Computed tomography analysis of acetabular anteversion and abduction

Aim: To explore an accurate method to calculate acetabular cup anteversion after total hip arthroplasty. Method: 1) A 3D coordinate system was established with the center of the hip joint rotation center base as coordinate center. The acetabular exit plane and Pettersson formula acetabular anteversion and Riten Pradhan formula acetabular anteversion and acetabular true anteversion were drawn; 2) Determine the mathematical expression of Pettersson formula acetabular anteversion α and Riten Pradhan formula acetabular anteversion β in the coordinate system. The true acetabular anteversion is projection angle of Pettersson formula acetabular anteversion α on cross-section in the presence of acetabular abduction δ, determining mathematical expression of the acetabular anteversion θ by trigonometric functions. Results: Real acetabular cup anteversion θ = arctg (tgβ/cosδ). Conclusion: The true acetabular cup anteversion and Pettersson formula anteversion and Riten Pradhan for mula anteversion were quite different. The difference was increased with the acetabular cup abduction angle increased. The formula was simple and accurate and worthy of clinical reference.

To evaluate whether acetabular orientation (abduction and anteversion) can be restored by lumbar pedicle subtraction osteotomy (PSO) in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis. A total of 33 consecutive AS patients with thoracolumbar kyphosis undergoing one-level lumbar PSO were retrospectively reviewed. Radiographical measurements included sagittal vertical axis, global kyphosis, thoracic kyphosis, local kyphosis, lumbar lordosis, pelvic incidence, sacral slope, and pelvic tilt. Acetabular abduction and anteversion were measured on CT scans of the pelvis before and after lumbar PSO. The preoperative and postoperative parameters were compared by the paired samples t test. Pearson's correlation analysis was conducted to determine the correlations between the changes in acetabular abduction and anteversion and the changes in sagittal spinopelvic parameters. After lumbar PSO, sagittal vertical axis, global kyphosis, and pelvic tilt were corrected from 15.7±6.7cm, 66.8°±17.5°, and 38.6°±9.0° to 2.9±4.9cm, 21.3°±8.2°, and 23.2°±8.2°, respectively (p<0.001). Of note, acetabular abduction and anteversion decreased from 59.6°±4.6° to 31.4°±6.5° before surgery to 51.4°±6.5° and 20.2°±4.4° after surgery, respectively (p<0.001). Moreover, the changes in acetabular abduction and anteversion were observed significantly correlated with the change in pelvic tilt (r=0.527, p=0.002; r=0.586, p<0.001). Abnormal acetabular abduction and anteversion could be corrected by lumbar PSO in AS patients with thoracolumbar kyphosis. Consequently, a relatively normal acetabular orientation could be achieved after lumbar PSO, which might decrease the potential risk of dislocation in AS patients with spine and hip deformities requiring subsequent THR surgery.

To evaluate the 3D deformity of the acetabula and lower limbs in subjects with adolescent idiopathic scoliosis (AIS) and their relationship with spino-pelvic alignment. Two hundred and seventy-four subjects with AIS (frontal Cobb: 33.5° ± 18° [10°-110°]) and 84 controls were enrolled. All subjects underwent full-body biplanar X-rays with subsequent 3D reconstructions. Classic spino-pelvic and lower limb parameters were collected as well as acetabular parameters: acetabular orientation in the 3 planes (tilt, anteversion and abduction), center-edge angle (CEA) and anterior and posterior sector angles. Subjects with AIS were represented by both lower limb sides and classified by elevated (ES) or lowered (LS), depending on the frontal pelvic obliquity. Parameters were then compared between groups. Determinants of acetabular and lower limb alterations were investigated among spino-pelvic parameters. Acetabular abduction was higher on the ES in AIS (59.2° ± 6°) when compared to both LS (55.6° ± 6°) and controls (57.5° ± 3.9°, p < 0.001). CEA and acetabular anteversion were higher on the LS in AIS (32° ± 6.1°, 20.5° ± 5.7°) when compared to both ES (28.7° ± 5.1°, 19.8° ± 5.1°) and controls (29.8° ± 4.8°, 19.1° ± 4°, respectively, p < 0.001). Anterior sector angle was lower on both ES and LS in AIS when compared to controls. CEA, acetabular abduction and acetabular anteversion were found to be mostly determined (adjusted R2: 0.08-0.32) by pelvic tilt and less by frontal pelvic obliquity, frontal Cobb and T1T12. Subjects with AIS had a more abducted acetabulum at the lowered side, more anteverted acetabulum and a lack of anterior coverage of both acetabula. These alterations were strongly related to pelvic tilt.

The acetabular cup positioning is one of the most crucial steps affecting stability and wear rates in total hip arthroplasty. Different methods have been described for determining the anteversion of the acetabular cup in the literature. But there is still not a widely accepted method to assess the acetabular anteversion radiography. The aim of this study is to measure the acetabular anteversion angle on a single pelvis AP radiography with our method which was proven with an experimental study before. A total of 15 patients (8 males, 7 females) who underwent total hip arthroplasty and have had a pelvis computed tomography scans in our outpatient clinic were evaluated retrospectively. The anteversion angle was calculated in all of pelvis CT scans. For radiological measurement, the formula defined by the authors in an experimental model previously was used. Statistically significant difference was not determined between radiographic and CT-based measurements (p = 0.207; p > 0.05). A statistically significant agreement was observed at a level of 98.8% between radiographic and CT-based measurements (ICC = 0.988; 95% CI 0.966-0.996; p < 0.01). Assessment of the acetabular cup anteversion is very important to predict the possible complications after total hip arthroplasty. Although many methods have been defined for this purpose, each of these has advantages and disadvantages. In particular, with computed tomography method, the patient is exposed to excessive radiation, whereas we think that our method is a preferred method due to features not requiring additional equipment, low radiation exposure, being simple, cost-effectiveness, easily applicable and almost 100% accurate.

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Radiographic measurements using two-dimensional (2D) plain radiographs or planes from computed tomography (CT) scans have several drawbacks, while measurements using images of three-dimensional (3D) reconstructed bone models can provide more consistent anthropometric information. We compared the consistency of results using measurements based on images of 3D reconstructed bone models (3D measurements) with those using planes from CT scans (measurements using 2D slice images). Ninety-six of 561 patients who had undergone deep vein thrombosis-CT between January 2013 and November 2014 were randomly selected. We evaluated measurements using 2D slice images and 3D measurements. The images used for 3D reconstruction of bone models were obtained and measured using [Formula: see text] and [Formula: see text] (Materialize, Leuven, Belgium). The mean acetabular inclination, acetabular anteversion and femoral anteversion values on 2D slice images were 42.01[Formula: see text], 18.64[Formula: see text] and 14.44[Formula: see text], respectively, while those using images of 3D reconstructed bone models were 52.80[Formula: see text], 14.98[Formula: see text] and 17.26[Formula: see text]. Intra-rater reliabilities for acetabular inclination, acetabular anteversion, and femoral anteversion on 2D slice images were 0.55, 0.81, and 0.85, respectively, while those for 3D measurements were 0.98, 0.99, and 0.98. Inter-rater reliabilities for acetabular inclination, acetabular anteversion and femoral anteversion on 2D slice images were 0.48, 0.86, and 0.84, respectively, while those for 3D measurements were 0.97, 0.99, and 0.97. The differences between the two measurements are explained by the use of different tools. However, more consistent measurements were possible using the images of 3D reconstructed bone models. Therefore, 3D measurement can be a good alternative to measurement using 2D slice images.

Various methods have been described for measuring acetabular component anteversion. However, accurate measurement of anteversion is difficult. We herein propose a new method using cross-table lateral (CL) radiography performed with the contralateral hip flexed to 45° (45° flexed CL radiography). The main purpose of this study was to evaluate the reliability and validity of this new method. The study group included 93 patients who underwent total hip arthroplasty (THA). All hips were evaluated with computed tomography (CT) and both standard and 45° flexed CL radiographs to measure acetabular component anteversion the week after THA. The intraobserver and interobserver reliability of each measurement was assessed. Plain radiography measurements were compared with reference CT measurements to evaluate their validity. All measurements had excellent intraobserver and interobserver reliability, and plain radiography measurements correlated well with CT measurements. The mean measurements were 21.9° (3°-39°) with CT, 24.9° (7°-47°; p<0.001) with standard CL radiographs, and 22.5° (7°-43°; p = 0.112) with 45° flexed CL radiographs. The anteversion values measured with our new method were closer to the CT values used as a reference standard than those with standard CL radiographs. Our new method appears to be reliable and valid for measuring acetabular component anteversion.

To compare the early effectiveness between by anterior approach via Bikini incision and by OCM approach in the primary total hip arthroplasty (THA). Between June 2015 and March 2016, 60 patients with ischemic necrosis of the femoral head who accorded with the inclusion criteria were chosen in the study, who were divided into 2 groups according to different surgical approaches. THA was performed on 30 patients by anterior approach via Bikini incision (group A), and on 30 patients by OCM approach (group B). There was no significant difference in age, gender, body mass index, side of affected hip, Steinberg stage of ischemic necrosis of femoral head, preoperative hemoglobin, preoperative Harris score, and preoperative visual analogue scale (VAS) between 2 groups ( P>0.05). The operation time, length of incision, intraoperative blood loss, transfusion rate, starting time of straight leg raising exercise, starting time of active abduction of hip, hospitalization time, the incidence of limb length discrepancy, postoperative Harris score and VAS score were recorded and compared between 2 groups. Anteroposterior pelvic X-ray films were taken to measure acetabular abduction and acetabular anteversion. Primary healing of incision was obtained in all patients of 2 groups, and there was no significant difference in complication between 2 groups ( χ2=0.144， P=0.704). All the patients of 2 groups were followed up 3 to 12 months, averaged 6 months. There was no significant difference in operation time, length of incision, intraoperative blood loss, transfusion rate, hospitalization time, and starting time of straight leg raising exercise between 2 groups ( P>0.05). Group A was significantly shorter than group B in starting time of active abduction of hip ( t=-4.591, P=0.000), and was significantly lower than group B in the incidence of limb length discrepancy ( χ2=5.455, P=0.020). After operation, neither Harris score at 2 weeks, 6 weeks, 3 months, and 6 months nor VSA score at 24 hours and 6 weeks showed significant difference between 2 groups ( P>0.05). The anteroposterior pelvic X-ray films showed that all the prostheses were in good position, and there was no femoral prosthesis subsidence, acetabular cup displacement or dislocation. No significant difference was found in acetabular abduction and acetabular anteversion at 2 days after operation between 2 groups ( t=0.887, P=0.379; t=0.652, P=0.517). Both of two approaches in THA can avoid muscle damage and achieve favorable short-term effectiveness. But, anterior approach via Bikini incision is superior to OCM approach in starting time of active abduction of hip and the incidence of limb length discrepancy.

Acetabular anteversion was measured by using two-dimensional (2-D) computed tomography (CT) scans in 39 dysplastic and 27 normal hips (patient age range, 3-33 years), and averaged 19.7 degrees in the dysplastic hips and 18.1 degrees in the normal hips. There was no statistically significant difference between the two groups, with a wide range of acetabular anteversion values noted in both groups (8-32 degrees ). Although acetabular anteversion may be increased in some patients with developmental dysplasia of the hip (DDH), it is not a universal finding. We believe that assessment and understanding of acetabular anteversion is needed before performing corrective osteotomies for hip dysplasia to optimize results and avoid the complications of acetabular retroversion.

Pelvic incidence (PI) is considered an important anatomical parameter for determining the sagittal balance of the spine. The contribution of an abnormal PI to hip osteoarthritis (OA) remains controversial. In this study, we aimed to investigate the relationship between PI and hip OA, and the difference in PI between hip OA without anatomical abnormalities (primary OA) and hip OA with developmental dysplasia of the hip (DDH-OA). In this study, 100 patients each of primary OA, DDH-OA, and control subjects with no history of hip disease were included. CT images were used to measure PI, sagittal femoral head coverage, α angle, and acetabular anteversion. PI was also subdivided into three categories: high PI (larger than 64.0°), medium PI (42.0° to 64.0°), and low PI (less than 42.0°). The anterior centre edge angles, posterior centre edge angles, and total sagittal femoral head coverage were measured. The correlations between PI and sagittal femoral head coverage, α angle, and acetabular anteversion were examined. No significant difference in PI was observed between the three groups. There was no significant difference between the groups in terms of the category distribution of PI. The DDH-OA group had lower mean sagittal femoral head coverage than the other groups. There were no significant correlations between PI and other anatomical factors, including sagittal femoral head coverage, α angle, and acetabular anteversion. No associations were found between mean PI values or PI categories and hip OA. Furthermore, there was no difference in PI between patients with primary OA and DDH-OA. From our evaluation, we found no evidence of PI being an independent factor associated with the development of hip OA. Cite this article: Bone Joint J2021;103-B(11):1656-1661.

PurposeSince sacroiliac joint (SIJ) dysfunction and hip pathology often coexist and may influence one another. While SIJ dysfunction is considered an important factor in the diagnosis and treatment of hip disorders, its relationship with hip joint bone morphology remains poorly dysfunction and hip joint understood. This study aimed to investigate the association between abnormal SIJ imaging findings and hip bone morphology in patients with hip arthroscopic surgery.MethodsThis cross-sectional study included patients who underwent hip arthroscopic surgery between January 2015 and August 2023. After applying exclusion criteria, 236 hips were analyzed and categorized into two groups; developmental dysplasia of the hip (DDH) group (the lateral center-edge angle [LCEA] <25°) and femoroacetabular impingement syndrome (FAIS) group (LCEA≧25°). Within each two groups, we assessed associations between abnormal SIJ findings on preoperative computed tomography (CT) or Magnetic resonance imaging (MRI) and various clinical and morphological parameters, including patient age, sex, bone mass index, LCEA, acetabular anteversion, femoral neck anteversion, and alpha angle.ResultsThe DDH group included 75 hips, and the FAIS group included 161 hips. In both t groups, patients with abnormal SIJ findings were significantly older than those without such findings (DDH group: 25.3 ± 12.6 vs. 33.9 ± 12.8, p-value = 0.007, the FAIS group: 23.7 ± 10.4 vs. 37.4 ± 15.0, p-value < 0.001). In the DDH group, patients with abnormal SIJ findings had significantly greater femoral neck anteversion than those without findings (24.2 ± 10.1 vs. 18.0 ± 12.7, p-value = 0.024). No significant differences were observed in LCEA, acetabular anteversion, and alpha angle between both groups.ConclusionIn patients with DDH undergoing hip arthroscopic surgery, the presence of abnormal SIJ image findings was associated with increased femoral neck anteversion. These findings suggest that hip joint instability in DDH may contribute to increased mechanical stress on the SIJ, potentially leading to abnormal imaging changes in the joint.

To investigate a method for selecting a protocol for body CT scan to acquire monochromatic images (MIs) by gemstone spectral imaging (GSI) with or without adaptive statistical iterative reconstruction (ASiR). We subjected a phantom to conventional scanning at 120 kVp and 50-700 mAs and GSI at 165-600 mAs; reconstructed MIs at 65 keV with ASiR 0-100 % for GSI; placed 5 regions of interest on each of 3 consecutive reconstructed slices to obtain the averaged standard deviation (SD) as image noise for conventional scan and GSI. Linear regression analysis yielded the mAs by conventional scan that could be used to achieve similar image noise by GSI. To achieve similar noise, we found excellent linear correlation of mAs between GSI with ASiR 0-100 % and conventional scan (r = 1.00, P < 0.0001), and obtained a table of equivalent mAs between MIs at 65 keV and conventional CT at 120 kVp. We can select a protocol for body CT scan for MIs at 65 keV with or without ASiR with results comparable to those of conventional CT at 120 kVp.

The use of computed tomography (CT) to confirm femoral head position after closed reduction and spica cast immobilization in the treatment of developmental dysplasia of the hip (DDH) has become a common practice. We retrospectively reviewed postreduction CT scans of 38 children younger than 24 months of age with unilateral DDH to determine whether they could predict acetabular remodeling potential. The measurements analyzed from the postreduction CT scans were the acetabular index, axial acetabular index, anterior and posterior acetabular angles, acetabular anteversion, and axial reduction index; the standard acetabular index was measured from the plain radiographs. The average age at reduction was 11 months and at follow-up was 61 months. No angle measured on the postreduction CT scan was found to be predictive of acetabular remodeling.

A comparative study on the use of ultra-low dose computed tomography scans with conventional computed tomography scans for the evaluation of proximal tibia intra-articular fractures

Instability after total hip arthroplasty: Analysis of combined anteversion and patient-related clinical parameters.