Radiomics as a measure superior to common similarity metrics for tumor segmentation performance evaluation.

PURPOSE: To propose radiomics features as a superior measure for evaluating the segmentation ability of physicians and auto-segmentation tools and to compare its performance with the most commonly used metrics: Dice similarity coefficient (DSC), surface Dice similarity coefficient (sDSC), and Hausdorff distance (HD). MATERIALS/METHODS: The data of 10 lung cancer patients' CT images with nine tumor segmentations per tumor were downloaded from the RIDER (Reference Database to Evaluate Response) database. Radiomics features of 90 segmented tumors were extracted using the PyRadiomics program. The intraclass correlation coefficient (ICC) of radiomics features were used to evaluate the segmentation similarity and compare their performance with DSC, sDSC, and HD. We calculated one ICC per radiomics feature and per tumor for nine segmentations and 36 ICCs per radiomics feature for 36 pairs of nine segmentations. Meanwhile, there were 360 DSC, sDSC, and HD values calculated for 36 pairs for 10 tumors. RESULTS: The ICC of radiomics features exhibited greater sensitivity to segmentation changes than DSC and sDSC. The ICCs of the wavelet-LLL first order Maximum, wavelet-LLL glcm MCC, wavelet-LLL glcm Cluster Shade features ranged from 0.130 to 0.997, 0.033 to 0.978, and 0.160 to 0.998, respectively. On the other hand, all DSC and sDSC were larger than 0.778 and 0.700, respectively, while HD varied from 0 to 1.9 mm. The results indicated that the radiomics features could capture subtle variations in tumor segmentation characteristics, which could not be easily detected by DSC and sDSC. CONCLUSIONS: This study demonstrates the superiority of radiomics features with ICC as a measure for evaluating a physician's tumor segmentation ability and the performance of auto-segmentation tools. Radiomics features offer a more sensitive and comprehensive evaluation, providing valuable insights into tumor characteristics. Therefore, the new metrics can be used to evaluate new auto-segmentation methods and enhance trainees' segmentation skills in medical training and education.

Rich-club organization of whole-brain spatio-temporal multilayer functional connectivity networks.

Objective: In this work, we propose a novel method for constructing whole-brain spatio-temporal multilayer functional connectivity networks (FCNs) and four innovative rich-club metrics. Methods: Spatio-temporal multilayer FCNs achieve a high-order representation of the spatio-temporal dynamic characteristics of brain networks by combining the sliding time window method with graph theory and hypergraph theory. The four proposed rich-club scales are based on the dynamic changes in rich-club node identity, providing a parameterized description of the topological dynamic characteristics of brain networks from both temporal and spatial perspectives. The proposed method was validated in three independent differential analysis experiments: male-female gender difference analysis, analysis of abnormality in patients with autism spectrum disorders (ASD), and individual difference analysis. Results: The proposed method yielded results consistent with previous relevant studies and revealed some innovative findings. For instance, the dynamic topological characteristics of specific white matter regions effectively reflected individual differences. The increased abnormality in internal functional connectivity within the basal ganglia may be a contributing factor to the occurrence of repetitive or restrictive behaviors in ASD patients. Conclusion: The proposed methodology provides an efficacious approach for constructing whole-brain spatio-temporal multilayer FCNs and conducting analysis of their dynamic topological structures. The dynamic topological characteristics of spatio-temporal multilayer FCNs may offer new insights into physiological variations and pathological abnormalities in neuroscience.

Test-retest reliability of resting-state cerebral blood flow quantification using pulsed Arterial Spin Labeling (PASL) over 3 weeks vs 8 weeks in healthy controls.

Arterial Spin Labeling is a valuable functional imaging tool for both clinical and research purposes. However, little is known about the test-retest reliability of cerebral blood flow measurements over longer periods. In this study, we investigated the reliability of pulsed Arterial Spin Labeling in assessing cerebral blood flow over a 3 (n = 28) vs 8 (n = 19) weeks interscan interval in 47 healthy participants. As a measure of cerebral blood flow reliability, we calculated voxel-wise, whole-brain, and regions of interest intraclass correlation coefficients. The whole-brain mean resting-state cerebral blood flow showed good to excellent reliability over time for both periods (intraclass correlation coefficients = 0.85 for the 3-week delay, intraclass correlation coefficients = 0.53 for the 8-week delay). However, the voxel-wise and regions of interest intraclass correlation coefficients fluctuated at 8-week compared to the 3-week interval, especially within cortical areas. These results confirmed previous findings that Arterial Spin Labeling could be used as a reliable method to assess brain perfusion. However, as the reliability seemed to decrease over time, caution is warranted when performing correlations with other variables, especially in clinical populations.

Test-retest reliability and time-of-day variations of perfusion imaging at rest and during a vigilance task.

Arterial spin-labeled perfusion and blood oxygenation level-dependent functional MRI are indispensable tools for noninvasive human brain imaging in clinical and cognitive neuroscience, yet concerns persist regarding the reliability and reproducibility of functional MRI findings. The circadian rhythm is known to play a significant role in physiological and psychological responses, leading to variability in brain function at different times of the day. Despite this, test-retest reliability of brain function across different times of the day remains poorly understood. This study examined the test-retest reliability of six repeated cerebral blood flow measurements using arterial spin-labeled perfusion imaging both at resting-state and during the psychomotor vigilance test, as well as task-induced cerebral blood flow changes in a cohort of 38 healthy participants over a full day. The results demonstrated excellent test-retest reliability for absolute cerebral blood flow measurements at rest and during the psychomotor vigilance test throughout the day. However, task-induced cerebral blood flow changes exhibited poor reliability across various brain regions and networks. Furthermore, reliability declined over longer time intervals within the day, particularly during nighttime scans compared to daytime scans. These findings highlight the superior reliability of absolute cerebral blood flow compared to task-induced cerebral blood flow changes and emphasize the importance of controlling time-of-day effects to enhance the reliability and reproducibility of future brain imaging studies.

CT radiomic features reproducibility of virtual non-contrast series derived from photon-counting CCTA datasets using a novel calcium-preserving reconstruction algorithm compared with standard non-contrast series: focusing on epicardial adipose tissue.

PURPOSE: We aimed to evaluate the reproducibility of computed tomography (CT) radiomic features (RFs) about Epicardial Adipose Tissue (EAT). The features derived from coronary photon-counting computed tomography (PCCT) angiography datasets using the PureCalcium (VNCPC) and conventional virtual non-contrast (VNCConv) algorithm were compared with true non-contrast (TNC) series. METHODS: RFs of EAT from 52 patients who underwent PCCT were quantified using VNCPC, VNCConv, and TNC series. The agreement of EAT volume (EATV) and EAT density (EATD) was evaluated using Pearson's correlation coefficient and Bland-Altman analysis. A total of 1530 RFs were included. They are divided into 17 feature categories, each containing 90 RFs. The intraclass correlation coefficients (ICCs) and concordance correlation coefficients (CCCs) were calculated to assess the reproducibility of RFs. The cutoff value considered indicative of reproducible features was > 0.75. RESULTS: the VNCPC and VNCConv tended to underestimate EATVs and overestimate EATDs. Both EATV and EATD of VNCPC series showed higher correlation and agreement with TNC than VNCConv series. All types of RFs from VNCPC series showed greater reproducibility than VNCConv series. Across all image filters, the Square filter exhibited the highest level of reproducibility (ICC = 67/90, 74.4%; CCC = 67/90, 74.4%). GLDM_GrayLevelNonUniformity feature had the highest reproducibility in the original image (ICC = 0.957, CCC = 0.958), exhibiting a high degree of reproducibility across all image filters. CONCLUSION: The accuracy evaluation of EATV and EATD and the reproducibility of RFs from VNCPC series make it an excellent substitute for TNC series exceeding VNCConv series.

Assessing the interrater and intrarater reliability of subglottic stenosis grading systems.

BACKGROUND: Subglottic stenosis (SGS) is a condition leading to narrowing of the upper airway which can lead to dyspnea and life-threatening airway obstruction. Although other proposed grading systems exist, the Cotton Myer (CM) and percent stenosis systems are the most widespread in clinical practice. Despite this, the CM system has not yet been validated for visual assessment of SGS. OBJECTIVE: To determine the interrater and intrarater reliability of the CM grading system among a cohort of physicians who manage patients with SGS. METHODS: An online survey created with videos of tracheoscopies from 20 adult patients with subglotticstenosis (SGS) was sent individually to 9 expert physicians from various medical specialties, all of whom managed patients with SGS. Physicians were asked to view the 20 tracheoscopy videos and assess both the percent stenosis and Cotton Myer (CM) grade of each patient. After a period of 4 weeks, the physicians were sent the same survey of the 20 tracheoscopy videos. The interrater and intrarater reliability was calculated using the intraclass correlation coefficient (ICC), a measurement used to evaluate the reliability (the extent to which a measurement can be replicated) of two or more raters measuring the same subject. RESULTS: Overall, CM and percent stenosis systems were found to have an ICC of 0.94 and 0.90 within the domain of interrater reliability, respectively, and ICC of 0.71 and 0.81 within the domain of intrarater reliability, respectively. CONCLUSION: Our findings suggest that the CM and percent stenosis grading systems remain a valid clinical tool to measure and communicate the severity of airway obstruction in SGS.

Reliability and measurement error of a maximal voluntary toe plantarflexion measurement process.

Despite the growing interest, information regarding the psychometric properties of maximal voluntary isometric toe plantarflexion force and rate of force development (RFD) is lacking. Hence, we investigate the test-retest reliability and measurement error of these outcome measurement instruments measured with a custom-built dynamometer. Twenty-six healthy adults participated in a crossed design with four sessions separated by 5-7 days. RFD was quantified using manual onset and calculating the impulse and the slope in the following time windows: 0-50 ms, 0-100 ms, 0-150 ms, 0-200 ms, 0-250 ms. We estimated the systematic bias of the mean, the intraclass correlation coefficient (ICC) and standard error of measurement (SEM) from the agreement and consistency models. The ICC and the SEM agreement for maximal voluntary isometric toe plantarflexion force along the perpendicular axis were respectively 0.87 (95%CI: 0.76, 0.93) and 27 N (22, 32), while along the resultant of the perpendicular and anterior posterior axis they were 0.85 (0.73, 0.92) and 29 N (23, 35). The results of the consistency model were similar as the estimated variance for session was closer to zero. A systematic bias of the mean between session 1 and 3 was found. For the RFD variables, the ICC agreement ranged from 0.35 to 0.65. The measurement process was found to be reliable to assess maximal voluntary isometric toe plantarflexion force but not RFD. However, a familiarization session is mandatory and these results need to be confirmed in less coordinated (e.g. aging population) individuals.

Effectiveness of and preference for a picture-based home office ergonomics assessment compared to a traditional in-person office ergonomics assessment: A case study from a Canadian University during the COVID-19 pandemic.

During the COVID-19 pandemic, telework best practices decreased in importance compared to the need for social distancing. It is important that ergonomics assessments for home office workstations are equally as effective as assessment for traditional offices to maintain teleworker wellbeing. The purpose of this case study is to compare a remote, picture-based, home office assessment to a traditional, in-person, office assessment for employees of one Canadian University. Intraclass Correlation Coefficients (ICCs) and Bland-Altman Analyses (BAAs) revealed that the two methods provide repeatable results, with good agreement. Feedback from the participants suggested that picture-based assessments were as effective as in-person assessments; but that picture-based assessments could be improved with video conferencing to discuss findings and ask follow-up questions. Participants found value in remote assessments and, while they preferred in-person assessments, picture-based assessments are suitable when needed as they allow for many assessments to be completed without violating social distancing restrictions.

Evaluation of measurement reliability for selected indices of postural stability based on data from the GYKO Inertial Sensor System.

The main aim of this study is to use comprehensive statistical analyses to evaluate measurement reliability of selected variables that characterize postural stability. The study examined twenty-nine healthy non-athlete students. The examinations were performed twice, with a one-week interval. The Microgate GYKO inertial sensor system was used to evaluate the reliability of variables that characterize postural stability. The relative reliability of the repeated test was evaluated using the intraclass correlation coefficient (ICC) with 95% confidence interval (95% CI). Next, the standard error of measurement (SEM) and minimal detectable change (MDC) were computed. Relative reliability of the repeated test for all analysed variables of ICC ranged from 0.31 to 0.75. For four variables, ICC values were ca. 0.7, i.e., they can be considered as good. For four other variables, ICC ranged from 0.41 to 0.54, with these values considered fair. Satisfactory reproducibility of postural stability measurements using the GYKO inertial sensor system demonstrates that it can offer an inexpensive and efficient alternative to measurements that use force balance platforms.

Reliability of the unified multiple system atrophy rating scale using the telephone.

OBJECTIVE: The unified multiple system atrophy rating scale (UMSARS) was used to evaluate various symptoms of multiple system atrophy (MSA). And UMSARS part 1 was originally developed for use in interviews, but the need for telemedicine is increasing in COVID-19 pandemic. The purpose of this study is to evaluate the reliability of the UMSARS part 1 telephone survey. METHODS: Thirty-two MSA patients took the UMSARS part 1 face-to-face, followed by two more telephone evaluations. Intraclass correlation coefficients (ICC) and Cronbach's alpha (α) coefficients were calculated, and the inter-rater reliability was determined. At the same time, we asked about the problems in COVID-19 pandemic. RESULTS: The study participants included 15 men and 17 women with mean age of 67.1 years (SD, 8.3). For the total UMSARS part 1 score, the inter-rater ICC and Cronbach's α coefficient were 0.89 to 0.92, and 0.84 to 0.87, respectively. More than half of the items had a relatively high ICC. Cronbach's α coefficients were more than 0.7 for all items. Changes that occurred in COVID-19 pandemic included reduced outings and lack of rehabilitation in about half of the cases. CONCLUSION: The UMSARS part 1 has high inter-rater reliability and internal consistency. Evaluation of subjective symptoms showed that some variability could occur. In addition, there was concern about the influence of lack of rehabilitation due to COVID-19 pandemic.

Short-term and long-term phenotypic stability of actigraphic sleep metrics involving repeated sleep loss and recovery.

For the first time, we determined whether actigraphic-assessed sleep measures show inter-individual differences and intra-individual stability during baseline (BL) and recovery (REC) phases surrounding repeated total sleep deprivation (TSD). We conducted a 5-day experiment at Months 2 and 4 in two separate studies (N = 11). During each experiment, sleep measures were collected via wrist actigraphy during two BL 8 h time-in-bed (TIB) nights (B1, B2) and during two REC 8-10 h TIB nights (R1, R2). Intraclass correlation coefficients (ICCs) assessed actigraphic measure long-term stability between 2 and 4 months for (1) the pre-experimental phase before BL; and (2) the BL (B1 + B2), REC (R1 + R2), and BL and REC average (BL + REC) phases; and short-term stability at Month 2 and at Month 4; and (3) between B1 versus B2 and R1 versus R2 in each 5-day experiment. Nearly all ICCs during the pre-experimental, BL, REC, and BL + REC phases were moderate to almost perfect (0.446-0.970) between Months 2 and 4. B1 versus B2 ICCs were more stable (0.440-0.899) than almost all R1 versus R2 ICCs (-0.696 to 0.588) at Month 2 and 4. Actigraphic sleep measures show phenotypic long-term stability during BL and REC surrounding repeated TSD between 2 and 4 months. Furthermore, within each 5-day experiment at Month 2 and 4, the two BL nights before TSD were more stable than the two REC nights following TSD, likely due to increased R1 homeostatic pressure. Given the consistency of actigraphic measures across the short-term and long-term, they can serve as biomarkers to predict physiological and neurobehavioral responses to sleep loss.

Designing multicenter individually randomized group treatment trials.

In an individually randomized group treatment (IRGT) trial, participant outcomes can be positively correlated due to, for example, shared therapists in treatment delivery. Oftentimes, because of limited treatment resources or participants at one location, an IRGT trial can be carried out across multiple centers. This design can be subject to potential correlations in the participant outcomes between arms within the same center. While the design of a single-center IRGT trial has been studied, little is known about the planning of a multicenter IRGT trial. To address this gap, this paper provides analytical sample size formulas for designing multicenter IRGT trials with a continuous endpoint under the linear mixed model framework. We found that accounting for the additional center-level correlation at the design stage can lead to sample size reduction, and the magnitude of reduction depends on the amount of between-therapist correlation. However, if the variance components of therapist-level random effects are considered as input parameters in the design stage, accounting for the additional center-level variance component has no impact on the sample size estimation. We presented our findings through numeric illustrations and performed simulation studies to validate our sample size procedures under different scenarios. Optimal design configurations under the multicenter IRGT trials have also been discussed, and two real-world trial examples are drawn to illustrate the use of our method.

Assessing intra- and inter-method agreement of functional data.

Modern medical devices are increasingly producing complex data that could offer deeper insights into physiological mechanisms of underlying diseases. One type of complex data that arises frequently in medical imaging studies is functional data, whose sampling unit is a smooth continuous function. In this work, with the goal of establishing the scientific validity of experiments involving modern medical imaging devices, we focus on the problem of evaluating reliability and reproducibility of multiple functional data that are measured on the same subjects by different methods (i.e. different technologies or raters). Specifically, we develop a series of intraclass correlation coefficient and concordance correlation coefficient indices that can assess intra-method, inter-method, and total (intra + inter) agreement based on multivariate multilevel functional data consisting of replicated functional data measurements produced by each of the different methods. For efficient estimation, the proposed indices are expressed using variance components of a multivariate multilevel functional mixed effect model, which can be smoothly estimated by functional principal component analysis. Extensive simulation studies are performed to assess the finite-sample properties of the estimators. The proposed method is applied to evaluate the reliability and reproducibility of renogram curves produced by a high-tech radionuclide image scan used to non-invasively detect kidney obstruction.

Planning stepped wedge cluster randomized trials to detect treatment effect heterogeneity.

Stepped wedge design is a popular research design that enables a rigorous evaluation of candidate interventions by using a staggered cluster randomization strategy. While analytical methods were developed for designing stepped wedge trials, the prior focus has been solely on testing for the average treatment effect. With a growing interest on formal evaluation of the heterogeneity of treatment effects across patient subpopulations, trial planning efforts need appropriate methods to accurately identify sample sizes or design configurations that can generate evidence for both the average treatment effect and variations in subgroup treatment effects. To fill in that important gap, this article derives novel variance formulas for confirmatory analyses of treatment effect heterogeneity, that are applicable to both cross-sectional and closed-cohort stepped wedge designs. We additionally point out that the same framework can be used for more efficient average treatment effect analyses via covariate adjustment, and allows the use of familiar power formulas for average treatment effect analyses to proceed. Our results further sheds light on optimal design allocations of clusters to maximize the weighted precision for assessing both the average and heterogeneous treatment effects. We apply the new methods to the Lumbar Imaging with Reporting of Epidemiology Trial, and carry out a simulation study to validate our new methods.

Remote visual estimation of shoulder range of motion has generally high interobserver reliability but limited accuracy.

Background: Surgeon visual estimation of shoulder range of motion (ROM) is commonplace in the outpatient office setting and routinely reported in clinical research, but the reliability and accuracy of this practice remain unclear. The purpose of this study is to establish the reliability and accuracy of remote visual estimation of shoulder ROM in healthy volunteers and symptomatic patients among a large group of shoulder surgeons. Our hypothesis is that remote visual estimation would be reliable and accurate compared with the digital goniometer method. Methods: Fifty shoulder surgeon members of the PacWest Shoulder and Elbow Society independently determined the active shoulder forward flexion (FF), internal rotation at 90° abduction (IR90), external rotation at 90° abduction, external rotation at the side , and maximal spinal level reached with internal rotation (IRspine) through visual estimation of video recordings taken from 10 healthy volunteers and 10 symptomatic patients. Variations in measurements were quantified using the interobserver reliability through calculation of the intraclass correlation coefficient. Accuracy was determined through comparison with digital goniometer measurements obtained with an on-screen protractor application using Bland-Altman mean differences and 95% limits of agreement. Results: The interobserver reliability among examiners showed moderate to excellent correlation, with intraclass correlation coefficient ranging from 0.768 to 0.928 for the healthy volunteers and 0.739 to 0.878 for the symptomatic patients. Accuracy was limited, with upper limits of agreement exceeding the established minimal clinically important differences (MCIDs) for FF (20° vs. MCID of 14°) and IR90 (25° vs. 18°) in the healthy volunteers and for FF (33° vs. 16°), external rotation at 90° abduction (21° vs. 18°), and IR90 (31° vs. 20°) in the symptomatic patients. Conclusion: Despite generally high intersurgeon reliability in the visual estimation of shoulder ROM, there was questionable accuracy when compared to digital goniometer measurements,with measurement errors often exceeding established MCID values. Given the potential implications for the clinical response to treatment and the significance of research findings, the adoption of validated instruments to measure ROM and the standardization of examination procedures should be considered.

Improving the reliability of measurements in orthopaedics and sports medicine.

A large space still exists for improving the measurements used in orthopaedics and sports medicine, especially as we face rapid technological progress in devices used for diagnostic or patient monitoring purposes. For a specific measure to be valuable and applicable in clinical practice, its reliability must be established. Reliability refers to the extent to which measurements can be replicated, and three types of reliability can be distinguished: inter-rater, intra-rater, and test-retest. The present article aims to provide insights into reliability as one of the most important and relevant properties of measurement tools. It covers essential knowledge about the methods used in orthopaedics and sports medicine for reliability studies. From design to interpretation, this article guides readers through the reliability study process. It addresses crucial issues such as the number of raters needed, sample size calculation, and breaks between particular trials. Different statistical methods and tests are presented for determining reliability depending on the type of gathered data, with particular attention to the commonly used intraclass correlation coefficient.

Evaluation of a simple activity measurement method in rats.

[Purpose] Behavioral analysis is widely used in animal research. However, such analysis requires specialized equipment and can be difficult to perform. Therefore, this study aimed to explore and validate a simple behavioral analysis method. [Participants and Methods] For behavioral assessments, Wistar rats were placed in a rearing cage and videotaped from two directions: overhead and side view. The filmed videos were analyzed using ImageJ software to calculate the distance traveled and activity and inactivity times of the rats. Intraclass correlation coefficients 1 and 2 were calculated to examine the reliability of the behavioral analysis method. [Results] Intraclass correlation coefficients 1 and 2 for distance traveled and activity and inactivity times determined using the behavioral analysis method showed high reliability. [Conclusion] The behavioral analysis method validated in this study used inexpensive and easily accessible equipment and devices. The results show high correlation coefficients for the measurement of distance traveled and activity time performed by experimental animals, demonstrating the reliability of this simple method.

The value of radiomics model based on ultrasound image features in the differentiation between minimal breast cancer and small benign breast masses.

BACKGROUND: Female breast cancer has surpassed lung cancer as the most common cancer, and is also the main cause of cancer death for women worldwide. Breast cancer <1 cm showed excellent survival rate. However, the diagnosis of minimal breast cancer (MBC) is challenging. OBJECTIVE: The purpose of our research is to develop and validate an radiomics model based on ultrasound images for early recognition of MBC. METHODS: 302 breast masses with a diameter of <10 mm were retrospectively studied, including 159 benign and 143 malignant breast masses. The radiomics features were extracted from the gray-scale ultrasound image of the largest face of each breast mass. The maximum relevance minimum reduncancy and recursive feature elimination methods were used to screen. Finally, 10 features with the most discriminating value were selected for modeling. The random forest was used to establish the prediction model, and the rad-score of each mass was calculated. In order to evaluate the effectiveness of the model, we calculated and compared the area under the curve (AUC) value, sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the model and three groups with different experience in predicting small breast masses, and drew calibration curves and decision curves to test the stability and consistency of the model. RESULTS: When we selected 10 radiomics features to calculate the rad-score, the prediction efficiency was the best, the AUC values for the training set and testing set were 0.840 and 0.793, which was significantly better than the insufficient experience group (AUC = 0.673), slightly better than the moderate experience group (AUC = 0.768), and was inferior to the experienced group (AUC = 0.877). The calibration curve and decision curve also showed that the radiomics model had satisfied stability and clinical application value. CONCLUSION: The radiomics model based on ultrasound image features has a satisfied predictive ability for small breast masses, and is expected to become a potential tool for the diagnosis of MBC, and it is a zero cost (in terms of patient participation and imaging time).

Validity of the Entralpi force plate in the assessment of finger flexor performance metrics in rock climbers.

This study assessed the validity of the Entralpi force plate in the assessment of finger flexor performance in rock climbers. In addition to a static force evaluation, peak force, peak impulse, and total impulse were measured during 30 all-out performance trials by 15 participants, in which force during the trials was recorded simultaneously by the Entralpi and a Pasco force plate. Agreement between devices was assessed by a variety of statistical analyses, including intraclass correlation coefficient (ICC), coefficient of variation (CV), and Bland-Altman analyses. The static force evaluation showed a mean relative error of 0.41% and excellent day-to-day reliability (ICC = 1; CV = 0.03%). Peak force, peak impulse, and total impulse from the performance trials demonstrated strong agreement (ICC ≥ 0.991, CV ≤ 1.9%, Bland-Altman mean bias ≤ 0.5%). These results illustrate that the Entralpi force plate provides accurate and reliable data for rock climbing related tasks at an affordable cost.

Five or more gender- and size-diverse customizations of distal femur prostheses are needed to improve fit for Chinese knees.

PURPOSE: Mismatch between partial imported prostheses and Chinese anatomy affects the clinical outcome of the procedure. The purpose of this study was to measure the anatomical dimensions of Chinese distal femurs to provide guidance for the design of more compatible distal femoral prostheses. METHODS: A total of 406 healthy distal femurs were reconstructed and measured. Consistency of these measurements and differences in sides, gender, and populations were examined. Parameter correlations were analyzed, and pairs with strong correlations underwent linear regression analysis. The design of distal femoral prostheses was referenced from the results of K-means and hierarchical clustering analysis. RESULTS: Ten parameters were measured, including the trans-epicondylar axis, width of the distal femur (ML), anteroposterior diameter of the distal femur (AP), etc. The intra-class correlation coefficient ranged from 0.795 to 0.999 for intra-observer consistency, and from 0.796 to 0.998 for inter-observer consistency. Males exhibited significantly larger parameters than females, except for the posterior condylar angle (all P values < 0.05). Compared to other populations, substantial differences were observed for most parameters, such as ML, AP, width of lateral femoral condyle, etc. (all P values < 0.05). Clustering analysis suggested that distal femoral prostheses should include at least five sizes to adequately accommodate the sampled population. ML sizes for males were 68, 70, 83, 73, and 89 mm, and for females 64, 65, 71, 67, and 77 mm. AP sizes for males were 56, 60, 60, 64, and 64 mm, and for females 48, 52, 54, 57, and 58 mm. CONCLUSIONS: Chinese distal femur morphology, as analyzed using 3D techniques, varies significantly between genders and when compared with international data. For improved patient fit, the creation of five or more distal femur prostheses, diversified by gender and size and informed by the associated morphological parameters, is recommended. LEVEL OF EVIDENCE: IV.