This study used CT analysis to determine the rotational alignment of 39 painful and 26 painless fixed-bearing total knee replacements (TKRs) from a cohort of 740 NexGen Legacy posterior-stabilised and cruciate-retaining prostheses implanted between May 1996 and August 2003. The mean rotation of the tibial component was 4.3° of internal rotation (25.4° internal to 13.9° external rotation) in the painful group and 2.2° of external rotation (8.5° internal to 18.2° external rotation) in the painfree group (p = 0.024). In the painful group 17 tibial components were internally rotated more than 9° compared with none in the painfree group (p < 0.001). Additionally, six femoral components in the painful group were internally rotated more than 6° compared with none in the painfree group (p = 0.017). External rotational errors were not found to be associated with pain. Overall, 22 (56.4%) of the painful TKRs had internal rotational errors involving the femoral, the tibial or both components. It is estimated that at least 4.6% of all our TKRs have been implanted with significant internal rotational errors

We performed a CT-based computer simulation study to determine how the relationship between any inbuilt posterior slope in the proximal tibial osteotomy and cutting jig rotational orientation errors affect tibial component alignment in total knee replacement. Four different posterior slopes (3°, 5°, 7° and 10°), each with a rotational error of 5°, 10°, 15°, 20°, 25° or 30°, were simulated. Tibial cutting block malalignment of 20° of external rotation can produce varus malalignment of 2.4° and 3.5° with a 7° and a 10° sloped cutting jig, respectively. Care must be taken in orientating the cutting jig in the sagittal plane when making a posterior sloped proximal tibial osteotomy in total knee replacement. Cite this article: Bone Joint J 2013;95-B:1201–3

Aims. We aimed to assess the reliability and validity of OpenPose, a posture estimation algorithm, for measurement of knee range of motion after total knee arthroplasty (TKA), in comparison to radiography and goniometry. Methods. In this prospective observational study, we analyzed 35 primary TKAs (24 patients) for knee osteoarthritis. We measured the knee angles in flexion and extension using OpenPose, radiography, and goniometry. We assessed the test-retest reliability of each method using intraclass correlation coefficient (1,1). We evaluated the ability to estimate other measurement values from the OpenPose value using linear regression analysis. We used intraclass correlation coefficients (2,1) and Bland–Altman analyses to evaluate the agreement and error between radiography and the other measurements. Results. OpenPose had excellent test-retest reliability (intraclass correlation coefficient (1,1) = 1.000). The R. 2. of all regression models indicated large correlations (0.747 to 0.927). In the flexion position, the intraclass correlation coefficients (2,1) of OpenPose indicated excellent agreement (0.953) with radiography. In the extension position, the intraclass correlation coefficients (2,1) indicated good agreement of OpenPose and radiography (0.815) and moderate agreement of goniometry with radiography (0.593). OpenPose had no systematic error in the flexion position, and a 2.3° fixed error in the extension position, compared to radiography. Conclusion. OpenPose is a reliable and valid tool for measuring flexion and extension positions after TKA. It has better accuracy than goniometry, especially in the extension position. Accurate measurement values can be obtained with low error, high reproducibility, and no contact, independent of the examiner’s skills. Cite this article: Bone Joint Res 2023;12(5):313–320

Aims. This study aimed to investigate the relationship between changes in patellar height and clinical outcomes at a mean follow-up of 7.7 years (5 to 10) after fixed-bearing posterior-stabilized total knee arthroplasty (PS-TKA). Methods. We retrospectively evaluated knee radiographs of 165 knees, which underwent fixed-bearing PS-TKA with patella resurfacing. The incidence of patella baja and changes in patellar height over a minimum of five years of follow-up were determined using Insall-Salvati ratio (ISR) measurement. We examined whether patella baja (ISR < 0.8) at final follow-up affected clinical outcomes, knee joint range of motion (ROM), and Knee Society Score (KSS). We also assessed inter- and intrarater reliability of ISR measurements and focused on the relationship between patellar height reduction beyond measurement error and clinical outcomes. Results. The ISR gradually decreased over five years after TKA, and finally 33 patients (20.0%) had patella baja. Patella baja at the final follow-up was not related to passive knee ROM or KSS. Interestingly, when we divided into two groups - patella baja and patella normal-alta (ISR ≥ 0.8) - the patella baja group already had a lower patellar height before surgery, compared with the patella normal-alta group. The ISR measurement error in this study was 0.17. Both passive knee flexion and KSS were significantly decreased in the group with a decrease in ISR of ≥ 0.17 at final follow-up. Conclusion. Patellar height gradually decreased over five years of follow-up after TKA. The reduction in patellar height beyond measurement error following TKA was associated with lower clinical outcomes. Cite this article: Bone Jt Open 2021;2(12):1075–1081

Aims. To map the Oxford Knee Score (OKS) and High Activity Arthroplasty Score (HAAS) items to a common scale, and to investigate the psychometric properties of this new scale for the measurement of knee health. Methods. Patient-reported outcome measure (PROM) data measuring knee health were obtained from the NHS PROMs dataset and Total or Partial Knee Arthroplasty Trial (TOPKAT). Assumptions for common scale modelling were tested. A graded response model (fitted to OKS item responses in the NHS PROMs dataset) was used as an anchor to calibrate paired HAAS items from the TOPKAT dataset. Information curves for the combined OKS-HAAS model were plotted. Bland-Altman analysis was used to compare common scale scores derived from OKS and HAAS items. A conversion table was developed to map between HAAS, OKS, and the common scale. Results. We included 3,329 response sets from 528 patients undergoing knee arthroplasty. These generally met the assumptions of unidimensionality, monotonicity, local independence, and measurement invariance. The HAAS items provided more information than OKS items at high levels of knee health. Combining both instruments resulted in higher test-level information than either instrument alone. The mean error between common scale scores derived from the OKS and HAAS was 0.29 logits. Conclusion. The common scale allowed more precise measurement of knee health than use of either the OKS or HAAS individually. These techniques for mapping PROM instruments may be useful for the standardization of outcome reporting, and pooling results across studies that use either PROM in individual-patient meta-analysis. Cite this article: Bone Joint Res 2023;12(10):624–635

Aims. The aims of this study were: 1) to describe extended restricted kinematic alignment (E-rKA), a novel alignment strategy during robotic-assisted total knee arthroplasty (RA-TKA); 2) to compare residual medial compartment tightness following virtual surgical planning during RA-TKA using mechanical alignment (MA) and E-rKA, in the same set of osteoarthritic varus knees; 3) to assess the requirement of soft-tissue releases during RA-TKA using E-rKA; and 4) to compare the accuracy of surgical plan execution between knees managed with adjustments in component positioning alone, and those which require additional soft-tissue releases. Methods. Patients who underwent RA-TKA between January and December 2022 for primary varus osteoarthritis were included. Safe boundaries for E-rKA were defined. Residual medial compartment tightness was compared following virtual surgical planning using E-rKA and MA, in the same set of knees. Soft-tissue releases were documented. Errors in postoperative alignment in relation to planned alignment were compared between patients who did (group A) and did not (group B) require soft-tissue releases. Results. The use of E-rKA helped restore all knees within the predefined boundaries, with appropriate soft-tissue balancing. E-rKA compared with MA resulted in reduced residual medial tightness following surgical planning, in full extension (2.71 mm (SD 1.66) vs 5.16 mm (SD 3.10), respectively; p < 0.001), and 90° of flexion (2.52 mm (SD 1.63) vs 6.27 mm (SD 3.11), respectively; p < 0.001). Among the study population, 156 patients (78%) were managed with minor adjustments in component positioning alone, while 44 (22%) required additional soft-tissue releases. The mean errors in postoperative alignment were 0.53 mm and 0.26 mm among patients in group A and group B, respectively (p = 0.328). Conclusion. E-rKA is an effective and reproducible alignment strategy during RA-TKA, permitting a large proportion of patients to be managed without soft-tissue releases. The execution of minor alterations in component positioning within predefined multiplanar boundaries is a better starting point for gap management than soft-tissue releases. Cite this article: Bone Jt Open 2024;5(8):628–636

Aims. The aim of this study was to identify the minimal clinically important difference (MCID), minimal important change (MIC), minimal detectable change (MDC), and patient-acceptable symptom state (PASS) threshold in the Forgotten Joint Score (FJS) according to patient satisfaction six months following total knee arthroplasty (TKA). Methods. During a one-year period 484 patients underwent a primary TKA and completed preoperative and six-month FJS and OKS. At six months patients were asked, “How satisfied are you with your operated knee?” Their response was recorded as: very satisfied, satisfied, neutral, dissatisfied, or very dissatisfied. The difference between patients recording neutral (n = 44) and satisfied (n = 153) was used to define the MCID. MIC for a cohort was defined as the change in the FJS for those patients declaring their outcome as satisfied, whereas receiver operating characteristic curve analysis was used to determine the MIC for an individual and the PASS threshold. Distribution-based methodology was used to calculate the MDC. Results. Using satisfaction as the anchor question, the MCID for the FJS was 16.6 (95% confidence interval (CIs) 8.9 to 24.3; p < 0.001) and when adjusting for confounding this decreased to 13.7 points (95% CI 4.8 to 22.5; p < 0.001). The MIC for the FJS for a cohort of patients was 17.7 points and for an individual patient was 10 points. The MDC90 for the FGS was 12 points; where 90% of patients scoring more than this will have experienced a real change that is beyond measurement error. The PASS was defined as 22 points or more in the postoperative FJS. Conclusion. The estimates for MCID and MIC can be used to assess whether there is clinical difference between two groups and whether a cohort/patient has had a meaningful change in their FJS, respectively. The MDC90 of 12 points suggests a value lower than this may fall within measurement error. A postoperative FJS of 22 or more was predictive of achieving PASS. Cite this article: Bone Joint J 2021;103-B(5):846–854

Aims. The objective of this study is to assess the use of ultrasound (US) as a radiation-free imaging modality to reconstruct 3D anatomy of the knee for use in preoperative templating in knee arthroplasty. Methods. Using an US system, which is fitted with an electromagnetic (EM) tracker that is integrated into the US probe, allows 3D tracking of the probe, femur, and tibia. The raw US radiofrequency (RF) signals are acquired and, using real-time signal processing, bone boundaries are extracted. Bone boundaries and the tracking information are fused in a 3D point cloud for the femur and tibia. Using a statistical shaping model, the patient-specific surface is reconstructed by optimizing bone geometry to match the point clouds. An accuracy analysis was conducted for 17 cadavers by comparing the 3D US models with those created using CT. US scans from 15 users were compared in order to examine the effect of operator variability on the output. Results. The results revealed that the US bone models were accurate compared with the CT models (root mean squared error (RM)S: femur, 1.07 mm (SD 0.15); tibia, 1.02 mm (SD 0.13). Additionally, femoral landmarking proved to be accurate (transepicondylar axis: 1.07° (SD 0.65°); posterior condylar axis: 0.73° (SD 0.41°); distal condylar axis: 0.96° (SD 0.89°); medial anteroposterior (AP): 1.22 mm (SD 0.69); lateral AP: 1.21 mm (SD 1.02)). Tibial landmarking errors were slightly higher (posterior slope axis: 1.92° (SD 1.31°); and tubercle axis: 1.91° (SD 1.24°)). For implant sizing, 90% of the femora and 60% of the tibiae were sized correctly, while the remainder were only one size different from the required implant size. No difference was observed between moderate and skilled users. Conclusion. The 3D US bone models were proven to be closely matched compared with CT and suitable for preoperative planning. The 3D US is radiation-free and offers numerous clinical opportunities for bone visualization rapidly during clinic visits, to enable preoperative planning with implant sizing. There is potential to extend its application to 3D dynamic ligament balancing, and intraoperative registration for use with robots and navigation systems. Cite this article: Bone Joint J 2021;103-B(6 Supple A):81–86

Aims. The aims of this study were to assess mapping models to predict the three-level version of EuroQoL five-dimension utility index (EQ-5D-3L) from the Oxford Knee Score (OKS) and validate these before and after total knee arthroplasty (TKA). Methods. A retrospective cohort of 5,857 patients was used to create the prediction models, and a second cohort of 721 patients from a different centre was used to validate the models, all of whom underwent TKA. Patient characteristics, BMI, OKS, and EQ-5D-3L were collected preoperatively and one year postoperatively. Generalized linear regression was used to formulate the prediction models. Results. There were significant correlations between the OKS and EQ-5D-3L preoperatively (r = 0.68; p < 0.001) and postoperatively (r = 0.77; p < 0.001) and for the change in the scores (r = 0.61; p < 0.001). Three different models (preoperative, postoperative, and change) were created. There were no significant differences between the actual and predicted mean EQ-5D-3L utilities at any timepoint or for change in the scores (p > 0.090) in the validation cohort. There was a significant correlation between the actual and predicted EQ-5D-3L utilities preoperatively (r = 0.63; p < 0.001) and postoperatively (r = 0.77; p < 0.001) and for the change in the scores (r = 0.56; p < 0.001). Bland-Altman plots demonstrated that a lower utility was overestimated, and higher utility was underestimated. The individual predicted EQ-5D-3L that was within ± 0.05 and ± 0.010 (minimal clinically important difference (MCID)) of the actual EQ-5D-3L varied between 13% to 35% and 26% to 64%, respectively, according to timepoint assessed and change in the scores, but was not significantly different between the modelling and validation cohorts (p ≥ 0.148). Conclusion. The OKS can be used to estimate EQ-5D-3L. Predicted individual patient utility error beyond the MCID varied from one-third to two-thirds depending on timepoint assessed, but the mean for a cohort did not differ and could be employed for this purpose. Cite this article: Bone Jt Open 2022;3(7):573–581

Aims. Blood transfusion and postoperative anaemia are complications of total knee arthroplasty (TKA) that are associated with substantial healthcare costs, morbidity, and mortality. There are few data from large datasets on the risk factors for these complications. Methods. We retrospectively reviewed the records of TKA patients from a single tertiary care institution from February 2016 to December 2020. There were a total of 14,901 patients in this cohort with a mean age of 67.9 years (SD 9.2), and 5,575 patients (37.4%) were male. Outcomes included perioperative blood transfusion and postoperative anaemia, defined a priori as haemoglobin level < 10 g/dl measured on the first day postoperatively. In order to establish a preoperative haemoglobin cutoff, we investigated a preoperative haemoglobin level that would limit transfusion likelihood to ≤ 1% (13 g/dl) and postoperative anaemia likelihood to 4.1%. Risk factors were assessed through multivariable Poisson regression modelling with robust error variance. Results. In multivariable analyses, each gram of tranexamic acid reduced transfusion likelihood by 39% (adjusted risk ratio (ARR) 0.61 (95% confidence interval (CI) 0.47 to 0.78)). Risk factors associated with an increased risk of transfusion included operating time (ARR 2.07 (95% CI 1.54 to 2.77)) and drain use (ARR 1.73 (95% CI 1.34 to 2.24)). Conclusion. In this study, we found that increased tranexamic acid dosing, decreased operating time, and decreased drain use may reduce transfusions following TKA. We also established a single preoperative haemoglobin cutoff of 13 g/dl that could help minimize transfusions and reduce postoperative complete blood counts. Cite this article: Bone Joint J 2023;105-B(10):1086–1093

Aims. The purpose of this study was to develop a personalized outcome prediction tool, to be used with knee arthroplasty patients, that predicts outcomes (lengths of stay (LOS), 90 day readmission, and one-year patient-reported outcome measures (PROMs) on an individual basis and allows for dynamic modifiable risk factors. Methods. Data were prospectively collected on all patients who underwent total or unicompartmental knee arthroplasty at a between July 2015 and June 2018. Cohort 1 (n = 5,958) was utilized to develop models for LOS and 90 day readmission. Cohort 2 (n = 2,391, surgery date 2015 to 2017) was utilized to develop models for one-year improvements in Knee Injury and Osteoarthritis Outcome Score (KOOS) pain score, KOOS function score, and KOOS quality of life (QOL) score. Model accuracies within the imputed data set were assessed through cross-validation with root mean square errors (RMSEs) and mean absolute errors (MAEs) for the LOS and PROMs models, and the index of prediction accuracy (IPA), and area under the curve (AUC) for the readmission models. Model accuracies in new patient data sets were assessed with AUC. Results. Within the imputed datasets, the LOS (RMSE 1.161) and PROMs models (RMSE 15.775, 11.056, 21.680 for KOOS pain, function, and QOL, respectively) demonstrated good accuracy. For all models, the accuracy of predicting outcomes in a new set of patients were consistent with the cross-validation accuracy overall. Upon validation with a new patient dataset, the LOS and readmission models demonstrated high accuracy (71.5% and 65.0%, respectively). Similarly, the one-year PROMs improvement models demonstrated high accuracy in predicting ten-point improvements in KOOS pain (72.1%), function (72.9%), and QOL (70.8%) scores. Conclusion. The data-driven models developed in this study offer scalable predictive tools that can accurately estimate the likelihood of improved pain, function, and quality of life one year after knee arthroplasty as well as LOS and 90 day readmission. Cite this article: Bone Joint J 2020;102-B(9):1183–1193

Aims. The purpose of this study was to compare the radiological outcomes of manual versus robotic-assisted medial unicompartmental knee arthroplasty (UKA). Methods. Postoperative radiological outcomes from 86 consecutive robotic-assisted UKAs (RAUKA group) from a single academic centre were retrospectively reviewed and compared to 253 manual UKAs (MUKA group) drawn from a prior study at our institution. Femoral coronal and sagittal angles (FCA, FSA), tibial coronal and sagittal angles (TCA, TSA), and implant overhang were radiologically measured to identify outliers. Results. When assessing the accuracy of RAUKAs, 91.6% of all alignment measurements and 99.2% of all overhang measurements were within the target range. All alignment and overhang targets were simultaneously met in 68.6% of RAUKAs. When comparing radiological outcomes between the RAUKA and MUKA groups, statistically significant differences were identified for combined outliers in FCA (2.3% vs 12.6%; p = 0.006), FSA (17.4% vs 50.2%; p < 0.001), TCA (5.8% vs 41.5%; p < 0.001), and TSA (8.1% vs 18.6%; p = 0.023), as well as anterior (0.0% vs 4.7%; p = 0.042), posterior (1.2% vs 13.4%; p = 0.001), and medial (1.2% vs 14.2%; p < 0.001) overhang outliers. Conclusion. Robotic system navigation decreases alignment and overhang outliers compared to manual UKA. Given the association between component placement errors and revision in UKA, this strong significant improvement in accuracy may improve implant survival. Level of Evidence: III. Cite this article: Bone Jt Open 2021;2-3:191–197

Aims. Unicompartmental knee arthroplasty (UKA) is a bone-preserving treatment option for osteoarthritis localized to a single compartment in the knee. The success of the procedure is sensitive to patient selection and alignment errors. Robotic arm-assisted UKA provides technological assistance to intraoperative bony resection accuracy, which is thought to improve ligament balancing. This paper presents the five-year outcomes of a comparison between manual and robotically assisted UKAs. Methods. The trial design was a prospective, randomized, parallel, single-centre study comparing surgical alignment in patients undergoing UKA for the treatment of medial compartment osteoarthritis (ISRCTN77119437). Participants underwent surgery using either robotic arm-assisted surgery or conventional manual instrumentation. The primary outcome measure (surgical accuracy) has previously been reported, and, along with secondary outcomes, were collected at one-, two-, and five-year timepoints. Analysis of five-year results and longitudinal analysis for all timepoints was performed to compare the two groups. Results. Overall, 104 (80%) patients of the original 130 who received surgery were available at five years (55 robotic, 49 manual). Both procedures reported successful results over all outcomes. At five years, there were no statistical differences between the groups in any of the patient reported or clinical outcomes. There was a lower reintervention rate in the robotic arm-assisted group with 0% requiring further surgery compared with six (9%) of the manual group requiring additional surgical intervention (p < 0.001). Conclusion. This study has shown excellent clinical outcomes in both groups with no statistical or clinical differences in the patient-reported outcome measures. The notable difference was the lower reintervention rate at five years for roboticarm-assisted UKA when compared with a manual approach. Cite this article: Bone Joint J 2021;103-B(6):1088–1095

Aims. A retrospective longitudinal study was conducted to compare directly volumetric wear of retrieved polyethylene inserts to predicted volumetric wear modelled from individual gait mechanics of total knee arthroplasty (TKA) patients. Methods. In total, 11 retrieved polyethylene tibial inserts were matched with gait analysis testing performed on those patients. Volumetric wear on the articular surfaces was measured using a laser coordinate measure machine and autonomous reconstruction. Knee kinematics and kinetics from individual gait trials drove computational models to calculate medial and lateral tibiofemoral contact paths and forces. Sliding distance along the contact path, normal forces and implantation time were used as inputs to Archard’s equation of wear to predict volumetric wear from gait mechanics. Measured and modelled wear were compared for each component. Results. Volumetric wear rates on eight non-delaminated components measured 15.9 mm. 3. /year (standard error (SE) ± 7.7) on the total part, 11.4 mm. 3. /year (SE ± 6.4) on the medial side and 4.4 (SE ± 2.6) mm. 3. /year on the lateral side. Volumetric wear rates modelled from patient gait mechanics predicted 16.4 mm. 3. /year (SE 2.4) on the total part, 11.7 mm. 3. /year (SE 2.1) on the medial side and 4.7 mm. 3. /year (SE 0.4) on the lateral side. Measured and modelled wear volumes correlated significantly on the total part (p = 0.017) and the medial side (p = 0.012) but not on the lateral side (p = 0.154). Conclusion. In the absence of delamination, patient-specific knee mechanics during gait directly affect wear of the tibial component in TKA. Cite this article: Bone Joint J 2020;102-B(6 Supple A):129–137

Objectives. The aim of this study was to determine the polyethylene wear rate of Phase 3 Oxford Unicompartmental Knee Replacement bearings and to investigate the effects of resin type and manufacturing process. Methods. A total of 63 patients with at least ten years’ follow-up with three bearing types (1900 resin machined, 1050 resin machined, and 1050 resin moulded) were recruited. Patients underwent full weight-bearing model-based radiostereometric analysis to determine the bearing thickness. The linear wear rate was estimated from the change in thickness divided by the duration of implantation. Results. The wear rate for 1900 resin machined (n = 19), 1050 machined (n = 21), and 1050 moulded bearings (n = 23) were 60 µm/year (. sd. 42), 76 µm/year (. sd. 32), and 57 µm/year (. sd. 30), respectively. There was no significant difference between 1900 machined and 1050 machined (p = 0.20), but 1050 moulded had significantly less wear than the 1050 machined (p = 0.05). Increasing femoral (p < 0.001) and tibial (p < 0.001) component size were associated with increasing wear. Conclusion. Wear rate is similar with 1050 and 1900 resin, but lower with moulded bearings than machined bearings. The currently used Phase 3 bearings wear rate is low (1050 moulded, 57 µm/year), but higher than the previously reported Phase 2 bearings (1900 moulded, 20 µm/year). This is unlikely to be due to the change in polyethylene but may relate to the minimally invasive approach used with the Phase 3. This approach, as well as improving function and thus increasing activity levels, may increase the risk of surgical errors, such as impingement or bearing overhang, which can increase wear. Surgeons should aim to use 4 mm thick bearings rather than 3 mm thick bearings in young patients, unless they are small and need conservative bone resections. Cite this article: Bone Joint Res 2019;8:535–543

Objectives. Up to 40% of unicompartmental knee arthroplasty (UKA) revisions are performed for unexplained pain which may be caused by elevated proximal tibial bone strain. This study investigates the effect of tibial component metal backing and polyethylene thickness on bone strain in a cemented fixed-bearing medial UKA using a finite element model (FEM) validated experimentally by digital image correlation (DIC) and acoustic emission (AE). Materials and Methods. A total of ten composite tibias implanted with all-polyethylene (AP) and metal-backed (MB) tibial components were loaded to 2500 N. Cortical strain was measured using DIC and cancellous microdamage using AE. FEMs were created and validated and polyethylene thickness varied from 6 mm to 10 mm. The volume of cancellous bone exposed to < -3000 µε (pathological loading) and < -7000 µε (yield point) minimum principal (compressive) microstrain and > 3000 µε and > 7000 µε maximum principal (tensile) microstrain was computed. Results. Experimental AE data and the FEM volume of cancellous bone with compressive strain < -3000 µε correlated strongly: R = 0.947, R. 2. = 0.847, percentage error 12.5% (p < 0.001). DIC and FEM data correlated: R = 0.838, R. 2. = 0.702, percentage error 4.5% (p < 0.001). FEM strain patterns included MB lateral edge concentrations; AP concentrations at keel, peg and at the region of load application. Cancellous strains were higher in AP implants at all loads: 2.2- (10 mm) to 3.2-times (6 mm) the volume of cancellous bone compressively strained < -7000 µε. Conclusion. AP tibial components display greater volumes of pathologically overstrained cancellous bone than MB implants of the same geometry. Increasing AP thickness does not overcome these pathological forces and comes at the cost of greater bone resection. Cite this article: C. E. H. Scott, M. J. Eaton, R. W. Nutton, F. A. Wade, S. L. Evans, P. Pankaj. Metal-backed versus all-polyethylene unicompartmental knee arthroplasty: Proximal tibial strain in an experimentally validated finite element model. Bone Joint Res 2017;6:22–30. DOI:10.1302/2046-3758.61.BJR-2016-0142.R1

Aims

Distal femoral resection in conventional total knee arthroplasty (TKA) utilizes an intramedullary guide to determine coronal alignment, commonly planned for 5° of valgus. However, a standard 5° resection angle may contribute to malalignment in patients with variability in the femoral anatomical and mechanical axis angle. The purpose of the study was to leverage deep learning (DL) to measure the femoral mechanical-anatomical axis angle (FMAA) in a heterogeneous cohort.

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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.

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The antidiabetic agent metformin inhibits fibrosis in various organs. This study aims to elucidate the effects of hyperglycaemia and metformin on knee joint capsule fibrosis in mice.

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The aim of this study was to estimate the incremental use of resources, costs, and quality of life outcomes associated with surgical reconstruction compared to rehabilitation for long-standing anterior cruciate ligament (ACL) injury in the NHS, and to estimate its cost-effectiveness.

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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.

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The impact of a diaphyseal femoral deformity on knee alignment varies according to its severity and localization. The aims of this study were to determine a method of assessing the impact of diaphyseal femoral deformities on knee alignment for the varus knee, and to evaluate the reliability and the reproducibility of this method in a large cohort of osteoarthritic patients.

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This study aimed to analyze kinematics and kinetics of the tibiofemoral joint in healthy subjects with valgus, neutral, and varus limb alignment throughout multiple gait activities using dynamic videofluoroscopy.

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The primary objective of this study was to compare the five-year tibial component migration and wear between highly crosslinked polyethylene (HXLPE) inserts and conventional polyethylene (PE) inserts of the uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA). Secondary objectives included clinical outcomes and patient-reported outcome measures (PROMs).

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This study investigated the effects of transcatheter arterial embolization (TAE) on pain, function, and quality of life in people with early-stage symptomatic knee osteoarthritis (OA) compared to a sham procedure.

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Micromotion of the polyethylene (PE) inlay may contribute to backside PE wear in addition to articulate wear of total knee arthroplasty (TKA). Using radiostereometric analysis (RSA) with tantalum beads in the PE inlay, we evaluated PE micromotion and its relationship to PE wear.

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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.

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The aim of this study was to compare the migration of the femoral component, five years postoperatively, between patients with a highly cross-linked polyethylene (HXLPE) insert and those with a conventional polyethylene (PE) insert in an uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA). Secondary aims included clinical outcomes and patient-reported outcome measures (PROMs). We have previously reported the migration and outcome of the tibial components in these patients.

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Adenosine, lidocaine, and Mg²⁺ (ALM) therapy exerts differential immuno-inflammatory responses in males and females early after anterior cruciate ligament (ACL) reconstruction (ACLR). Our aim was to investigate sex-specific effects of ALM therapy on joint tissue repair and recovery 28 days after surgery.

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The purpose of this study is to determine an individual’s age-specific prevalence of total knee arthroplasty (TKA) after cruciate ligament surgery, and to identify clinical and genetic risk factors associated with undergoing TKA.

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This study aimed to evaluate if total knee arthroplasty (TKA) femoral components aligned in either mechanical alignment (MA) or kinematic alignment (KA) are more biomimetic concerning trochlear sulcus orientation and restoration of trochlear height.

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Knee osteoarthritis (OA) is characterized by a chronic inflammatory process involving multiple cytokine pathways, leading to articular cartilage degeneration. Intra-articular therapies using pharmaceutical or autologous anti-inflammatory factors offer potential non-surgical treatment options. Autologous protein solution (APS) is one such product that uses the patient’s blood to produce a concentrate of cells and anti-inflammatory cytokines. This study evaluated the effect of a specific APS intra-articular injection (nSTRIDE) on patient-reported outcome measures compared to saline in moderate knee OA.

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The surgical target for optimal implant positioning in robotic-assisted total knee arthroplasty remains the subject of ongoing discussion. One of the proposed targets is to recreate the knee’s functional behaviour as per its pre-diseased state. The aim of this study was to optimize implant positioning, starting from mechanical alignment (MA), toward restoring the pre-diseased status, including ligament strain and kinematic patterns, in a patient population.

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The aim of this study was to assess factors associated with the estimated lifetime risk of revision surgery after primary knee arthroplasty (KA).

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The aim of this study was to determine the risk of tibial eminence avulsion intraoperatively for bi-unicondylar knee arthroplasty (Bi-UKA), with consideration of the effect of implant positioning, overstuffing, and sex, compared to the risk for isolated medial unicondylar knee arthroplasty (UKA-M) and bicruciate-retaining total knee arthroplasty (BCR-TKA).

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Despite new technologies for total knee arthroplasty (TKA), approximately 20% of patients are dissatisfied. A major reason for dissatisfaction and revision surgery after TKA is persistent pain. The radiological grade of osteoarthritis (OA) preoperatively has been investigated as a predictor of the outcome after TKA, with conflicting results. The aim of this study was to determine if there is a difference in the intensity of pain 12 months after TKA in relation to the preoperative radiological grade of OA alone, and the combination of the intensity of preoperative pain and radiological grade of OA.

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Accurate identification of the ankle joint centre is critical for estimating tibial coronal alignment in total knee arthroplasty (TKA). The purpose of the current study was to leverage artificial intelligence (AI) to determine the accuracy and effect of using different radiological anatomical landmarks to quantify mechanical alignment in relation to a traditionally defined radiological ankle centre.

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This study examined windswept deformity (WSD) of the knee, comparing prevalence and contributing factors in healthy and osteoarthritic (OA) cohorts.

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The aim of this study was to investigate the distribution of phenotypes in Asian patients with end-stage osteoarthritis (OA) and assess whether the phenotype affected the clinical outcome and survival of mechanically aligned total knee arthroplasty (TKA). We also compared the survival of the group in which the phenotype unintentionally remained unchanged with those in which it was corrected to neutral.

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In the last decade, perioperative advancements have expanded the use of outpatient primary total knee arthroplasty (TKA). Despite this, there remains limited data on expedited discharge after revision TKA. This study compared 30-day readmissions and reoperations in patients undergoing revision TKA with a hospital stay greater or less than 24 hours. The authors hypothesized that expedited discharge in select patients would not be associated with increased 30-day readmissions and reoperations.

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Sagittal plane imbalance (SPI), or asymmetry between extension and flexion gaps, is an important issue in total knee arthroplasty (TKA). The purpose of this study was to compare SPI between kinematic alignment (KA), mechanical alignment (MA), and functional alignment (FA) strategies.

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The metabolic equivalent of task (MET) score examines patient performance in relation to energy expenditure before and after knee arthroplasty. This study assesses its use in a knee arthroplasty population in comparison with the widely used Oxford Knee Score (OKS) and EuroQol five-dimension index (EQ-5D), which are reported to be limited by ceiling effects.

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While residual fixed flexion deformity (FFD) in unicompartmental knee arthroplasty (UKA) has been associated with worse functional outcomes, limited evidence exists regarding FFD changes. The objective of this study was to quantify FFD changes in patients with medial unicompartmental knee arthritis undergoing UKA, and investigate any correlation with clinical outcomes.

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Revision total knee arthroplasty (rTKA) is a technically challenging and costly procedure. It is well-documented that primary TKA (pTKA) have better survivorship than rTKA; however, we were unable to identify any studies explicitly investigating previous rTKA as a risk factor for failure following rTKA. The purpose of this study is to compare the outcomes following rTKA between patients undergoing index rTKA and those who had been previously revised.

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The aims were to assess whether joint-specific outcome after total knee arthroplasty (TKA) was influenced by implant design over a 12-year follow-up period, and whether patient-related factors were associated with loss to follow-up and mortality risk.

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The aim of this study was to evaluate whether achieving medial joint opening, as measured by the change in the joint line convergence angle (∆JLCA), is a better predictor of clinical outcomes after high tibial osteotomy (HTO) compared with the mechanical axis deviation, and to find individualized targets for the redistribution of load that reflect bony alignment, joint laxity, and surgical technique.

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While mechanical alignment (MA) is the traditional technique in total knee arthroplasty (TKA), its potential for altering constitutional alignment remains poorly understood. This study aimed to quantify unintentional changes to constitutional coronal alignment and joint line obliquity (JLO) resulting from MA.

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The aim of this study was to identify variables associated with time to revision, demographic details associated with revision indication, and type of prosthesis employed, and to describe the survival of hinge knee arthroplasty (HKA) when used for first-time knee revision surgery and factors that were associated with re-revision.

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To assess the cost-effectiveness of a two-layer compression bandage versus a standard wool and crepe bandage following total knee arthroplasty, using patient-level data from the Knee Replacement Bandage Study (KReBS).

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The aim was to assess whether robotic-assisted total knee arthroplasty (rTKA) had greater knee-specific outcomes, improved fulfilment of expectations, health-related quality of life (HRQoL), and patient satisfaction when compared with manual TKA (mTKA).

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The primary aim was to assess whether robotic total knee arthroplasty (rTKA) had a greater early knee-specific outcome when compared to manual TKA (mTKA). Secondary aims were to assess whether rTKA was associated with improved expectation fulfilment, health-related quality of life (HRQoL), and patient satisfaction when compared to mTKA.

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The aim of this study was to compare a bicruciate-retaining (BCR) total knee arthroplasty (TKA) with a posterior cruciate-retaining (CR) TKA design in terms of kinematics, measured using fluoroscopy and stability as micromotion using radiostereometric analysis (RSA).

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As has been shown in larger animal models, knee immobilization can lead to arthrofibrotic phenotypes. Our study included 168 C57BL/6J female mice, with 24 serving as controls, and 144 undergoing a knee procedure to induce a contracture without osteoarthritis (OA).

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This study aimed to explore the biological and clinical importance of dysregulated key genes in osteoarthritis (OA) patients at the cartilage level to find potential biomarkers and targets for diagnosing and treating OA.

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A fracture of the medial tibial plateau is a serious complication of Oxford mobile-bearing unicompartmental knee arthroplasty (OUKA). The risk of these fractures is reportedly lower when using components with a longer keel-cortex distance (KCDs). The aim of this study was to examine how slight varus placement of the tibial component might affect the KCDs, and the rate of tibial plateau fracture, in a clinical setting.

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The aim of this study was to report the meaningful values of the EuroQol five-dimension three-level questionnaire (EQ-5D-3L) and EuroQol visual analogue scale (EQ-VAS) in patients undergoing primary knee arthroplasty (KA).

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Both the femoral and tibial component are usually cemented at revision total knee arthroplasty (rTKA), while stems can be added with either cemented or press-fit (hybrid) fixation. The aim of this study was to compare the long-term stability of rTKA with cemented and press-fitted stems, using radiostereometric analysis (RSA).

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Thresholds of acceptable early migration of the components in total knee arthroplasty (TKA) have traditionally ignored the effects of patient and implant factors that may influence migration. The aim of this study was to determine which of these factors are associated with overall longitudinal migration of well-fixed tibial components following TKA.

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The aim of this study was to compare any differences in the primary outcome (biphasic flexion knee moment during gait) of robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) at one year post-surgery.

The object of this study was to develop a method to assess the accuracy of an image-free total knee replacement navigation system in legs with normal or abnormal mechanical axes. A phantom leg was constructed with simulated hip and knee joints and provided a means to locate the centre of the ankle joint. Additional joints located at the midshaft of the tibia and femur allowed deformation in the flexion/extension, varus/valgus and rotational planes. Using a digital caliper unit to measure the coordinates precisely, a software program was developed to convert these local coordinates into a determination of actual leg alignment. At specific points in the procedure, information was compared between the digital caliper measurements and the image-free navigation system. Repeated serial measurements were undertaken. In the setting of normal alignment the mean error of the system was within 0.5°. In the setting of abnormal plane alignment in both the femur and the tibia, the error was within 1°. This is the first study designed to assess the accuracy of a clinically-validated navigation system. It demonstrates in vitro accuracy of the image-free navigation system in both normal and abnormal leg alignment settings

Our study evaluated the accuracy of an image-guided total knee replacement system based on CT with regard to preparation of the femoral and tibial bone using nine limbs from five cadavers. The accuracy was assessed by direct measurement using an extramedullary alignment rod without radiographs. The mean angular errors of the femur and tibia, which represent angular gaps from the real mechanical axis in the coronal plane, were 0.3° and 1.1°, respectively. The CT-based system, provided almost perfect alignment of the femoral component with less than 1° of error and excellent alignment with less than 3° of error for the tibial component. Our results suggest that standardisation of knee replacement by the use of this system will lead to improved long-term survival of total knee arthroplasty

Previous studies of failure mechanisms leading to revision total knee replacement (TKR) performed between 1986 and 2000 determined that many failed early, with a disproportionate amount accounted for by infection and implant-associated factors including wear, loosening and instability. Since then, efforts have been made to improve implant performance and instruct surgeons in best practice. Recently our centre participated in a multi-centre evaluation of 844 revision TKRs from 2010 to 2011. The purpose was to report a detailed analysis of failure mechanisms over time and to see if failure modes have changed over the past 10 to 15 years. Aseptic loosening was the predominant mechanism of failure (31.2%), followed by instability (18.7%), infection (16.2%), polyethylene wear (10.0%), arthrofibrosis (6.9%) and malalignment (6.6%). The mean time to failure was 5.9 years (ten days to 31 years), 35.3% of all revisions occurred at less than two years, and 60.2% in the first five years. With improvements in implant and polyethylene manufacture, polyethylene wear is no longer a leading cause of failure. Early mechanisms of failure are primarily technical errors. In addition to improving implant longevity, industry and surgeons must work together to decrease these technical errors. All reports on failure of TKR contain patients with unexplained pain who not infrequently have unmet expectations. Surgeons must work to achieve realistic patient expectations pre-operatively, and therefore, improve patient satisfaction post-operatively. Cite this article: Bone Joint J 2014;96-B(11 Suppl A):101–4

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No predictive model has been published to forecast operating time for total knee arthroplasty (TKA). The aims of this study were to design and validate a predictive model to estimate operating time for robotic-assisted TKA based on demographic data, and evaluate the added predictive power of CT scan-based predictors and their impact on the accuracy of the predictive model.

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Periprosthetic joint infection (PJI) occurs in approximately 1% to 2% of total knee arthroplasties (TKA) presenting multiple challenges, such as difficulty in diagnosis, technical complexity, and financial costs. Two-stage exchange is the gold standard for treating PJI but emerging evidence suggests 'two-in-one' single-stage revision as an alternative, delivering comparable outcomes, reduced morbidity, and cost-effectiveness. This study investigates five-year results of modified single-stage revision for treatment of PJI following TKA with bone loss.

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Outcomes of current operative treatments for arthrofibrosis after total knee arthroplasty (TKA) are not consistently positive or predictable. Pharmacological in vivo studies have focused mostly on prevention of arthrofibrosis. This study used a rabbit model to evaluate intra-articular (IA) effects of celecoxib in treating contracted knees alone, or in combination with capsular release.

Introduction. Wear of polyethylene inserts plays an important role in failure of total knee replacement and can be monitored in vivo by measuring the minimum joint space width in anteroposterior radiographs. The objective of this retrospective cross-sectional study was to compare the accuracy and precision of a new model-based method with the conventional method by analysing the difference between the minimum joint space width measurements and the actual thickness of retrieved polyethylene tibial inserts. . Method. Before revision, the minimum joint space width values and their locations on the insert were measured in 15 fully weight-bearing radiographs. These measurements were compared with the actual minimum thickness values and locations of the retrieved tibial inserts after revision. . Results. The mean error in the model-based minimum joint space width measurement was significantly smaller than the conventional method for medial condyles (0.50 vs 0.94 mm, p < 0.01) and for lateral condyles (0.06 vs 0.34 mm, p = 0.02). The precision (standard deviation of the error) of the methods was similar (0.84 vs 0.79 mm medially and both 0.46 mm laterally). The distance between the true minimum joint space width locations and the locations from the model-based measurements was less than 10 mm in the medial direction in 12 cases and less in the lateral direction in 13 cases. Conclusion. The model-based minimum joint space width measurement method is more accurate than the conventional measurement with the same precision. Cite this article: Bone Joint Res 2014;3:289–96

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Hereditary haemochromatosis is a genetic disorder that is caused by several known mutations in the human homeostatic iron regulator protein (HFE) gene. Abnormal accumulation of iron causes a joint disease that resembles osteoarthritis (OA), but appears at a relatively younger age and is accompanied by cirrhosis, diabetes, and injury to other organs. Increased serum transferrin saturation and ferritin levels are known markers of haemochromatosis with high positive predictive values.

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Anterior cruciate ligament (ACL) rupture commonly leads to post-traumatic osteoarthritis, regardless of surgical reconstruction. This study uses standing MRI to investigate changes in contact area, contact centroid location, and tibiofemoral alignment between ACL-injured knees and healthy controls, to examine the effect of ACL reconstruction on these parameters.

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Medial pivot (MP) total knee arthroplasties (TKAs) were designed to mimic native knee kinematics with their deep medial congruent fitting of the tibia to the femur almost like a ball-on-socket, and a flat lateral part. GMK Sphere is a novel MP implant. Our primary aim was to study the migration pattern of the tibial tray of this TKA.

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Nearly 99,000 total knee arthroplasties (TKAs) are performed in UK annually. Despite plenty of research, the satisfaction rate of this surgery is around 80%. One of the important intraoperative factors affecting the outcome is alignment. The relationship between joint obliquity and functional outcomes is not well understood. Therefore, a study is required to investigate and compare the effects of two types of alignment (mechanical and kinematic) on functional outcomes and range of motion.

We explored the literature surrounding whether allergy and hypersensitivity has a clinical basis for implant selection in total knee arthroplasty (TKA). In error, the terms hypersensitivity and allergy are often used synonymously. Although a relationship is present, we could not find any evidence of implant failure due to allergy. There is however increasing basic science that suggests a link between loosening and metal ion production. This is not an allergic response but is a potential problem. With a lack of evidence logically there can be no justification to use ‘hypoallergenic’ implants in patients who have pre-existing skin sensitivity to the metals used in TKA. Cite this article: Bone Joint J 2016;98-B:437–41

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This study used an artificial neural network (ANN) model to determine the most important pre- and perioperative variables to predict same-day discharge in patients undergoing total knee arthroplasty (TKA).

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Alternative alignment concepts, including kinematic and restricted kinematic, have been introduced to help improve clinical outcomes following total knee arthroplasty (TKA). The purpose of this study was to evaluate the clinical results, along with patient satisfaction, following TKA using the concept of restricted kinematic alignment.

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Many patients undergoing total knee arthroplasty (TKA) have severe osteoarthritis (OA) in both knees and may consider either simultaneous or staged bilateral TKA. The implications of simultaneous versus staged bilateral TKA for return to work are not well understood. We hypothesized that employed patients who underwent simultaneous bilateral TKA would have significantly fewer days missed from work compared with the sum of days missed from each operation for patients who underwent staged bilateral TKA.

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The primary aim of this study was to assess whether non-fatal postoperative venous thromboembolism (VTE) within six months of surgery influences the knee-specific functional outcome (Oxford Knee Score (OKS)) one year after total knee arthroplasty (TKA). Secondary aims were to assess whether non-fatal postoperative VTE influences generic health and patient satisfaction at this time.

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The patient-acceptable symptom state (PASS) is a level of wellbeing, which is measured by the patient. The aim of this study was to determine if the proportion of patients who achieved an acceptable level of function (PASS) after medial unicompartmental knee arthroplasty (UKA) was different based on the status of the anterior cruciate ligament (ACL) at the time of surgery.

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Social determinants of health (SDOHs) may contribute to the total cost of care (TCOC) for patients undergoing total knee arthroplasty (TKA). The aim of this study was to investigate the association between demographic data, health status, and SDOHs on 30-day length of stay (LOS) and TCOC after this procedure.

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Neither a surgeon’s intraoperative impression nor the parameters of computer navigation have been shown to be predictive of the outcomes following total knee arthroplasty (TKA). The aim of this study was to determine whether a surgeon, with robotic assistance, can predict the outcome as assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) for pain (KPS), one year postoperatively, and establish what factors correlate with poor KOOS scores in a well-aligned and balanced TKA.

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The aims of this study were to evaluate wear on the surface of cobalt-chromium (CoCr) femoral components used in total knee arthroplasty (TKA) and compare the wear of these components with that of ceramic femoral components.

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The objective of this study was to compare the two-year migration pattern and clinical outcomes of a total knee arthroplasty (TKA) with an asymmetrical tibial design (Persona PS) and a well-proven TKA with a symmetrical tibial design (NexGen LPS).

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Many surgeons choose to perform total knee arthroplasty (TKA) surgery with the aid of a tourniquet. A tourniquet is a device that fits around the leg and restricts blood flow to the limb. There is a need to understand whether tourniquets are safe, and if they benefit, or harm, patients. The aim of this study was to determine the benefits and harms of tourniquet use in TKA surgery.

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Uncemented mobile bearing designs in medial unicompartmental knee arthroplasty (UKA) have seen an increase over the last decade. However, there are a lack of large-scale studies comparing survivorship of these specific designs to commonly used cemented mobile and fixed bearing designs. The aim of this study was to evaluate the survivorship of these designs.

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Infection complicating primary total knee arthroplasty (TKA) is a common reason for revision surgery, hospital readmission, patient morbidity, and mortality. Increasing incidence of methicillin-resistant Staphylococcus aureus (MRSA) is a particular concern. The use of vancomycin as prophylactic agent alone or in combination with cephalosporin has not demonstrated lower periprosthetic joint infection (PJI) rates, partly due to timing and dosing of intravenous (IV) vancomycin administration, which have proven important factors in effectiveness. This is a retrospective review of a consecutive series of primary TKAs examining incidence of PJI, adverse reactions, and complications using IV versus intraosseous (IO) vancomycin at 30-day, 90-day, and one-year follow-up.

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Once knee arthritis and deformity have occurred, it is currently not known how to determine a patient’s constitutional (pre-arthritic) limb alignment. The purpose of this study was to describe and validate the arithmetic hip-knee-ankle (aHKA) algorithm as a straightforward method for preoperative planning and intraoperative restoration of the constitutional limb alignment in total knee arthroplasty (TKA).

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Ideal component sizing may be difficult to achieve in unicompartmental knee arthroplasty (UKA). Anatomical variants, incremental implant size, and a reduced surgical exposure may lead to over- or under-sizing of the components. The purpose of this study was to compare the accuracy of UKA sizing with robotic-assisted techniques versus a conventional surgical technique.

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The aim of this study was to screen the entire genome for genetic markers associated with risk for anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) injury.

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To estimate the measurement properties for the Oxford Knee Score (OKS) in patients undergoing revision knee arthroplasty (responsiveness, minimal detectable change (MDC-90), minimal important change (MIC), minimal important difference (MID), internal consistency, construct validity, and interpretability).

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It has previously been shown that higher-volume hospitals have better outcomes following revision total knee arthroplasty (rTKA). We were unable to identify any studies which investigated the effect of surgeon volume on the outcome of rTKA. We sought to investigate whether patients of high-volume (HV) rTKA surgeons have better outcomes following this procedure compared with those of low-volume (LV) surgeons.

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The aim of this study was to compare ten-year longitudinal healthcare costs and revision rates for patients undergoing unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA).

We prospectively assessed the benefits of using either a range-of-movement technique or an anatomical landmark method to determine the rotational alignment of the tibial component during total knee replacement. We analysed the cut proximal tibia intraoperatively, determining anteroposterior axes by the range-of-movement technique and comparing them with the anatomical anteroposterior axis. We found that the range-of-movement technique tended to leave the tibial component more internally rotated than when anatomical landmarks were used. In addition, it gave widely variable results (mean 7.5°; 2° to 17°), determined to some extent by which posterior reference point was used. Because of the wide variability and the possibilities for error, we consider that it is inappropriate to use the range-of-movement technique as the sole method of determining alignment of the tibial component during total knee replacement

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The purpose is to determine the non-inferiority of a smartphone-based exercise educational care management system after primary knee arthroplasty compared with a traditional in-person physiotherapy rehabilitation model.

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The primary aim of this study was to compare the postoperative systemic inflammatory response in conventional jig-based total knee arthroplasty (conventional TKA) versus robotic-arm assisted total knee arthroplasty (robotic TKA). Secondary aims were to compare the macroscopic soft tissue injury, femoral and tibial bone trauma, localized thermal response, and the accuracy of component positioning between the two treatment groups.

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Modern total knee arthroplasty (TKA) prostheses are designed to restore near normal kinematics including high flexion. Kneeling is a high flexion, kinematically demanding activity after TKA. The debate about design choice has not yet been informed by six-degrees-of-freedom in vivo kinematics. This prospective randomized clinical trial compared kneeling kinematics in three TKA designs.

The rotational alignment of the tibia is an unresolved issue in knee replacement. A poor functional outcome may be due to malrotation of the tibial component. Our aim was to find a reliable method for positioning the tibial component in knee replacement. CT scans of 19 knees were reconstructed in three dimensions and orientated vertically. An axial plane was identified 20 mm below the tibial spines. The centre of each tibial condyle was calculated from ten points taken round the condylar cortex. The tibial tubercle centre was also generated as the centre of the circle which best fitted eight points on the outside of the tubercle in an axial plane at the level of its most prominent point. The derived points were identified by three observers with errors of 0.6 mm to 1 mm. The medial and lateral tibial centres were constant features (radius 24 mm (. sd. 3), and 22 mm (. sd. 3), respectively). An anatomical axis was created perpendicular to the line joining these two points. The tubercle centre was found to be 20 mm (. sd. 7) lateral to the centre of the medial tibial condyle. Compared with this axis, an axis perpendicular to the posterior condylar axis was internally rotated by 6° (. sd. 3). An axis based on the tibial tubercle and the tibial spines was also internally rotated by 5° (. sd. 10). Alignment of the knee when based on this anatomical axis was more reliable than either the posterior surfaces or any axis involving the tubercle which was the least reliable landmark in the region

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A comprehensive classification for coronal lower limb alignment with predictive capabilities for knee balance would be beneficial in total knee arthroplasty (TKA). This paper describes the Coronal Plane Alignment of the Knee (CPAK) classification and examines its utility in preoperative soft tissue balance prediction, comparing kinematic alignment (KA) to mechanical alignment (MA).

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Debate continues regarding the optimum management of periprosthetic distal femoral fractures (PDFFs). This study aims to determine which operative treatment is associated with the lowest perioperative morbidity and mortality when treating low (Su type II and III) PDFFs comparing lateral locking plate fixation (LLP-ORIF) or distal femoral arthroplasty (DFA).

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Total knee arthroplasty (TKA) using functional alignment aims to implant the components with minimal compromise of the soft-tissue envelope by restoring the plane and obliquity of the non-arthritic joint. The objective of this study was to determine the effect of TKA with functional alignment on mediolateral soft-tissue balance as assessed using intraoperative sensor-guided technology.

We report the clinical and radiological results of a two- to three-year prospective randomised study which was designed to compare a minimally-invasive technique with a standard technique in total knee replacement and was undertaken between January 2004 and May 2007. The mini-midvastus approach was used on 50 patients (group A) and a standard approach on 50 patients (group B). The mean follow-up in both groups was 23 months (24 to 35). The functional outcome was better in group A up to nine months after operation, as shown by statistically significant differences in the mean function score, mean total score and the mean Oxford knee score (all, p = 0.05). Patients in group A had statistically significant greater early flexion (p = 0.04) and reached their greatest mean knee flexion of 126.5° (95° to 135°) 21 days after operation. However, at final follow-up there was no significant difference in the mean maximum flexion between the groups (p = 0.08). Technical errors were identified in six patients from group A (12%) on radiological evaluation. Based on these results, the authors currently use minimally-invasive techniques in total knee replacement in selected cases only

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This study aimed to identify the tibial component and femoral component coronal angles (TCCAs and FCCAs), which concomitantly are associated with the best outcomes and survivorship in a cohort of fixed-bearing, cemented, medial unicompartmental knee arthroplasties (UKAs). We also investigated the potential two-way interactions between the TCCA and FCCA.

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The aim of this study was to compare robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) in order to determine the changes in the anatomy of the knee and alignment of the lower limb following surgery.