Reliability of Overcoverage Parameters With Varying Morphologic Pincer Features: Comparison of EOSA (R) and Radiography
ABSTRACT BACKGROUND: Multiple radiographic parameters used for diagnosis and quantification of morphologic pincer features have emerged, but the degree to which pelvic tilt or rotation affects conventional radiography and EOS(®) is unknown. QUESTION/PURPOSES: We asked: (1) What is the reliability of EOS(®) and conventional radiography at increasing sizes of morphologic pincer features with varying degrees of tilt and rotation? (2) What is the effect of tilt and rotation on acetabular overcoverage measurements? METHODS: Using a dry cadaveric pelvis, AP conventional radiographs and EOS(®) images were taken at intervals of increasing modeled pincer size with 0° to 15° varying tilt and rotation. Lateral center-edge angle, Sharp angle, Tönnis angle, crossover sign, and retroversion index were measured on all images. Statistical analysis was conducted. RESULTS: The intermodality intraclass correlation coefficients for conventional radiography and EOS(®) radiography across all pincer sizes, rotations, and tilts were excellent (0.93-0.98). Crossover sign was in perfect agreement in conventional radiography and EOS(®). Rotation of the hip away from the beam source and/or increased anterior tilt falsely increased all overcoverage parameters except for Tönnis angle. Rotation away from the beam of 10°or greater or anterior tilt of 5° or greater produced a false-positive crossover sign. CONCLUSIONS: EOS(®) radiography maintained excellent reliability in comparison to conventional radiography but both were equally vulnerable to the effects of tilt and rotation for quantification of hip parameters used in acetabular overcoverage assessment. A standardized pelvic radiograph ensuring that the pelvis is not excessively tilted or rotated should be used for assessing acetabular overcoverage parameters.
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ABSTRACT: Acetabular anatomy on AP pelvic radiographs depends on pelvic orientation during radiograph acquisition. However, not all parameters may change to a clinically relevant degree with differences in pelvic orientation. This issue may influence the diagnosis of acetabular pathologies and planning of corrective acetabular surgery (reorientation or rim trimming). However, to this point, it has not been well characterized.Clinical Orthopaedics and Related Research 09/2014; 473(4). DOI:10.1007/s11999-014-3936-8 · 2.88 Impact Factor
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ABSTRACT: Excessive acetabular coverage is the most common cause of pincer-type femoroacetabular impingement. To date, an association between acetabular over-coverage and genetic variations has not been studied. In this study we investigated the association between single nucleotide polymorphisms (SNPs) of paralogous Homeobox (HOX)9 genes and acetabular coverage in Japanese individuals to identify a possible genetic variation associated with acetabular over-coverage. We investigated 19 total SNPs in the four HOX9 paralogs, then focused in detail on seven of those located in the 3' untranslated region of HOXB9 (rs8844, rs3826541, rs3826540, rs7405887, rs2303485, rs2303486, rs79931349) using a case-control association study. The seven HOXB9 SNPs were genotyped in 316 subjects who had all undergone radiological examination. The association study was performed by both single-locus and haplotype-based analyses. The genotype and allele frequencies of the five HOXB9 SNPs showed significant association with acetabular over-coverage compared with controls (rs7405887 OR = 3.16, p = 5.29E-6, 95% CI 1.91 to 5.25). A significant difference was also detected when haplotypes were evaluated (OR = 2.59, p = 2.61E-5, 95% CI 1.65 to 4.08). The two HOXB9 SNPs (rs2303485, rs2303486) were associated with decreased acetabular coverage (rs2303485 OR = 0.524, p = 0.0091, 95% CI 0.322 to 0.855; rs2303486 OR = 0.519, p = 0.011, 95% CI 0.312 to 0.865). The five HOXB9 SNPs (rs8844, rs3826541, rs3826540, rs7405887, rs79931349) were associated with acetabular over-coverage. On the other hand, the two SNPs (rs2303485 and rs2303486) were associated with the lower acetabular coverage. The association of rs2303486 would be consistent with the previous study. Therefore, the HOXB9 SNPs might be involved in the morphogenesis of acetabular coverage, and could be an independent risk factor for developing pincer-type femoroacetabular impingement. Cite this article: Bone Joint Res 2015;4:50-5. ©2015 The British Editorial Society of Bone & Joint Surgery.04/2015; 4(4):50-5. DOI:10.1302/2046-3758.44.2000349