The pelvic radiograph: lines, arcs and stripes.
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ABSTRACT:
SUBMITTER: Yeap PM
PROVIDER: S-EPMC8801847 | biostudies-literature | 2021 Jul
REPOSITORIES: biostudies-literature
Publications
The pelvic radiograph: lines, arcs and stripes.
Yeap Phey Ming PM Budak Matthew J MJ
Singapore medical journal 20210701 7
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Project description:Pelvic sagittal inclination (PSI) is often evaluated in patients with hip pathology using lateral radiographs. However, it would be useful if PSI could be predicted from an anteroposterior radiograph since this film is ubiquitous in the evaluation of hip pathology. Herein, computer-modeling was applied to predict PSI from radiographic measurements assessed in the anteroposterior plane. Three-dimensional surface models of the pelvis, femur, and sacrum were reconstructed from computed tomography images of 50 women with hip dysplasia. This study cohort was selected as changes in PSI alter femoral head coverage, which is relevant to the diagnosis and treatment of hip dysplasia, a known cause of hip osteoarthritis. Five radiographic parameters commonly used to independently estimate PSI were evaluated after bone surfaces were projected to an anteroposterior plane, including the symphysis to sacrococcygeal joint distance (S-S distance), the pelvic foramen aspect ratio (PF ratio), the distance between the symphysis and a line connecting the femoral head centers (S-H distance), the sacro-femoral-pubic angle (SFP angle), and the pelvic vertical ratio (PVR). Regression models determined the ability of these parameters to predict PSI from -20° to 20° at 1° increment. All five parameters showed a strong correlation with the PSI (all r > 0.9). From the regression models, PSI was estimated with a median (maximum) absolute error of 3.6° (18.4°), 3.8° (17.7°), 5.2° (17.9°), 5.8° (28.8°), and 3.2° (23.5°) for the S-S distance, PF ratio, S-H distance, SFP angle, and PVR, respectively. The regression model for S-S distance had a mean slope of 2.18 that ranged from 1.98 to 2.41 when the sacrococcygeal joint was located superior to the symphysis. Results indicated that substantial errors occur when estimating the actual value of PSI from an anteroposterior radiograph. However, the change in PSI could be estimated from the S-S distance, which may aid surgeons to successfully increase head coverage through periacetabular osteotomy and to locate the acetabular cup in a functional position for total hip arthroplasty.
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Project description:BackgroundFunctional patient-specific acetabular component positioning is important in total hip arthroplasty. We preoperatively evaluate the pelvic tilt (PT) on standing anteroposterior (AP) pelvis radiographs using a novel measurement and then recreate this intraoperatively using imaging. The purpose of this study was to determine if there is a linear correlation between this novel measurement and the actual PT.MethodsA retrospective study of 200 patients was performed, measuring PT on standing lateral radiographs as the angle between the anterior superior iliac spines and the pubic symphysis. On the AP pelvis radiographs, the trans-teardrop (TT) line was drawn between the teardrops. The vertical distance between the TT line and the top of the pubic symphysis (TTPS) was then measured. A ratio was made between the lengths of both lines to account for the overall size of the pelvis (TTPS/TT). Linear regression analysis was then performed between PT and TTPS/TT.ResultsThere was a strong linear correlation between the TTPS/TT ratio on AP pelvis radiographs and PT on lateral radiographs (r = 0.785, r2 = 0.616, P < .001). On subanalysis of the female cohort, the correlation became even stronger (r = 0.864, r2 = 0.747, P < .001). Using regression analysis, a linear equation was created (PT = 97.32 [TTPS/TT] - 5.51), to calculate the PT using the TTPS/TT ratio.ConclusionsThere is a strong linear correlation between the TTPS/TT ratio and PT. Using this information, a surgeon can reliably use the distance between the TT line and the superior pubic symphysis on an AP radiograph to recreate the patient's functional PT intraoperatively, allowing for a more accurate patient-specific placement of the acetabular component.
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Project description:BackgroundSymptomatic leg length discrepancies (LLDs) are a significant complication after total hip arthroplasty. Many surgeons incorporate an intraoperative anteroposterior pelvis radiograph, to help prevent LLD; however, obtaining a high-quality radiograph is often difficult. The purpose of this study is to evaluate the accuracy and reliability of estimating LLD using different radiographic reference landmarks on suboptimal anteroposterior pelvis radiographs.Material and methodsWe obtained 2 pelvis Sawbones models with attached femurs and created a true shortening of the left femur of the experimental model by 7 mm. We then obtained a series of radiographs manipulating each model in standardized increments for a total of 66 different permutations of suboptimal radiographs. Each radiograph was evaluated for LLD by 2 separate orthopedic surgeons using reference lines bisecting the following anatomic landmarks: ischial tuberosities, acetabular teardrops, obturator foramina, sacroiliac joints, and the femoral heads, to the lesser trochanters. The accuracy and reliability of each line were then analyzed.ResultsThe obturator foramina line yielded the most reliable LLD estimates with an intraclass correlation coefficient of 0.939. This reference line was also the most accurate, with an average difference of 1.5 mm from the true LLD (P < .001), with 95% confidence to be within 1.8 mm.ConclusionThe obturator foramen reference line on an intraoperative radiograph is an accurate and reliable tool that should be utilized by joint replacement surgeons to estimate LLD even if the radiograph is suboptimal. This estimate is reliably reproduced among multiple observers and puts the estimate within 1.8 mm of a true LLD.
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Project description:Cytochrome oxidase (CO) reveals two compartments in V1 (patches and interpatches) and three compartments in V2 (thin, pale, and thick stripes). Previously, it was shown that thin stripes receive input predominantly from patches. Here we examined the projections to thick and pale stripes in macaques, revealed by retrograde tracer injections. After thick stripe injection, cells were distributed in layer 2/3 (67%), layer 4A (7%), layer 4B (23%), and layer 5/6 (2%). Except in layer 5/6, cells were concentrated in interpatches, with a stronger bias in layer 2/3 (84%) than in layer 4B (75%). After pale stripe injection, cells were found in layer 2/3 (87%), layer 4A (2%), layer 4B (10%), and layer 5/6 (2%). As for thick stripes, cells were located preferentially in interpatches in layer 2/3 (84%) and layer 4B (72%) but not in layer 5/6. Thick stripes received a higher proportion of their input from layer 4B, compared with pale stripes, consistent with reports that thick stripe neurons exhibit a pronounced layer 4B influence. This difference aside, both stripe types receive similar inputs from V1, at least in terms of cortical layer and CO compartment. This finding was bolstered by injecting different tracers into pale and thick stripes; 10-27% of cells were double labeled, with most located in interpatches. These results suggest that the distinctive receptive field properties of neurons in thick and pale stripes are generated by local V2 circuits, or by other specific projections, rather than by differing sources of laminar and compartmental input from V1.
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Project description:The availability of oxygen is a major environmental factor for many microbes, in particular for bacteria, such as Shewanella species, which thrive in redox-stratified environments. One of the best studied systems involved in mediating the response to changes in environmental oxygen levels is the Arc two-component system of Escherichia coli, consisting of the sensor kinase ArcB and the cognate response regulator ArcA. An ArcA ortholog was previously identified in Shewanella, and as in E. coli, Shewanella ArcA is involved in regulating the response to shifts in oxygen levels. Here, we identified the hybrid sensor kinase SO_0577, now designated ArcS, as the previously elusive cognate sensor kinase of the Arc system in S. oneidensis MR-1. Phenotypic mutant characterization, transcriptomic analysis, protein-protein interaction and phosphotransfer studies revealed that the Shewanella Arc system consists of the sensor kinase ArcS, the single phosphotransfer domain protein HptA, and the response regulator ArcA. Phylogenetic analysis suggests that HptA might be a relict of ArcB. Conversely, ArcS is substantially different with respect to overall sequence homologies and domain organization. Thus, we speculate ArcS might have adopted the role of ArcB after loss of the original sensor kinase, perhaps as a consequence of regulatory adaptation to a redox-stratified environment.
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