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Purpose: In vivo kinematics of skeletal joints and prostheses is affected by gravity; therefore, absolute tilt must be taken into account. However, current fluoroscopic kinematic analysis cannot measure the tilt. This study introduces and validates a method for defining the horizontal plane in fluoroscopy systems to measure the tilt of an object. Methods: A rectangular metal plate (200 ​× ​200 ​× ​10 ​mm) with a flatness of 0.03/100 ​mm was horizontally adjusted using a leveler (sensitivity of 0.02° and accuracy of ±0.06°), and its three-dimensional coordinate was calculated from a two-dimensional fluoroscopic image. A coordinate calculation formula was developed, with precision and accuracy assessed via computer simulations. Actual fluoroscopic tests included four aspects: accuracy under the same condition; accuracy under different X-ray tube height; reproducibility when changing X-ray tube height; and reproducibility when the flat panel was tilted and returned. Results: The theoretical measurement error indicated by the computer simulations was 0.0 ​± ​0.2° on the xy-plane and 0.0 ​± ​0.0° on the yz-plane. The actual experimental results showed that the horizontal plane tilt was measured to be −0.2 ​± ​0.1° tilt on the xy-plane and 0.3 ​± ​0.0° tilt on the yz-plane for the device used in this study. The F-test showed no significant differences between the computer simulations and the actual experiments. There were no significant differences between the four actual tests. Conclusions: This method enables the horizontal plane to be defined and the tilt of an object to be measured in fluoroscopic kinematic analysis.

Abstract Background Acute kidney injury (AKI) incidence is extremely high worldwide, and patients who develop AKI are at increased risk of developing chronic kidney disease (CKD), CKD progression, and end-stage kidney disease (ESKD). However, there is no established treatment strategy for AKI. Based on the idea that exercise has a stabilizing effect on hemodynamics, we hypothesized that rehabilitation would have beneficial renal outcomes in patients with AKI associated with cardiovascular disease. Therefore, the purpose of this study was to determine whether rehabilitation can stabilize hemodynamics and positively impact renal outcomes in patients with AKI associated with cardiovascular disease. Methods In total, 107 patients with AKI associated with cardiovascular disease were enrolled in this single-center retrospective study and were either assigned to the exposure group (n = 36), which received rehabilitation at least once a week for at least 8 consecutive weeks, or to the control group (n = 71). Estimated glomerular filtration rate was assessed at baseline before admission, at the lowest value during hospitalization, and at 3, 12, and 24 months after enrolment. Trends over time (group × time) between the two groups were compared using generalized estimating equations. Moreover, congestive status was assessed by amino-terminal pro-B-type natriuretic peptide (NT-proBNP), and the effect of rehabilitation on congestion improvement was investigated using logistical regression analysis. Results The time course of renal function after AKI, from baseline to each of the three timepoints suggested significant differences between the two groups (p

Background/objective: This study aimed to clarify the kinematics of bi-cruciate-retaining (BCR) total knee arthroplasty (TKA) by comparing the mechanical alignment (MA) and functional alignment (FA) methods and to evaluate differences between the two alignment methods. Methods: The in vivo kinematics of 20 MA TKA and 20 FA TKA knees were investigated under fluoroscopy during squatting using a two-to three-dimensional registration technique. Accordingly, knee flexion angle, axial rotational angle, varus–valgus angle, anteroposterior translation of the medial and lateral low contact points of the femoral component relative to the tibial component and kinematic pathway were evaluated. Results: No difference in the knee flexion angle was observed between the MA and FA TKA groups. Femoral external rotation was observed in both groups and no significant difference was observed. Significant varus alignment from extension to early flexion range was observed in the FA TKA group. The posterior translation of the medial side was smaller in the FA TKA group than in the MA TKA group. Conversely, no significant difference in the anteroposterior translation of the lateral side was observed. In the kinematic pathway, a medial pivot motion from 0° to 20° of flexion and a lateral pivot motion beyond 20° of flexion were observed in both groups. Conclusion: During squatting in BCR TKA, the FA TKA group significantly showed varus alignment and smaller posterior translation of the medial side than the MA TKA group from extension to early flexion range.

Purpose: The medial preserving gap technique has recently been used in total knee arthroplasty. Generally, the deep medial collateral ligament (DMCL) is released using this technique. However, the effect of DMCL release on the kinematics and length of the ligaments remains unknown. This study aimed to clarify how DMCL release affects the kinematics and length change of the ligaments during high knee flexion movements. Methods: Three cadaveric knees were examined using a computed tomography-based navigation system. The following parameters were evaluated: femoral rotation and varus-valgus angle relative to the tibia; anteroposterior translation of the sulcus distal to the medial epicondyle (medial side) and tip of the lateral epicondyle of the femur (lateral side); mediolateral translation of the medial and lateral sides of the plane perpendicular to the tibial mechanical axis; and kinematic pathways during non-weight-bearing knee flexion, cross-legged motion, and sideways motion. Results: There were no significant differences in the kinematics and length change of the ligaments during all movements after DMCL release compared with that before DMCL release. Conclusion: DMCL release did not affect the kinematics and length change of the ligaments.

Background/Objective: Normal knee kinematics during flexion and extension activities over the whole range of motion remains unknown. This study aimed to clarify in vivo kinematics during knee flexion and extension activities of normal knees by comparing continuous flexion and extension activities up to a high flexion angle. Methods: Twenty knees of 10 Japanese volunteers were enrolled in this study. Each volunteer performed a continuous squatting motion under fluoroscopy, and a two- or three-dimensional registration technique was used. Rotation and anteroposterior translation of the medial and lateral sides of the femur relative to the tibia at each flexion angle were evaluated. Results: Femoral external rotation was significantly smaller from 10° to 40° flexion during extension activities than during flexion activities. However, the femoral external rotation was larger from 120° to 130° flexion during extension activities than during flexion activities. From 10° to 60° of flexion, the medial side was significantly more posteriorly located during extension activities than during flexion activities. Furthermore, the lateral side was significantly more posteriorly located at 130° of flexion during extension activities than during flexion activities. Conclusion: In vivo kinematics of normal knees during extension activities differ from those during flexion activities in early and high flexion.

Background: Previous studies have aimed to determine the use of certain risk factors in predicting the occurrence of noncontact anterior cruciate ligament (ACL) injuries. Unfortunately, evidence regarding noncontact ACL injuries in male American football players is limited. This prospective cohort study aimed to identify intrinsic risk factors for noncontact ACL injury among male American football players. Methods: This study evaluated 152 male American football players in Japan for potential noncontact ACL injury risk factors during a preseason medical assessment, including anthropometric, joint laxity, and flexibility, muscle flexibility, muscle strength, and balance measurements. A total of 25 variables were examined. Participants were monitored during each season for noncontact ACL injury, as diagnosed by physicians. Results: Noncontact ACL injuries occurred in 11 knees of 11 players (prevalence; 7.1 %). Injured players were significantly more likely to have lightweight (P = 0.049). No statistically significant between-group differences were found for any other variables. Participants with a lower hamstring to quadriceps (H/Q) ratio (P = 0.04) were more likely to sustain noncontact ACL injuries. Conclusion: Lower H/Q ratio and lower body weight were significantly associated with new-onset noncontact ACL injury in male American football players. These findings will help develop strategies to prevent noncontact ACL injuries in male American football players.

Background The single-radius design is one of the major total knee arthroplasty (TKA) designs and widely used all over the world. The objective of this study was to compare in vivo kinematics between the anteroposterior (AP) single-radius design with mediolateral (ML) single-radius (Non Restricted Geometry; NRG) and ML dual-radius (Triathlon) during stair activities. Methods A total of 21 knees in 18 patients (NRG group: 10 knees in 7 patients, Triathlon group: 11 knees in 11 patients) with a clinically successful posterior stabilized TKA were examined. Under fluoroscopic surveillance, each patient performed stair ascending and descending motions. In vivo kinematics were analyzed using 2D/3D registration technique. The knee flexion angle, rotation angle, varus-valgus angle, AP translation of the femorotibial contact point for both the medial and lateral sides of the knee, and post-cam engagement were evaluated. Results There were no significant differences between the two groups in rotation angle and AP translation at each flexion angle. Examining the varus-valgus angle, the NRG group showed varus position at an early flexion angle during both stair activities. Post-cam engagement was observed in both groups during both stair activities. The mean flexion angle of engagement in the NRG group, the post of which was located anterior to the Triathlon, was larger than that in the Triathlon group during both stair activities. Conclusion Despite the same AP single-radius TKA, ML single-radius might affect varus motion at an early flexion angle.

Purpose: Graft failure or recurrence of instability without obvious trauma remains one of the problems following anterior cruciate ligament (ACL) reconstruction. This retrospective study aimed to identify risk factors for abnormal knee laxity after anatomical ACL reconstruction. Methods: A total of 291 patients who underwent primary anatomical ACL reconstruction were included in this study. Sex, age, body mass index (BMI), time to surgery, medial meniscal status, lateral meniscal status, graft materials, initial graft tension protocol, preoperative and postoperative pivot shift test and side-to-side differences in anterior tibial translation using the arthrometer were reviewed. Abnormal knee laxity was defined as constituting one or both of the following criteria: (i) a side-to-side difference of ≥3 mm by arthrometer; and (ii) a positive pivot shift test, being “glide,” “clunk”, or “gross”. Results: Abnormal knee laxity occurred in 30 patients (10.3%) at a median follow-up of 25 months. Results of univariate analysis indicated that a higher likelihood of abnormal knee laxity was associated with female sex, greater BMI, longer time to surgery, higher initial graft tension protocol, and lateral meniscus resection. Multivariate logistic regression analysis showed that abnormal knee laxity was significantly associated with time to surgery [1-month increase; odds ratio (OR), 1.01], higher initial graft tension protocol (vs. lower tension; OR, 3.5), and lateral meniscus resection (vs. intact and repaired lateral meniscus; OR, 12.8). Conclusion: Higher initial graft tension protocol, chronicity of ACL deficiency, and lateral meniscus resection were risk factors for abnormal knee laxity after anatomical ACL reconstruction. Level of evidence: Level III retrospective prognostic study.

Purpose: This study aimed to review the causes of failure after total knee arthroplasty (TKA), focusing on the causes of revision and persistent pain. Methods: A literature search was conducted in the databases of PubMed, Cochrane Library, and Google Scholar for articles published before October 4, 2022. In addition, registry data from 11 countries were obtained from national registry archives. Results: National registry data and recent articles show that aseptic loosening, infection, instability, patellofemoral complication, and pain are major overall causes of TKA revisions. The most common etiologies of TKA revisions were aseptic loosening in six countries and infection in four countries. In contrast, polyethylene wear has become one of the minor reasons for revision, although it used to be one of the major causes of revision. Additionally, various causes of persistent pain include improper component placement, oversizing, patellofemoral overstuffing, ligament imbalance, elevated joint lines, kinematic abnormalities, and preoperative psychological factors such as catastrophizing state and central sensitization of pain. Conclusions: With the evolution of surgical techniques and prosthetic designs, a paradigm shift in the etiology of failure mechanisms after TKA might have occurred. However, the number of patients with TKA failure suffering from persistent pain and requiring revision is increasing. Thus, orthopedic surgeons must understand the current situations of TKA failures to improve clinical outcomes and reduce post-TKA dissatisfaction.

Purpose: Attempts have been made to enhance knee prostheses design to improve clinical outcomes including bi-cruciate stabilized (BCS) TKA design and single-radius (SR) femoral component design. The complication rate of first generation BCS (fBCS) TKA was higher than that of standard TKA. Regarding BCS TKA, modification of the fBCS TKA system to the second-generation BCS (sBCS) TKA system was performed to avoid complications. This study aimed to compare the midterm clinical results of sBCS TKA and SR TKA. Methods: We retrospectively reviewed data from TKA patients. A total of 142 patients who were followed up for at least 5 years were enrolled: 61 TKAs using sBCS and 81 TKAs using the posterior stabilized (PS) single-radius (SR) design. The clinical results at 6 months, 2 years, and 5 years postoperatively were compared between the sBCS and SR PS groups. Results: At 6 months postoperatively, the maximum flexion angle (MFA) of the sBCS group was larger than that of the SR PS group. At 2 years, MFA, KOOS subscales of pain and ADL in the sBCS group were better and at 5 years, the MFA, KOOS subscales of pain and QOL in the sBCS group were better than those in the SR group. There was no significant differences of the ratios of complications and revision surgeries between the two groups. Conclusion: The midterm clinical results of sBCS TKA were better than those of SR PS TKA in terms of the MFA and KOOS subscales of pain and QOL.

Purpose: “Rotational self-alignment mechanism'' was designed for mobile-bearing total knee arthroplasty (MB TKA) to maintain a natural femorotibial rotational alignment independent of component rotational alignment. However, it is clinically unknown if the influence of component rotational alignment on a postoperative anatomical femorotibial rotational angle (FTRA) in MB TKA is eliminated. This study aimed to determine the effect of component rotational alignments on postoperative anatomical FTRA in MB TKA as compared to fixed-bearing TKA (FB TKA). Methods: This research comprised a total of 161 knees: 54 ​MB TKAs and 107 FB TKAs. In computed tomography, the postoperative FTRA and rotational alignment of tibial and femoral components to anatomical axes were assessed, and the association between the postoperative FTRA and perioperative radiographic data, including component rotational alignments, was examined. Result: Rotational alignments of both tibial and femoral components did not correlate postoperative FTRA in MB TKA (tibial component: r ​= ​−0.15, p ​= ​0.26, femoral component: r ​= ​0.22, p ​= ​0.10), however, in FB TKA, rotational alignment of tibial component did correlate postoperative FTRA, while that of femoral component did not (tibial component: r ​= ​−0.65, p ​

Abstract Background Bicruciate-retaining (BCR) prosthesis has been introduced to recreate normal knee movement by preserving both the anterior and posterior cruciate ligaments. However, the use of BCR total knee arthroplasty (TKA) is still debatable because of several disappointing reports. We have been performing BCR TKAs with personalized alignment (PA). This study aimed to reveal the limb alignment and soft tissue balance of FA-BCR TKAs and compare the clinical outcomes of FA-BCR TKAs with those of unicompartmental knee arthroplasty (UKA). Methods Fifty BCR TKAs and 58 UKAs were included in this study. The joint component gaps of BCR TKA were evaluated intraoperatively and the postoperative hip–knee–ankle (HKA) angle, medial proximal tibial angle (MPTA), and lateral distal femoral angle (LDFA) were measured using full-length standing radiography. The short-term clinical outcomes of BCR TKAs were compared with those of UKA using the scoring system of 2011 Knee Society Scoring (KSS) and the knee injury and osteoarthritis outcome score (KOOS) at an average of 2 years postoperatively (1-4yeras). Results The coronal alignment values of PA-BCR TKA were as follows: HKA angle, 177.9° ± 2.3°; MPTA, 85.4° ± 1.9°; and LDFA, 87.5° ± 1.9°. The joint component gaps at flexion angles of 10°, 30°, 60°, and 90° were 11.1 ± 1.2, 10.9 ± 1.4, 10.7 ± 1.3, and 11.2 ± 1.4 mm for the medial compartment and 12.9 ± 1.5, 12.6 ± 1.8, 12.5 ± 1.8 and 12.5 ± 1.7 mm for the lateral compartment, respectively. The patient expectation score and maximum extension angle of PA-BCR TKA were significantly better than those of UKAs. Conclusions The short-term clinical outcomes of PA-BCR TKA were comparable or a slightly superior to those of UKAs.

Abstract Background Given rapid aging of the global population, preventing adverse events such as falls is essential for preserving functional capacity and quality of life among older adults, especially those at high risk due to hemodialysis (HD) treatment. We aimed to investigate the effects of a 3-year intradialytic exercise intervention on fall occurrence and physical performance in older patients undergoing HD. Methods Sixty-one patients were non-randomly assigned to the exercise (n = 31) and control groups (n = 30). The exercise group performed aerobic and resistance training during HD three times per week for 3 years. Handgrip strength, lower extremity muscle strength, 10-m walking speed, and Short Physical Performance Battery (SPPB) scores were assessed at baseline. Physical function was reassessed every year in the exercise group. All participants were followed up until the first fall or the end of the study period. Results There were no significant between-group differences in baseline data. Over a median follow-up of 35 months, 10 (16.3%) falls occurred, including 1 (3.2%) in the exercise group and 9 (30%) in the control group. Kaplan–Meier analysis revealed that the exercise intervention significantly reduced the occurrence of falls. No significant differences in physical function were observed among four time points in patients who completed the 3-year program. Conclusion Intradialytic exercise may represent an essential intervention for preventing falls in older patients undergoing HD. Trial registration: This study was retrospectively registered with the University Hospital Medical Information Network (UMIN 00044821, February 4, 2021).

Abstract Introduction Walking ability is an important prognostic factor for patients undergoing maintenance hemodialysis (HD). Since complications such as poor nutrition, anemia, malnutrition, and inflammation in patients undergoing HD may affect walking ability, the factors affected by 10-m walking speed must be investigated. This cross-sectional study enrolled 1205 outpatients undergoing HD and measured their 10-m walking speed. Methods Lower extremity muscle strength (LES), grip strength, one-leg standing time (OLST), and short physical performance battery (SPPB) score were measured as physical functions. Age, sex, body mass index, dialysis history, comorbidities, and hematological data were collected. Results A multiple regression analysis revealed that the 10-m walking speed was significantly associated with LES, grip strength, OLST, SPPB, and % creatinine production rate, even after adjusting for corresponding variables (R 2 = 0.69, p

Abstract Background Given the frequency of hamstring strain injuries (HSI) among male college American football players, several studies have attempted to determine whether certain risk factors can predict their occurrence. However, no consensus on modifiable risk factors for HSIs in male college American football players has yet been reached to prevent these injuries. This study aimed to clarify risk factors for HSI prospectively in college male American football players. Methods A total of 78 male college American football players, whose positions were limited to skill positions, were medically assessed for potential risk factors of HSI. The preseason medical assessment included anthropometric measurements, joint laxity and flexibility, muscle flexibility, muscle strength, and balance ability. Results HSI occurred in a total of 25 thighs from 25 players (32.1%). Injured players had significantly lower hamstring flexibility (p = 0.02) and hamstring to quadriceps strength ratio (H/Q) (p = 0.047) compared to uninjured players. Additionally, injured players had significantly lower general joint laxity scores, especially for the total (p = 0.04), hip (p = 0.007), and elbow (p = 0.04) scores, compared to uninjured players. Conclusions Lower hamstring flexibility, lower hamstring to quadriceps strength ratio, and lower general joint laxity score were identified as risk factors for HSI in male college American football players placed in skill positions. The muscle flexibility and H/Q ratio could be useful in preventing HSI in such players.

Background: Tunnel widening (TW) after anterior cruciate ligament (ACL) reconstruction has been a research area of interest in ACL reconstruction. In recent years, it has been noted that posterior tibial slope (PTS) affects several types of outcomes after ACL reconstruction including TW. However, the relationships between femoral and tibial TW and between PTS and TW following anatomical ACL reconstruction using a bone–patellar tendon–bone (BTB) graft are often not understood. Therefore, the purpose of this study was to retrospectively clarify the magnitude of femoral and tibial TW and the effect of PTS on TW following anatomical ACL reconstruction using a BTB graft. Methods: A total of 111 patients who underwent isolated ACL reconstructions using BTB grafts were included in this study. Femoral and tibial tunnel aperture areas were measured using three-dimensional computed tomography (3D CT) at 1 week and 1 year postoperatively, and femoral and tibial TW (%) was calculated. Lateral and medial PTS was also measured using 3D CT. Results: As compared with 1 week postoperatively, the mean tibial tunnel aperture areas increased by 30.6% ± 28.5%, and the mean femoral tunnel aperture areas increased by 28.3% ± 27.9% when measured at 1 year postoperatively. Although no significant difference was observed between femoral and tibial TW, a significant positive correlation was noted between femoral and tibial TW (r = 0.240, p = 0.011). A significant correlation was observed only between lateral PTS and tibial TW (r = 0.354, p

Abstract Background In bicruciate-stabilized total knee arthroplasty (BCS-TKA), the relationship between the postoperative kinematics and sports subscales in patient-reported outcome measures (PROMs) remains unknown. The purpose of this study was to determine the relationship between kinematics and sports subscales using the PROMs after BCS-TKA. Methods Sixty-one patients with severe knee osteoarthritis were examined at 13.5 ± 7.8 months after BCS-TKA. The patients performed squats under single fluoroscopic surveillance in the sagittal plane. Range of motion of the knee, axial rotation of the femur relative to the tibial component, and anteroposterior (AP) translation of the medial and lateral femorotibial contact points were measured using a 2D-to-3D registration technique. In addition, the relationship between the kinematics and improvement of the sports subscales in the Knee Injury and Osteoarthritis Outcome Score (KOOS) was evaluated. Results In rotation angle, the femoral external rotation was observed from 0 to 50° of flexion. The amount of femoral external rotation did not correlate with PROMs-SP. In medial AP translation, posterior translation was observed from 0 to 20° and 80–110° of flexion. Mild anterior translation was observed from 20 to 80° of flexion. Beyond 80° of flexion, posterior translation was positively correlated with squatting. In lateral AP translation, posterior translation was observed from 0 to 20° and 80–110° of flexion. Beyond 80° of flexion, posterior translation was positively correlated with running, jumping, twisting/pivoting, and kneeling. Conclusion Femoral rollback at high flexion during squatting may be important to improve sports performance after BCS-TKA.

Abstract Background The choice of mobile bearing (MB) thickness is essential for obtaining successful results after mobile-bearing Oxford unicompartmental knee arthroplasty (UKA). This study aimed to investigate the effects of a 1-mm difference in bearing thickness on intraoperative MB movement and intraoperative knee kinematics in Oxford UKAs. Methods We prospectively investigated the effects of a 1-mm difference in bearing thickness on intraoperative MB movement and knee kinematics in 25 patients who underwent Oxford UKAs when surgeons didn’t know which bearing thickness to choose with 1-mm difference. A trial tibial component that was scaled every 2 mm was used to measure the intraoperative MB movement, and the tibial internal rotation relative to the femur and the knee varus angle was simultaneously evaluated using the navigation system as the knee kinematics. We separately evaluated sets of two MB thicknesses with 1-mm differences, and we compared the intraoperative parameters at maximum extension; 30º, 45º, 60º, and 90º flexion; and maximum flexion between the thicker MB (thick group) and the thinner MB (thin group). Results The MB in the thin group was located significantly posteriorly at 90º flexion compared with that in the thick group; however, there were no differences at the other flexion angles. There was significantly less tibial internal rotation in the thin group at 90º flexion than that in the thick group; however, there were no differences at the other flexion angles. The knee varus angles in the thick group were significantly smaller than those in the thin group by approximately one degree at all angles other than at 30º and 45º flexion. Conclusion The thicker MB could bring the less posterior MB movement and the more tibial internal rotation at 90º flexion, additionally the valgus correction angle in the thicker MB should be paid attention. These results could help surgeons to decide the thickness of MBs when they wonder the thickness of MB.

Abstract Background The normal knee kinematics during asymmetrical kneeling such as the sitting sideways remains unknown. This study aimed to clarify in vivo kinematics during sitting sideways of normal knees. Methods Twelve knees from six volunteers were examined. Under fluoroscopy, each volunteer performed a sitting sideways. A two-dimensional/three-dimensional registration technique was used. The rotation angle, varus-valgus angle, anteroposterior translation of the medial and lateral sides of the femur relative to the tibia, and kinematic pathway in each flexion angle was evaluated. Results Bilateral knees during sitting sideways showed a femoral external rotation relative to the tibia with flexion (ipsilateral: 13.7 ± 3.5°, contralateral: 5.8 ± 6.8°). Whereas the ipsilateral knees showed valgus movement of 4.6 ± 2.5° from 130° to 150° of flexion, and the contralateral knees showed varus movement of -3.1 ± 4.4° from 110° to 150° of flexion. The medial side of the contralateral knees was more posteriorly located than that of the ipsilateral knees beyond 110° of flexion. The lateral side of the contralateral knees was more anteriorly located than that of the ipsilateral knees from 120° to 150° of flexion. In the ipsilateral knees, a medial pivot pattern followed by a bicondylar rollback was observed. In the contralateral knees, no significant movement followed by a bicondylar rollback was observed. Conclusion Even though the asymmetrical kneeling such as sitting sideways, the knees did not display asymmetrical movement.

Abstract Background The first objective of this study was to determine the relationship between muscle strength or physical performance and mortality, and the second objective was to show the relationship of Geriatric Nutritional Risk Index (GNRI) to muscle strength and physical performance decline. Methods We examined handgrip, the 5-times chair stand test, and GNRI in 635 maintenance hemodialysis patients and followed up for 72 months. Predictors for all-cause death were examined using Kaplan-Meier analysis and Cox proportional analysis. The relationship between possible sarcopenia and nutritional disorder (GNRI) was constructed receiver operating characteristic (ROC) curve. We used the Youden index to determine the optimal cutoff points for GNRI. Results The multivariate Cox proportional hazard analysis revealed that the GNRI did not show any significance, although handgrip (HR 3.61, 95% CI 1.70–7.68, p

Abstract Background Tibial internal rotation following total knee arthroplasty (TKA) is important in achieving favorable postoperative clinical outcomes. Studies have reported the effect of intraoperative soft tissue balance on tibial internal rotation in conventional TKA, no studies have evaluated the effects of soft tissue balance at medial or lateral compartments separately on tibial internal rotation in bi-cruciate stabilized (BCS) TKA. The purpose of this study was to clarify the relationship between medial or lateral component gaps and rotational knee kinematics in BCS TKA. Methods One hundred fifty-eight knees that underwent BCS TKA were included in this study. The intraoperative medial and lateral joint laxities which was defined as the value of component gap minus the thickness of the tibial component were firstly divided into two groups, respectively: Group M-stable (medial joint laxity, ≤ 2 mm) or Group M-loose (medial joint laxity, ≥ 3 mm) and Group L-stable (lateral joint laxity, ≤ 3 mm) or Group L-loose (lateral joint laxity, ≥ 4 mm). And finally, the knees enrolled in this study were divided into four groups based on the combination of Group M and Group L: Group A (M-stable and L-stable), Group B (M-stable and L-loose), Group C (M-loose and L-stable), and Group D (M-loose and L-loose). The intraoperative rotational knee kinematics were compared between the four Groups at 0°, 30°, 60°, and 90° flexion, respectively. Results The rotational angular difference between 0° flexion and maximum flexion in Group B at 30° flexion was significantly larger than that in Group A at 30° flexion (*p

Abstract We analyzed the implantation effects on cruciate ligament force in unicompartmental knee arthroplasty (UKA) and determined whether kinematics is associated with the cruciate ligament force. We examined 16 patients (17 knees) undergoing medial UKA. Under fluoroscopy, each participant performed a deep knee bend before and after UKA. A two-dimensional/three-dimensional registration technique was employed to measure tibiofemoral kinematics. Forces in the anteromedial and posterolateral bundles of both the anterior cruciate ligament (aACL and pACL) and the anterolateral and posteromedial bundles of the posterior cruciate ligament (aPCL and pPCL) during knee flexion were analyzed pre- and post-UKA. Correlations between changes in kinematics and ligament forces post-UKA were also analyzed. Preoperatively, the aACL forces were highly correlated with anteroposterior (AP) translation of the lateral condyles (Correlation coefficient [r] = 0.59). The pPCL forces were highly correlated with the varus–valgus angulation (r = − 0.57). However, postoperatively, the PCL forces in both bundles were highly correlated with the AP translation of the medial femoral condyle (aPCL: r = 0.62, pPCL: r = 0.60). The ACL and PCL forces of the knees post-UKA were larger than those of the knees pre-UKA. Kinematic changes were significantly correlated with the cruciate ligament force changes.

Abstract Background This study aims to elucidate and compare the relationship between the knee flexion angle and patient-reported outcome measures (PROM) in both non-weight-bearing (NWB) and weight-bearing (WB) conditions. Methods This retrospective cohort study included 61 knees (47 patients) who underwent total knee arthroplasty. The knee flexion angle was measured by three conditions: NWB in manual goniometer, NWB in fluoroscopic three-dimensional (3D) analysis and WB in the fluoroscopic 3D analysis. The PROM was evaluated by postoperative 2011 Knee Society Score (2011 KSS) and Knee injury and Osteoarthritis Outcome Score (KOOS). Correlations between the knee flexion angle and PROM was analyzed using Spearman’s correlation coefficient. Additionally, whether the angular difference between NWB and WB correlated with the PROM or not was evaluated. Results The NWB knee flexion angle in a goniometer, NWB in 3D analysis, and WB in 3D analysis were 124.6° ± 8.4°, 118.0° ± 10.5°, and 109.5° ± 13.3°, respectively. The angular difference was 8.5° ± 12.8°. No PROM correlation existed in NWB using a goniometer. Moreover, significant positive correlations in 2011 KSS symptoms (r = 0.35) and 2011 KSS functional activities (r = 0.27) were noted in NWB using 3D analysis. Significant positive correlations existed in 2011 KSS symptoms (r = 0.32), 2011 KSS functional activities (r = 0.57), KOOS pain (r = 0.37), KOOS activity of daily living (ADL; r = 0.45), KOOS sports (r = 0.42), and KOOS quality of life (r = 0.36) in WB using 3D analysis. Significant negative correlations were noted in 2011 KSS functional activities (r = − 0.45), KOOS ADL (r = − 0.30), and KOOS sports (r = − 0.38) in angular difference. Conclusions The WB knee flexion angle better correlated with PROM compared with NWB by evaluation of 3D analysis. The larger the angular difference existed between NWB and WB, the lower the PROM score.

Abstract Background Although Oxford unicompartmental knee arthroplasty (UKA) is used in patients of wide age ranges, there is no clear information regarding the age differences in terms of intraoperative femorotibial rotational kinematics and its influence on clinical outcomes. Therefore, this study was conducted to examine the age differences in terms of intraoperative rotational kinematics and postoperative clinical outcomes and to analyze their relationship with classification according to the age group. Methods We investigated 111 knees of patients who underwent Oxford UKA using a navigation system and divided them into two groups: elderly (aged ≥75 years; 48 knees) and nonelderly (aged

Abstract Background Low physical fitness is often found in patients undergoing hemodialysis. It may be possible that the recovery of impaired motor function with rehabilitative training might be affected when the patient is on hemodialysis. So far, however, no researcher has clinically investigated this issue in post-stroke patients. The purpose of this study is to clarify the difference of functional recovery during the convalescent phase between post-stroke patients with and without hemodialysis. Methods A cohort of 82 post-stroke hemiparetic patients who were admitted to our rehabilitation hospital, were subjected. On the day of admission and discharge, some clinical parameters including Functional Independence Measure (FIM) and Functional Ambulation Category (FAC) were evaluated for each patient. The changes during the hospitalization and the values at the discharge in these parameters were statistically compared between the patients with and without hemodialysis. Results The FIM motor score at the discharge was significantly lower in hemodialysis patients than non-hemodialysis patients (64.7 ± 21.2 points in hemodialysis patients and 81.8 ± 28.0 points in non-hemodialysis patients, p < 0.05). In addition, the frequency of FAC at the discharge of ≥ 3 was significantly lower in hemodialysis patients than non-hemodialysis patients (40.0% in hemodialysis patients and 72.2% in non-hemodialysis patients, p < 0.05). Conclusion In patients undergoing hemodialysis seem to experience a worse functional recovery during the convalescent phase compared to those not undergoing hemodialysis. We might have to modify the rehabilitative program during the convalescent phase after stroke if the patient was on hemodialysis.

Abstract Background The risk of adverse events associated with peritoneal dialysis (PD) in elderly patients has not been thoroughly investigated. The purpose of this study was to assess the association between physical function and hospitalization in elderly PD patients. Methods This is a single-center prospective observational cohort study. Thirty-three aged patients (74.8 ± 5.9 years) participated in a 6-min walk distance, short physical performance battery (SPPB), lower extremity muscle strength, and 10-m walk speed. All subjects were followed until hospitalization to the end of the follow-up period. Results The 6-min walk distance was 332 ± 112.5 m; SPPB was 11 (8.3–12) points; the lower extremity muscle strength was 36.6 ± 9.6%; 10-m walk speed was 1.1± 0.2 m/s. During the follow-up, 19 patients (57.5%) were hospitalized. In the Kaplan-Meier survival analysis and log-rank test, a lower 6-min walk distance and PD vintage were significantly associated with hospitalization (p

Abstract We analyzed the effects of bicruciate-retaining total knee arthroplasty (BCR-TKA) on knee kinematics and cruciate ligament forces. Patients (N = 15) with osteoarthritis (OA) and an intact anterior cruciate ligament (ACL) underwent magnetic resonance imaging and single-plane fluoroscopy to measure tibiofemoral kinematics during two deep knee bend activities before and after BCR-TKA: (1) weight-bearing squat; (2) non-weight-bearing cross-legged sitting. Forces in ligament bundles were calculated using VivoSim. The dynamic range of varus-valgus angulation decreased from 3.9 ± 4.4° preoperatively to 2.2 ± 2.7° postoperatively. Preoperatively, the medial femoral condyle translated anteriorly from 10° to 50° of flexion, and posteriorly beyond 50° of flexion. Postoperatively, the medial and lateral femoral condyles translated posteriorly throughout flexion in a medial pivot pattern. ACL forces were high in extension and decreased with flexion pre- and postoperatively. PCL forces increased with flexion preoperatively and did not change significantly postoperatively. Preoperatively, ACL forces correlated with anteroposterior translation of the femoral condyles. Postoperatively, PCL forces correlated with anteroposterior translation of the lateral femoral condyle. BCR-TKA altered knee kinematics during high flexion activity which correlated significantly with changes in cruciate ligament forces.

Abstract Background One of the causes of dissatisfaction following total knee arthroplasty (TKA) is abnormal knee kinematics. A newly designed bi-cruciate stabilized (BCS) TKA system has been developed to produce close-to-normal kinematics because of its anatomic tibiofemoral articular geometry and cam-post mechanism. Although BCS TKA is expected to improve patient satisfaction, no reports have described the appropriate technique or soft tissue handling required to achieve excellent satisfaction with BCS TKA. This study is to identify intraoperative surgical predictors of patient satisfaction after BCS TKA. Methods We studied 104 knees with primary varus knee osteoarthritis that underwent BCS TKA with a navigation system retrospectively. Surgical parameters including coronal, sagittal and axial alignment and joint laxity in each compartment that affected patient satisfaction was evaluated. Satisfaction score was evaluated with use of the 2011 Knee Society Scoring system. The multivariate regression analysis included age, gender, body mass index and intraoperative parameters that correlated with satisfaction scores in the univariate analysis (P

Abstract Background Few studies compared the length change of ligaments of normal knees during dynamic activities of daily living. The aim of this study was to investigate in vivo length change of ligaments of the normal knees during high flexion. Methods Eight normal knees were investigated. Each volunteer performed squatting, kneeling, and cross-leg motions. Each sequential motion was performed under fluoroscopic surveillance in the sagittal plane. The femoral, tibial, and fibular attachment areas of the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), deep medial collateral ligament (dMCL), superficial medial collateral ligament (sMCL), and lateral collateral ligament (LCL) were determined according to osseous landmarks. After 2D/3D registration, the direct distance from the femoral attachment to the tibial or fibular attachment was measured as the ligament length. Results From 20° to 90° with flexion, the ACL was significantly shorter during cross-leg motion than during squatting. For the PCL, dMCL, sMCL, and LCL, there were no significant differences among the 3 motions. Conclusion The ACL was shorter during cross-leg motion than during squatting in mid-flexion. This suggests that the ACL is looser during cross-leg motion than during squatting. On the other hand, the length change of the PCL, MCL, and LCL did not change even though the high flexion motions were different.

Abstract Background This study investigated the association between the blood pressure response during hemodialysis (HD) and exercise tolerance or heart rate recovery (HRR) measured with cardiopulmonary exercise testing (CPX). Methods The study enrolled 23 patients who had been undergoing 4-h regular maintenance HD. The maximum workload (Loadpeak), peak oxygen uptake (VO2peak), workload and oxygen uptake at the anaerobic threshold (LoadAT and VO2AT, respectively), and HRR were measured with CPX. The average systolic blood pressure during HD (SBPav) was measured, and the number of times the SBP was less than 100 mmHg was determined in the 2-week period after CPX. Results The SBPav showed a significant correlation with LoadAT (r = 0.46) and Loadpeak (r = 0.43, p < 0.05). The number of times the SBP was less than 100 mmHg showed a significant correlation with the HRR (r = − 0.44, p < 0.05). Conclusion Exercise intolerance and HRR in HD patients may be associated with blood pressure instability during HD.

Patients with chronic kidney disease require intervention planning because their physical function declines with worsening disease. Providers can work closely with patients during the induction phase of dialysis. This single-center, retrospective observational study aimed to investigate the rate of decline in walking independence during the induction phase of dialysis and the factors that influence this decline, and to provide information on prevention and treatment during this period. Of the 354 patients who were newly initiated on hemodialysis between April 2018 and January 2022, 285 were included in the analysis. The functional independence measure-walking score was used to sort patients into decreased walking independence (DWI; n = 46) and maintained walking independence (no DWI; n = 239) groups, and patient characteristics were compared. After adjusting for various factors by logistic regression analysis, we observed that age, high Charlson comorbidity index (CCI), C-reactive protein, and emergency dialysis start (EDS) were significant predictors of DWI. Even during the very short period of dialysis induction, as many as 16.1% of patients had DWI, which was associated with older age, higher CCI, higher inflammation, and EDS. Therefore, we recommend the early identification of patients with these characteristics and early rehabilitation.

Background: One of the causes of dissatisfaction following total knee arthroplasty (TKA) is abnormal knee kinematics. A newly designed bi-cruciate stabilized (BCS) TKA system has been developed to produce close-to-normal kinematics because of its anatomic tibiofemoral articular geometry and cam-post mechanism. Although BCS TKA is expected to improve patient satisfaction, no reports have described the appropriate technique or soft tissue handling required to achieve excellent satisfaction with BCS TKA. This study is to identify preoperative and intraoperative predictors of patient satisfaction after BCS TKA. Methods: Altogether, we studied 113 knees with primary varus knee osteoarthritis that underwent BCS TKA with a navigation system. Preoperative parameters including Knee Society Score and patient-reported scores [the Knee injury and Osteoarthritis Outcome Score (KOOS)] and intraoperative parameters including coronal, sagittal and axial alignment and joint laxity in each compartment that affected patient satisfaction was evaluated. Satisfaction score was evaluated with use of the 2011 Knee Society Scoring system. The multivariate regression analysis included age and preoperative and intraoperative parameters that correlated with satisfaction scores in the univariate analysis ( P < 0.05). Results: The mean satisfaction score was 28.2 ± 6.1. Multivariate regression analysis showed that the predictors of patient satisfaction were a preoperative high KOOS score for activities of daily living ( P < 0.001), male sex ( P = 0.005), older age ( P = 0.027), and minimal medial joint laxity during flexion ( P = 0.031). Conclusion: When performing BCS TKA, surgeons should pay attention to maintaining proper stability of the medial compartment, especially during flexion.

Abstract Background Reduced muscle strength and physical performance are prevalent in patients of maintenance hemodialysis (MHD), and deleterious changes in these parameters are associated with increased mortality. Methods This retrospective observational study included 306 patients, who received a 6-month resistance exercise program during hemodialysis, three times per week on an outpatient basis. The training protocol consisted of two sets of 10 repetitions of knee extension, hip abduction, and hip flexion, using an elastic band in a sitting or supine position. Primary outcome measures included muscle strength, measured by percent knee extension muscle power to dry body weight (pKEMP-dBW), and physical performance, measured by short physical performance battery (SPPB). The adjusted mean differences in these variables during the 6 months were estimated using a multivariate linear regression model. Results The mean age with standard deviation was 70 ± 11 years. One hundred and sixty patients (52.3%) were men and the dry weight was 55.6 ± 11.3 kg. Sarcopenia, defined as SPPB ≤8, was present in 21.4% patients. Their hemodialysis adequacy was acceptable, with a Kt/V of 1.65 ± 0.29, and their nutritional status was good, with a normalized protein catabolism rate of 0.89 ± 0.18 g/kg/day. During the 6 months, both pKEMP-dBW and SPPB showed a slight but significant increase with an adjusted mean difference of 2.8 (95% confidence interval 1.3–4.3, p

Previous reports have shown the benefits of intradialytic exercise to patients undergoing hemodialysis. However, most of those studies assessed the effects of exercise in middle-aged patients and little is known about advanced-age patients undergoing hemodialysis. Therefore, the present randomized controlled trial was performed to determine the effectiveness of exercise therapy in advanced-age patients undergoing hemodialysis. This non-blinded, randomized controlled parallel trial enrolled a total of 101 patients who were randomly assigned to intradialytic exercise (n = 51) or usual care (n = 50) groups. The training program included both resistance and aerobic exercises and was performed three times per week for 6 months. The aerobic exercise intensity was adjusted to a target Borg score of 13 for 20 minutes. Four types of resistance exercises were performed using elastic tubing, with three sets of 10 exercises performed at moderate intensity (13/20 on the Borg scale). The usual care group received standard care. Lower extremity muscle strength, Short Physical Performance Battery score, and 10-m walking speed were the outcomes and were evaluated before the hemodialysis session and after 6 months of training. There were statistically significant improvements in Short Physical Performance Battery score (effect size, 0.57; 95% confidence interval, 0.15‒1.95) in the exercise group relative to the control group. There were no statistically significant differences in lower extremity muscle strength or in the 10-m walking speed between the two groups. These findings suggest that 6 months of intradialytic training could improve physical function in older patients undergoing hemodialysis.

Corticosteroids are most commonly used to treat HTLV-1-associated myelopathy (HAM); however, their clinical efficacy has not been tested in randomized clinical trials. This randomized controlled trial included 8 and 30 HAM patients with rapidly and slowly progressing walking disabilities, respectively. Rapid progressors were assigned (1:1) to receive or not receive a 3-day course of intravenous methylprednisolone in addition to oral prednisolone therapy. Meanwhile, slow progressors were assigned (1:1) to receive oral prednisolone or placebo. The primary outcomes were a composite of ≥1-grade improvement in the Osame Motor Disability Score or ≥30% improvement in the 10 m walking time (10 mWT) at week 2 for rapid progressors and changes from baseline in 10 mWT at week 24 for slow progressors. In the rapid progressor trial, all four patients with but only one of four without intravenous methylprednisolone achieved the primary outcome (p = 0.14). In the slow progressor trial, the median changes in 10 mWT were −13.8% (95% CI: −20.1–−7.1; p < 0.001) and −6.0% (95% CI: −12.8–1.3; p = 0.10) with prednisolone and placebo, respectively (p for between-group difference = 0.12). Whereas statistical significance was not reached for the primary endpoints, the overall data indicated the benefit of corticosteroid therapy. (Registration number: UMIN000023798, UMIN000024085)

BACKGROUND: Recent clinical studies have shown that recanalization rates are lower in stent-assisted coil embolization than in coiling alone in the treatment of cerebral aneurysms. OBJECTIVE: This study aimed to assess and compare the hemodynamic effect of stent struts and straightening of vessels by stent placement on reducing flow velocity in sidewall aneurysms, with the goal of reducing recanalization rates. METHODS: We evaluated 16 sidewall aneurysms treated with Enterprise stents. We performed computational fluid dynamics simulations using patient-specific geometries before and after treatment, with or without stent struts. RESULTS: Stent placement straightened vessels by a mean (±standard deviation) of 12.9° ± 13.1° 6 months after treatment. Placement of stent struts in the initial vessel geometries reduced flow velocity in aneurysms by 23.1% ± 6.3%. Straightening of vessels without stent struts reduced flow velocity by 9.6% ± 12.6%. Stent struts had significantly stronger effects on reducing flow velocity than straightening (P = 0.004, Wilcoxon test). Deviation of the effects was larger by straightening than by stent struts (P = 0.01, F-test). The combination of stent struts and straightening reduced flow velocity by 32.6% ± 12.2%. There was a trend that larger inflow angles produced a larger reduction in flow velocity by straightening of vessels (P = 0.16). CONCLUSION: In sidewall aneurysms, stent struts have stronger effects (approximately 2 times) on reduction in flow velocity than straightening of vessels. Hemodynamic effects by straightening vary in each case and can be predicted by inflow angles of pre-operative vessel geometry. These results may be useful to design a treatment strategy for reducing recanalization rates.