of walking speed, stride length, cadence, step length, the percentage of stance phase. Comparisons of preoperative and postoperative outcomes were done by the paired t-test. Independent t-test was also done to compare the postoperative outcomes of MR designed implant and GR designed implant. Results. In spatiotemporal parameters of GR implant group, there was an increase in walking speed, stride length and cadence (all p<0.05) and no change in step length and the percentage of stance phase postoperatively. GR implant group showed large reductions in varus angle and adduction moment (all p<0.001), a significant increase in extensor moment (p=0.01), and a small reduction in sagittal plane excursion (p=0.04) after surgery. In comparison of two groups at one year after surgery, there were no significant differences of all spatiotemporal, kinematic and kinetic parameters between two groups except varus angle. GR implant group showed more reduction in varus angle than MR implant group (p=0.01). Conclusions. Total knee arthroplasty performed with gradually reducing radius knee design reduces frontal plane loading patterns of knee varus angle and adduction moment and provided improvement in spatiotemporal parameters. Post-operatively there were no statistical differences between the MR implant group and the GR implant group in any of the kinematic and kinetic measures except knee varus angle during level ground walking

Purpose. Analysis of the morphology of the distal femur, and by extension of the femoral components in total knee arthroplasty (TKA), has been related to the aspect ratio, which represents the width of the femur. Little is known about variations in trapezoidicity (i.e whether the femur is more rectangular or more trapezoidal). This study aimed to quantify additional morphological characteristics of the distal femur and identify anatomical features associated with higher risks of over- or under-sizing of components in TKA. Method. We analyzed the shape of 114 arthritic knees at the time of primary TKA using the pre-operative CT scans. The maximum AP dimension was measured. The mediolateral dimensions were measured on the theoretical distal resection slice at three levels: the posterior region (MLP), the central region (MLC) and the anterior region (MLA) (Fig 1). The ‘aspect’ ratio (MLC/AP) ratio quantified how wide or narrow the shape is. The ‘trapezoidicity’ ratio (MLP/MLA) ratio quantified how rectangular or trapezoidal the shape is. We also quantified the medial and lateral ‘narrowing angles’ in the anterior and central zones (α and β) (Fig 2). The post-operative prosthetic overhang was calculated from CT-scan. We compared the morphological characteristics with those of twelve TKA models scanned using a three-dimensional optical scanning machine (ATOS II, GOM mbH, Braunschweig, Germany) and its photogrammetric analysis software (TRITOP, GOM mbH, Braunschweig, Germany). Results. There were significant variations in both the aspect ratio (1.16±0.07; range 0.98–1.31) and the trapezoidicity ratio (1.21±0.08; range 1.06– 1.46). Femoral trapezoidicity was mostly due to an inward curve of the medial cortex. The multivariate analysis indicated that prosthetic overhang was correlated to the ‘aspect ratio’ (more overhang in narrow femurs, p=0.002), to the ‘trapezoidicity ratio’ (more overhang in trapezoidal femurs, p=0.002), and to the Tibio Femoral Angle (more overhang in valgus knees, p=0.035). The geometries of the twelve specimen components can be compared directly with the morphological findings of this study. Some components had excessively low trapezoidicity ratios (i.e. were too rectangular) such as DePuy LCS and Stryker Scorpio. Other designs had trapezoidicity ratios closer to anatomic values such as Zimmer Nexgen, Zimmer Persona, DePuy Attune and Smith and Nephew Journey (Fig 3). Several components had excessively low anterior lateral narrowing angle (αL) such as DePuy LCS, Stryker Scorpio. All had insufficiently low medial narrowing angles. Conclusion. This study shows that rectangular/trapezoidal variability of the distal femur cannot be ignored. Most of the femoral components, which were tested appeared to be excessively rectangular when compared with the bony contours of the distal femur. These findings suggest that the design of TKA should be more concerned with matching the trapezoidal/rectangular shape of the native femur

Aims

This systematic review and meta-analysis aimed to compare the influence of patellar resurfacing following cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasty (TKA) on the incidence of anterior knee pain, knee-specific patient-reported outcome measures, complication rates, and reoperation rates.

The COVID-19 pandemic has led to unprecedented times worldwide. From lockdowns to masks now being part of our everyday routine, to the halting of elective surgeries, the virus has touched everyone and every part of our personal and professional lives. Perhaps, now more than ever, our ability to adapt, change and persevere is critical to our survival. This year's closed meeting of The Knee Society demonstrated exactly those characteristics. When it became evident that an in-person meeting would not be feasible, The Knee Society leadership, under the direction of President John Callaghan, MD and Program Chair Craig Della Valle, MD created a unique and engaging meeting held on September 10–12, 2020. Special recognition should be given to Olga Foley and Cynthia Garcia at The Knee Society for their flexibility and creativeness in putting together a world-class flawless virtual program. The Bone & Joint Journal is very pleased to partner with The Knee Society to once again publish the proceedings of the closed meeting of the Knee Society. The Knee Society is a United States based society of highly selected members who have shown leadership in education and research in knee surgery. It invites up to 15% international members; this includes some of the key opinion leaders in knee surgery from outside the USA. Each year, the top research papers from The Knee Society meeting will be published and made available to the wider orthopaedic community in The Bone & Joint Journal. The first such proceedings were published in BJJ in 2019. International dissemination should help to fulfil the mission and vision of the Knee Society of advancing the care of patients with knee disorders through leadership, education and research. The quality of dissemination that The Bone & Joint Journal provides should enhance the profile of this work and allow a larger body of surgeons, associated healthcare professionals and patients to benefit from the expertise of the members of The Knee Society. The meeting is one of the highlights of the annual academic calendar for knee surgeons. With nearly every member in attendance virtually throughout the 3 days, the top research papers from the membership were presented and discussed in a virtual format that allowed for lively interaction and discussion. There are 75 abstracts presented. More selective proceedings with full papers will be available after a robust peer review process in 2021, both online and in The Bone & Joint Journal. The meeting commenced with the first group of scientific papers focused on Periprosthetic Joint Infection. Dr Berry and colleagues from the Mayo Clinic further help to clarify the issue of serology and aspirate results to diagnose TKA PJI in the acute postoperative setting. 177 TKA's had an aspiration within 12 weeks and 22 were proven to have PJI. Their results demonstrated that acute PJI after TKA should be suspected within 6 weeks if CRP is ≥81 mg/L, synovial WBCs are ≥8500 cells/μL, and/or synovial neutrophils≥86%. Between 6– 12 weeks, concerning thresholds include a CRP ≥ 32 mg/L, synovial WBC ≥7450, and synovial neutrophils ≥ 84%. While historically the results of a DAIR procedure for PJI have been variable, Tom Fehring's study showed promise with the local delivery of vancomycin through the Intraosseous route improved early results. New member Simon Young contrasted the efficacy of the DAIR procedure when comparing early infections to late acute hematogenous PJI. DAIR failed in 63% of late hematogenous PJIs (implant age>1 year) compared to 36% of early (<1year) PJIs. Dr Masri demonstrated in a small group of patients that those with well-functioning articulating spacers can retain their spacers for over 12 months with no difference in infection from those that had a formal two stage exchange. The mental toll of PJI was demonstrated in a longitudinal study by Doug Dennis, where patient being treated with 2 stage exchange had 4x higher rates of depression compared to patient undergoing aseptic revision. The second session focused on both postoperative issues with regards to anticoagulation and manipulation. Steven Haas demonstrated high complication rates with utilization of anticoagulation for treatment of postoperative pulmonary embolism with modern therapeutic anticoagulation (warfarin, enoxaparin, Xa inhibitors) with the Xa inhibitors demonstrating lower complication rates. Two papers focused on the topic of manipulation. Mark Pagnano presented data on timing of manipulation under anesthesia up to even past 12 months. While gains were modest, a subset of patients did achieve substantial gains in ROM > 20degrees even after 3 months post op. Dr Westrich's study demonstrated no difference in MUA outcomes with either IV sedation or neuraxial anesthesia although the length of stay was shorter in the IV sedation group. Several studies in Session II focused on kinematics and femoral component position. Dr Li's in vivo kinematic study during weightbearing flexion and gait demonstrated that several knees rotated with a lateral pivot motion and not all knees can be described with a single motion character. Dr Mayman and his group utilized a computational knee model to demonstrate that additional distal femoral resection results in increasing levels of mid -flexion instability and cautioned against the use of additional bony resection as the first line for flexion contractures. Using computer navigation, Dr Huddleston's study nicely outlined the variability in femoral component rotation to achieve a rectangular flexion gap utilizing a gap balanced method. The third session opened the meeting on Friday morning. The focus was on unicompartmental knee arthroplasty and the increasing utilization of robotic assisted total knee arthroplasty. David Murray showed using registry data that for patient with higher comorbidities (ASA >3), UKA was safer and more cost effective than TKA while Dr Della Valle's group demonstrated overall lower average healthcare costs in UKA patients compared to TKA in the first 10 years after surgery. Dr Geller assessed UKA survivorship among 3 international registries. While survivorship varied by nation and designs, certain designs consistently had better overall performance. Dr Nunley and his group showed robotic navigation UKA significantly reduced outliers in alignment and overhang compared to manual UKA. Dr Catani's data demonstrated that full thickness cartilage loss should still be considered a requirement for UKA success even with robotic assistance. Despite a high dislocation rate of 4%, Mr Dodd demonstrated high survivorship for lateral UKA despite historical contraindications. The growing evidence for robotics TKA was demonstrated in two studies. Professor Haddad showed less soft tissue injury, reduced bone trauma and improved accuracy or rTKA compared to manual TKA while Dr Gustke single surgeon study showed his rTKA had improved forgotten joint scores and less ligament releasing required for balancing. Despite these finding, Dr Lee's study demonstrated that a robotic TKA could not guarantee excellent pain relief and other factors such a patient expectations and psychological factors play a role. Our fourth session was devoted to machine learning and smart tools and modeling. Dr Meneghini used machine learning algorithms to identify optimal alignment outcomes that correlated with patient outcomes. Several parameters such as native tibial slope, femoral sagittal position and coronal limb alignment correlated with outcomes. Along the same lines, Bozic and coauthors demonstrated that using AI algorithms incorporated with PROM's improved levels of shared decision making and patient satisfaction. Dr Lombardi demonstrated that a mobile patient engagement platform that provided smart phone-based exercise and education was comparable to traditional methods. Dr Mahfouz demonstrated the accuracy of using ultrasound to produce 3D models of the bone compared to conventional CT based strategies and Dr Mahoney showed the valued of a preop 3D model in reproducing more normal knee kinematics. The last two talks of the session focused on some of the positives of the COVID-19 pandemic, namely the embracing of telemedicine by patients and surgeons as demonstrated by Dr Slover and the increasing and far reaching educational opportunities made available to residents and fellows during the pandemic. Session five focused on risk stratification and optimization prior to TKA. Dr O'Connor demonstrated that that the implementation of an optimization program preoperatively reduced length of stay and ED visits, and Charles Nelson's study showed that risk stratification tool can lower complication rates in obese patients undergoing TKA comparable to those that are nonobese. Dr Markel's study demonstrated that those who have preoperative depression and anxiety are at higher risk of complications and readmissions after surgery and these issues should be addressed preoperatively. Interestingly, a study by Dr Callaghan demonstrated that care improvement pathways have not lowered the gap in complications for morbidly obese patients undergoing TKA, Dr Barsoum argued that the overall complication rates were low and this patient cohort had significant gains in PROMS after TKA that would not be experienced if arbitrary cutoff for limited surgery were established. The final session on Friday, Session six, had several well done and interesting studies. There continues to be mounting evidence that liposomal bupivacaine has little effect on managing post-operative pain to warrant its increased use. Bill Macaulay and colleagues showed no change in pain scores, opioid consumption and functional scores when liposomal bupivacaine was discontinued at a large academic medical center. Dr Bugbee importantly demonstrated that a supervised ambulation program reduced falls in the early postoperative period. Several paper on healthcare economics were presented. Rich Iorio showed that stratifying complexity of total joint cases between hospitals with a system can be efficient and cost savings while Dr Jiranek demonstrated in his study that complex TKAs can be identified preoperatively and are associated with prolonged operative time and cost of care and consideration should be given in future reimbursement models to a complexity modifier. Dr Springer, in their evaluation of Medicare bundled payment models, demonstrated that providers and hospitals in historical bundled models that became efficient were penalized in the new model, forcing many groups to drop out and return to a fee for service model. Ron Delanois important work showed that social determinants can have a major negative impact on outcomes following TKA. Our final day on Saturday opened with Session seven, and several interesting paper on metal ions/debris in TKA. Dr Whitesides simulator study showed the absence of scratches and material loss in a ceramic TKA compared with Co-Cr TKA and suggested an advantage to this material in patients with metal sensitivity. Conversely, in a histological study of failed TKA, perivascular lymphocytic infiltration was not associated with worse clinical outcomes or differences in revision in a series of 617 aseptic revisions, 19% of which had PVLI found on histology. The Mayo group and Dr Trousdale however, noted that serum metal ion levels can be helpful in identifying implant failure in a group of revision TKAs, especially those with metallic junctions. Dr Dalury demonstrated nicely that use of maximally conforming inserts did not have a negative effect on implant loosening in a series of 76 revision TKA's at an average follow up of 7 years, while Kevin Garvin and his group showed no difference in end of stem pain between cemented and cementless stems in revision TKA. The final two studies in the session by Bolognesi and Peters respectively showed that metaphyseal cones continue to demonstrate excelled survivorship in rTKA setting despite extensive bone loss. Session eight was highlighted by a large series of revision reported by new member Dr Schwarzkopf, who showed that revision TKA done by high volume surgeons demonstrated better outcomes and lower revision rates compared to surgeon who did less than 18 rTKA's per year. Dr Maniar importantly showed that preoperatively, patients with high activity level and low pain and indicated by a high preop forgotten joint score did poorly following TKA while David Ayers nicely demonstrated that KOOS scores that assess specific postoperative outcomes can predict patient dissatisfaction after TKA. The final paper in this session by Max Courtney showed that the majority of surgical cancellations are due to medical issues, yet a minority of these undergo any intervention specifically for that condition, but they resulted in a delay of 5 months. The first two studies of Session nine focused on polyethylene thickness. Dr Backstein demonstrated no difference in KSS scores, change in ROM and aseptic revision rates based on polyethylene thickness in a series of 195 TKA's. An interesting lab study by Dr Tim Wright showed a surprising consistency in liner thickness choice among varying levels of surgeon experience that did not correlate with applied forces or gap stability estimates. Two studies looked specifically at the issue of tibial loosening and implant design. Nam and colleagues were not able to demonstrate concerning findings for increasing tibial loosening in a tibial baseplate with a shortened tibial keel at short term follow up, while Lachiewicz demonstrated a 19% revision or revision pending rate in 223 cemented fixed bearing ATTUNE TKA at a mean of 30 months. Our final session of the meeting, began with encouraging news, that despite only currently capturing about 40% of TJA's done in the US, the American Joint Replacement Registry data is representative of data in other representative US databases. An interesting study presented by Robert Barrack looked at bone remodeling in the proximal tibia after cemented and cementless TKA of two different designs. No significant difference was noted among the groups with the exception of the cemented thicker cobalt chrome tray which demonstrated significantly more bone mineral density loss. Along the same lines, a study out of Dr Bostrom's lab demonstrated treatment of a murine tibial model with iPTH prevents fibrous tissue formation and enhances bone formation in cementless implants. New Member Jamie Howard showed no difference in implant migration and kinematics of a single radius cementless design using either a measured resection or gap balancing technique and Dr Cushner show no difference in blood loss with cemented or cementless TKA with the use of TKA. The final two studies looked at staging and bilateral TKA's. Peter Sharkey showed that simultaneous TKA's were associated with higher complication compared to staged TKA and that staged TKA with less than a 90-day interval was not associated with higher risk. However, Mark Figgie showed that patients undergoing simultaneous TKA compared to staged TKA, missed 17 fewer days of work. In spite of the virtual nature of the meeting, there were some outstanding scientific interactions and the material presented will continue to generate debate and to guide the direction of knee arthroplasty as we move forwards

Aims

Access to total knee arthroplasty (TKA) is sometimes restricted for patients with severe obesity (BMI ≥ 40 kg/m²). This study compares the cost per quality-adjusted life year (QALY) associated with TKA in patients with a BMI above and below 40 kg/m² to examine whether this is supported.

Introduction. Proper alignment (tibial alignment, femoral alignment, and overall anatomic alignment) of the prosthesis during total knee replacement is critical in maximizing implant survival[7] and to reduce polyethylene wear[1]. Poor overall anatomic alignment of a total knee replacement was associated with a 6.9 times greater risk of failure due to tibial collapse, that varus tibial alignment is associated with a 3.2 times greater risk[2] and valgus femoral alignment is associated with a 5.1 times greater risk of failure[7]. To reduce this variability intramedullary (IM) instruments have been widely used, with increased risk of the fat emboli rate to the lungs and brain during TKA[6] and possible increase of blood loss[4, 5]. Or, alternatively, navigation has been used to achieve proper alignment and to reduce morbidity[3]. Recently, for distal femoral resection, inertial sensors have been coupled to extramedullary (EM) instruments to improve TKA surgery in terms of femoral implant alignment, with respect to femoral mechanical axis, and reduced morbidity by avoidance of IM canal violation. The purpose if this study is to compare blood loss and alignment of distal femoral cut in three cohorts of patients: 1 Operated with inertial based cutting guide; 2 Operated with navigation instruments; 3 operated with conventional IM instruments. Material and methods. From September to November 2014 30 consecutive patients, eligible for TKA, were randomly divided into three cohorts with 10 patients each:x 1 “EM Perseus”, patient operated with EM inertial based instruments (Perseus, Orthokey Italia srl, Florence, Italy); 2 “EM Nav”, operated with standard navigated technique, where bone resections were planned and verified by mean of navigation system (BLUIGS, Orthokey Italia srl, Florence, Italy); 3 “IM Conv”, operated with standard IM instrumentation. All patients were operated by the same surgical technique, implanted TKA were mobile bearing PS models, Gemini (Waldemar Link, Hamburg, Germany) and Attune (Depuy, Warsaw, Indiana). Anteroposterior, lateral, and full-limb weightbearing views preoperatively and postoperatively at discharge were obtained, taking care of neutral limb rotational positioning in all patients enrolled in the study. Angles between femoral mechanical axis and implant orientation on frontal and lateral planes were measured with a CAD software (Rhinoceros 3, McNeel Europe, Rome, Italy) by two independent persons, average value was used for statistical analysis. Haemoglobin values were recorded at three time intervals: the day before surgery, at 24h follow-up and at patients discharge. Statistical analysis. Kruskal-Wallis test was used to compare differences between the three cohorts in blood loss and femoral implant alignment. Results. All the three cohorts were comparable in terms of age, sex, preoperative limb alignment and preoperative haemoglobin values (Tab. 1). Haemoglobin ad discharge was reduced for all three cohorts (Tab. 2), no significant differences was found even if IM Conv group showed higher loss compared to EM Perseus and EM Nav groups. Femoral implant alignment deviation, considering perpendicularity with femoral mechanical axis as goal, was comparable in frontal and lateral plane for all three cohorts (Tab. 2). Discussion. The aim of the study was to compare the accuracy in femoral component positioning, on the coronal and sagittal plane obtained with a new inertial based EM instrument, with a standard IM distal femoral cutting jig and with navigation. We confirm our hypothesis that the use of inertial based EM instruments to perform the distal femoral bone cut in TKA is reliable and at least as accurate as the standard IM technique and navigation. Our study did not show a statistical decrease in blood loss when the femoral canal was not reamed (in inertial based EM, and navigated groups), even if patient operated with IM instruments had sensibly higher blood loss compared to the other two groups. This study was not exactly powered for that purpose, a study with a larger cohort and strict patient selection criteria would be required. This study demonstrates that inertial based EM instruments is accurate for femoral component alignment in TKA and compares favorably to navigation systems and standard IM techniques. Other indications for the use of inertial based EM instruments include all major femoral extraarticular deformities, the presence of ipsilateral long-stemmed hip arthroplasty, and the presence of hardware such as distal femoral plates and screws or IM nails

Aims

The material and design of knee components can have a considerable effect on the contact characteristics of the tibial post. This study aimed to analyze the stress distribution on the tibial post when using different grades of polyethylene for the tibial inserts. In addition, the contact properties of fixed-bearing and mobile-bearing inserts were evaluated.

Evidence suggests that the alleviation of pain is enhancedby a strong patient-clinician relationship and attending to a patient’s social and mental health. There is a limited role for medication, opioids in particular.

Orthopaedic surgeons can use comprehensive biopsychosocial strategies to help people recover and can work with colleagues who have the appropriate expertise in order to maximize pain alleviation with optimal opioid stewardship.

Preparing patients for elective surgery and caring for them after unplanned injury or surgery can benefit from planned and practiced strategies based in communication science.

Cite this article: Bone Joint J 2020;102-B(9):1122–1127.

Aims

The introduction of a novel design of total knee arthroplasty (TKA) must achieve outcomes at least as good as existing designs. A novel design of TKA with a reducing radius of the femoral component and a modified cam-post articulation has been released and requires assessment of the fixation to bone. Radiostereometric analysis (RSA) of the components within the first two postoperative years has been shown to be predictive of medium- to long-term fixation. The aim of this study was to assess the stability of the tibial component of this system during this period of time using RSA.

Aims

The aim of this study was to evaluate the surface damage, the density of crosslinking, and oxidation in retrieved antioxidant-stabilized highly crosslinked polyethylene (A-XLPE) tibial inserts from total knee arthroplasty (TKA), and to compare the results with a matched cohort of standard remelted highly crosslinked polyethylene (XLPE) inserts.

Aims

Anterior cruciate ligament (ACL) and multiligament knee (MLK) injuries increase the risk of development of knee osteoarthritis and eventual need for total knee arthroplasty (TKA). There are limited data regarding implant use and outcomes in these patients. The aim of this study was to compare the use of constrained implants and outcomes among patients undergoing TKA with a history of prior knee ligament reconstruction (PKLR) versus a matched cohort of patients undergoing TKA with no history of PKLR.

Aims

Analysis of the morphology of the distal femur, and by extension of the femoral components in total knee arthroplasty (TKA), has largely been related to the aspect ratio, which represents the width of the femur. Little is known about variations in trapezoidicity (i.e. whether the femur is more rectangular or more trapezoidal). This study aimed to quantify additional morphological characteristics of the distal femur and identify anatomical features associated with higher risks of over- or under-sizing of components in TKA.

The need to demonstrate probity and fair market competition has increased scrutiny of the relationships between orthopaedic surgeons and the industry that supplies them with their tools and devices. Investigations and judgements from the US Department of Justice and the introduction of the AdvaMed and Eucomed codes have defined new boundaries for interactions between these groups. This article summarises the current interplay between orthopaedic surgeons and industry, and provides recommendations for the future.