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[Purpose] Quadriceps muscle strength is essential for daily living activities. Therefore, we developed a compact and simple lower limb muscle strength measuring device (LocomoScan [LCS]). This study aimed to compare LCS with other instruments to analyze its simplicity, reproducibility, and accuracy. [Participants and Methods] One hundred and four healthy university students (56 males and 48 females) were included in the study. The knee extension force was measured using LCS, and the knee extension torque was measured using other devices (Cybex). In addition, lower leg muscle mass was measured using a body composition meter. The reproducibility of LCS and the correlation between the knee extension torque and lower leg muscle mass were evaluated. [Results] The measurement reproducibility of LCS was significantly higher. The knee extension force confirmed the proportional relative reliability of Cybex with knee extension torque. A relationship between knee extension force and lower limb muscle mass was also observed, indicating that muscle mass cannot be estimated as muscle strength. [Conclusion] The high reproducibility of the knee extension force measurement using LCS demonstrates its potential as a portable alternative instrument for muscle strength measurement in clinical practice. Therefore, LCS device is a simple and effective tool for assessing muscle strength.

DOI： 10.1589/jpts.36.343

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Language：Japanese   Publisher：(一社)日本人工関節学会  

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PURPOSE: The longitudinal changes in alignment and structure, including the joint line and cortical bone thickness (CBT) of the femur and tibia, and knee phenotype in patients with knee osteoarthritis (OA) remain unknown. The aim of this retrospective study was to clarify the longitudinal changes in matched healthy subjects. METHODS: The follow-up Matsudai Knee Osteoarthritis Survey was administered between 23 and 28 years. This study included 285 healthy knees from 235 females with an average age of 53 ± 6 years at baseline. The non-OA individuals, with an average age of 79 ± 4 years, were divided into three groups at baseline according to their follow-up radiographic results [the non-OA (n = 52), early OA (n = 131), and advanced OA groups (n = 102)]. Changes in alignment, joint line, CBT, and knee phenotype were assessed at baseline and at follow-up using standing anteroposterior radiographs. RESULTS: This study showed significant varus changes in the alignment (p < 0.001) and tibial and femoral joint line parameters (p < 0.05) in the OA group. Decreased CBT and increased mediolateral CBT ratios were observed in all groups (p < 0.001). The knee phenotypes in the OA groups were changed to varus angles, especially in the alignment and tibial joint line. CONCLUSIONS: The longitudinal changes of knee phenotypes in alignment and structure (CBT and joint line) from baseline to follow-up were shown in the OA groups. In addition, alignment and tibial structural factors at baseline are useful in predicting the incidence of knee OA in daily practice. LEVELS OF EVIDENCE: III.

DOI： 10.1007/s00167-023-07554-1

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(一社)日本臨床バイオメカニクス学会  

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Language：Japanese   Publisher：(一社)日本臨床バイオメカニクス学会  

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BACKGROUND: During gait, healthy knee coronal kinematics of each bony axis and lower extremity alignment are important because they could be useful as reference data for several surgeries and provide clarification of the etiology of diseases around the knee in healthy participants; however, it remains unknown. OBJECTIVE: The objective of this study was to clarify the kinematics of lower extremity alignment and the bony axes relative to the ground during gait, focused on the coronal plane, in healthy individuals by applying our unique three-dimensional (3D) motion analysis. METHODS: The study included 21 healthy individuals, including 9 healthy females and 12 healthy males with an average age of 36 ± 17 years. Knee kinematics were calculated in a gait analysis by combining the data from a motion-capture system and a 3D lower-extremity alignment assessment system on biplanar long-leg radiographs by using a 3D-2D registration technique. The main kinematic parameters were the dynamic position change relative to the ground, applying the femoral anatomical axis (FAA), tibial anatomical axis (TAA), and dynamic alignment in the coronal plane during the stance phase of gait. RESULTS: The average changes in FAA, TAA, and dynamic varus alignment were 3.7° ± 1.2°, 3.5° ± 0.8°, and 3.0° ± 1.2°, respectively. The TAA tilted laterally during the loading response and a plateau area appeared afterwards; the FAA gradually inclined laterally until the terminal stance phase, and the dynamic alignment showed varus angular change during the loading response. CONCLUSIONS: The tibia and femur were found to change approximately 2-5° of the position of the bony axes relative to the ground. In terms of clinical relevance, our findings can be used to clarify the etiology of diseases around the knee joint and as reference data for surgeries.

DOI： 10.3233/BME-211383

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PURPOSE: This study aims to (1) measure the kinematics of lower extremity alignment and the bony position relative to the ground during walking, focusing on the coronal plane, and (2) determine the correlation between the kinematics and coronal inclination of the medial tibial plateau (coronal inclination) for healthy and varus knee osteoarthritis (OA). METHODS: In this study, 43 women (non-OA, 9 knees; early OA, 13 knees; advanced OA, 21 knees; mean age 58 ± 17 years) were examined. The knee phenotypes in varus knee OA were varied. Three-dimensional (3D) knee kinematics were calculated in gait analysis by combining the motion capture system and the 3D lower extremity alignment assessment system via biplanar long-leg X-rays, applying the 3D-2D registration technique. The main parameters were the kinematics of the bony axes relative to the ground in the coronal plane during the stance phase of the gait. The differences in overall kinematics were assessed using repeated measures ANOVA with Tukey's post hoc test. The association between kinematic parameters and coronal inclination was evaluated by multiple linear regression after univariate analysis. RESULTS: The tibia tilted laterally during the loading response, and a plateau area subsequently appeared until the terminal stance phase, whereas the femur slowly tilted laterally until the terminal stance phase. The dynamic alignment showed a relatively large varus angular change during the loading response in all groups. The trend of motion was similar among all groups (p = n.s.), although to varying degrees. The coronal inclination was the more dominant factor than the Kellgren-Lawrence (K-L) grades (β =  - 0.423, p = 0.005) when the change in dynamic alignment was determined. CONCLUSIONS: The TAA plateau area after the loading response implies that the tibial articular surface may become horizontal. The femur slowly tilted laterally until the terminal stance phase in response to the tibial motion. Consequently, the dynamic alignment showed a varus angular change, in which coronal MCT was more involved than K-L grades.

DOI： 10.1007/s00167-022-07019-x

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Language：Japanese   Publisher：新潟整形外科研究会  

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Language：Japanese   Publisher：新潟整形外科研究会  

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Language：Japanese   Publisher：新潟整形外科研究会  

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Language：Japanese   Publisher：新潟整形外科研究会  

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Language：Japanese   Publisher：新潟整形外科研究会  

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Language：Japanese   Publisher：日本臨床バイオメカニクス学会  

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Language：Japanese   Publisher：日本臨床バイオメカニクス学会  

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Language：Japanese   Publisher：日本臨床バイオメカニクス学会  

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BACKGROUND: Identifying indicators of early knee osteoarthritis is important for preventing the onset and/or progression of the disease. Although low quadriceps strength and changes in stride and knee kinematics during gait have been suggested as possible indicators, their relevance and relationships have not been fully examined. This study aimed to analyze the association of quadriceps strength with stride and knee kinematics during gait in adults with normal knee or early knee osteoarthritis. METHODS: A total of 881 knees from 474 community dwelling adults (238 males and 236 females) were included. Radiographic images of the knee in standing position were obtained, and grading of knee osteoarthritis was classified. Isometric quadriceps strength was measured using a force detector device. Three-dimensional knee kinematics during gait was obtained by a motion capture system. Sex-based difference of quadriceps strength, stride and knee kinematics during gait was evaluated by multiple comparison among grades by sex and multiple regression of quadriceps strength was analyzed by stride and knee kinematics during gait. FINDINGS: Stride length and quadriceps strength were significantly reduced with higher grade in both sexes, and changes in knee kinematics during gait differed by sex from early knee osteoarthritis. Quadriceps strength in both sexes was significantly correlated with changes in stride length and knee kinematics during gait. INTERPRETATION: Improving quadriceps strength in early knee osteoarthritis was related with maintaining gait ability and restraining abnormal knee kinematics during gait. This may help to develop clinical approaches to prevent the onset and/or progression of knee osteoarthritis.

DOI： 10.1016/j.clinbiomech.2021.105325

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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BACKGROUND: Identifying the time course of rotational knee alignment is crucial for elucidating the etiology in knee osteoarthritis. OBJECTIVE: The aim of this study was to propose new rotational indices for calculating the change in relative rotational angles between the femur and tibia in standing anteroposterior (AP) radiographs. METHODS: Forty healthy elderly volunteers (20 women and 20 men; mean age, 70 ± 6 years) were assessed. The evaluation parameters were as follows: (1) femoral rotational index: the distance between the sphere center of the medial posterior femoral condyle and the lateral edge of the patella, and (2) tibial rotational index: the distance between the medial eminence of the tibia and the lateral edge of the fibula head. The indices were standardized by the diameter of the sphere of the medial posterior femoral condyle. This study (1) identified the relationship between changes in rotational indices and the simulated rotational knee angles in the standing position, (2) proposed a regression equation for the change in relative rotational angles between the femur and tibia in standing AP radiographs, and (3) verified the accuracy of the regression equation. RESULTS: The rotational indices increased in direct proportion to simulated rotational knee angles (femoral index: r > 0.9,p < 0.0001; tibial index: r > 0.9, p < 0.0001). Based on the results, the regression equation with the accuracy of 0.45 ± 0.26° was determined. CONCLUSIONS: The proposed regression equations can potentially predict the change in relative rotational angles between the femur and tibia in a pair of standing AP radiographs taken at different dates in longitudinal studies.

DOI： 10.3233/BME-201138

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PURPOSE: Whether the inclined articular surface on the medial proximal tibia and the external knee adduction moment (KAM) correlate remains unclear. The hypothesis was that a steeper inclined articular surface correlated with a larger KAM in advanced knee osteoarthritis (OA). METHODS: A total of 44 females (non-OA, 9 knees; early OA, 14 knees; advanced OA, 21 knees; mean age, 58 ± 16 years) were examined. Three-dimensional (3D) assessment was used on biplanar long-leg radiographs and 3D bone models using a 3D to 2D image registration technique. The approximation plane in the proximal tibia was determined using the least-square method. The joint moments were mathematically calculated in a gait analysis, applying a motion capture system and force plates. The main evaluation parameters were the femorotibial angle (FTA), the coronal inclination of the approximation plane in the medial proximal tibia (coronal inclination), and internal knee joint moments. The KAM means the external moments balanced with the internal knee abduction moments. RESULTS: The advanced OA showed a larger internal abduction moment (p = 0.017) at the loading response than the other groups. The larger FTA and steeper coronal inclination correlated with the larger internal abduction moment (FTA, p < 0.001; coronal inclination, p = 0.003) at the loading response. CONCLUSIONS: As the clinical relevance, the association among the coronal inclination of the medial proximal tibia, lower extremity alignment, and KAM is one of the key factors to help better understand the etiology of knee OA. LEVEL OF EVIDENCE: III.

DOI： 10.1007/s00167-020-06323-8

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PURPOSE: This study aimed to evaluate the age- and sex-related characteristics in cortical thickness of the tibial diaphysis between non-obese healthy young and elderly subjects as reference data. METHODS: The study investigated 31 young subjects (12 men and 19 women; mean age, 25 ± 8 years) and 54 elderly subjects (29 men and 25 women; mean age, 70 ± 6 years). Three-dimensional estimated cortical thickness of the tibial diaphysis was automatically calculated for 5000-9000 measurement points using the high-resolution cortical thickness measurement from clinical computed tomography data. In 12 assessment regions created by combining three heights (proximal, central, and distal diaphysis) and four areas of the axial plane at 90° (medial, anterior, lateral, and posterior areas) in the tibial coordinate system, the standardized thickness was assessed using the tibial length. RESULTS: As structural characteristics, there were no differences in the medial and lateral thicknesses, while the anterior thickness was greater than the posterior thickness in all groups. The sex-related difference was not shown. As an age-related difference, elderly subjects showed greater or lesser cortical thickness than the young subjects, depending on the regions of the tibia. CONCLUSIONS: Cortical thickness was different depending on sex, age, and regions in the tibia. The results of this study are of clinical relevance as reference points to clarify the causes of various pathological conditions for diseases. LEVEL OF EVIDENCE: Level 3.

DOI： 10.1186/s40634-020-00297-9

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PURPOSE: To test the hypothesis that an inclined articular surface on the medial proximal tibia is aligned more parallel to the ground in three-dimensional (3D) space under weight-bearing (WB) conditions (parallel phenomenon) than under non-WB (NWB) conditions in healthy and varus osteoarthritic knees. METHODS: We examined 55 healthy knees (26 women, 29 men; mean age, 70 ± 6 years) and 108 varus osteoarthritic knees (66 women, 16 men; mean age, 74 ± 7 years). For the evaluation under WB conditions, a 3D assessment system was used on biplanar long-leg radiographs and 3D bone models using a 3D-to-2D image registration technique. In addition, the least square method was used to determine the approximation plane. The angles between the normal vector for the approximation plane of an articular surface on the medial proximal tibia and each axis of the tibial or world coordinate system were calculated. RESULTS: Morphologically, the inclination of the approximation plane was steeper in osteoarthritic knees than in healthy knees (p < 0.0001). The approximation plane was aligned more parallel to the ground under WB conditions than under NWB conditions in healthy (p < 0.0001) and osteoarthritic knees (p < 0.0001). CONCLUSIONS: The parallel phenomenon in the medial proximal tibia was confirmed for healthy and varus osteoarthritic knees. The medial proximal tibia plays an important role in the parallel phenomenon, assumingly associated with varus alignment and varus thrust. The inclination of the medial proximal tibia may become a new parameter for imaging investigations. LEVEL OF EVIDENCE: III.

DOI： 10.1007/s00167-019-05829-0

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Language：Japanese   Publisher：日本臨床バイオメカニクス学会  

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Language：Japanese   Publisher：日本臨床バイオメカニクス学会  

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INTRODUCTION: Cortical thickness of the femoral diaphysis is assumed to be a preferred parameter in the assessment of the structural adaptation by mechanical use and biological factors. This study aimed to investigate the age- and sex-specific characteristics in cortical thickness of the femoral diaphysis between young and elderly non-obese people. MATERIALS AND METHODS: This study investigated 34 young subjects (21 men and 13 women; mean age: 27 ± 8 years) and 52 elderly subjects (29 men and 23 women; mean age: 70 ± 6 years). Three-dimensional (3D) cortical thickness of the femoral diaphysis was automatically calculated for 5000-8000 measurement points using the high-resolution cortical thickness measurement from clinical CT data. In 12 assessment regions created by combining three heights (proximal, central, and distal diaphysis) and four areas of the axial plane at 90° (medial, anterior, lateral, and posterior areas) in the femoral coordinate system, the standardized thickness was assessed using the femoral length. RESULTS: As per the trends, (1) there were no differences in medial and lateral thicknesses, while the posterior thickness was greater than the anterior thickness, (2) the thickness in men was higher than that in women, and (3) the thickness in young subjects was higher than that in elderly subjects. CONCLUSIONS: The results of this study are of clinical relevance as reference points to clarify the causes of various pathological conditions for diseases of the lower extremities.

DOI： 10.1007/s00774-019-01079-9

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Language：Japanese   Publisher：日本臨床バイオメカニクス学会  

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Language：Japanese   Publisher：(株)メジカルビュー社  

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BACKGROUND: The inclination of the medial compartment of the proximal tibia (MCT) is assumed to be a critical factor for varus alignment in advanced knee osteoarthritis (OA). This study was aimed at investigating; (1) whether the inclination of MCT is aligned parallel to the ground under weight-bearing (WB) conditions; (2) whether this is associated with the change in alignment and the relative position between the bones; and (3) whether the tibia or femur mainly contributes to the changes. METHODS: We examined 102 knees (84 women, 18 men; mean 75 years). A three-dimensional (3D) assessment system was applied on biplanar whole lower extremity radiographies using 3D-to-2D image registration technique. The evaluation parameters were 1) MCT angle, 2) femorotibial angle (FTA), 3) medial-lateral femoral location to the tibia (M-L femoral location), 4) WB line passing point, and 5) tibial position to WB line (tibial position) and 6) femoral postion to WB line (femoral position). Each parameter was evaluated in non-WB and WB conditions, and the differences (Δ-parameters). RESULTS: MCT angle in the world coordinate system was larger than that in the tibial coordinate system (p <  0.0001). ΔMCT angle was correlated with ΔFTA (p = 0.002) and ΔM-L femoral location (p = 0.004). The tibial position was the more dominant factor for ΔMCT angle (p = 0.001), ΔFTA (p <  0.0001), and ΔWB line passing point (p <  0.0001) . CONCLUSIONS: The inclination in MCT was aligned parallel to the ground under WB conditions (tibial parallel phenomenon). The parallel phenomenon was associated with the change of alignment and the relative position between the bones in the coronal plane. These phenomena were produced mainly by the tibia, not the femur. LEVEL OF EVIDENCE: Level IV.

DOI： 10.1186/s40634-019-0180-x

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(一社)日本関節病学会  

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Language：Japanese   Publisher：日本臨床バイオメカニクス学会  

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PURPOSE: The purpose of this study was to investigate the causal relationship between quadriceps muscle strength and radiographic knee osteoarthritis (OA) in a longitudinal study. METHODS: The present study included 976 knees from 488 subjects who participated in both the 5th (2007) and 7th (2013) surveys of the Matsudai Knee Osteoarthritis Survey. Bilateral quadriceps strengths of each subject were measured using the quadriceps training machine (QTM-05F, Alcare Co., Ltd., Tokyo, Japan). Additionally, weight-bearing standing knee radiographs were obtained, and knee OA was graded according to the Kellgren-Lawrence classification system. The relationships between quadriceps strength and the incidence and progression of radiographic knee OA were assessed using multiple logistic regression analysis. RESULTS: After adjusting for age and body mass index (BMI), both female and male knees in the lowest quantile of quadriceps strength had higher risk of the incidence of radiographic knee OA compared with the highest quantile of quadriceps strength (women: OR 2.414, 95% CI 1.098-5.311; men: OR 2.774, 95% CI 1.053-7.309). In contrast, after adjusting for age, BMI and femorotibial angle, both female and male knees in the lowest quantile compared with the highest quantile of quadriceps strength did not differ in risk of the progression of radiographic knee OA (women: OR 1.040, 95% CI 0.386-2.802; men: OR 2.814, 95% CI 0.532-14.898). CONCLUSION: Quadriceps muscle weakness was related to increased risk of the incidence of radiographic knee OA, but not its progression, in both women and men. Therefore, the clinically important finding of this study is that, in both women and men, maintaining higher quadriceps muscle strength may be one of the most effective prevention methods for incident radiographic knee OA. LEVEL OF EVIDENCE: II.

DOI： 10.1007/s00167-017-4551-5

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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BACKGROUND: Studies on the epidemiology of pediatric fractures have been scarce in recent years although fractures are very common in childhood. Boys have a higher incidence of fractures than girls. Currently, societal trends have seemed to influence the difference in activity patterns between boys and girls, but the sex difference regarding longitudinal changes in fracture incidence is not well known. METHODS: We analyzed the school accident report in Niigata city, Japan and compared the incidence of fractures in elementary and junior high school students and the sex-related risk ratio between two 9-year periods separated by 20 years from their start and end points (1999-2007 and 1979-1987). RESULTS: The study included 383,273 students from 1999 to 2007 and 561,109 students from 1979 to 1987. Comparing these periods, the fracture incidence increased significantly by 2.4 times in boys vs 2.1 times in girls from elementary school and by 2.2 times in boys vs 2.9 times in girls from junior high school (all p ＜ 0.001). The sex-related risk ratio of boys to girls increased significantly from 1.47 to 1.64 in elementary school students. In contrast, it decreased significantly from 3.29 to 2.52 in junior high school students and the change was markedly significant because of the drastic increase in fracture incidence in junior high school girls. CONCLUSIONS: The reasons proposed for the increase in schoolchildren's fractures were an improvement in diagnosis owing to social background and increased participation in sports activities despite the general decline in children's physical fitness and exercise ability. In junior high school girls, in particular, there was an increase in fracture risk due to increased participation in sports activities.

DOI： 10.1016/j.jos.2017.09.005

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INTRODUCTION: Instability after total knee arthroplasty is a critical problem. The purpose of this study was to clarify the stability of implanted knees during walking by comparing differences in dynamic instability during knee acceleration between individuals with or without previously experienced subjective instability, as measured by self-reported questionnaire. MATERIALS AND METHODS: We examined 92 knees with medial pivot implants. Mean patient age and follow-up duration were 78.4 years and 32.8 months, respectively. An accelerometer was used to investigate the accelerations along three axes; that is, vertical (VT), mediolateral (ML), and anteroposterior (AP) directions in 3-dimensional (3D) space. The analysis in the stance phase and gait cycle was performed by: (1) root mean square (RMS) values of acceleration and (2) frequency domain analysis using fast Fourier transformation (FFT). A self-reported knee instability score was used for the subjective feeling of instability. RESULTS: A total of 76 knees did not feel unstable (group 0), but 16 knees felt unstable (group 1) in patients during activities of daily living. Regarding the RMS, there were no differences in each direction between the groups. For FFT, the cumulative amplitude in the frequency < 30 Hz also showed no significant differences in all directions between the groups during the stance phase (VT, p = 0.335; ML, p = 0.219; AP, p = 0.523) or gait cycle (VT, p = 0.077; ML, p = 0.082; AP, p = 0.499). DISCUSSION: Gait analysis based on the acceleration data showed that there were no between-group differences in objective dynamic instability during acceleration of the knee, with or without reports of previously experienced subjective instability, as assessed by the self-reported questionnaire.

DOI： 10.1371/journal.pone.0194221

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INTRODUCTION: Posterior tibial slope (PTS) and sagittal alignment are important factors in the etiology of knee osteoarthritis and knee surgery. Clinically, sagittal alignment, which indicates flexion contracture of the knee, contributes to knee function in weight-bearing (WB) conditions. PTS and sagittal alignment under WB conditions in varus osteoarthritic knees are presumed to affect each other, but their association remains unclear. In this study, we aimed to clarify the association. MATERIAL AND METHODS: In total, 140 osteoarthritic varus knees were investigated. Under WB conditions, a three-dimensional (3D) alignment assessment system was applied via biplanar long-leg X-rays, using 3D-to-2D image registration technique. The evaluation parameters were as follows: 1) 3D mechanical flexion angle (3DMFA) in regards to sagittal alignment, 2) passing point in the WB line (PP), and 3) medial and lateral PTS. RESULTS: The medial and lateral PTS showed a positive correlation with 3DMFA and PP, respectively (medial PTS-3DMFA, p = 0.001; medial PTS-PP, p < 0.0001; lateral PTS-3DMFA, p < 0.0001; lateral PTS-PP, p = 0.002). The flexion contracture group with 3DMFA >5° demonstrated greater PTS than non-flexion contracture group (medial PTS, p = 0.006; lateral PTS, p = 0.006). CONCLUSIONS: Both medial and lateral PTS were correlated with sagittal alignment under WB conditions and were larger in the flexion contracture group. This finding can explain the function to take the load articular surface parallel to the ground for holding the balance in WB conditions in the sagittal plane for osteoarthritic knees. Moreover, surgeons may be required to decrease the PTS during knee arthroplasty to restore full extension in knees of patients with fixed flexion contracture.

DOI： 10.1371/journal.pone.0202488

PubMed

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BACKGROUND: The posterolateral (PL) graft experiences a high failure rate in anterior cruciate ligament double-bundle (DB) reconstruction. It is hypothesized that tunnel positions could dramatically affect the graft forces. METHODS: A validated computational model was used to simulate DB reconstruction with various femoral PL tunnel locations (8-11 mm center-center tunnel spacing). Graft fixation was simulated at both 0° and 30°. Knee biomechanics were examined with the knee under a 134 N anterior load and 400 N quadriceps load at 0°, 30°, 60°, and 90° of flexion. Graft forces, tibial translation, and tibial rotation were calculated. RESULTS: PL graft forces at full extension increased with increasing tunnel spacing under both fixation settings, but the knee kinematics was not dramatically affected. CONCLUSION: Small changes in the femoral PL tunnel position could result in large changes in graft forces, implying that precise PL tunnel position is an important factor in a successful DB reconstruction.

DOI： 10.1002/rcs.1840

PubMed

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Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: Flexion instability following total knee arthroplasty (TKA) is a common indication of early revision. The association between the objective anteroposterior (AP) laxity direction in mid-range flexion and the subjective healing of instability remains unclear; thus, this study aimed to clarify this association. METHODS: In this study, 110 knees (74 females, 92 knees; 16 males, 18 knees) with medial pivot implants were examined with a median age of 79 (range 60-92) years for a median follow-up duration of 22 (range 6-125) months. AP laxity was measured using a KT-1000 arthrometer. Self-reported knee instability score was used for the subjective healing of instability. RESULTS: Eighty-seven knees did not feel unstable (Group 0), whereas 23 knees felt unstable (Group 1). There was a significant difference in AP displacement [Group 0: median 6 mm; range 2-15 mm and Group 1: median 8 mm; range 4-14; p < 0.0001]. The threshold value of 7 mm was determined using the area under receiver operating characteristic curve of 0.79 [95% confidence interval (CI) 0.69-0.88, p < 0.0001]. In multivariate analysis, AP displacement of ≥7 mm was an independent risk factor for feelings of instability (odds ratio 7.695; 95% CI 2.306-25.674; p = 0.001). CONCLUSIONS: AP laxity of ≥7 mm represents a known cause of feelings of instability. By controlling AP laxity in TKAs, without stiffness in the knee, it is possible to prevent feelings of instability. The clinical relevance is that AP laxity of <7 mm is one of the target areas in TKA. LEVEL OF EVIDENCE: IV.

DOI： 10.1007/s00167-016-4375-8

PubMed

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Language：Japanese   Publisher：日本臨床バイオメカニクス学会  

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Other Link： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2017&ichushi_jid=J05471&link_issn=&doc_id=20171016110048&doc_link_id=%2Fcx9biomc%2F2017%2F003800%2F048%2F0313-0318%26dl%3D0&url=http%3A%2F%2Fwww.medicalonline.jp%2Fjamas.php%3FGoodsID%3D%2Fcx9biomc%2F2017%2F003800%2F048%2F0313-0318%26dl%3D0&type=MedicalOnline&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00004_2.gif

Language：Japanese   Publisher：(一社)日本関節鏡・膝・スポーツ整形外科学会  

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Language：Japanese   Publisher：(一社)日本関節鏡・膝・スポーツ整形外科学会  

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Language：Japanese   Publisher：(一社)日本関節鏡・膝・スポーツ整形外科学会  

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Language：Japanese   Publisher：(一社)日本関節鏡・膝・スポーツ整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(公社)日本整形外科学会  

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Language：Japanese   Publisher：(一社)日本関節鏡・膝・スポーツ整形外科学会  

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Language：Japanese   Publisher：(一社)日本関節鏡・膝・スポーツ整形外科学会  

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Language：Japanese   Publisher：日本運動器科学会  

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Language：Japanese   Publisher：日本運動器科学会  

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Language：English   Publishing type：Research paper (scientific journal)  

We conducted a survey of fracture incidences associated with senile osteoporosis in 2010 in Sado City, Niigata Prefecture, Japan, including compression vertebral fractures, hip fractures, distal radius fractures, and fractures of the proximal end of the humerus. We previously conducted a similar survey from 2004-2006 in Sado City. The purpose of the current study was to determine the incidence of osteoporotic fractures in Sado City in 2010 and to examine changes over time. We calculated the incidence of each fracture per 100,000 person-years based on the population of Sado City. Hip and vertebral fractures showed marked increases from 2004-2006, but a similar increase was not found from 2006-2010. The average age at injury increased in 2010 compared to 2004, except for fractures of the radius. Among the subjects with hip fractures, 14 % had a history of contralateral hip fracture. The percentage of patients taking medication for osteoporosis before injury was higher in 2010 compared with 2004, but these percentages were still only 7 and 13 % for those with subsequent hip and vertebral fractures, respectively.

DOI： 10.1007/s00774-013-0486-1

PubMed

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Language：Japanese   Publisher：東北整形災害外科学会  

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Language：Japanese   Publisher：東北整形災害外科学会  

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Language：Japanese   Publisher：東北整形災害外科学会  

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Language：Japanese   Publisher：新潟整形外科研究会  

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Language：Japanese   Publisher：新潟整形外科研究会  

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Language：Japanese   Publisher：金原出版(株)  

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Language：Japanese   Publisher：日本臨床バイオメカニクス学会  

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Language：Japanese   Publisher：日本臨床バイオメカニクス学会  

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Language：Japanese   Publisher：(株)南江堂  

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Other Link： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2019&ichushi_jid=J00764&link_issn=&doc_id=20190523170026&doc_link_id=10.15106%2Fj_seikei70_661&url=https%3A%2F%2Fdoi.org%2F10.15106%2Fj_seikei70_661&type=%88%E3%8F%91.jp_%83I%81%5B%83%8B%83A%83N%83Z%83X&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00024_2.gif

Language：Japanese   Publisher：新潟県医師会  

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Other Link： http://search.jamas.or.jp/link/ui/2017080655

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Language：Japanese   Publisher：(株)メジカルビュー社  

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Language：Japanese   Publisher：ライフサイエンス出版(株)  

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