Functional Shape of the Proximal Radioulnar Joint: Anatomical Characterization through Alpha and Beta Angles

Is beta angle the new alpha angle? Reliability and correlation with cartilage health in femoroacetabular impingement syndrome

Alpha and beta angles are commonly used radiographic measures to assess the sphericity of the proximal femur and distance between the pathologic head-neck junction and the acetabular rim, respectively. The aim of this study was to explore the relationship between these two measurements on frog-leg lateral hip radiographs. Fifty frog-leg lateral hip radiographs were evaluated by two orthopaedic surgeons and two radiologists. Each reviewer measured the alpha and beta angles on two separate occasions to determine the relationship between positive alpha and beta angles and the inter- and intra-observer reliability of these measurements. There was no significant association between positive alpha and beta angles, [kappa range -0.043 (95 % CI -0.17 to 0.086) to 0.54 (95 % CI 0.33-0.75)]. Intra-observer reliability was high [alpha angle intra-class correlation coefficient (ICC) range 0.74 (95 % CI 0.58-0.84) to 0.99 (95 % CI 0.98-0.99) and beta angle ICC range 0.86 (95 % CI 0.76-0.92) to 0.97 (95 % CI 0.95-0.98)]. There is no statistical or functional relationship between readings of positive alpha and beta angles. The radiographic measurements resulted in high intra-observer and fair-to-moderate inter-observer reliability. Results of this study suggest that the presence of a CAM lesion on lateral radiographs as suggested by a positive alpha angle does not necessitate a decrease in clearance between the femoral head and acetabular rim as measured by the beta angle and thus may not be the best measure of functional impingement. Understanding the relationship between these two aspects of femoroacetabular impingement improves a surgeon's ability to anticipate potential operative management.

Assessment of the positional and morphological differences of unilaterally impacted canines: A cross-sectional study

Current measures of the reduced head-neck offset such as residual deformity of slipped capital femoral epiphysis (SCFE) including the alpha angle, which measures the femoral head-neck sphericity but does not account for acetabular abnormalities, do not represent the true magnitude of the deformity and the mechanical consequences. The beta angle (angle between the femoral head-neck junction and acetabular rim) accounts for the morphology of both the acetabulum and femur and, thus, may be the more appropriate parameter for assessing SCFE deformity. We determined (1) whether the beta angle could be reliably measured on MRI; and (2) whether the beta angle correlates with the cartilage status. We recruited 10 adult patients (mean age, 28 years) with symptomatic cam femoroacetabular impingement and 15 asymptomatic volunteers (mean age, 24 years) to have three-dimensional MRI including delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) for cartilage status assessment. Corresponding alpha angles, beta angles, and acetabular dGEMRIC indices were obtained in seven radial reformats to assess the hip in seven regions (anterior to superior and posterior). We noted high reproducibility for both alpha and beta angle measurements. The dGEMRIC indices correlated with beta angles in the superoinferior and superior regions but not the alpha angles. Beta angle measurement in radial MR images is reproducible and appears to correspond to cartilage damage in the superior regions of the hip. The beta angle may be a useful parameter to assess hip deformity in the followup of SCFE although further confirmation is warranted.

Background: Reverse Hill-Sachs (RHS) lesions can cause recurrent posterior shoulder instability because of engagement with the posterior glenoid rim; however, the effect of defect size and localization have yet to be determined. Hypothesis: Both size and localization are critical for the engagement of an RHS defect with the posterior glenoid rim. Study design: Controlled laboratory study. Methods: Ten RHS defects with predefined extent and localization were created through an anterolateral rotator cuff sparing approach in 10 fresh-frozen cadaveric shoulder specimens using a custom-made saw guide. Computed tomography scans of all specimens were completed, and standardized measurements were performed to determine the size (alpha angle) and localization (beta angle) of the defect as well as a combination of both parameters (gamma angle). Internal rotation motions were imposed on the shoulder joint in different arm positions and with varying amount of posterior translation by means of a robot-assisted shoulder simulator. The association between engagement of the defects and the defined parameters (alpha, beta, and gamma angles) was analyzed. Results: In 0° of abduction, a cutoff value between engaging and nonengaging defects of 37.5° for the alpha angle (100% sensitivity; 75% specificity; area under the curve [AUC], 0.875; P = .055) and 36.5° for the beta angle (100% sensitivity; 25% specificity; AUC, 0.708; P = .286) was determined. The gamma angle showed the highest discriminatory power (AUC, 0.938; P = .025) with a cutoff value of 85.5° rendering 100% sensitivity and 75% specificity in the prediction of engagement. An increase in the applied posterior translation force decreased the degrees of internal rotation necessary before engagement occurred. No engagement occurred during internal rotation with the arm in 60° of abduction or 60° of flexion. Conclusion: The size and localization of RHS defects are both critical factors for engagement. The combination of both parameters in terms of the gamma angle measurement might be a helpful tool to identify defects prone to engagement. Clinical Relevance: Not only the size but also the localization is decisive for engagement of RHS defects. The standardized measurement of the gamma angle combines both factors and might be a helpful tool to identify defects prone to engagement warranting surgical treatment.

To compare the features of localized retinal nerve fiber layer (RNFL) defects between a low-teen intraocular pressure (IOP) group and a high-teen IOP group in normal-tension glaucoma (NTG) patients. Seventy-seven eyes of 77 NTG patients showing localized RNFL defects on RNFL photographs and corresponding visual filed defects at the initial visit to a glaucoma specialist were selected for this study. Patients with range of diurnal IOP within low-teen or high-teen in both eyes were included. All participants completed refraction, diurnal IOP measurement, central corneal thickness (CCT) measurement, stereoscopic disc photography, RNFL photography, and automated perimetry. On RNFL photograph, approximation of the defect to the macula (angle alpha) and width of the defects (angle beta) were measured to represent RNFL defects. The patients were divided into 2 groups according to the level of IOP. A low-teen group had highest IOP of <or=15 mm Hg (group A) and a high-teen group had lowest IOP of >15 mm Hg (group B). Age at diagnosis, percentage of male patients, systemic disease, refraction, CCT, highest IOP, angle alpha, angle beta, and mean deviation and pattern standard deviation of visual field were compared between the 2 groups. Age at diagnosis of NTG, age distribution, percentage of male patients, systemic disease, spherical equivalent of refraction, CCT, mean deviation, and pattern standard deviation were not different between the 2 groups. Highest IOP was 13.8+/-1.2 mm Hg in group A and 19.2+/-1.4 mm Hg in group B (P<0.001). Angle alpha was significantly smaller in group A than in group B (37.0+/-14.0 vs. 56.5+/-21.2 degrees, P<0.001), whereas angle beta was not different between the 2 groups (39.9+/-17.9 vs. 37.5+/-15.9 degrees, P=0.54). There were no significant correlations between spherical equivalent and angle alpha (r=-0.03, P=0.82), between spherical equivalent and angle beta (r=-0.04, P=0.74), and between angle alpha and angle beta (r=-0.21, P=0.07). Localized RNFL defect was closer to the center of the macula in group A than in group B, whereas width of defects was not different between the 2 groups. These findings provide indirect evidence to suggest that more than one pathogenic mechanism may exist in the development of RNFL defects in NTG.

Ultrasound is a non-invasive, cheap and readily available imaging modality for studying the infant hip. Early detection of developmental hip subluxation, acetabular dysplasia and the prevention of late presentation of a developmentally dislocated hip with consequent secondary premature degenerative arthritis are goals that all practitioners should strive for. Provision of axial indices of alpha and beta angles of the infant hip joint in Kano, Nigeria using ultrasonography to establish a normogram as reference values for further studies is the objective of this study. This descriptive prospective study was conducted at the Radiology Department of Aminu Kano Teaching Hospital, Kano state, Nigeria. Successive four hundred appropriately consented infants were recruited for this study. The axial angle relationships of both hip joints were measured using 7.5 MHz linear transducer of Mindray DP-8800 Digital plus ultrasound machine. The mean alpha and beta angles for both hips in females were 56.590 and 49.580 respectively while those for males were 56.730 and 50.530 respectively. Minimum and maximum alpha angle for both hips ranged from 380 to 780 while the beta angles ranged 290 to 660 respectively. The age group 1-3 months has the highest frequency of respondents (251) while age group 10 - 12 months has the lowest (22). There was no statistically significant difference in the alpha and beta angles between males and females hips and age of the infants did not affect the hip indices. The study showed no statistical significant difference in the measured alpha and beta angles between males and females. Age of measurement in infants did not affect the hip indices.

Sonographic diagnosis of developmental dysplasia of the hip allows treatment with a flexion-abduction orthosis preventing hip luxation. Accurate determination of alpha and beta angles according to Graf is crucial for correct diagnosis. It is unclear if algorithms could predict the angles. We aimed to compare the accuracy for users and automation reporting root mean squared errors (RMSE). We used 303 306 ultrasound images of newborn hips collected between 2009 and 2016 in screening consultations. Trained physicians labelled every second image with alpha and beta angles during the consultations. A random subset of images was labeled with time and precision under lab conditions as ground truth. Automation predicted the two angles using a convolutional neural network (CNN). The analysis was focused on the alpha angle. Three methods were implemented, each with a different abstraction of the problem: (1) CNNs that directly learn the angles without any post-processing steps; (2) CNNs that return the relevant landmarks in the image to identify the angles; (3) CNNs that return the base line, bony roof line, and the cartilage roof line which are necessary to calculate the angles. The RMSE between physicians and ground truth were found to be 7.1° for alpha. The best CNN architecture was (2) landmark detection. The RMSE between landmark detection and ground truth was 3.9° for alpha. The accuracy of physicians in their daily routine is inferior to deep learning-based algorithms for determining angles in ultrasound of the newborn hip. Similar methods could be used to support physicians.

Stress urinary incontinence (SUI) is a common condition among women that significantly impacts their quality of life. Transperineal ultrasound has emerged as a non-invasive diagnostic modality for assessing pelvic floor dysfunction in SUI, with alpha and beta angles proposed as potential markers of urethral and bladder neck mobility. However, variability in findings across studies necessitates a comprehensive evaluation of their diagnostic utility. This meta-analysis aimed to synthesize evidence on the diagnostic accuracy of alpha and beta angles measured by transperineal ultrasound in differentiating women with SUI from controls. A systematic search of PubMed, Embase, Cochrane Library, and Scopus was conducted to identify relevant studies. Nine studies with 1,157 participants (584 with SUI and 573 controls) were included. The pooled mean differences in alpha and beta angles between SUI and control groups were calculated using a random-effects model. Heterogeneity was assessed using the I² statistic, and potential publication bias was evaluated through funnel plot analysis. The pooled mean alpha angle was significantly larger in the SUI group, with a mean difference of 15.77° (95% CI: 9.62, 21.91; I²=93%), indicating altered urethral mobility during the Valsalva maneuver. Similarly, the pooled mean beta angle was significantly higher in the SUI group, with a mean difference of 21.18° (95% CI: 12.11, 30.25; I²=95%), reflecting greater bladder neck descent. Despite substantial heterogeneity, the findings consistently support the diagnostic value of these ultrasound parameters. In conclusion, alpha and beta angles measured via transperineal ultrasound are significantly larger in women with SUI, highlighting their potential as non-invasive markers for pelvic floor dysfunction. However, variability in imaging protocols and patient characteristics underscores the need for standardization to enhance diagnostic accuracy. These findings support the incorporation of ultrasound measurements into clinical assessments for SUI.

Correlation of Measurements of the Prearthritic Hip Between Plain Radiography and Computed Tomography.

Implication of uterine configuration on dosimetry to point a using the Amersham afterloading system

The primate scapula has been studied widely since its shape has been shown to correlate with how the forelimb is used in daily activities. In this study, we expand on the existing literature and use an image-based methodology that was originally developed for orthopaedic practice to quantify and compare the three-dimensional (3D) morphology of the scapula across humans and great apes. We expect that this image-based approach will allow us to identify differences between great apes and humans that can be related to differences in mobility and loading regime of the shoulder. We hypothesize that gorillas and chimpanzees will have a similar scapular morphology, geared towards stability and weight-bearing in knuckle-walking, whilst the scapular morphology of orangutans is expected to be more similar to that of humans given their high glenohumeral mobility associated with their suspensory lifestyle. We made 3D reconstructions of computed tomography scans of 69 scapulae from four hominid genera (Pongo, Gorilla, Pan and Homo). On these 3D bone meshes, the inferior glenoid plane was determined, and subsequently, a set of bony landmarks on the scapular body, coracoid, and acromion were defined. These landmarks allowed us to measure a set of functionally relevant angles which represent acromial overhang, subacromial space and coracoacromial space. The angles that were measured are: the delto-fulcral triangle (DFT), comprising the alpha, beta, and delta angle, the acromion-glenoid angle (AGA), the coracoid-glenoid centre-posterior acromial angle (CGA), the anterior tilt (TA CGA) and the posterior tilt of the CGA (PT CGA). Three observers placed the landmarks on the 3D bone meshes, allowing us to calculate the inter-observer error. The main differences in the DFT were found between humans and the great apes, with small differences between the great apes. The DFT of humans was significantly lower compared to that of the great apes, with the smallest alpha (32.7°), smallest delta (45.7°) and highest beta angle (101.6°) of all genera. The DFT of chimpanzees was significantly higher compared to that of humans (p < 0.01), with a larger alpha (37.6°) and delta angle (54.5°) and smaller beta angle (87.9°). The mean AGA of humans (59.1°) was significantly smaller (p < 0.001) than that of gorillas (68.8°). The mean CGA of humans (110.1°) was significantly higher (p < 0.001) than in orangutans (92.9°). Humans and gorillas showed mainly a posterior tilt of their coracoacromial complex whilst chimpanzees showed mainly an anterior tilt. The coracoacromial complex of the orangutans was not tilted anteriorly or posteriorly. With our image-based method, we were able to identify morphological features of the scapula that differed significantly between hominid genera. However, we did not find an overall dichotomy in scapular morphology geared towards high stability (Pan/Gorilla) or high mobility (Homo/Pongo). Further research is needed to investigate the functional implications of these differences in scapular morphology.

Ultrasonographic study of 463 normal children (926 hips) from birth to 6 months of age with equal sex distribution was performed. Hip morphometry, including Graf's alpha and beta angles. Morin's head coverage percentage, and head size were measured. Using the same technique, a group of 52 babies was measured longitudinally from birth to 6 months of age, with three measurements taken for each hip for a total of 312 measurements. Results showed that the boys had a consistently higher alpha angle, a lower beta angle, better head coverage, and larger head size through the 6 months. Differences between the right and left hips were only noted in the beta angle. The containment of the hip was found to increase rapidly in the first 4 months. Comparing data from the longitudinal versus the cross-sectional group, no statistically significant differences were detectable in all the parameters measured. Intraobserver variations were found to be best with alpha angle measurements, with a standard deviation of 3.22 degrees.

The purposes of this study were to determine the interobserver and intraobserver reliability of ultrasound measurements in unstable neonatal hips treated with the Pavlik harness and to determine whether ultrasound measurements correlate with radiological outcome at 6 months. Sixty-four babies treated from birth with the Pavlik harness for neonatal hip instability were scanned at 2 and 6 weeks. The alpha and beta angles of Graf, the combined (H) angle of Hosny, and the femoral head coverage (FHC) were measured by 3 observers and remeasured by each observer on a minimum of 50 scans. From 248 scans, 792 sets of measurements were made. Hips were categorized as normal, abnormal, or borderline for each parameter; and interobserver and intraobserver repeatability coefficients and Kappa values were calculated. The alpha angle had the smallest interobserver range (17 degrees), the H angle range was 21 degrees, and the beta angle 28 degrees. Kappa values were best for the FHC and beta angle (0.66-0.8). The mean acetabular index (AI) of all hips at 6 months was 26 degrees (SD, 4.9). The AI was 30 degrees or greater in 24 hips (18 babies) despite prolonged splintage in 9 hips (6 babies). A stepwise linear regression analysis showed that the FHC at 6 weeks was predictive of AI at 6 months (regression coefficient -0.27; 95% confidence interval -0.42 to -0.12; P<0.001). We recommend the FHC as being reproducible, useful, and predictive of outcome in neonatal hips treated for instability.

developmental dysplasia of the hip (DDH) is a condition characterized by abnormal hip development in infancy. Early diagnosis allows for effective treatment, while late presentation often necessitates complex surgical interventions. Current recommendations advise screening between the 6th and 8th week postnatal using an ultrasound, typically employing the Graf method. However, there is no universal consensus on whether ultrasound screening significantly increases treatment likelihood compared to clinical examination-guided ultrasound. This study aims to explore the feasibility of prenatal ultrasound for the early identification of DDH risk. This prospective observational study involved 100 pregnant women undergoing fetal hip ultrasounds during the second and third trimesters. Using the modified Graf method, alpha and beta angles were calculated on the fetus. Postnatally, alpha and beta angles were compared with the prenatal values. Prenatal ultrasound at the 24th week showed inconclusive results because of the difficulty in identification of Graf landmarks, while ultrasound at the 34th week proved to be a reliable and safe method for the quantitative determination of alpha and beta angles. Significant correlations were found between prenatal and postnatal alpha and beta angles. Moreover, significant differences in prenatal alpha and beta values were observed in patients developing mature/immature hips postnatally. Prenatal diagnostics show promise for predicting infant hip development. Further research is warranted to validate correlation strength and clinical applicability.