The variation in hip stability measurements between supine and standing radiographs of dysplastic hips

Aims The aims of this study were to compare clinically relevant measurements of hip dysplasia on radiographs taken in the supine and standing position, and to compare Hip2Norm software and Picture Archiving and Communication System (PACS)-derived digital radiological measurements. Methods Preoperative supine and standing radiographs of 36 consecutive patients (43 hips) who underwent periacetabular osteotomy surgery were retrospectively analyzed from a single-centre, two-surgeon cohort. Anterior coverage (AC), posterior coverage (PC), lateral centre-edge angle (LCEA), acetabular inclination (AI), sharp angle (SA), pelvic tilt (PT), retroversion index (RI), femoroepiphyseal acetabular roof (FEAR) index, femoroepiphyseal horizontal angle (FEHA), leg length discrepancy (LLD), and pelvic obliquity (PO) were analyzed using both Hip2Norm software and PACS-derived measurements where applicable. Results Analysis of supine and standing radiographs resulted in significant variation for measurements of PT (p < 0.001) and AC (p = 0.005). The variation in PT correlated with the variation in AC in a limited number of patients (R2 = 0.378; p = 0.012). Conclusion The significant variation in PT and AC between supine and standing radiographs suggests that it may benefit surgeons to have both radiographs when planning surgical correction of hip dysplasia. We also recommend using PACS-derived measurements of AI and SA due to the poor interobserver error on Hip2Norm. Cite this article: Bone Joint J 2021;103-B(11):1662–1668.

551 The Relationship Between Canal Diameter and the DORR Classification - Presented by Dr John Vincent and Dr Ryan Doherty of NIMDTA, formerly Queen's University Belfast

Background Particularly in broach-only uncemented total hip arthroplasty, a narrow femoral canal presents a technical challenge. Traditionally such femurs have been considered to be Dorr A. To our knowledge, however, no study has reported on the relationship between isthmus width and the Dorr classification. Method We reviewed 500 high-quality, hard copy radiographs. Dorr classification and isthmus canal width were measured using an electronic caliper by 5 independent observers with intraobserver and interobserver error calculated. For this study, we defined a narrow canal as being 10 mm at its narrowest point (isthmus). Results Eight percent (40) were Dorr A, 85% (424) Dorr B, and 7% (36) Dorr C. With respect to isthmus width for Dorr A, 63% (25) were 10 mm compared to just 13% (55) of Dorr B. However, overall because there were more Dorr B femurs, 69% of those with an isthmus of 10 mm were Dorr B. Conclusions In this population, almost 70% of patients with an isthmus 10 mm were Dorr B, with only 30% being Dorr A. When using a broach-only technique, isthmus width should be routinely measured on the preoperative anteroposterior radiographs so as to alert the surgeon to potential problems.

Wearing down the constraints of low magnification tooth microwear analysis: reproducibility and variability of results based on extant ungulates

Low magnification dental microwear analysis is a widespread dietary proxy for palaeoenvironmental analyses. The limitations of the method, such as observer bias or variation of microwear scars between different tooth positions, are still not quite understood. This study aims to reveal that reproducibility and variability of low magnification dental microwear is better, than it was previously thought. The main focuses of this study were differences between results produced by independent observers, and individual variability of the wear features on different teeth of the same specimen. To approach these issues, the microwear of 1944 0.4 × 0.4 mm areas on every right molar and premolar (144 teeth of 12 extant ungulate specimens) was quantified. Reproducibility and interobserver error was tested by calculating the intraclass correlation coefficients for the scores produced by the observers. The microwear features of each tooth were characterized by the mean, median, standard deviation, range, skewness and kurtosis. These statistical parameters were than compared. To test whether observed differences between the microwear patterns of different tooth positions are significant, ANOVA and Dunnett’s post hoc tests were performed. To calculate the minimal number of sampling sites required for characterizing a tooth, a computer-assisted bootstrap method was applied. As a result, it can be suggested that the low magnification microwear method is quite robust, with low interobserver error. The variance of microwear scars seems uniform throughout the dentition of the examined specimens. Some differences can be noted between tooth positions, however, some limitations could be lifted, at least in the case of ungulates.

Ultrasonographic assessment of ossification of the distal radial epiphysis for estimating forensic age

Since forensic age estimation is not a valid medical indication, research on the use of nonionizing methods is increasing. Ultrasonography is a radiological approach that protects patients from radiation exposure and offers special convenience to them. In this study, ultrasonography was used for age estimation by investigating the degree of ossification of the distal radial epiphysis. Its applicability on the Turkish population was investigated. The left wrist of 688 (322 males, 366 females) patients between the ages of 9 and 25 years was prospectively evaluated by ultrasonography. The intra- and interobserver reliabilities in evaluating the distal radial epiphysis and Cohen’s kappa statistics show that the interobserver error was very low, and the kappa value was found to be 0.919. Stage 3 and 4 ossification of the distal radial epiphysis was first detected at age 14.3 and 15.3 years in males and 12.7 and 14.8 years in females, respectively. The data obtained may help determine legally critical age limits of 14 and 15. Although it does not seem useful for the age of 18, ultrasonography may be recommended in selected cases as a fast, inexpensive, frequently reproducible radiological method without concern about radiation and without a predictable health risk.

Ellipse method for measuring Liaw’s anteversion of the acetabular component after total hip arthroplasty

Background Several cup anteversion measurements for post-operative total hip arthroplasty (THA) surgery have been described. We developed the standardized Liaw’s trigonometric method to eliminate the influence of patient position, which is the most accurate method for cup anteversion measurement. We then developed an ellipse method using the Elliversion software and reported an interobserver error reduction in 2013. In this study, we attempted to apply this ellipse method in the clinic and compared its accuracy with the standard trigonometric version. Methods In the present study, we attempted to incorporate the ellipse method with Liaw’s standardized anteversion in the simulated cup position. We measured standardized Liaw’s anteversion for 434 radiographs in the clinic using the ellipse method. Repeated standard deviation (RSD) was calculated for accuracy evaluation. Furthermore, paired t-test was used for comparison with the interobserver and intraobserver errors. Results We found that the standardized Liaw’s anteversion measured using the ellipse method showed lower RSD than the radiographic version. RSD was 0.795 in the standardized Liaw’s anteversion with ellipse method group. The p-values of the paired t-test were all higher than 0.05 when measuring the interobserver and intraobserver errors. It indicated that the ellipse method was a precise and simple tool for cup anteversion measurement. Conclusion We believe that this ellipse measurement can assist surgeons while placing the acetabulum cup into the precise position and enable early diagnosis of acetabulum loosening.

Personalized Dental Medicine: Impact of Intraoral and Extraoral Clinical Variables on the Precision and Efficiency of Intraoral Scanning

(1) Objectives: The aim is to measure the influence of different intraoral (crowding and molar inclination) and extraoral (surface material and ambient light) conditions on the efficacy and efficiency of intraoral scanning. (2) Methods: In a controlled in vitro experimental study, the samples were divided into six groups showing two types of intraoral conditions—lower incisor crowding (groups 1–3) and lower molar mesial tipping (groups 4–6). Each modified model was replicated using three types of materials with different light-absorption properties (n = 18 models). Each sample was scanned 30 times at light intensities of 0.0, 1800, or 3600 l×, yielding 3240 scans. Scanning efficiency (digital acquisition; scanning chair-time; and scanning failures) and scanning efficacy (undetected volume) were assessed using virtual superimpositions and Mecano Equate software. The intra- and interobserver error and reliability of the method were calculated and data analyses were performed using the t-test, paired t-test, and one-way analysis of variance (p < 0.05). (3) Results: Digital acquisition was influenced by the degree of crowding and molar inclination (p < 0.05). The scanning surface material affected the efficacy and efficiency, which were lower with a calcium sulfate hemihydrate A modified compound scanning surface (p < 0.05). Higher intensities of ambient light in the scanning room were associated with reduced scanning efficacy (p < 0.05). Moreover, the scanner showed greater amounts of undetected volume as the degrees of crowding and mesial tipping of the lower second molar increased over 25°, with mean error values of 0.97 mm3 and 1.12 mm3, respectively. (4) Conclusions: For scanning procedures employing digital acquisition, differences in the degrees of crowding and mesial tipping of the lower second molar, scanning surface material, and external light source intensity influence the efficacy and efficiency of the scanning procedures, scanning chair-time, scanning failures, and undetected volume.

Interobserver error in grassland vegetation surveys: sources and implications

Aims Observer error is an unavoidable aspect of vegetation surveys involving human observers. We quantified four components of interobserver error associated with long-term monitoring of prairie vegetation: overlooking error, misidentification error, cautious error and estimation error. We also evaluated the association of plot size with pseudoturnover due to observer error, and how documented pseudochanges in species composition and abundance compared with recorded changes in the vegetation over a 4-year interval. Methods This study was conducted at Tallgrass Prairie National Preserve, Kansas. Monitoring sites contained 10 plots; each plot consisted of a series of four nested frames (0.01, 0.1, 1 and 10 m2). The herbaceous species present were recorded in each of the nested frames, and foliar cover was visually estimated within seven cover categories at the 10 m2 spatial scale only. Three hundred total plots (30 sites) were surveyed, and 28 plots selected at random were resurveyed to assess observer error. Four surveyors worked in teams of two. Important Findings At the 10 m2 spatial scale, pseudoturnover resulting from overlooking error averaged 18.6%, compared with 1.4% resulting from misidentification error and 0.6% resulting from cautious error. Pseudoturnover resulting from overlooking error increased as plot size decreased, although relocation error likely played a role. Recorded change in species composition over a 4-year interval (excluding potential misidentification error and cautious error) was 30.7%, which encompassed both pseudoturnover due to overlooking error and actual change. Given a documented overlooking error rate of 18.6%, this suggests the actual change for the 4-year period was only 12.1%. For estimation error, 26.2% of the time a different cover class was recorded. Over the 4-year interval, 46.9% of all records revealed different cover classes, suggesting that 56% of the records of change in cover between the two time periods were due to observer error.

Ellipse method for measuring Liaw’s anteversion of the acetabular component after total hip arthroplasty

Background: Several cup anteversion measurements for post-operative total hip arthroplasty (THA) surgery have been described. We developed the standardized Liaw’s trigonometric method to eliminate the influence of patient position, which is the most accurate method for cup anteversion measurement. We then developed an ellipse method using the Elliversion software and reported an interobserver error reduction in 2013. In our study, we attempted to apply this ellipse method in the clinic and compared its accuracy with the standard trigonometric version.Methods: In the present study, we attempted to incorporate the ellipse method with Liaw’s standardized anteversion in the simulated cup position. We measured standardized Liaw’s anteversion for 434 radiographs in the clinic using the ellipse method. The Repeatedly Standard Deviation (RSD) was applied for accuracy evaluation. Furthermore, paired t-test was used for comparison with the interobserver and intraobserver errors. Results: We found that the standardized Liaw’s anteversion measured using the ellipse method showed lower repeated standard deviation than the radiographic version. RSD was 0.795 in the standardized Liaw’s anteversion with ellipse method group. The p-values of the paired t-test were all higher than 0.05 when measuring the interobserver and intraobserver bias. It indicated that the ellipse method was a precise and simple tool for cup anteversion measurement. Conclusion: We believe that this ellipse measurement can assist surgeons while placing the acetabulum cup into the precise position and enable early diagnosis of acetabulum loosening.

Quantifying Uncertainty and Robustness in a Biomathematical Model–Based Patient-Specific Response Metric for Glioblastoma

Purpose Glioblastomas, lethal primary brain tumors, are known for their heterogeneity and invasiveness. A growing body of literature has been developed demonstrating the clinical relevance of a biomathematical model, the proliferation-invasion model, of glioblastoma growth. Of interest here is the development of a treatment response metric, days gained (DG). This metric is based on individual tumor kinetics estimated through segmented volumes of hyperintense regions on T1-weighted gadolinium-enhanced and T2-weighted magnetic resonance images. This metric was shown to be prognostic of time to progression. Furthermore, it was shown to be more prognostic of outcome than standard response metrics. Although promising, the original article did not account for uncertainty in the calculation of the DG metric, leaving the robustness of this cutoff in question. Methods We harnessed the Bayesian framework to consider the impact of two sources of uncertainty: (1) image acquisition and (2) interobserver error in image segmentation. We first used synthetic data to characterize what nonerror variants are influencing the final uncertainty in the DG metric. We then considered the original patient cohort to investigate clinical patterns of uncertainty and to determine how robust this metric is for predicting time to progression and overall survival. Results Our results indicate that the key clinical variants are the time between pretreatment images and the underlying tumor growth kinetics, matching our observations in the clinical cohort. Finally, we demonstrated that for this cohort, there was a continuous range of cutoffs between 94 and 105 for which the prediction of the time to progression was over 80% reliable. Conclusion Although additional validation must be performed, this work represents a key step in ascertaining the clinical utility of this metric.

Orientation of Cone-Beam Computed Tomography Image: Pursuit of Perfect Orientation Plane in Three Dimensions—A Retrospective Cross-Sectional Study

Objective This study aimed to evaluate the reproducibility of nine reference planes used in orientation of as-received cone-beam computed tomography (CBCT) images in all three dimensions. Materials and Methods The study was conducted on CBCT images of 15 adult subjects (mean age 21.2 ± 5.8 years). The anonymized CBCT images were oriented using five different methods created from nine reference planes by two experienced orthodontists. For each subject, pitch, yaw, and roll changes with five orientation methods were recorded twice by each observer. Statistical Analysis The inter- and intraobserver agreement was tested using intraclass correlation (ICC) and Bland–Altman plot. The intra- and interobserver error was analyzed using paired t-test. Analysis of variance and paired t-test were used to analyze the differences among the various pitch, roll, and yaw orientation planes. Results Inter- and intraobserver agreement (ICC, 0.9) was excellent for all the nine reference planes. The interobserver reliability showed statistically significant differences for four planes namely Frankfort horizontal plane constructed on right side (p = 0.014) and left side (p = 0.000), transorbital plane (p = 0.001), and midsagittal plane on top view (p = 0.036); however, the mean differences were clinically insignificant. Conclusion The landmark-based nine reference planes used in this study to orient CBCT images showed good reproducibility. Therefore, these reference planes can be used to orient CBCT images and can be incorporated into automated software.