Digitalized analyses of intraoperative acetabular component position using image-matching technique in total hip arthroplasty

Aims Appropriate acetabular component placement has been proposed for prevention of postoperative dislocation in total hip arthroplasty (THA). Manual placements often cause outliers in spite of attempts to insert the component within the intended safe zone; therefore, some surgeons routinely evaluate intraoperative pelvic radiographs to exclude excessive acetabular component malposition. However, their evaluation is often ambiguous in case of the tilted or rotated pelvic position. The purpose of this study was to develop the computational analysis to digitalize the acetabular component orientation regardless of the pelvic tilt or rotation. Methods Intraoperative pelvic radiographs of 50 patients who underwent THA were collected retrospectively. The 3D pelvic bone model and the acetabular component were image-matched to the intraoperative pelvic radiograph. The radiological anteversion (RA) and radiological inclination (RI) of the acetabular component were calculated and those measurement errors from the postoperative CT data were compared relative to those of the 2D measurements. In addition, the intra- and interobserver differences of the image-matching analysis were evaluated. Results Mean measurement errors of the image-matching analyses were significantly small (2.5° (SD 1.4°) and 0.1° (SD 0.9°) in the RA and RI, respectively) relative to those of the 2D measurements. Intra- and interobserver differences were similarly small from the clinical perspective. Conclusion We have developed a computational analysis of acetabular component orientation using an image-matching technique with small measurement errors compared to visual evaluations regardless of the pelvic tilt or rotation. Cite this article: Bone Joint Res 2020;9(7):360–367.

Standardisation in Ultrasonography: Principle and Diagnostic Significance

Disadvantage of ultrasonography is its dependence on subjective assessment of displayed images. The way how to minimize both intraobserver and interobserver differences is creation of standard conditions for examination including a quantitative approach to evaluation of tissue reflectivity. The oldest mode of standardisation is standardised A- scan, used in ophthalmology. It enables differentiation of echoes, reflected from different ocular structures and is helpful in assessment of extraocular muscle thickness. Standardisation of B- scan depends on the type of diagnostic device and is based on quantification of image echogenicity. In our study reference values of grey-level histogram were established for some thyroid diseases using standard setting of imaging parameters. Results indicate that both standardised A- and B- scan should be helpful in differential diagnostics.

Daily Otolith increments in juvenile tropical Parrotfishes and Surgeonfishes

Otolith microstructure was examined in juvenile tropical herbivorous fish belonging to the families Acanthuridae and Saridae at Lizard Island. Growth increments on the lapilli of 14 species were validated by tetracycline marking in the laboratory. All species examined deposited growth increments on a daily basis. Increment counts in left and right lapilli were compared for consistency in increment deposition. Interobserver differences were examined as a possible cause of bias in age estimates for Ctenochaetus binotatus and Scarus schlegeli. Given the precision of otolith increment counts by an observer, the differences between counts of the left and right otoliths were acceptable, as were differences between independent observers reading the same otoliths.