Computed tomography in congenital hip dislocation. The role of acetabular anteversion.

Browning, W. H.; Rosenkrantz, Harvey; Tarquinio, Thom A.

doi:10.2106/00004623-198264010-00005

Cited by 73 publications

(16 citation statements)

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“…More exacting techniques are a shootthrough lateral radiograph of the pelvis on the CT scanner bed [14], or obtaining a three-dimensional CT scan so that the reconstructed pelvis can be reoriented anatomically before making measurements [1,19]. It is possible that inconsistencies in pelvic orientation explain the conflicting findings between studies that associate hip dysplasia with increased acetabular anteversion [7,12,22,29,42], retroversion [15,27,43,46], or no difference in acetabular orientation [26].…”

Section: Discussionmentioning

confidence: 99%

Pelvic Positioning Creates Error in CT Acetabular Measurements

Bosse¹,

Lee

Henderson

et al. 2011

Clinical Orthopaedics &Amp; Related Research

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Background CT allows for accurate measurement of acetabular orientation and shape, but malpositioning of the pelvis may lead to measurement variance. Purpose We therefore sought to determine: (1) whether acetabular anteversion measurements using the femoral head centers differed from those using the posterior ischia, and (2) the extent to which changing obliquity, rotation, and tilt of a pelvis in a CT scanner affected the measurement of acetabular variables. Methods A radiopaque human pelvis model with articulated hips was suspended from a plastic sheet as part of an adjustable frame. Changes in the transverse and sagittal planes created rotation and tilt, while rotating the frame in the coronal plane created obliquity. CT scans were obtained, varying the combinations of obliquity, rotation, and tilt by intervals of 5°, up to 20°. Acetabular anteversion (AA), anterior acetabular sector angle (AASA), posterior acetabular sector angle (PASA), and horizontal acetabular sector angle (HASA) were measured. Results The two methods for measuring AA yielded values differing by 1°to 4°but correlated (r = 0.981) across the spectrum of pelvis positioning. Pelvic obliquity and tilt were linearly associated with changes in the measurements. For each 1°-increase in pelvic obliquity, AA changed À0.4°, and AASA, PASA, and HASA changed 1.93°, 0.99°, and 2.80°, respectively. For each 1°-increase in pelvic tilt, AA changed 0.8°, and AASA, PASA, and HASA changed À1.07°, 0.52°, and À0.51°, respectively. Rotation had no affect on the variables. Conclusions Small changes in pelvic obliquity and tilt were associated with variances in acetabular measurements. The measured changes were directly proportional to the changes in obliquity and tilt, and were additive. Pelvic rotation created no changes in measurement. Clinical Relevance Incorrect interpretation of acetabular anteversion and coverage may lead to unsatisfactory acetabular fragment positioning during reorientational surgery. Although intraoperative positioning of an acetabular fragment may not be as precise as the tools for preoperative planning, it is important for a surgeon to have the most precise data available for planning a procedure, and know where error can occur in collecting the data.Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.

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Section: Discussionmentioning

confidence: 99%

Pelvic Positioning Creates Error in CT Acetabular Measurements

Bosse¹,

Lee

Henderson

et al. 2011

Clinical Orthopaedics &Amp; Related Research

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“…Therefore, exactly evaluating the anteversion of acetabulum and femur could be quite crucial before surgical decision-making for children with DDH to avoid complications. Several investigators have reported that anteversion of the acetabulum is significantly increased on the side involved in DDH [7][8][9], whereas others have failed to confirm those findings [10][11][12][13]. In the past, the widely held belief was that there was increased femoral anteversion on the involved side in DDH; and so femoral derotational osteotomy was believed to be required.…”

Section: Introductionmentioning

confidence: 99%

Three dimensional-CT evaluation of femoral neck anteversion, acetabular anteversion and combined anteversion in unilateral DDH in an early walking age group

Jia

Zhang

et al. 2011

International Orthopaedics (SICOT)

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Femoral derotational osteotomy seems not to be necessary in Tönnis II and III types in unilateral DDH. Femoral derotational osteotomy should be considered in DDH, especially in Tönnis IV type, if the CA is still above 62° and the hip joints present instability in operation after abnormal acetabular anteversion, acetabular index and acetabular coverage of the femoral head are recovered to normal range through pelvic osteotomy.

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“…With the advent of advanced imaging (CT and MRI), investigators have traditionally measured hip abduction using selected axial images through the hip joint. 9 , 10 However, traditional methods that use only axial imaging may be misguided because axial measurements actually describe a projection of the abduction angle rather than the true angle. When a hip is flexed to 90° in spica, axial CT or MRI images can be appropriately used to measure the true angle of abduction.…”

Section: Discussionmentioning

confidence: 99%

“… 1 , 7 , 8 Despite this shortfall in measurement technique, it has been our observation that practitioners and researchers continue to use the traditional method of radiographically estimating hip abduction—measuring the deviation of the femoral axis from midline as seen on axial imaging—even when the hip is flexed to < 90°. 9 , 10 The purpose of this study was to develop a novel way to accurately estimate hip abduction regardless of hip flexion angle. We also sought to analyse the traditional method’s accuracy and reliability compared with our novel method.…”

Section: Introductionmentioning

confidence: 99%

An improved method for measuring hip abduction in spica after surgical reduction for developmental dysplasia of the hip

DeFrancesco

Blumberg

Chauvin

et al. 2017

Journal of Children's Orthopaedics

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PurposeExcessive in-spica abduction is a risk factor for oste-onecrosis after surgical reduction for developmental dysplasia of the hip (DDH). The traditional method for radiographically measuring hip abduction using axial imaging does not reflect the true angle, which usually lies in an oblique plane. The purpose of this study was to describe a novel method for measuring true hip position using advanced imaging.MethodsA trigonometric model was derived to define hip position based upon the femoral axis angular deviation from midline as measured on axial and coronal sequences of MRI studies. In-spica MRIs of 28 hips having undergone surgery for DDH were reviewed. On two separate occasions, the same three raters measured the femoral axis deviation from mid-line on axial and coronal imaging. Abduction was estimated using the traditional method of measurement and our novel method. Intra- and inter-rater reliability were assessed.ResultsThe methods yielded different estimates (p < 0.001). Inter- and intra-rater reliability were excellent for both methods (inter-rater ICC > 0.922, intra-rater ICC > 0.919). The traditional method is accurate at 90° of flexion, but it increasingly overestimates abduction as hip flexion decreases. All cases where hip flexion was ≤ 40° exhibited ≥ 10° of error.ConclusionsDecreasing hip flexion in spica modifies the perceived angle of abduction as measured using axial imaging. This inaccuracy can be overcome through assessment of orthogonal views using our new approach, which is accurate and reliable. It should be considered for future research investigating the effects of in-spica hip position on outcomes of DDH treatment.

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Computed tomography in congenital hip dislocation. The role of acetabular anteversion.

Cited by 73 publications

References 0 publications

Pelvic Positioning Creates Error in CT Acetabular Measurements

Pelvic Positioning Creates Error in CT Acetabular Measurements

Three dimensional-CT evaluation of femoral neck anteversion, acetabular anteversion and combined anteversion in unilateral DDH in an early walking age group

An improved method for measuring hip abduction in spica after surgical reduction for developmental dysplasia of the hip

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