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Background: Accumulating evidence suggests that synovial inflammation plays a pivotal role in knee osteoarthritis. Although biomechanical findings have shown that medial open-wedge proximal tibial osteotomy (OWPTO) decreases medial compartment loading by correcting knee alignment, the relationship between knee alignment and synovial inflammation in the biological microenvironment has not yet been elucidated., Purposes: To investigate the relationship between preoperative and postoperative knee alignment and synovial gene expression and to determine the cutoff point of postoperative knee alignment at which gene expression of synovial inflammation improves., Study Design: Cohort study; Level of evidence, 3., Methods: A total of 36 patients with osteoarthritis who underwent OWPTO between June 2018 and May 2020 were enrolled. Synovial tissue was collected from affected knees during initial OWPTO and plate removal surgeries, and gene expression associated with the pathogenesis of osteoarthritis in the synovial tissue was investigated using real-time polymerase chain reaction. The correlation between weightbearing line ratio (WBLR) and synovial gene expression was determined. Receiver operating characteristic curve analysis was used to determine the cutoff values of WBLR for improving gene expression. The participants were divided into 2 groups, according to the cutoff values of their WBLR, and compared according to Knee injury and Osteoarthritis Outcome Score (KOOS) and synovial gene expression., Results: Postoperative WBLR was correlated with gene expression of interleukin 1β ( IL1B ) (ρ = -0.43; P = .008) and of interleukin 6 ( IL6 ) (ρ = -0.41; P = .01). The cutoff value to predict improvement of IL6 was postoperative WBLR of 52%, with an area under the curve of 0.74 ( P = .03). Patients with WBLR of <52% showed higher postoperative inflammatory gene ( IL1B [ P = .04] and IL6 [ P = .03]) and inferior postoperative KOOS values compared with those with WBLR of >52%., Conclusion: The novel cutoff alignment for biological improvement after OWPTO in patients with medial compartment osteoarthritis was determined to be WBLR of 52%, and WBLR of <52% was associated with higher residual intra-articular inflammation and poor clinical outcomes. After accounting for surgical errors, the surgeon should set the target surgical alignment so that the postoperative WBLR does not fall below 52%., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: This work was supported by Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science (grant No. 18H02927, 20K09408, 21H03053). The Department of Advanced Medicine for Rheumatic Diseases is supported by Nagahama City, Shiga, Japan; Toyooka City, Hyogo, Japan; and 2 pharmaceutical companies (Asahi Kasei Pharma Corp and AYUMI Pharmaceutical Co). K.N. has received a research grant from Asahi Kasei Pharma Corp and speaking and/or consulting fees from AbbVie GK, Eisai Co Ltd, Pfizer Inc, Chugai Pharmaceutical Co Ltd, Mitsubishi Tanabe Pharma Corporation, Pfizer Inc, Bristol-Myers Squibb, Daiichi Sankyo Co Ltd, and Asahi Kasei Pharma Corp. S.K. has received a research grant from Olympus-Terumo Biomaterials Corp. T.F. has received speaking fees from AbbVie GK, Asahi Kasei Pharma Corp, Chugai Pharmaceutical Co Ltd, Eisai Co Ltd, and Janssen Pharmaceutical K.K. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Objective: This study evaluated whether preoperative radiographs accurately predicted intra-articular cartilage damage in varus knees., Methods: The study assessed 181 knees in 156 patients who underwent total knee arthroplasty. Cartilage damage was graded by two examiners with the International Cartilage Repair Society classification; one used knee radiographs and the other used intraoperative photographs. It was then determined if this radiographic cartilage assessment over- or underestimated the actual damage severity. Knee morphological characteristics affecting radiographic misestimation of damage severity were also identified., Results: The concordance rate between radiographic and intraoperative assessments of the medial femoral condyle was high, at around 0.7. Large discrepancies were found for the lateral femoral condyle and medial trochlear groove. Radiographic assessment underestimated cartilage damage on the medial side of the lateral femoral condyle due to a large lateral tibiofemoral joint opening and severe varus alignment {both r = -0.43}. Medial trochlear damage was also underdiagnosed, in cases of residual medial tibiofemoral cartilage and shallow medial tibial slope {r = -0.25 and -0.21, respectively}., Conclusions: Radiographic evaluation of knee osteoarthritis was moderately practical using International Cartilage Repair Society grades. Lateral femoral condyle and medial trochlear cartilage damage tended to be misestimated, but considering morphologic factors might improve the diagnostic rate., (© Japan College of Rheumatology 2024. Published by Oxford University Press. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site–for further information please contact journals.permissions@oup.com.)

Background: The perioperative pain and function of total knee arthroplasty (TKA) in patients with rheumatoid arthritis (RA) approach those in patients with osteoarthritis (OA). This study aimed to evaluate whether the clinical outcomes, especially functions, of patients with RA reached those of OA, utilizing a background-matched cohort., Methods: Patients who underwent TKA between 2013 and 2021 were enrolled. Preoperative and minimum 2-year postoperative scores, specifically the Original Knee Society Score (OKSS) and New Knee Society Score (2011KSS), between RA and OA were compared. Clinical assessments were performed on unadjusted and propensity-score matched cohorts, ensuring age, sex, body mass index, and valgus deformity rate parity., Results: In an unadjusted cohort involving 98 patients with RA and 560 patients with OA, patients with RA demonstrated inferior preoperative OKSS-Function Score (FS) but similar postoperative functional scores to OA patients. In the matched cohort of 83, patients with RA displayed lower preoperative OKSS- FS (median difference: 20, P < 0.001) and 2011KSS functional activities (difference: 9, P = 0.01) beyond minimum clinically important differences than patients with OA. Patients with RA improved more in OKSS-FS, yielding no postoperative difference compared with patients with OA. However, postoperative 2011KSS functional activities remained lower in patients with RA (difference: 9.5, P = 0.03), especially in advanced functions, than in those with OA., Conclusion: Postoperative function showed no difference between patients with RA and OA in the unadjusted cohort; within the background-matched cohort, postoperative function, especially advanced function, was inferior in patients with RA to those with OA., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: ‘K.N. received research grants and/or honorarium for lectures from Kyocera, Asahi-Kasei Pharma, and Daiichi-Sankyo. H.I. and K.M. belong or belonged to the department that is financially supported by Nagahama City, Shiga, Japan, Toyooka City, Hyogo, Japan and five pharmaceutical companies (Tanabe-Mitsubishi, Chugai, UCB Japan, Ayumi and Asahi-Kasei Pharma). H.I. received a research grant from Bristol-Myers. S.N. received a research grant Kyocera. S.K. declares no conflicts of interest. S.M. received a research grant and honorarium for lectures from Kyocera. KURAMA cohort is supported by Daiichi-Sankyo. The sponsors had no role in the design or conduct of the study.’., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Purpose: The degree to which varus knees can be corrected manually is important when considering total versus unicompartmental knee arthroplasty (UKA). The primary aim was to clarify the relationship between the degree of coronal alignment correction and radiographic parameters involved in UKA prognosis using preoperative full-length lower extremity valgus stress radiography. The secondary aim was to identify the factors affecting alignment correction., Methods: This retrospective observational study included 115 knees with medial osteoarthritis that underwent knee osteotomy or arthroplasty. Percent mechanical axis without valgus stress (%MA: neutral, 50%; varus, <50% and valgus, >50%), mechanical lateral distal femoral angle, lateral bowing femoral angle, medial proximal tibial angle (MPTA), joint line convergence angle, medial and lateral joint space width (LJSW) and medial femoral and tibial joint osteophyte size were measured using preoperative full-length weight-bearing radiographs. Correlation and multiple linear regression analyses were used to assess associations between parameters and %MA with valgus stress or amount of %MA change (%MA with valgus stress minus %MA without valgus stress)., Results: %MA with valgus stress was correlated with all radiographic parameters. %MA change was correlated with parameters except for MPTA and LJSW. Multiple regression analyses showed that %MA without valgus stress and MPTA were associated with both %MA with valgus stress and %MA change. When %MA with valgus stress was set at 30%, 40% and 50%, MPTA cutoff values were 81.6°, 83.5° and 84.9°, and cutoffs for %MA without valgus stress were 10.7%, 17.1% and 25.1%, respectively., Conclusion: Small MPTA is strongly associated with less alignment correction under valgus stress in varus knees. The finding is useful in surgical planning, especially to avoid undercorrection with UKA when valgus stress radiographs are unavailable., Level of Evidence: Level III., (© 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Objectives: The concept of locomotive syndrome (LS) and its evaluation method, the LS risk test, have been applied in an integrated manner to capture the decline in mobility resulting from musculoskeletal disorders. The purpose of this study was to evaluate the impact of total knee arthroplasty (TKA) in the elderly with knee osteoarthritis, a common disorder found in LS., Methods: A total of 111 patients were registered prior to TKA and postoperatively followed up for 1 year. Three components of the LS risk test (the two-step test, stand-up test, and Geriatric Locomotive Function Scale-25) were assessed pre- and postoperatively., Results: After surgery, all three components of the test showed significant improvements from the baseline. The ratio of Stage 3 LS patients (progressed stage of decrease in mobility) reduced from 82.3% to 33.9% postoperatively. There was no significant difference in the degree of change in the scores between the younger (60-74 years) and older (≥75 years) age groups., Conclusions: We found that TKA has a major impact in preventing the progression of LS in patients with knee osteoarthritis. The LS risk test is a feasible tool for the longitudinal evaluation of patients with musculoskeletal diseases of varying severity and with multiple symptoms., (© Japan College of Rheumatology 2022. Published by Oxford University Press.)

Purpose: This study evaluated the clinical outcomes of medial open-wedge high tibial osteotomy (MOWHTO) and bone marrow lesion (BML) scores and volumes. The hypotheses were that quantitative BML volume is more associated with clinical outcomes of MOWHTO than qualitative BML evaluations, and pre-operative BML volume is associated with the improvement of clinical outcomes., Methods: Patients who underwent MOWHTO were retrospectively enrolled. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was recorded before the initial surgery and at plate removal surgery. Using pre-operative short-time inversion recovery magnetic resonance imaging, BMLs were evaluated using three qualitative scores, reflecting the maximum length, proportion, and intensity of BML. For quantification, BMLs of the femur and tibia were separately defined as lesions with a threshold greater than the mean signal intensity plus two standard deviations, using the corresponding lateral condyles as controls. The association between the KOOS scales and BML scores/volume was evaluated using Spearman's correlation coefficient. Multivariate linear regression analyses for post-operative KOOS scales were performed using the tibial BML volume as one of the four independent variables., Results: The final analysis included 40 MOWHTO cases. Two qualitative BML scores correlated only with pre-operative KOOS sports. Femoral and tibial BML volumes were correlated with post-operative KOOS QOL (ρ = 0.40, p = 0.01) and sports (ρ = 0.36, p = 0.02), respectively. Tibial BML volume was significantly correlated with all five delta KOOS scales (ρ = 0.39-0.51, p = 0.01-0.001), however, femoral BML volume was only correlated with delta KOOS QOL (ρ = 0.41, p = 0.01). In multivariate analyses, tibial BML volume was a significant positive predictor for every post-operative KOOS scale, while post-operative % mechanical axis was also a positive significant variable, except post-operative KOOS pain., Conclusion: Tibial BML volume was positively correlated with one post-operative KOOS scale and all delta KOOS scales. A larger pre-operative tibial BML and appropriate alignment correction were associated with a better post-operative KOOS scales. Pre-operative large BML had no negative influence on post-operative clinical outcomes; hence, surgeons need not hesitate to perform MOWHTO in patients with large BMLs in the medial condyles., Level of Evidence: Retrospective case series, Level IV., (© 2022. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Background: Lower limb malrotations can be observed in long leg radiographs, affecting the measurement of the angle between the mechanical and anatomical axes. The purposes were to analyze the effect of limb rotation and to evaluate the accuracy of the corrected angle between the mechanical and anatomical axes based on the patellar ML position., Hypothesis: The hypothesis was that the correction of the angle between the mechanical and anatomical axes according to the patellar ML position can reduce the error from the angle in the true AP view in most of the knees., Patients and Methods: A total of 100 consecutive knees with varus deformity undergoing primary total knee arthroplasty were included. Computed tomography images were digitally reconstructed in the neutral position, and internally and externally rotated at 10° and 20°, respectively. The patellar ML position relative to the medial (0%) and lateral (100%) epicondyles and the angle between the mechanical and anatomical axes of the femur were measured. The corrected angle between the mechanical and anatomical axes was calculated using the averaged translational ratio., Results: In the neutral position, the patellar center position was 56.1% (standard deviation [SD]=4.7%), which was 31.4% (SD=7.2%) and 80.2% (SD=5.4%) in the 20° internal and external rotation, respectively. The angle between the mechanical and anatomical axes was 2.6° (SD=2.0°) and 8.1° (SD=2.1°) in the 20° internal and external rotation, respectively. On average, if the patellar center shifted 10%, the change of the angle between the mechanical and anatomical axes of the femur was 1.13°. Applying the corrected angle, a discrepancy from the neutral position decreased., Conclusion: The method to correct the angle between the mechanical and anatomical axes according to the patellar ML position can be used to reduce the measurement error for preoperative planning using a long leg radiograph., Level of Evidence: III., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Background: Polygenic risk score (PRS) analysis is used to predict disease risk. Although PRS has been shown to have great potential in improving clinical care, PRS accuracy assessment has been mainly focused on European ancestry. This study aimed to develop an accurate genetic risk score for knee osteoarthritis (OA) using a multi-population PRS and leveraging a multi-trait PRS in the Japanese population., Methods: We calculated PRS using PRS-CS-auto, derived from genome-wide association study (GWAS) summary statistics for knee OA in the Japanese population (same ancestry) and multi-population. We further identified risk factor traits for which PRS could predict knee OA and subsequently developed an integrated PRS based on multi-trait analysis of GWAS (MTAG), including genetically correlated risk traits. PRS performance was evaluated in participants of the Nagahama cohort study who underwent radiographic evaluation of the knees (n = 3,279). PRSs were incorporated into knee OA integrated risk models along with clinical risk factors., Results: A total of 2,852 genotyped individuals were included in the PRS analysis. The PRS based on Japanese knee OA GWAS was not associated with knee OA (p = 0.228). In contrast, PRS based on multi-population knee OA GWAS showed a significant association with knee OA (p = 6.7 × 10 -5 , odds ratio (OR) per standard deviation = 1.19), whereas PRS based on MTAG of multi-population knee OA, along with risk factor traits such as body mass index GWAS, displayed an even stronger association with knee OA (p = 5.4 × 10 -7 , OR = 1.24). Incorporating this PRS into traditional risk factors improved the predictive ability of knee OA (area under the curve, 74.4% to 74.7%; p = 0.029)., Conclusions: This study showed that multi-trait PRS based on MTAG, combined with traditional risk factors, and using large sample size multi-population GWAS, significantly improved predictive accuracy for knee OA in the Japanese population, even when the sample size of GWAS of the same ancestry was small. To the best of our knowledge, this is the first study to show a statistically significant association between the PRS and knee OA in a non-European population., Trial Registration: No. C278., (© 2023. The Author(s).)

Objective: This study aimed to determine whether alignment correction by high tibial osteotomy (HTO) can change the biologic intraarticular microenvironment of osteoarthritic (OA) knees., Methods: Synovial tissue (ST) and fluid (SF) were collected from the affected knees of 31 OA patients during initial HTO and plate removal surgeries. Changes in gene expression in ST were investigated by microarray and real-time polymerase chain reaction (PCR). ST specimens were also evaluated histologically using synovitis scores and immunofluorescence staining to determine macrophage polarity. Cytokines and chemokines in SF were analyzed by enzyme-linked immunosorbent assays. The mechanism of macrophage polarization was investigated in human peripheral blood mononuclear cell-derived macrophages and fibroblast-like synoviocytes (FLS) stimulated with cartilage fragments. We also evaluated Spearman correlations between Knee Injury and Osteoarthritis Outcome scores (KOOS) and macrophage-related gene expression., Results: The microarray results indicated down-regulated inflammatory genes and pathways. Real-time PCR determined that genes expressing proinflammatory IL1B and IL6 were down-regulated and M2 macrophage-related IL1RA, IL10, CCL18, and CD206 were up-regulated. Histologic findings revealed attenuated synovitis scores and a shift from M1 to M2 macrophages. Interleukin-1β (IL-1β) concentrations in SF decreased after HTO. Cartilage fragments were responsible for M1 macrophage polarization and proinflammatory gene and protein expression in macrophages, whereas cartilage fragments up-regulated only IL-6 protein in FLS. Postoperative KOOS positively correlated with the expression of the M2-related genes CCL18 and CD206., Conclusion: Correction of lower limb alignment with HTO attenuated synovial inflammation and changed macrophage polarization from M1 to M2, suggesting an improved intraarticular environment in knee OA., (© 2022 American College of Rheumatology.)

The correlation between static and dynamic mediolateral (ML) tilts of the joint line in the coronal plane remains unknown after total knee arthroplasty (TKA). The purpose was to evaluate the ML tilt as measured by two-dimensional to three-dimensional registration during stair ascent in TKA patients, and to examine the correlation between the dynamic ML tilt and radiographic measurements of static indices. Thirty-two knees that underwent TKA using the mechanical alignment method were included. Continuous sagittal fluoroscopy was taken from before initial contact (IC) until after the toe-off (TO) phase during the stair ascent. The ML tilt of the tibial component relative to the ground was analyzed in terms of dynamic alignment using image-matching techniques, whereas static alignment was measured using standing long-leg radiographs. The correlation between static and dynamic ML tilts was evaluated. In the fluoroscopic analysis, the joint line was neutral (0.0 degree, standard deviation [SD] = 3.4 degrees) around IC phases, then was tilted valgus (5.5° valgus, SD = 2.6 degrees) in the mid-stance (MS) phase. After the TO phase, the joint line became almost neutral (0.4 degrees valgus, SD = 3.1 degrees). The dynamic ML tilt was significantly more varus during the IC phase and significantly more valgus in MS and TO phases than the static ML tilt (1.4 degrees valgus, SD = 2.0 degrees). No correlation was found between static and dynamic ML tilts in weight-bearing phases. During stair ascent, the static tilt had no correlation with the dynamic tilt in weight-bearing phases despite being in the same range. Static lower limb alignment does not reflect coronal alignment during motion. Further research should be conducted to determine whether the horizontal dynamic ML tilt can improve long-term durability and clinical outcomes after TKA., Competing Interests: S.N. reports grants from Kyocera, during the conduct of the study. K.N. reports grants from Kyocera, during the conduct of the study. H.I. reports grants from research grant, other from belonging to the department supported by companies, outside the submitted work. S.M. reports grants and personal fees from Kyocera, outside the submitted work. Rest authors declare no conflict of interest., (Thieme. All rights reserved.)

Introduction: Achieving adequate posterior cruciate ligament (PCL) tension is important during PCL-retaining total knee arthroplasty (CR-TKA), but the effect of PCL release on this tension is unpredictable. This study assessed the relationship between postoperative PCL laxity and patient satisfaction at a 2-year follow-up., Methods: There were 44 varus osteoarthritis knees undergoing CR-TKA included. The PCL tension was adjusted by resizing the femoral component and modifying the posterior tibial slope, without PCL release. Postoperative PCL laxity at 90° of knee flexion was defined as the difference in radiographic anterior-posterior tibial translation with or without an 80-Newton posterior load at the tibial tubercle measured using a load device. Four subgroups were defined according to the PCL laxity: laxity ≤0 mm (n = 5); 0 mm < laxity ≤2 mm (n = 19); 2 mm < laxity ≤4 mm (n = 10); and laxity >4 mm (n = 10). The effect of PCL laxity on the 2-year postoperative 2011 Knee Society Score was determined., Results: The femoral component was downsized in 27 of 44 knees, while the posterior tibia slope was increased in 6 of 44 knees, but no PCL was released intraoperatively. The 2011 Knee Society Score subscores improved significantly from preoperatively to postoperatively, and patients reported "neutral satisfaction" or better after 96% of operations. The mean PCL laxity was 2.3 mm on postoperative stress radiographs, and postoperative satisfaction scores were significantly highest in the subgroup with 2-4 mm laxity., Conclusion: CR-TKA was successfully performed without PCL release. Moderate PCL laxity (2-4 mm) achieved excellent postoperative satisfaction., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Postoperative knee instability is a leading cause of revision total knee arthroplasty (TKA). This study used a commercially available insert-shaped electronic force sensor to measure joint loads and facilitate ligament balance adjustment, and assessed the ability of this sensor to detect increased or decreased soft tissue tension during primary TKA., Methods: Changes in medial and lateral tibiofemoral joint loads during knee flexion were evaluated with sensor thicknesses ranging from 10 to 16 mm using six varus osteoarthritis cadaver knees with intact medial collateral ligaments (MCLs), and the measurements were repeated after MCL resection. Correlations between joint loads and maximum knee extension angle were also evaluated. To validate the efficacy of the sensor, the values were compared with those obtained using a conventional tension device., Results: For MCL-intact knees in extension, the medial joint load increased with sensor thickness. The maximum knee extension angle decreased with sensor thickness (ρ = -0.4), resulting in extension restriction up to -20°. Knee flexion contracture was below 5° when the total tibiofemoral joint load was below a cut-off of 42 lb. After the MCL was resected, medial joint loads remained unchanged at low values, even with increased sensor thickness. In contrast, the tension device clearly detected an increased gap as the degree of tension decreased., Conclusions: The electronic sensor identified increased joint loads associated with increased ligament tension, and could predict knee flexion contracture during TKA. However, unlike the tension device, it did not accurately detect excessively decreased ligament tension., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Objective: To clarify the interactive combinations of various clinical factors associated with physical activity (PA) at 2 years after total knee arthroplasty (TKA) using classification and regression tree (CART) analysis., Design: A retrospective cohort study., Setting: A single university hospital., Participants: 286 patients who underwent TKA (N=286)., Main Outcome Measures: PA was assessed preoperatively, 3 weeks, and 2 years after TKA. Physical functions, namely, 10 m walking test (10MWT), timed Up and Go test, 1-leg standing time, isometric knee extension and flexion strength, knee joint stability, knee pain, femora-tibial angle, and the passive knee extension and flexion angle, were measured before surgery as a baseline and 3 weeks after TKA as acute phase. CART analysis was conducted to clarify the interactive combinations that accurately predict the PA at 2 years after TKA., Results: The results of CART analysis indicated that gait speed (≥1.05 m/s) at the acute phase after TKA was the primal predictor for the postoperative PA at 2 years. The highest postoperative PA at 2 years was determined by gait speed (≥1.05 m/s) and PA (>74.5) at the acute phase. The PA at baseline and at acute phase, as well as the body mass index were also selected as predictors of postoperative PA at 2 years., Conclusion: The present study suggested that acquiring gait speed (≥1.05 m/s) and PA (>74.5) in the postoperative acute phase is the predictive of a high PA at 2 years after TKA., (Copyright © 2023 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

Purpose: The purpose of this study was to use the finite element method (FEM) to reproduce fracture lines that reach the lateral tibial plateau during open-wedge high tibial osteotomy (OWHTO) in patients with Type III lateral hinge fracture (LHF). It was hypothesized that the FEM could clarify biomechanical causes of Type III LHF, enabling prevention of adverse complications., Methods: This study used the nonlinear FEM to analyze the data of eight knees in eight patients (two males and six females) with Type III LHF among 82 patients who underwent OWHTO, as well as the data of eight individuals with no LHF. To predict the onset of Type III LHF, simulation models were also developed in which posterior osteotomy sufficiency varied from 50% to perfect, the latter defined as osteotomy reaching the hinge point., Results: Real-life instances of Type III LHF caused by insufficient posterior osteotomy were reproduced in all patient-specific FEM models, and these models accurately predicted fracture types and locations. During opening of the osteotomy gap, the fracture line reached the lateral tibial plateau, and extended vertically from the end of the insufficient posterior osteotomy, avoiding the rigid proximal tibiofibular joint. In contrast, sufficient posterior osteotomy resulted in a lack of LHF. Posterior osteotomy extension ≥ 70% of the width of the osteotomy plane was the cut-off value to prevent Type III LHF., Conclusion: Forced opening of insufficient posterior osteotomy was found to be a biomechanical cause of Type III LHF that extended perpendicularly to the lateral tibial plateau, avoiding the proximal tibiofibular joint. The clinical significance of this study is that sufficient posterior osteotomy during OWHTO, defined as at least 70% of the width of the osteotomy plane, can prevent Type III LHF., (© 2021. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Objectives: This study aimed to evaluate the changes in knee pain, a dominant cause of physical disability, following the coronavirus disease (COVID-19) pandemic, and to identify factors affecting the changes in knee pain., Methods: We analysed the pre- and post-COVID-19 longitudinal data set of the Nagahama Study. Knee pain was assessed using the Knee Society Score (KSS). The estimated KSS from the age and sex using regression model in the pre- and post-COVID-19 data set was compared. Factors including the activity score, educational level, and various impacts of COVID-19 were analysed for correlation analyses with changes in KSS., Results: Data collected from 6409 participants showed statistically significant differences in KSS, pre- (mean = 22.0; SD = 4.4) and post-COVID-19 (mean = 19.5; SD = 6.4). Low activity score (p = .008), low educational level (p < .001), and undesirable financial impact (p = .030) were independently associated with knee pain exacerbation., Conclusion: The harmful effects of the COVID-19 pandemic on knee pain were suggested. People should be encouraged to engage in physical activities, such as walking, despite the state of emergency. Furthermore, social support for economically disadvantaged groups may improve healthcare access, preventing the acute exacerbations of knee pain., (© Japan College of Rheumatology 2022. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Purpose: The primary aim of this study was to evaluate the 3-dimensional morphology of the proximal tibia around the osteotomy plane in open-wedge high tibial osteotomy, focusing on the posterolateral (PL) and posteromedial (PM) tibial condyles, and to clarify the changes in morphologic parameters due to differences in patient characteristics and hinge position. The secondary aim was to examine whether morphologic features were associated with insufficient osteotomy, which increases the risk of lateral hinge fracture (LHF)., Methods: The PL and PM anteroposterior distance, asymmetry ratio, and discrepancy between PL and PM distances along the tibial osteotomy plane were measured. We investigated changes in the parameters due to differences in patient characteristics and hinge position. Osteotomy configurations and LHFs were evaluated using postoperative computed tomography scans., Results: The 3-dimensional preoperative plans of 117 knees (male, 41 knees; female, 76 knees) were evaluated. PL distances were larger than PM distances in almost all cases. The average asymmetry ratio was 1.35, and the standard deviation was 0.22. Higher hinge position was associated with a larger asymmetry ratio and discrepancy (P < .001). The asymmetry ratio and discrepancy were independently positively correlated with male sex (P = .002 and P = .001, respectively) and gentle posterior tibial slope (P < .001 and P < .001, respectively). Osteotomies with type III LHFs showed lower osteotomy sufficiency than osteotomies without LHFs (P < .001)., Conclusions: PL tibial condyle protrusion was more pronounced in male patients and those with a high hinge position, and may result in insufficient PL osteotomy, which is a risk factor for type III LHF during open-wedge high tibial osteotomy. The optimal hinge position was located approximately 15 mm and 20 mm distal to the lateral tibial plateau in female and male patients, respectively., Level of Evidence: IV: retrospective case series., (Copyright © 2022 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: This study evaluated whether patients with particular lower limb morphological factors have femoral and tibial component malpositioning during mechanically aligned total knee arthroplasty (TKA) and lower postoperative satisfaction., Methods: This study included 146 knees in 117 Asian patients undergoing TKA for medial osteoarthritis. Preoperative bony morphological factors such as the angle between the femoral mechanical and anatomical axes (MA-AA angle), angle between the anatomical axes of the proximal and distal femur (lateral bowing femoral angle, LBFA), mechanical lateral distal femoral angle, medial proximal tibial angle, and % anatomical axis of the tibia were evaluated, as well as preoperative and 1-year postoperative 2011 Knee Society scores (KSSs)., Results: MA-AA angle and LBFA were significantly larger in knees with varus femoral component alignment versus neutral alignment. Preoperative MA-AA angle was underestimated in patients with larger MA-AA angle or LBFA, especially by inexperienced surgeons. Tibial morphological factors did not affect tibial component alignment. Changes in 2011 KSSs were similar among groups by lower limb alignment or femoral and tibial component alignment., Conclusion: Femoral bowing affects varus femoral component alignment by obscuring preoperative planning, but it had little impact on patient satisfaction when mechanical alignment is targeted during TKA., (© 2021. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Objective: To examine the association of low back pain (LBP) and lumbar kyphosis with functional disabilities and knee symptoms in patients with knee osteoarthritis (OA)., Methods: We analyzed 586 participants (80.1% female; mean ± SD age 68.8 ± 5.2 years) from the Nagahama Study who were age ≥60 years and had radiographically confirmed knee OA. The Knee Society Knee Scoring System (KSS) was used to assess functional disabilities and knee symptoms. LBP was defined as the presence of any persistent back pain for more than 3 months. Lumbar kyphosis was determined by skin-surface methods using a computer-aided electronic device called the Spinal Mouse. Multiple linear regression analysis was used for assessing the association of LBP and lumbar kyphosis with the KSS scores. Subgroup analyses based on sex were also performed., Results: LBP and lumbar kyphosis were independently associated with a lower KSS function score after adjustment for covariates (mean difference -4.96 [95% confidence interval (95% CI) -7.56, -2.36] points for LBP alone, mean difference -4.47 [95% CI -8.51, -0.43] points for lumbar kyphosis alone, and mean difference -13.86 [95% CI -18.86, -8.86] points for the coexistence of LBP and lumbar kyphosis, respectively). The coexistence of LBP and lumbar kyphosis in women was associated with a lower KSS symptom score (mean difference -4.49 [95% CI -6.42, -2.55] points)., Conclusion: These findings suggest that both LBP and lumbar kyphosis are useful clinical signals indicating functional disability and knee symptoms in patients with knee OA., (© 2021 American College of Rheumatology.)

Objective: Radiographic changes in knee osteoarthritis (OA) are not always associated with symptoms, especially in its early stages. Ultrasonography (US) can detect early changes in the knee joint, but the changes that reflect symptoms have not been fully elucidated. This study aimed to identify US-detectable changes in the knee that are often associated with knee symptoms and demonstrate the feasibility of early diagnosis in symptomatic knee OA using US., Design: In this cross-sectional community-based study, 1,667 participants aged ≥60 years (1,103 women [66%]) were included. All participants concurrently underwent US and radiography of the knee and completed the Knee Society Knee Scoring System (KSS) questionnaire. Simple and multiple regression analyses were used to examine the associations between US findings and KSS symptom subscales., Results: Among all participants, medial meniscus protrusion and medial osteophytes, age, and body mass index showed significant associations with KSS symptom scores. Among 894 participants with Kellgren-Lawrence (KL) grade ≤1, medial osteophytes and age were significantly associated with KSS symptom score. US measures were more related to KSS symptoms than KL grades., Conclusions: Among the knee US-detectable changes, medial osteophytes were strongly associated with knee symptoms. Osteophytes are reliable predictors of symptomatic early knee OA, even in participants with few radiographic OA changes.

Objective: This study aimed to evaluate variations in anterior condylar height (ACH) of the distal femur in varus knee osteoarthritis and evaluate the association between ACH and knee flexion., Design: Computed tomography (CT) images of 171 knees (143 patients; age 73.7 ± 8.3 years; 132 females, 39 males) with symptomatic primary knee osteoarthritis and varus alignment undergoing primary total knee arthroplasty, unilateral knee arthroplasty, or high tibial osteotomy were evaluated. Several other anatomic parameters were measured on CT or radiography. The ACH and knee flexion correlation was analyzed, and factors contributing to knee flexion were determined using multivariable regression analysis., Results: Medial ACH (mean, 8.1 mm; range, -2.8 to 19.9 mm) was smaller ( P < 0.001) but more variable ( F = 1.8, P < 0.001) than lateral ACH (mean, 10.7 mm; range, 3.6-18.3 mm). Medial ACH was moderately correlated with flexion ( r = -0.44, 95% confidence interval [CI], -0.55 to -0.32), whereas lateral ACH was weakly correlated ( r = -0.38; 95% CI, -0.50 to -0.25). On multivariable linear regression analysis of knee flexion, body mass index ( B [partial regression coefficient] = -1.1), patellofemoral Kellgren-Lawrence grade ( B = -4.3), medial ACH ( B = -1.2), medial posterior condylar offset ( B = 1.2), age ( B = -0.4), and varus alignment ( B = -0.6) remained significant independent variables (adjusted R 2 = 0.35)., Conclusions: Wide variation and anteriorization of the anterior condyle of the distal femur was observed in advanced osteoarthritis, as an independent determinant of limited knee flexion.

Background: Total knee arthroplasty (TKA) is commonly performed to reduce knee pain and improve physical function. Compared with the values for healthy, age-matched women, previous studies have reported large deficits in functional ability, such as muscle strength and ambulatory ability, in women 1 year post-TKA. Ambulatory ability is to move around, particularly by walking and is clinically assessed by the timed up and go test (TUG)., Aim: This study aimed to clarify the characteristics of knee functions in female patients whose ambulatory ability recovered to a normal level at 1 year after TKA., Methods: This cross-sectional study included 151 female patients who underwent TKA. The muscle strength of the lower extremity was measured, and the 2011 Knee Society Scoring (2011 KSS) system was used postoperatively. The TUG was conducted to assess ambulatory ability after TKA; then the patients were classified into the fast and slow ambulation groups based on previously reported gait-speed values of healthy female individuals. Then, we identified significant indicators of ambulatory ability at 1 year after TKA., Results: Forty-nine percent of patients after TKA achieved the level of ambulatory ability of a healthy female. Logistic regression analysis identified that the non-operative side knee extensor strength and the functional activity score, as assessed by the 2011 KSS, were variables significantly associated with the mid-term ambulatory ability after TKA., Conclusion: Female patients with high non-operative knee extensor strength and a functional activity score at 1 year postoperatively can achieve better ambulatory ability than those of healthy, age-matched females., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Objective: This cross-sectional study aimed to explore the differences of the medial and lateral sides of the knee joint and precise radiographic abnormalities in contribution to the knee pain and clinical outcomes., Design: Participants 60 years or older who underwent radiographic evaluation were included. Knee radiography was assessed using grading systems of the Osteoarthritis Research Society International (OARSI) atlas. The Japanese Knee Osteoarthritis Measure (JKOM) was evaluated as clinical outcomes. Serum high-sensitivity C-reactive protein (hsCRP) was used to evaluate systemic inflammation. We divided the participants into normal, medial-, lateral-, and medial & lateral-OA types and compared their JKOM using an analysis of covariance. Furthermore, we analyzed the relationship between the knee pain and stiffness of JKOM and the grading of each radiographic feature using a multiple regression model., Results: Lateral- and medial & lateral-OA groups had a significantly worse symptoms in the total and the pain score, especially in movement subscales, in JKOM score. Lateral-OA groups had higher hsCRP than medial-OA group. Multivariate analysis showed that medial joint space narrowing (JSN), and lateral femoral and tibial osteophytes significantly affected knee pain (adjusted odds ratios: 1.73, 1.28, and 1.55, respectively). The radiographic changes are associated with pain more in JSN in the medial side and osteophytes in the lateral side., Conclusion: Lateral- and medial & lateral-OA groups showed worth symptom. In addition, medial JSN and lateral osteophytes have potent effects on the knee pain.

Objectives: To investigate whether lower limb arterial calcification (LLAC) quantified using computed tomography (CT) was a risk factor for bilateral severe knee osteoarthritis (OA)., Methods: This cross-sectional study included patients who were scheduled for surgical treatment of primary varus knee OA. Knee OA was evaluated using the Kellgren-Lawrence (KL) classification, KL grades 3 and 4 were defined as severe OA. The LLAC score in the bilateral whole leg CT was quantitatively measured and categorized into low or high groups based on the median value. A modified Poisson regression model was used to examine the relationship between the categorized LLAC score and the presence of bilateral severe knee OA with adjustment for possible confounders., Results: Of a total of 252 patients examined, multivariable modified Poisson regression analysis showed a significant association between higher LLAC score and the presence of bilateral severe knee OA (adjusted risk ratio = 1.28; 95% confidence interval [CI], 1.12-1.48; p  < .001). A substantial interaction was observed between male sex and high LLAC ( p for interaction = .03)., Conclusion: LLAC was associated with bilateral severe knee OA, and the LLAC score may be a useful measurement to identify patients at risk of bilateral severe knee OA.

Introduction/objectives: To test the hypothesis that greater extracellular-to-intracellular water (ECW/ICW) ratios in lower-limb muscles are associated with worsened functional abilities in patients with knee osteoarthritis (OA)., Methods: We analyzed data from 787 participants (82.2% female; mean age, 69.6 ± 5.3 years) from the Nagahama Prospective Cohort who were ≥60 years old and had radiographically confirmed bilateral knee OA. The Knee Scoring System (KSS) was used to assess functional abilities. Lower-limb ECW/ICW ratios and skeletal mass index values were determined with multi-frequency bioelectrical impedance analysis (BIA). Multiple linear regression analysis was used to test for associations between ECW/ICW ratios and functional abilities. Subgroup analyses based on OA severities and symptomaticity were also conducted., Results: Increased ECW/ICW ratios were associated with a 4.38-point decrease in the KSS function scores (95% confidence interval [CI], 3.15-5.62 points) after adjusting for covariates. This association varied according to the degree of knee symptoms, especially in individuals with radiologically mild OA. ECW/ICW ratios in individuals with asymptomatic mild OA were associated with a 2.14-point decrease in the KSS function score (95% CI, 0.32-3.96 points), whereas those in individuals with severe symptomatic mild OA were associated with a 6.16-point decrease (95% CI, 2.13-10.19 points)., Conclusions: Our findings indicate that higher ECW/ICW ratios are associated with greater functional disability in patients with knee OA. Therefore, ECW/ICW ratio measurements with multi-frequency BIA can serve as valuable indicators for functional disability in patients with knee OA. Key Points • Higher extracellular-to-intracellular water (ECW/ICW) ratios are associated with greater functional disability levels in patients with knee osteoarthritis (OA). • ECW/ICW ratios are useful clinical signs as a biomarker for poor functional abilities in patients with knee OA.

Purpose: Medial release during total knee arthroplasty (TKA) is used to correct ligament imbalance in knees with varus deformity. However, questions remain on whether residual ligament imbalance would be related to inferior clinical results. The purposes of the present study were to measure the intraoperative joint gap and to evaluate the effect of intraoperative soft tissue condition on the new Knee Society Score (KSS 2011) at 2-year follow-up, without the maneuver of additional medial release to correct the asymmetrical gap balance., Methods: Varus-valgus gap angle and joint gap were measured using a tensor device without medial release for 100 knees with preoperative varus deformity. The knees were categorized according to the varus-valgus gap angle and the laxity. The preoperative and postoperative clinical outcomes using KSS 2011 were compared between the groups., Results: The average varus-valgus angles had a residual imbalance of 2.8° varus and 1.3° varus in extension and flexion, respectively. In comparison, according to varus-valgus joint gap angle and knee laxity in extension and flexion, no significant differences were found in postoperative range of motion and subscale of KSS 2011 among the groups., Conclusion: Intraoperative asymmetrical joint gap and physiological laxity do not affect early clinical results after TKA., Level of Evidence: III.

Background: In knee osteoarthritis (OA), pain is the most frequent and dominant symptom. However, which factors other than radiological changes contribute to the symptoms is unresolved. The aims of this study were to identify factors affecting knee pain from various variables with radiological changes taken into count and exploratively examine what subgroups or phenotype could be identified by cluster analysis using the identified knee pain factors., Methods: Patients 60 years or older who underwent radiographic evaluation were included in this cross-sectional study, and those subjects who completed a questionnaire about knee symptoms without missing data were eligible for analysis. Multiple regression analysis was used to examine the associations between selected variables and The Japanese Knee Osteoarthritis Measure (JKOM) pain score. We grouped the subjects by cluster analysis using identified variables., Results: Two thousand five hundred forty-two subjects were included in the full set of analyses. Age, body mass index (BMI), radiological grade, bone mineral density (BMD), and high-sensitivity C-reactive protein (hs-CRP) showed a statistically significant correlation with radiological showing the strongest value. For dichotomous variable, presence of depression showed a statistically significant result. We used BMI, radiological grade, BMD, hs-CRP, and presence of depression as a variable for cluster analysis and identified six subgroups: (1) minimal joint disease subgroup, (2) male and high BMD subgroup, (3) high CRP subgroup, (4) severe radiological OA subgroup, (5) depressive subgroup, and (6) moderate radiological OA with high BMI subgroup, showing the worst knee outcome., Conclusion: This study identified the factors affecting knee pain other than radiological changes and identified six subgroups of knee outcome in the general population. The results showed that obesity with radiological changes or depression was associated with worse knee outcome.

Background: The new Knee Society Score (2011KSS) has been used to evaluate post-operative outcomes after total knee arthroplasty (TKA). However, there is no minimum clinically important difference (MCID) for 2011KSS. The purpose of this study is to define MCID of 2011KSS after TKA., Methods: Patients who underwent primary TKA for primary knee osteoarthritis between April 2012 and December 2016 were included in the study. The Japanese version of 2011KSS and original Knee Society Score (OKSS) were recorded preoperatively and at one-year postoperatively. With improvement in pain score of OKSS as an anchor, an anchor-based approach was used to identify the MCID of 2011KSS. The improvement in pain of OKSS was classified into 5 categories. The MCID was determined using a linear regression analysis of delta 2011KSS against improvement in the category of pain in OKSS. The MCID for 2011KSS expectation was not calculated because the items of pre- and post-operative questionnaires were different., Results: Five hundred and twenty-two cases were enrolled (age: 74.8 ± 7.3 years, female: 80.0%). After 1-year follow-up, 344 TKAs were finally included (age: 74.6 ± 7.1 years, female: 77.9%). Linear regression analyses showed that MCID for 2011KSS was 1.9 (95% confidential interval (CI): 1.3-2.5) in symptom, 2.2 (95%CI: 1.4-2.9) in satisfaction, and 4.1 (95%CI: 2.5-5.7) in functional activities., Conclusions: MCID for 2011KSS was successfully calculated. These MCID values make the 2011KSS a more efficient tool for evaluating the physical activities of the populations of patients undergoing TKA. These MCID values can also be used to calculate sample size to evaluate the power of a study in designing clinical studies., (Copyright © 2019 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Nonsurgical treatment such as exercise is the preferred method for management of knee osteoarthritis (OA). A combination of aerobic, muscle strengthening, and flexibility exercises is recommended for older adults. However, effects of the exercise intervention on cartilage metabolism remain unclear. This study used biomarkers to investigate the effects of well-rounded exercise program on cartilage metabolism in 42 women (mean age: 59 years). Participants started a weekly supervised exercise program and continued for 12 weeks. Before and after the program, we measured physical performance on the Timed Up-and-Go Test, 3-Minute Walk Test, and 30-Second Chair Stand Test. We collected serum and urine samples at the start of the program until 24 weeks and measured the concentrations of 4 biomarkers related to type II collagen metabolism: serum cartilage type II procollagen carboxy propeptide (sPIICP), urine C-terminal telopeptide of collagen type II (uCTX-II), urine cleavage of type II collagen by collagenases (uC2C), and serum cartilage oligomeric matrix protein (sCOMP). Participants were divided into pre-OA and OA groups based on X-ray findings. The pre-OA group showed significant increases and decreases in sPIICP and uCTX-II concentrations with improved physical performance, respectively. sCOMP concentrations significantly increased in both groups. The exercise also improved physical performance with no detrimental effect on type II collagen metabolism in the OA group. Thus, well-rounded exercise may not only improve physical capacity but also have beneficial effects on type II collagen metabolism, especially in people without radiological OA.

Purpose: Total knee arthroplasty (TKA) for valgus knee osteoarthritis is challenging. Although overcorrection in TKA for valgus knee osteoarthritis is recommended, supportive data based on biomechanics have rarely been reported. The purpose of this study was to elucidate whether coronal rotation of the femoral compartment causes abnormal kinematics with or without medial looseness., Methods: Multi- and single-radius posterior-stabilised TKA implants were utilised in a computer simulation. A total of 4 mm of slack were provided in the medial collateral ligament (MCL) with varus or valgus position of the femoral component to simulate the context of valgus knee osteoarthritis. Kinematics during gait and squatting activities were evaluated in each condition., Results: During squatting, medial looseness and valgus replacement caused anterior translation of the medial femoral component in mid-flexion in the multi-radius implant. In the worst condition (7° valgus replacement with MCL looseness), there was rapid anterior translation in the multi-radius implant, and moderate anterior translation in the single-radius implant. Although medial looseness alone did not cause abnormal kinematics during gait, the worst condition exhibited an anterior translation to 4.9 mm in the multi-radius implant. This worst condition also exhibited a marked lift-off of 8.0 and 2.9 mm in the multi- and single-radius implants, respectively. Varus position caused little abnormal kinematics even with MCL looseness., Conclusion: Valgus, not varus position of the femoral component caused abnormal kinematics with MCL looseness. To avoid valgus position, the safety target angle of femoral component would be slight varus rather than neutral in valgus knee OA.

Introduction: This study aimed to examine the interaction effect between ambulatory physical activity (PA) and varus thrust on knee pain in individuals with knee osteoarthritis (OA)., Method: Subjects (n = 207; mean age: 73.1 years, 71.5% women) in orthopedic clinics with diagnosed knee OA (Kellgren/Lawrence grade ≥ 1) were enrolled in this 12-month observational cohort study. Participants underwent gait observation for varus thrust assessment and pedometer-based ambulatory PA measurements at baseline and 12-month follow-up. Knee pain intensity was assessed using the Japanese Knee Osteoarthritis Measure pain subscale as a primary outcome measure. Multiple linear regression analyses were performed to evaluate ambulatory PA-thrust interaction on knee pain intensity., Results: Ninety-two subjects (mean age, 73.4 years; 68.5% women) completed the 12-month follow-up assessment. Baseline ambulatory PA-thrust interaction was significant (P = 0.017) in the cross-sectional analysis, adjusting for covariates, which yielded R 2  = 0.310. Subgroup analysis showed that varus thrust was significantly associated with worse knee pain in subjects walking ≥ 5000 steps/day adjusting for covariates (beta: 7.94; 95% CI: 3.82, 12.1; P < 0.001) with a higher predictive ability (R 2  = 0.664). In contrast, ambulatory PA-thrust interaction in the longitudinal analysis showed no significant association with knee pain changes., Conclusions: Ambulatory PA interacted with varus thrust in the association with knee pain, as coexisting high ambulatory PA and varus thrust had the strongest association with higher knee pain. Maximal pain relief effects might be achieved when both ambulatory PA and varus thrust are treated simultaneously, rather than treating each separately.

Purpose: One of the causes of aseptic loosening is marked tibial bone resorption (TR) at the tibial bone-component interface after total knee arthroplasty (TKA). It was hypothesized that insufficient coverage of the tibial component and improper cementing technique would cause increased TR after cemented TKA., Methods: One hundred thirty-four primary TKAs in 107 patients with varus osteoarthritis were included in this study. The relationships between the TRs at 2 years after TKA and the tibial component underhang (TUH), the thickness of the cement mantle around the keel, and clinical parameters were evaluated., Results: The widths of TRs on anteroposterior radiographs were significantly larger on the medial side than on the lateral side (p = 0.001), whereas the difference between the anterior and posterior sides on lateral radiographs was relatively small. Multiple regression analyses showed that medial TR was positively related to medial TUH (p = 0.006), and lateral TR was positively related to a thicker distal cement mantle (p = 0.027). On the lateral view, stepwise selection indicated that postoperative knee flexion angle was the most significant risk factor (p = 0.005) for anterior TR, and posterior TUH was the strongest predictor (p = 0.001) of posterior TR., Conclusions: To avert postoperative progressive TR, surgeons should perfectly fit a suitably sized tibial component to the medial edge of the tibia. Also, care should be taken to avoid an excessive cement mantle at the distal portion of the keel during TKA., Level of Evidence: IV.

Background: In general, the flexion gap is larger than the extension gap with posterior cruciate ligament-sacrificing total knee arthroplasty. Several methods compensate for an excessive flexion gap, but their effects are unknown. The purpose of this study was to compare three methods to compensate for an increased flexion gap., Methods: In this study, squatting in knees with excessive (4 mm) and moderate (2 mm) flexion gaps was simulated in a computer model. Differences in knee kinematics and kinetics with joint line elevation, setting the femoral component in flexion, and using a larger femoral component as compensatory methods were investigated., Findings: The rotational kinematics during flexion with setting the femoral component in flexion were opposite to those in the other models. Using a larger femoral component resulted in the most physiological motion. The peak anterior translation was 10 mm in the joint line elevation model compared with approximately 6 mm in the other models. In the joint line elevation model, patellofemoral contact stress was excessively increased at 90° of knee flexion. In contrast, tibiofemoral contact stress was higher during knee extension with setting the femoral component in flexion due to anterior impingement. There were few differences in the effect of the three compensatory methods with a moderate flexion gap., Interpretation: A larger femoral component should be used to compensate for an excessive flexion gap because it has less negative impact on posterior cruciate ligament-sacrificing total knee arthroplasty, whereas any compensation method might be acceptable for a moderate flexion gap., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Although total knee arthroplasty (TKA) using a medial pivot insert reportedly improves kinematics compared with a symmetrical insert, improvements in patient-reported outcomes have not yet been reported. The aim of this study was to determine whether insert designs influenced patient-reported outcomes., Methods: Seventy TKAs for osteoarthritis were randomly allocated to a symmetrical dish insert (SD group: 35 knees) or medial pivot insert (MP group: 35 knees). Thirty-two of the SD group (74.4 ± 6.6 years old) and 33 of the MP group (73.8 ± 6.0 years old) completed the two-year follow-up. The knee range of motion (ROM) and 2011 Knee Society score (2011KSS) were analyzed pre-operatively and postoperatively., Results: There was no difference in pre-operative ROM or 2011KSS (Symptom: 7.3 ± 5.9 in SD group, 8.4 ± 5.4 in MP group, P = 0.432; Satisfaction: 12.6 ± 6.9 in SD group, 11.8 ± 5.9 in MP group, P = 0.581; Activity: 35.8 ± 18.1 in SD group, 35.2 ± 18.6 in MP group, P = 0.883). At two years, although both group showed good improvement, there were no differences in ROM or 2011KSS (Symptom: 19.3 ± 5.0 in SD group, 18.3 ± 4.1 in MP group, P = 0.351; Satisfaction: 24.0 ± 7.6 in SD group, 22.9 ± 7.9 in MP group, P = 0.548; Activity: 60.3 ± 14.8 in SD group, 54.3 ± 17.3 in MP group, P = 0.137)., Conclusions: The medial pivot insert was not superior to the symmetrical insert in patient-reported outcomes at two years after TKA., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Introduction: The relationship between postoperative tibiofemoral ligament balance and patient satisfaction in total knee arthroplasty (TKA) has been explored previously. However, the optimal intraoperative medial-lateral ligament balance during knee flexion in terms of postoperative patient satisfaction remains unknown. We evaluated the effect of intraoperative flexion instability on patient satisfaction after TKA., Materials and Methods: This study consisted of 46 knees with varus osteoarthritis undergoing TKA. Medial-lateral component gaps at 0° knee extension and 90° flexion were measured intraoperatively using a knee balancer. Differences in postoperative patient outcomes at 3 weeks and 1 year were compared between medially tight knees in 90° flexion with a medial component gap of < 4 mm and medially loose knees in 90° flexion with a gap of ≥ 4 mm. Outcomes were measured using the 2011 Knee Society Scoring System (2011 KS)., Results: The median total 2011 KS score at 1 year postoperatively in the medially loose knees [median 97; interquartile range (IQR) 75-117] was significantly lower than that in the medially tight knees (median 128; IQR 104-139, P < 0.01), while preoperative and 3-week postoperative scores were similar. In addition, medial flexion gaps were not significantly associated with total 2011 KS scores before surgery or at 3 weeks postoperatively. However, at 1 year after surgery, medial component flexion gaps were negatively associated with the total 2011 KS score (R = - 0.42; P < 0.01) and the 2011 KS satisfaction subscale score (R = - 0.36; P = 0.01)., Conclusions: Excessive intraoperative medial joint laxity of ≥ 4 mm at 90° flexion progressively decreased patient satisfaction for 1 year. Since intraoperative medial laxity in flexion is likely to interfere with functional recovery after TKA, medial stabilization during TKA is important throughout knee flexion., Level of Evidence: Therapeutic study, Level III.

Background: While abnormal rearfoot posture and its relationship to patellofemoral (PF) pain has been thoroughly discussed in the literature, its relationship to patellofemoral osteoarthritis (PFOA) has not been determined. This study aimed to examine whether rearfoot posture is associated with a higher prevalence of radiographic PFOA in a compartment-specific manner in patients with medial tibiofemoral osteoarthritis (TFOA)., Methods: Participants from orthopedic clinics ( n  = 68, age 56-90 years, 75.0% female), diagnosed with radiographic medial TFOA (Kellgren/Lawrence [K/L] grade ≥ 2) were included in this study. The presence of PFOA and static rearfoot posture were evaluated using a radiographic skyline view and a footprint automatic measurement apparatus, respectively. The relationship between rearfoot posture and PFOA was examined using analysis of covariance and propensity score-adjusted logistic regression analysis., Results: On average, patients with coexisting PFOA and medial TFOA ( n  = 39) had an inverted calcaneus 3.1° greater than those with isolated medial TFOA ( n  = 29). Increased calcaneus inverted angle was significantly associated with a higher probability of the presence of medial PFOA (odds ratio: 1.180, 95% confidence interval: [1.005, 1.439]; p  = 0.043). Calcaneus inverted angle was not associated with higher odds of lateral PFOA presence based on the adjusted values., Conclusions: The presence of an inverted rearfoot was associated with PFOA. Although these findings do not clearly indicate a biomechanical link between rearfoot posture and PFOA, this study shed light on the potential relationship between altered rearfoot posture and PFOA, as can be seen between rearfoot abnormality and PF pain., Competing Interests: The ethical committee of Kyoto University approved the study (approval number: E1923), and written informed consent was obtained from all participants before their enrollment.The authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Background: Depressive symptoms are a major comorbidity in older adults with knee osteoarthritis (OA). However, the type of activity-induced knee pain associated with depression has not been examined. Furthermore, there is conflicting evidence regarding the association between depression and performance-based physical function. This study aimed to examine (i) the association between depressive symptoms and knee pain intensity, particularly task-specific knee pain during daily living, and (ii) the association between depressive symptoms and performance-based physical function, while considering other potential risk factors, including bilateral knee pain and ambulatory physical activity., Methods: Patients in orthopaedic clinics (n = 95; age, 61-91 years; 67.4% female) who were diagnosed with radiographic knee OA (Kellgren/Lawrence [K/L] grade ≥ 1) underwent evaluation of psychological health using the Geriatric Depression Scale (GDS). Knee pain and physical function were assessed using the Japanese Knee Osteoarthritis Measure (JKOM), 10-m walk, timed up and go (TUG), and five-repetition chair stand tests., Results: Ordinal logistic regression analysis showed that depression, defined as a GDS score ≥ 5 points, was significantly associated with a worse score on the JKOM pain-subcategory and a higher level of task-specific knee pain intensity during daily living, after being adjusted for age, sex, body mass index (BMI), K/L grade, and ambulatory physical activity. Furthermore, depression was significantly associated with a slower gait velocity and a longer TUG time, after adjusting for age, sex, BMI, K/L grade, presence of bilateral knee pain, and ambulatory physical activity., Conclusions: These findings indicate that depression may be associated with increased knee pain intensity during daily living in a non-task-specific manner and is associated with functional limitation in patients with knee OA, even after controlling for covariates, including bilateral knee pain and ambulatory physical activity.

The foot is speculated to play a role in knee joint kinematics. This exploratory cross-sectional study examined the association between static foot posture and the presence of varus thrust visualized during gait in patients with medial knee osteoarthritis (OA). Patients (n = 88 patients and 134 knees; age, 61-91 years; 68.2% female) with Kellgren/Lawrence (K/L) grade ≥1 in the medial compartment were included in this study and underwent gait observation for varus thrust. These patients' three-dimensional static foot posture while standing was evaluated and their tibiofemoral joint K/L grades and anatomical axis angles were also assessed as covariates. Knees with varus thrust (22 knees, 16.4%) on average had a 4° more inverted calcaneus relative to the floor than those without varus thrust (P < 0.001). A logistic regression analysis showed that an increased calcaneus inversion angle was significantly associated with higher odds of the presence of varus thrust with adjustments for age, sex, body mass index, K/L grade, and anatomical axis angle. The other predictors, such as navicular height, navicular height/foot length, and rearfoot angle relative to the lower leg, were not significantly associated with varus thrust. These results suggest that patients with varus thrust had a different static rearfoot posture as compared with those without varus thrust, a finding that may indicate an important role of static rearfoot posture in the pathogenesis of varus thrust. Furthermore, investigating the potential influence of foot posture on the efficacy of biomechanical interventions, such as lateral wedge insole use, on varus thrust would be of particular interest in the further studies., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This cross-sectional study examined the relationship of flat feet with knee pain, disability, and physical performance in patients with knee osteoarthritis (OA). Orthopedic clinic participants (n = 95; age 61-91 years; 68.4% women) with Kellgren-Lawrence (K/L) grade ≥1 in the medial compartment underwent evaluation of navicular height and foot length for flat feet. Knee pain intensity, disability, and physical performance were evaluated using the Japanese Knee Osteoarthritis Measure, 10-m walk, timed up and go, and five-repetition chair stand tests. Of the 95 enrolled patients, 24 (25.3%) had bilateral flat feet, and significantly higher knee pain compared to patients with no flat feet (11.3 ± 8.23 points vs. 6.58 ± 6.37 points; p = 0.043). A ordinal logistic regression analysis showed that bilateral flat feet were significantly associated with increased knee pain (proportional odds ratio: 5.48, 95% confidence interval: 1.96, 15.3; p = 0.001) compared with no flat feet, adjusted for age, sex, body mass index, and tibiofemoral joint K/L grade, which is consistent across various different cutoffs of the definition of flat feet. Physical performance was similar between patients with and without bilateral flat feet. The presence of unilateral flat feet was not significantly associated with any outcome measures. These findings indicate that bilateral, but not unilateral, flat feet are associated with worse knee pain. A prospective study investigating a causal relationship between bilateral flat feet posture and knee pain as well as disability would be of particular interest to verify the potential adverse effect of altered foot posture. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2490-2498, 2017., (© 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

This cross-sectional study investigated (i) the association of varus thrust during gait with the presence of patellofemoral osteoarthritis (PFOA) in patients with medial knee osteoarthritis (OA) and (ii) patellar alignment in the knees with varus thrust. Participants from orthopedic clinics (n=171; mean age, 73.4 years; 71.9% female) diagnosed with radiographic medial knee OA (Kellgren/Lawrence [K/L] grade ≥1) were included in this study, and underwent gait observation for varus thrust assessment using 2D video analysis. A radiographic skyline view was used to assess the presence of medial PFOA using the grading system from the Osteoarthritis Research Society International Atlas. The tibiofemoral joint K/L grade, patellar alignment (i.e., lateral shift and tilting angle), and knee pain intensity were also evaluated as covariates. Thirty-two (18.7%) of 171 patients exhibited varus thrust and they presented significantly higher knee pain (46.0±3.04mm vs. 32.4±2.73mm; P=0.024), a lower patellar tilting angle (P=0.024), and a higher prevalence of PFOA compared with those without varus thrust. A logistic regression analysis with adjustment of covariates showed that varus thrust was significantly associated with higher odds of the presence of mixed and medial PFOA, and trended to significantly associate with any PFOA, including lateral PFOA. This indicates that varus thrust was associated with PFOA in a compartment-nonspecific manner in patients with medial knee OA. Varus thrust may represent a clinical disease feature of more advanced and multicompartmental disease., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Objective: To examine the clinical impact of coexisting lateral osteoarthritis (OA) in knees with mild medial OA., Design: In patients with Kellgren/Lawrence (K/L) grade 2 OA in the medial compartment (n = 100; age: 56-89 years; 80.0% female), anteroposterior knee radiography was used to assess the presence of lateral OA, using grading systems from the Osteoarthritis Research Society International (OARSI) atlas and the K/L classification. The Japanese Knee Osteoarthritis Measure (JKOM), knee range of motion (ROM), and performance-based functional measures (10 m walk, timed up and go and five repetition chair stand maneuvers) were evaluated. The outcomes were compared between patients with and without lateral OA using an analysis of covariance (ANCOVA) or nonparametric rank ANCOVA. Furthermore, ordinal logistic regression analysis was performed, with responses on individual JKOM pain questionnaires as the outcomes and lateral OA as the predictor., Results: Knees with coexisting lateral OA had a significantly worse score of JKOM pain question compared with those without, after adjusting for covariates. The presence of lateral OA was significantly associated with knee pain while ascending/descending stairs and standing. These results were consistent between different definitions of the K/L and OARSI grading systems. The knee ROM and performance-based functional measures were not significantly different between patients with and without lateral OA., Conclusion: Knees with concomitant lateral and mild medial OA may be more symptomatic compared to those without lateral OA. These findings might help to define a clinically distinct subgroup based on a simple radiographic finding in mild knee OA., (Copyright © 2017 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Objective: To examine the association between pedometer-based ambulatory physical activity (PA) and physical function in patients with knee osteoarthritis (OA)., Design: Cross-sectional observational study., Setting: Institutional practice., Participants: Participants in orthopedic clinics (N=207; age, 56-90y; 71.5% women) with diagnosed radiographic knee OA (Kellgren/Lawrence [K/L] grade ≥1)., Interventions: Not applicable., Main Outcome Measures: Ambulatory PA was objectively measured as steps per day. Physical function was assessed using the Japanese Knee Osteoarthritis Measure (JKOM) functional subcategory, 10-m walk, Timed Up and Go (TUG), and 5-repetition chair stand (5CS) tests., Results: Patients walking <2500 steps/d had a low level of physical function with a slower gait speed, longer TUG time, and worse JKOM functional score compared with those who walk 2500 to 4999, 5000 to 7499, and ≥7500 steps/d adjusted for age, sex, body mass index [BMI], and K/L grade. Ordinal logistic regression analysis revealed that steps per day (continuous) was associated with better physical function adjusted for age, sex, BMI, and K/L grade. These relationships were still robust in sensitivity analyses that included patients with K/L grades ≥2 (n=140)., Conclusions: Although increased ambulatory PA had a positive relationship with better physical function, walking <2500 steps/d may be a simple indicator for a decrease in physical function in patients with knee OA among standard PA categories. Our findings might be a basis for counseling patients with knee OA about their ambulatory PA and for developing better strategies for improving physical function in sedentary patients with knee OA., (Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

Background: This 1-year prospective cohort study aimed to compare the changes in clinical symptoms and functional disability between patients with coexisting patellofemoral (PF) and tibiofemoral (TF) osteoarthritis (OA) and those with isolated TFOA., Methods: Seventy-two patients with medial knee OA were enrolled. Knee pain and functional disability were assessed at baseline and at 1-year follow-up using the Japanese Knee Osteoarthritis Measure (JKOM) and a visual analog scale (VAS). We performed two-way analysis of covariance for the clinical outcome variables to examine, time (baseline and follow-up), group (coexisting PFOA and isolated TFOA), and time-group interaction effects. Furthermore, we conducted post-hoc exploratory analysis to address the possibility that dividing patients according to location of PFOA (i.e., isolated lateral, isolated medial, and mixed [bilateral]) may identify a distinct subgroup with different changes in clinical outcomes at 1-year follow-up., Results: We detected group effects only in scores of the JKOM pain subscale (P = 0.012) and VAS (P = 0.033), adjusted for age, sex, and body mass index. Patients with coexisting PFOA have stable moderate level knee pain and functional disability throughout the year which is significantly worse than that in those with isolated TFOA. Post-hoc subgroup analysis demonstrated that change of knee pain likely varied with location of PFOA. Patients with isolated lateral PFOA had mild/moderate level knee pain, and their VAS scores were likely to improve, whereas those with mixed PFOA exhibited stable to worsening moderate/severe knee pain., Conclusions: Although we did not detect differences in changes in clinical symptoms and functional disability between patients with coexisting PFOA and those with isolated TFOA, our findings indicate that patients with coexisting PFOA had worse clinical symptoms and functional disability than those with isolated TFOA. The results of the exploratory analysis suggested that patients with coexisting PFOA might have heterogeneous clinical outcomes, and presence of mixed PFOA might be an indicator of severe clinical knee OA.

This study aimed to investigate whether knee pain during various activities of daily living (ADLs) is associated with physical activity in patients with early and severe knee osteoarthritis (OA). We hypothesized that the painful ADLs associated with decreased physical activity differ according to disease severity. This cross-sectional study enrolled 270 patients with medial knee OA, assigned to either the early (Kellgren Lawrence [K/L] grade 1-2) or the severe group (K/L grade 3-4). Physical activity was assessed using a pedometer. Knee pain during six ADLs (waking up in the morning, walking on a flat surface, ascending stairs, etc.) was evaluated using a questionnaire. We performed multiple regression and quantile regression analysis to investigate whether knee pain during each ADL was associated with physical activity. In the early group, the more knee pain they experienced while ascending stairs, the lower their physical activity was (75th regression coefficient = -1033.70, P = 0.018). In the severe group, the more knee pain they experienced while walking on a flat surface or bending to the floor or standing up, the lower their physical activity was (unstandardized coefficients = -1850.87, P = 0.026; unstandardized coefficients = -2640.35, P = 0.010). Knee pain while ascending stairs and while walking on a flat surface or bending to the floor or standing up was a probable limiting factor for physical activity in early and severe knee OA, respectively. These findings suggested that a reduction in task-specific knee pain according to disease severity could improve physical activity levels.

Objective: To evaluate the clinical impact in knee osteoarthritis (OA) of coexisting patellofemoral (PF) joint OA (PFOA) in Japanese patients with medial tibiofemoral (TF) joint OA (TFOA)., Methods: Patients with medial knee OA (n = 143) were enrolled. The radiographic severity of the TF and PF joints, anatomic axis angle of the TF joint, patellar alignment, trochlear morphology, patellar height, and passive range of motion (ROM) of the painful knee were evaluated. Additionally, the Japanese Knee Osteoarthritis Measure (JKOM) was used to investigate the association between the presence of PFOA and clinical symptoms., Results: PFOA was present in 98 of 143 patients (68.5%) with medial knee OA. Quantile regression analysis revealed that coexisting PFOA was associated with the pain-related subcategory of the JKOM. Furthermore, multiple logistic regression analysis showed that coexisting PFOA was associated with higher odds of reporting knee pain on using stairs while ascending (odds ratio [OR] 4.81 [95% confidence interval (95% CI) 1.73, 14.3]) and descending (OR 3.86 [95% CI 1.44, 10.8]). A more varus knee alignment and lower knee flexion ROM, which are features of patients with coexisting PFOA, were associated with knee pain while ascending/descending stairs. However, patellar alignment, trochlear morphology, and patellar height were not significantly associated with knee pain., Conclusion: PFOA coexisting with medial knee OA was associated with worse clinical symptoms, particularly while ascending/descending stairs, although patellar alignment did not contribute to reporting knee pain. Further studies that include evaluation of the PF joint are warranted to develop a basis for an optimal intervention based on compartmental involvement., (© 2016, American College of Rheumatology.)

Background: Increasing evidence highlights potential associations between varus thrust and health domains associated with knee osteoarthritis (OA)., Objective: The aim of this study was to investigate the association between varus thrust and 2 subcategories-"pain and stiffness" and "activities of daily living (ADL)"-of the Japanese Knee Osteoarthritis Measure (JKOM)., Design: This was a cross-sectional study., Methods: In total, 296 outpatients with knee OA visiting orthopedic clinics were enrolled. The inclusion criteria were age ≥50 years, medial knee OA and Kellgren-Lawrence (K/L) grade ≥1 in one or both knees, and the ability to walk independently. Standard posterior-anterior knee radiographs were measured for varus alignment. Participants were video recorded while walking and were evaluated for the presence or absence of varus thrust. Pain and stiffness of the knee joint and ADL were evaluated using the JKOM. Multivariate regressions (outcomes: pain and stiffness and ADL; predictor variable: varus thrust) were performed., Results: Varus thrust was present in 46 (16.2%) of 284 patients. Multivariate regression analyses demonstrated that varus thrust is independently associated with pain and stiffness, adjusted for age, sex, body mass index, K/L grade, and varus alignment (β=.17, P=.005). However, the association between varus thrust and ADL was not significant (β=.11, P=.058). Based on sensitivity analyses, including participants of K/L grade 1 had little influence on this analysis., Limitations: Only 16.2% of participants had a varus thrust. Moreover, a cause-effect relationship between varus thrust and pain and stiffness remains unknown due to the cross-sectional design of this study., Conclusions: Varus thrust was associated with pain and stiffness in patients with medial knee OA. However, the association between varus thrust and ADL did not reach significance., (© 2016 American Physical Therapy Association.)

The purpose was to measure the morphology of the proximal tibia at different levels for consideration of tibial tray design and placement. The morphology was analysed in 51 knees at 10, 15, 20, and 25 mm below the centre of the lateral tibial plateau. Surface rotation was measured by fitting an ellipse on the resection surface. The anteroposterior (AP), mediolateral (ML), medial AP (MAP) and lateral AP (LAP) dimensions were also measured. The resection surface showed internal rotation of 22.9° from the 10 mm level to the 25 mm level. More distally, the ML/AP and MAP/LAP ratios showed significant changes. Surgeons should pay attention to morphological changes for patients with gross tibial bone defects in primary and revision total knee arthroplasty., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: To investigate the association between knee pain during gait and 4 clinical phenotypes based on static varus alignment and varus thrust in patients with medial knee osteoarthritis (OA)., Methods: Patients in an orthopedic clinic (n = 266) diagnosed as having knee OA (Kellgren/Lawrence [K/L] grade ≥1) were divided into 4 phenotype groups according to the presence or absence of static varus alignment and varus thrust (dynamic varus): no varus (n = 173), dynamic varus (n = 17), static varus (n = 50), and static varus + dynamic varus (n = 26). The knee range of motion, spatiotemporal gait parameters, visual analog scale scores for knee pain, and scores on the Japanese Knee Osteoarthritis Measure were used to assess clinical outcomes. Multiple logistic regression analyses identified the relationship between knee pain during gait and the 4 phenotypes, adjusted for possible risk factors, including age, sex, body mass index, K/L grade, and gait velocity., Results: Multiple logistic regression analysis showed that varus thrust without varus alignment was associated with knee pain during gait (odds ratio [OR] 3.30, 95% confidence interval [95% CI] 1.08-12.4), and that varus thrust combined with varus alignment was strongly associated with knee pain during gait (OR 17.1, 95% CI 3.19-320.0). Sensitivity analyses applying alternative cutoff values for defining static varus alignment showed comparable results., Conclusion: Varus thrust with or without static varus alignment was associated with the occurrence of knee pain during gait. Tailored interventions based on individual malalignment phenotypes may improve clinical outcomes in patients with knee OA., (© 2015 The Authors. Arthritis & Rheumatology is published by Wiley Periodicals, Inc. on behalf of the American College of Rheumatology.)

Background: The purposes of this study were to translate the new Knee Society Score (KSS) into Japanese and to evaluate the construct and content validity, test-retest reliability, and internal consistency of the Japanese version of the new KSS., Methods: The Japanese version of the KSS was developed according to cross-cultural guidelines by using the "translation-back translation" method to ensure content validity. KSS data were then obtained from patients who had undergone total knee arthroplasty (TKA). The psychometric properties evaluated were as follows: for feasibility, response rate, and floor and ceiling effects; for construct validity, internal consistency using Cronbach's alpha, and correlations with quality of life. Construct validity was evaluated by using Spearman's correlation coefficient to quantify the correlation between the KSS and the Japanese version of the Oxford 12-item Knee Score or Short Form 36 Health Survey (SF-36) questionnaires., Results: The Japanese version of the KSS was sent to 93 consecutive osteoarthritic patients who underwent primary TKA in our institution. Fifty-five patients completed the questionnaires and were included in this study. Neither a floor nor ceiling effect was observed. The reliability proved excellent in the majority of domains, with intraclass correlation coefficients of 0.65-0.88. Internal consistency, assessed by Cronbach's alpha, was good to excellent for all domains (0.78-0.94). All of the four domains of the KSS correlated significantly with the Oxford 12-item Knee Score. The activity and satisfaction domains of the KSS correlated significantly with all and the majority of subscales of the SF-36, respectively, whereas symptoms and expectation domains showed significant correlations only with bodily pain and vitality subscales and with the physical function, bodily pain, and vitality subscales, respectively., Conclusions: The Japanese version of the new KSS is a valid, reliable, and responsive instrument to capture subjective aspects of the functional symptoms and abilities of patients who undergo TKA.

Background: Patient satisfaction has become an important parameter for assessing overall outcomes after total knee arthroplasty (TKA). The level of difficulty in performing activities of daily life that affects overall patient satisfaction is unknown. We therefore evaluated the influence of difficulty in performing activities of daily life on patient satisfaction and expectations., Methods: The 2011 Knee Society Knee Scoring System Questionnaire was mailed to patients who had undergone TKA with 375 patients completing and returning it. We evaluated the relationship between the ability to perform daily activities, as assessed via the questionnaire, and patient satisfaction and expectations of the same score in each patient using linear regression analysis. We also determined which activities affected patient satisfaction and expectations using multivariate linear regression analyses., Results: All patient-derived functional activities correlated significantly with the patient satisfaction score. In particular, "climbing up or down a flight of stairs" followed by "getting into or out of a car," "moving laterally (stepping to the side)" and "walking and standing" correlated strongly with patient satisfaction by linear regression analysis and were revealed to have significant contributions to patient satisfaction by multivariate linear regression analysis. Regarding expectations, all patient-derived functional activities correlated significantly with the patient expectation score, although none of the correlation coefficients was very high. "Squatting," followed by "walking and standing," contributed to the patient expectation score by multivariate linear regression analysis., Conclusion: Activities related to walking and standing are some of the most basic movements and basic demands for patients. In addition, "climbing up or down a flight of stairs," "getting into and out of a car" and "squatting" are very important and distressing activities that significantly correlate with patient satisfaction after TKA.

Background: Cultural and ethnic differences are present both in subjective and objective measures of patient health, but scoring systems do not always reflect these differences, and so validation of outcomes tools in different cultural settings is important. Recently, a revised version of The Knee Society Score® (KSS 2011) was developed, but to our knowledge, the degree that this tool evaluates clinical symptoms, physical activities, and radiographic grades in the general Japanese population is not known., Questions/purposes: We therefore asked: (1) how KSS 2011 reflects knee conditions and function in the general Japanese population, in particular evaluating changes with increasing patient age; (2) can objective measures of physical function be correlated with KSS 2011; and (3) does radiographic osteoarthritis (OA) grade correlate with KSS 2011?, Methods: Two hundred twenty-six people in the general Japanese population, aged 35 to 92 years, with and without knee arthritis, voluntarily participated in this cross-sectional study. Residents who had no serious disease or symptoms based on a self-assessment were recruited. This study consisted of a questionnaire including self-administered KSS 2011, physical examination, and weightbearing radiographs of the knee. Leg muscle strength, Timed Up and Go test, and body mass index (BMI) were examined in all the participants. Radiographs were graded according to the Kellgren and Lawrence scale (KL grade)., Results: Multivariable linear regression analysis showed that KSS 2011 correlated with age (coefficient: -0.30±0.12, p=0.011), BMI (coefficient: -1.47±0.42, p<0.001), leg muscle strength (coefficient: 0.41±0.13, p=0.002), and Timed Up and Go Test (coefficient: -1.96±0.92, p=0.034), but not sex, as independent variables by a stepwise method. KSS 2011 was also correlated with radiographic OA evaluated by KL grade (coefficient: -12.2±2.9, p<0.001)., Conclusions: KSS 2011 reflects symptoms, physical activities, and radiographic OA grades of the knee in an age-dependent manner in the general Japanese population., Level of Evidence: Level IV, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.