Acetabular Anteversion Research Articles

A novel method of acetabular component anteversion measurement on plain radiographs.

Acetabular component anteversion (ACA) markedly impacts the outcome of total hip arthroplasty (THA) and thus is routinely measured on radiographs postoperatively. However, clinical ACA measurement methods are either too complicated or subjective due to three drawbacks: complex calculations, measurement of obscured points, and complex geometric drawings. This study aimed to develop a precise and convenient novel method of measuring ACA on routine radiographs without the three drawbacks and to verify its accuracy and reliability by comparing it against existing methods. A novel geometric principle to measure ACA was developed. Accordingly, a protractor was designed to measure radiographic anteversion (RA) on anteroposterior (AP) hip radiographs. Three researchers measured RA twice, using the protractor, McLaren's, and Pradhan's method on 26 computer-simulated radiographs with pre-set RAs and 20 actual radiographs. Accuracy was assessed by errors on simulated radiographs, and reliability was assessed by results of measurements on simulated and actual radiographs. The absolute error of the novel method (1.01° ± 1.06°) was lower than McLaren's method (1.34° ± 1.16°) (p < 0.05) and not significantly different from Pradhan's method (1.10° ± 1.02°) (p = 0.392). The protractor's intra-rater and inter-rater reliability were good-to-excellent or excellent and higher or equivalent to the two other methods. The novel method avoids the three major drawbacks of conventional methods. Its accuracy is significantly higher than McLaren's method and comparable to Pradhan's. The novel method has higher or non-inferior accuracy and reliability than McLaren's and Pradhan's methods.

The accuracy and efficiency of design and development of 3D printed integral anatomical acetabular prosthesis in total hip arthroplasty for Crowe type Ⅱ and Ⅲ developmental dysplasia of the hip

Objective: To compare the accuracy and efficiency between the model development method and the software development method, which design and develop 3D printed integral anatomical acetabular prosthesis to be used in total hip arthroplasty(THA) for patients with Crowe type Ⅱ and Ⅲ developmental dysplasia of the hip(DDH). Methods: Fifteen patients with end-stage hip osteoarthritis due to Crowe type Ⅱ and Ⅲ DDH who underwent THA in the Orthopedics Department of the First Affiliated Hospital of Bengbu Medical College between January 2015 and June 2023 were selected in this study retrospectively. There were 1 male (1 hip) and 14 females (17 hips) with a mean age of (55.1±9.1) years. There were 12 hips with Crowe type Ⅱ, 6 hips with Crowe type Ⅲ. The preoperative pelvis three-dimensional CT data in those patients were used to design integral anatomical acetabular prosthesis. The model development group used 3D printing technology to print life-size pelvis models. The acetabulum was reamed and the acetabulum cup was inserted into the socket according to conventional THA procedures. The bone defect above the acetabulum cup was filled with bone wax. The Mimics and 3-matic software were used to simulate the THA procedures, design and install the integrated anatomical acetabular prosthesis in the software development group. The operation time, the size of the acetabular cup, the volume and surface area of the acetabulum bone defect, the acetabular cup's inclination and anteversion, the horizontal distance and the vertical distance of hip rotation center were compared between the two methods. Results: The study in the two groups were all based on the data of 18 hips in the 15 patients. The horizontal and vertical distances of rotation center in the model development group and software development group was (32.08±1.80) mm, (32.17±2.40) mm and (14.36±1.53) mm, (15.11±1.45) mm, respectively (both P>0.05). The cup size in model development group was (48.56±1.15)mm, and it was (48.77±1.22) mm in the software group (P=0.160). The anteversion and inclination of the acetabular cup in the model and software groups were 23.79°±6.31°, 30.49°±11.03° and 15.17°±0.52°, 40.24°±0.58°, respectively (both P<0.01). The volume and surface area of the acetabulum bone defect in the model development group was (5.06±2.86) mm3 and (8.31±2.21) mm2, respectively, while it was (4.01±2.56)mm3 and (6.83±2.71) mm2, respectively, in the software development group (both P<0.05). The work time in the model development group was (24.43±0.68) h and (0.47±0.12) h in the software development group, respectively (P<0.001). Conclusion: Compared with the 3D printing model development method, the application of Mimics and 3-matic software to design and develop integrated anatomical acetabular prosthesis in total hip arthroplasty for Crowe type Ⅱ and Ⅲ DDH show advantages of convenience, high efficiency and more accuracy.

Evaluating Alternative Registration Planes in Imageless, Computer-Assisted Navigation Systems for Direct Anterior Total Hip Arthroplasty.

(1) Background: Imageless computer navigation systems have the potential to improve the accuracy of acetabular cup position in total hip arthroplasty (THA). Popular imageless navigation methods include locating the patient in a three-dimensional space (registration method) while using a baseline to angle the acetabular cup (reference plane). This study aims to compare the accuracy of different methods for determining postoperative acetabular cup positioning in THA via the direct anterior approach. (2) Methods: Fifty-one participants were recruited. Optical and inertial sensor imageless navigation systems were used simultaneously with three combinations of registration methods and reference planes: the anterior pelvic plane (APP), the anterior superior iliac spine (ASIS) and the table tilt (TT) method. Postoperative acetabular cup position, inclination, and anteversion were assessed using CT scans. (3) Results: For inclination, the mean absolute error (MAE) was lower using the TT method (2.4° ± 1.7°) compared to the ASIS (2.8° ± 1.7°, p = 0.17) and APP method (3.7° ± 2.1°, p < 0.001). For anteversion, the MAE was significantly lower for the TT method (2.4° ± 1.8°) in contrast to the ASIS (3.9° ± 3.2°, p = 0.005) and APP method (9.1° ± 6.2°, p < 0.001). (4) Conclusion: A functional reference plane is superior to an anatomic reference plane to accurately measure intraoperative acetabular cup inclination and anteversion in THA using inertial imageless navigation systems.

Erect weight-bearing pelvic radiographs are superior to supine radiographs for diagnosis of mixed type acetabular retroversion plus developmental dysplasia hip deformity

PurposeThis study focused on the mixed-type deformities of acetabular retroversion (AR) and developmental dysplasia hip deformity (DDH) and aimed to ascertain the changes in pelvic tilt from a supine to a standing position in these cases and identify potential underlying mechanisms. MethodsA retrospective study was conducted on cases with symptomatic DDH from January 1, 2019, to April 30, 2023. DDH was defined as LCEA < 20°. AR was diagnosed by using a crossover index threshold of 0.2 in standing pelvic X-ray. Two observers assessed the supine and weight-bearing pelvic radiographs, along with computed tomography (CT) scans. The evaluated parameters included pelvic tilt (sacrofemoral-pubic angle (SFP), symphysis to sacrococcygeal distance (PSSC), pubic symphysis to sacroiliac (PSSI)), acetabular retroversion (crossover index, posterior wall sign), acetabular coverage (lateral center-edge angle (LCEA), ischial spine sign (ISS)), and axial rotation of the hemipelvis (pelvic width index, obturator index, and ilio-ischial angle). Acetabular orientation and coverage was measured by CT through anterior sector angle (ASA), posterior sector angle (PSA) and acetabular anteversion (AA). Cases with acetabular retroversion plus DDH were defined as the mixed-type deformity. Comparative analyses between mixed-type deformities and DDH cases were performed along with subgroup and correlation analyses within mixed-type cases. Inter-observer and intra-observer reliabilities were assessed using intraclass correlation coefficients. ResultsA total of 85 were included. 26 cases (30.59%) had mixed-type deformity, where transition from the supine to standing position led to an increased posterior pelvic tilt (SFP (supine: 64.35±4.6°, standing: 74.75±4.16°, p<0.001), PSSC (supine: 6.37±2.47, standing: 2.08±1.32, p<0.001) and PSSI (supine: 9.47±1.66, standing: 6.33±1.08, p<0.001)). Compared to cases with DDH, CT examination revealed a significantly greater anterior acetabular coverage and less posterior superior coverage, with smaller posterior sector angle and greater anterior sector angle (ASA) (p<0.05) for cases with AR. The superior iliac wing angle (mixed type: 45.63±9.22°, isolated type: 50.70±8.77°, p=0.013), inferior iliac wing angle(mixed type: 60.77±8.24°, isolated type: 65.24±8.02°, p=0.013), and ischiopubic angle (IPA) (mixed type: 32.27±3.19°, isolated type: 36.71±5.38°, p<0.001) were significantly reduced in AR cases, suggesting external rotation of the hemipelvis. Subgroup analysis showed that cases with a higher crossover index had a significantly higher PSSC and a significantly lower IPA. ConclusionAR was observed in 31% of DDH cases and was associated with a notable posterior pelvic tilt during postural transitions. This tilt appeared to be a compensatory mechanism affecting the AR diagnosis. Key changes in the acetabular coverage, including increased anterior coverage and decreased superior posterior coverage, were also observed. Additionally, external rotation of the hemipelvis in mixed-type cases correlated strongly with the extent of AR and anterior acetabular coverage, suggesting that it may be a key contributor to the underlying mechanism of this mixed-type deformity. Level of evidenceIII, retrospective case series.

Body Mass Index is Related to Femoral Anteversion, Hip Rotation During Gait, and Passive Hip Range of Motion in Children and Adolescents.

Overweight and obesity are major global health issues, often linked to orthopaedic problems, skeletal malalignments, and altered gait biomechanics. However, skeletal and biomechanical adaptions in the transverse plane remain underexplored. Therefore, this study aimed to investigate the relationship between body mass index (BMI) and variables describing lower extremity torsional profiles, hip rotation mobility, and transverse plane gait characteristics in children and adolescents. Acetabular and femoral anteversion, tibial torsion (measured through computed tomography), hip and knee rotation, and foot progression angles during the stance phase of gait (measured by 3D gait analysis), as well as passive hip rotation range of motion (evaluated as the midpoint of hip rotation in clinical examination), were retrospectively analyzed in 122 children and adolescents. Correlations between all variables and logit-transformed BMI percentiles were calculated. Moderate correlations were found between BMI percentile and hip rotation during the stance phase (r=-0.68, P<0.001), the passive midpoint of hip rotation (r=-0.51, P<0.001), and femoral anteversion (r=-0.50, P<0.001). Small correlations were observed for acetabular anteversion (r=-0.36, P<0.001), knee rotation during stance phase (r=0.34, P<0.001), and foot progression angle during stance phase (r=-0.31, P<0.001). Tibial torsion showed a nonsignificant negligible relationship with BMI percentile (r=-0.26, P=0.004). BMI percentile was positively correlated with external hip rotation during the stance phase of gait and passive external hip rotation, and negatively correlated with femoral anteversion. These findings suggest abnormal body weight is associated with static and dynamic biomechanical alterations. Therefore, weight management should be considered in orthopaedic assessments and treatment planning for children and adolescents.

The Influence of Pelvic Tilt and Femoral Torsion on Hip Biomechanics: Implications for Clinical Assessment and Treatment

Background: Hip biomechanics are crucial in understanding movement disorders and joint pathologies. Pelvic tilt and femoral torsion are key factors influencing hip function and stability. This review aims to elucidate their effects on acetabular orientation, hip range of motion (ROM), and associated compensatory mechanisms. Methods: A comprehensive search of databases, including PubMed, Scopus, and Pedro, was conducted. Studies were selected based on Population, Concept, and Context (PCC) criteria, focusing on those examining the relationship between pelvic tilt, femoral torsion, and hip biomechanics. Eight studies were included, utilizing methodologies such as CT imaging, musculoskeletal modeling, and gait analysis, covering populations ranging from asymptomatic adults to elderly women with pelvic retroversion. Results: The review identified significant effects of pelvic retroversion on acetabular anteversion and hip extension. Some studies found no correlation between pelvic index (PI) and acetabular orientation, while others reported a linear increase in acetabular anteversion with pelvic retroversion. Subjects with pelvic retroversion showed greater hip extension. Additionally, femoral anteversion was linked to increased internal rotation and altered hip joint contact forces during gait, with changes in hip ROM and force distribution. No relationship was found between femoral and acetabular anteversion in patients with hip osteoarthritis. Conclusions: Pelvic tilt and femoral torsion significantly affect hip biomechanics, influencing acetabular orientation, ROM, and compensatory mechanisms. Future studies should include symptomatic populations to explore these relationships further. These findings emphasize the critical need for individualized clinical assessments and further research on symptomatic populations to enhance our understanding of pelvic tilt and femoral torsion’s impact on hip biomechanics.

Does the utilization of fluoroscopy affect the accuracy of prosthesis position in patients undergoing hip replacement surgery via the direct anterior approach compared to the posterolateral approach for an experienced surgeon? A single-center retrospective study

BackgroundThe direct anterior approach (DAA) for total hip arthroplasty (THA) has gained popularity due to perceived advantages in achieving better early outcomes. However, the theoretical benefits such as precise implant positioning and accurate leg length restoration are still inconsistent. In this study, we compared implant position and leg length discrepancy (LLD) of the DAA and posterolateral approach (PLA) conducted by a single surgeon who had mastered both approaches.MethodsThis study retrospectively reviewed the medical records and radiographic images of 244 patients who underwent THA between 2012 and 2021 by a single experienced surgeon using either the DAA (n = 120) or PLA (n = 124). Postoperative pelvic anteroposterior radiographs at 6 months follow-up were used to assess acetabular component inclination and anteversion, as well as LLD. Mann-Whitney U tests and Chi-squared test were performed to compare outcomes between the two approaches.ResultsNo significant differences were observed in patient demographics between the two groups. The DAA group demonstrated significantly lower postoperative LLD (0.00 mm) compared to the PLA group (5.00 mm, p < 0.0001). No significant difference was observed in the Lewinnek zone for cup anteversion and inclination angles between the two groups.ConclusionsFor experienced surgeons in other approaches, our findings suggest transferring to the DAA may not substantially improve cup positioning, but it might slightly enhance limb length measurement. For surgeons already proficient in other approaches and deciding to maintain those approaches, their primary concern for optimal THA outcome should be striving for leg length equivalence.

Influence of hip prosthesis position on postoperative gait in symptomatic hip osteoarthritis secondary to hip dysplasia patients after primary total hip arthroplasty: a short-term follow-up study

BackgroundThe aim of this study was to analyze the influence of the positioning of the components of total hip arthroplasty (THA) evaluated by the acetabular anteversion (AA) and femoral anteversion (FA) angle on postoperative gait in patients with symptomatic hip osteoarthritis secondary to hip dysplasia undergoing THA.MethodsBetween May 2023 and May 2024, patients with symptomatic hip osteoarthritis secondary to hip dysplasia (Crowe Type I and IV) who underwent THA were enrolled in the study. The AA angle and FA angle were measured by computer tomography (CT). Gait data were determined by using the Dynamic Right Gait & Posture analysis system. The relationship between FA, AA and gait data was analyzed by Pearson correlation test, subgroup Pearson correlation test, multiple linear regression.ResultsA total of 40 patients (45hips) were included in the study. Compared with preoperative, the patient’s postoperative foot progression angle, foot contact angle, plantarflexion velocity, swing foot speed, gait velocity, cadence, stride length were significantly improved. Preoperative FA is significantly different from postoperative FA (P < 0.05), while the difference between preoperative and postoperative AA is not significant. BMI, Crowe Type, AA were related to change of cadence. The less the postoperative AA of patients, and the more the cadence in the postoperative gait of patients.ConclusionOur study showed that THA could improve the gait function of patients with symptomatic hip osteoarthritis secondary to hip dysplasia. Adjusting AA lower could obtain a much more postoperative cadence.

Imaging characteristics of hip joint microinstability: a case-control study of hip arthroscopy patients.

Hip microinstability is a clinical entity increasingly recognized and treated but challenging to diagnose with a lack of objective criteria. This study assessed the prevalence and diagnostic accuracy of different imaging findings for hip microinstability on radiograph and MR. A retrospective case-control study of 224 hips treated with arthroscopic surgery by a single orthopedic surgeon, 112 hips with clinical microinstability and 112 controls without. Pre-operative radiograph and MRI/MRA imaging were evaluated by two musculoskeletal radiologists to assess morphological parameters and imaging signs reportedly associated with hip microinstability. Four imaging features reached significance as predictors of microinstability via three-step logistic regression: labral hyperplasia and decreased lateral center edge angle on MR (OR 2.45 and 0.93, respectively) and the absence of positive ischial spine sign and absence of osteophytes on radiographs (OR 0.47 and 0.28, respectively). Increased acetabular anteversion and absence of cam lesions were more likely in the microinstability group (p = 0.02 and 0.04, respectively), but not independent predictors. Labral tears, chondral loss, abnormal ligamentum teres, anterior capsule thinning, iliocapsularis to rectus femoris ratio, posterior crescent sign, cliff sign, and femoro-epiphyseal acetabular roof (FEAR) index were not associated with microinstabillity. Imaging features may be predictive of hip microinstability in some cases. Decreased LCEA, increased acetabular anteversion, and labral hyperplasia were associated with microinstability in this study, while many other published imaging findings were not. Imaging remains complementary, but not definitive, in the diagnosis of hip microinstability.

Lower limb maltorsion and acetabular deformity in children and adolescents with X-linked hypophosphatemia.

X-linked hypophosphatemia (XLH) is a rare monogenetic skeletal disorder. Lower limb deformities contribute substantially to impaired gait quality and burden of disease in patients with XLH. Standardized data regarding onset and severity of lower limb maltorsion are unavailable. This study aimed to evaluate lower limb maltorsion using rotational magnetic resonance imaging (MRI) and computed tomography (CT). Rotational MRI and CT of children and adolescents with verified XLH were evaluated retrospectively. Femoral and tibial torsion, acetabular anteversion, and axial acetabular coverage were measured and compared with published age-adapted radiographic, clinical measurements and MRI data, respectively. Fifteen patients (mean age, 10.7 years) were included in the study. Decreased femoral torsion was observed in 47% (14/30 femora) and femoral retrotorsion in 17% (5/30 femora). Ten of 13 hips with coxa vara deformity presented with decreased femoral antetorsion. Reduced external tibial torsion manifested in 64% (18/28 tibiae). Abnormal axial femoral head coverage was present in 67% (20/30 hips), whereas 53% (16/30 hips) showed increased acetabular anteversion. Femoral and tibial torsional pathologies were found in children and adolescents with XLH. The occurrence of severe femoral retrotorsion in a 2-year-old child prior to ambulation raises questions regarding the biomechanical impact of gait on the development of torsional deformities in XLH.

Acetabular morphology variations in a Hispanic population.

Rotational abnormalities of the hip have been implicated in the etiology of diseases, such as hip dysplasia, osteoarthritis, and femoroacetabular impingement. Despite the extensive literature on hip morphology, there is a gap in knowledge regarding variations in the Hispanic population. To describe the bony anatomy variations of the acetabulum in a Hispanic population. This is a cross-sectional study. We studied 182 computed tomography (CT) images in patients aged older than 21 years, who had undergone pelvic CT for any condition, except hip fracture. Measurements of acetabular version, anterior and posterior acetabular sector angles (AASA/PASA) and horizontal acetabular sector angles (HASA) were made. Acetabular variations were then compared to weight and sex data. The mean acetabular anteversion was greater in women (P < 0.001). Women exhibited a greater PASA (P < 0.05); however, men had a greater AASA (P < 0.05). Underweight individuals had a smaller PASA (P < 0.01) and HASA (P < 0.05) than individuals with a normal weight. The Hispanic hip is morphologically similar to other populations previously reported in the literature; however, Hispanic men have less coverage of the femoral head by the posterior acetabular wall when compared to women of the same ethnicity. These abnormalities have a direct impact on management and surgical approach in patients treated for femoroacetabular impingement and hip dysplasia.

Long-term computed tomographic osteolytic analysis of highly cross-linked polyethylene prosthesis after total hip arthroplasty

To analyze the occurrence of osteolysis in total hip arthroplasty (THA) with highly cross-linked polyethylene prosthesis during a follow-up of more than 15 years. The clinical data of 84 patients (105 hips) treated with THA in the Affiliated Hospital of Kanazawa Medical University in Japan between June 2000 and April 2004 and met the selection criteria was retrospectively analyzed. There were 7 males and 77 females, aged from 41 to 75 years, with an average of 56.4 years. There were 94 hips with secondary hip osteoarthritis, 4 hips after pelvic osteotomy, 2 hips with primary hip osteoarthritis, 2 hips with traumatic hip osteoarthritis, 2 hips with osteonecrosis of the femoral head, and 1 hip with rheumatoid arthritis. According to Crowe classification, there were 79 hips of type Ⅰ, 19 hips of type Ⅱ, 6 hips of type Ⅲ, and 1 hip of type Ⅳ. The highly cross-linked polyethylene acetabular liner combined with a 26 mm zirconia femoral head were used in all patients. X-ray films were taken after operation to analyze the radiation transmission and osteolysis around the acetabular prosthesis. The vertical distance (the distance between the teardrop line at the lower edge of the pelvis and the perpendicular line of the hip rotation center), the horizontal distance (the horizontal distance between the hip rotation center and the interteardrop line and the vertical line at the lower edge of the teardrop), and the acetabular cup anteversion angle were measured at last follow-up. The acetabular and femoral osteolysis was analyzed by CT scan and three-dimensional multiplanar reconstruction (3D-MPR). Combined with X-ray film and CT results, osteolysis was evaluated according to the Narkbunnam score. Deep vein thrombosis of lower limbs occurred in 2 cases. All patients were followed up 15-18 years, with an average of 15.9 years. One hip dislocation and 1 periprosthetic fracture occurred postoperatively, and no acetabular loosening or prosthetic lining ruptures occurred. Except for 1 patient who had a radiolucent line in the acetabulum after operation, the other 83 patients did not show any radiolucent line in the acetabulum or the femur. None of the patients underwent hip revision. X-ray films at last follow-up showed an acetabular cup anteversion angle of -10°-39°, with an average of 22°; a vertical distance of 3.5-47.1 mm, with an average of 24.6 mm; and a horizontal distance of 22.6-48.1 mm, with an average of 31.7 mm. There was no acetabular or femoral osteolysis in all patients on X-ray films and CT 3D-MPR images at last follow-up, and the Narkbunnam score was 0 in any region. Highly cross-linked polyethylene prosthesis does not increase the risk of long-term complications such as osteolysis after THA.

The effect of intraoperative fluoroscopy on acetabular component positioning and patient anatomy restoration during total hip arthroplasty: A systematic review and meta-analysis.

In total hip arthroplasty (THA), the positioning of components holds critical importance for factors such as joint stability, polyethylene liner wear, and range of motion. This meta-analysis aimed to compare the effects of intraoperative fluoroscopy (IF) versus no use of IF on component positioning and the restoration of patient anatomy during THA. We conducted our systematic review following the recommendations outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. The literature search was performed from the inception of medical databases up to August 2023. PubMed, Embase, Web of Science, Cochrane Controlled Trials Register, Cochrane Library, Highwire, Wanfang, China National Knowledge Infrastructure (CNKI), China Biology Medicine Disc (CBM), and China Science and Technology Journal (CSTD) databases were systematically searched to identify relevant studies comparing IF versus no IF during primary THA. Thirteen studies involving 2195 patients (2207 hips) were incorporated in the Analysis. No statistically significant differences were observed between the groups in terms of acetabular cup inclination angle (ACIA, P = .9), ACIA within the safe zone rate (P = .87), acetabular cup anteversion angle (ACAA, P = .42), ACAA within the safe zone rate (P = .35), combined safe zone rate (P = .30), limb length difference (LLD, P = .13), dislocation rate (P = .76), and infection rate (P = .97). In comparison to the no fluoroscopy group, the IF group exhibited prolonged operation time (P < .00001) and reduced femoral component offset difference (FCOD, P = .03). IF did not demonstrate improvements in acetabular cup placement, limb length difference, or dislocation occurrence. Nonetheless, IF showed a significant enhancement in restoring femoral offset. It is noteworthy that surgeons operating in facilities with lower patient volumes may observe more pronounced benefits from IF.

Relation of native acetabular anteversion to the orientation of transverse acetabular ligament.

Precise positioning of the acetabular component during total hip replacement is the key to achieving optimal implant function and ensuring long-term patient comfort. However, different anatomical variations, degenerative changes, dysplasia, and other diseases make it difficult. In this study, we discuss a method based on the three-dimensional direction of the transverse ligament, predicting native acetabular anteversion with higher accuracy. Angular positions of the acetabulum and direction of the transverse ligament were automatically calculated from routine computed tomography data of 270 patients using a registration algorithm. The relationship between acetabular angles and ligament direction and their relationship with sex, age, and pelvic tilt were sought. These relationships were then modelled using multilinear regression. Including the direction of the transverse ligament in the sagittal and transverse planes as a regressor in the multilinear model explained the variation in acetabular anteversion (R2 = 0.76 for men, R2 = 0.63 for women; standard deviation in prediction: men, 3.92° and women, 4.00°). The results indicate that the ligament was suitable as a guidance structure almost insensitive to the ligament in the sagittal and transverse planes must be considered. Estimation based on the direction in only 1 plane was not sufficiently accurate. The operative acetabular inclination was not correlated with the direction of the ligament. The correlations were higher in men than in women.

Assessing the Reliability of Postoperative Cross-Table Radiographs Compared to CT Scans for Measuring Acetabular Anteversion Angle Following Total Hip Arthroplasty.

This study aimed to evaluate acetabular anteversion following total hip arthroplasty (THA) using cross-table lateral radiographs and CT scans and to determine the reliability of cross-table lateral radiographs compared to computed tomography (CT) scans for measuring acetabular anteversion. We conducted a cross-sectional study of patients undergoing THA at Justice K.S. Hegde Charitable Hospital, Deralakatte, Mangalore, from January 2020 to June 2021. Radiographs are typically taken in both anteroposterior (AP) and lateral views after THA. However, for this study, a cross-table lateral view was used instead of the usual lateral radiograph to measure the angle of anteversion. The anteversion was calculated using the method described by Woo and Morrey. Additionally, CT scans were performed on all patients as part of the study protocol. The anteversion measured in these scans was compared to that in the cross-table radiographs to assess the latter's reliability for routine use. The risk of radiation exposure from CT scans was minimized by adhering to the ALARA (As Low as Reasonably Achievable) principle, with only axial sections of the acetabular cup being scanned. The results show that the radiographic acetabular anteversion and CT scan measurements have a mean difference of 0.3036. There is a positive correlation between these measurements. The p-value is not statistically significant (p=0.698). Therefore, the measurements are correlated with each other with a linear relationship (r=0.919). For anteversion measurements using the X-ray method, the mean was 27.16 degrees with a standard deviation of ±9.49. The median was 27.26 degrees, ranging from 10.27 to 42.58 degrees. In comparison, the CT method yielded a mean anteversion of 27.40 degrees with a standard deviation of ±8.50 degrees. The median was 27.64 degrees, ranging from 12.35 to 43.11 degrees. Cross-table lateral radiographs are a reliable and comparable method to CT scans for measuring acetabular anteversion following total hip arthroplasty.

Change of Sacral Slope according to the Surgical Position in Total Hip Arthroplasty.

Pelvis tilting in sagittal plane influences the acetabular cup position. Majority of total hip arthroplasty (THA) are performed in lateral decubitus surgical position. This study is to assess whether there is any difference in sacral slope between standing and lateral decubitus position and influence of this variation in planning acetabular cup anteversion. This is a prospective study including 50 patients operated between January 2020 to March 2022. Preoperative radiograph included lumbosacral spine lateral X-ray in standing, supine and lateral decubitus positions to calculate the sacral slope for assessment of anterior or posterior pelvic tilting. In our study, we determined the position of the acetabular cup based on changes in sacral slope between standing and lateral decubitus postures. For patients whose sacral slope increased from lateral decubitus to standing, we implanted the acetabular component with a higher degree of anteversion. Conversely, for patients with reverse phenomenon, the cup was inserted at lower anteversion. Twenty-four patients (48.0%) had increase in sacral slope from lateral decubitus to standing whereas 26 patients (52.0%) had decrease in sacral slope. There was linear correlation between difference in preoperative sacral slope and postoperative cross table lateral cup anteversion. Harris hip scores improved from 40.78 to 85.43. There was no subluxation or dislocation in any patient at minimum 2-year follow-up. Individualized acetabular cup placement is important for better functional outcome in THA. Evaluation of pelvic tilting in lateral decubitus position is necessary for better positioning of acetabular cup and avoid postoperative complications.

Total Hip Arthroplasty for Osteonecrosis of the Femoral Head: A Mid-term Follow-Up in Patients From Northern India.

Osteonecrosis of femoral head (ONFH) is a disabling condition of the hip joint with multifactorial etiology and is associated with genetic predilection and exposure to certain risk factors most commonly being chronic alcohol or steroid intake. Total hip arthroplasty (THA) remains the gold standard for end-stage femoral head osteonecrosis. The outcome after the surgery is mainly affected by age, activity levels and other factors that affect the development of ONFH. Through this study we aimed to evaluate the clinical and radiological outcomes in the patients who have undergone uncemented THA for ONFH. We included 111 uncemented THA on 84 patients with ONFH done by a single surgeon in our institution. The patients were followed up postoperatively and were evaluated based on their functional outcome using Harris hip scores (HHS) and the radiological outcome by serial radiographs on every follow-up. The mean preoperative HHSwas 49.30 which showed significant improvement inthe final follow-up to96.17. The mean acetabular inclination and anteversion at final follow-up radiographs were 47.70 and 18.67 degrees respectively. Fifteen patients had complications which included post-operative surgical site infection (three), hip pain (six) and thigh pain (six). Complications like osteolysis, poly wear and femoral subsidence were recorded in a total of six patients at the final follow-up. Three patients underwent revision THA due to increased femoral subsidence, accelerated poly wear, and aseptic loosening due to osteolysis. Our current observational study, which included 84 patients and 111 hips affected by osteonecrosis of the femoral head, examined the outcomes of total hip arthroplasty using metal on ultra-high molecular weight polyethylene liners. The results showed excellent clinical and radiological outcomes at a mean follow-up period of 4.8 years, particularly in younger patients with a mean age of 37.05 years.

The Effect of the Morphology of the Femur and Acetabulum in Dysplastic Hips on the Selection of Arthroplasty Femoral Implants: A Computer Tomography-Based Study.

Due to the technical challenges associated with femoral reconstruction in total hip arthroplasty for patients with developmental dysplasia of the hip (DDH), the exact indications for using femoral modular stems, despite their satisfactory clinical outcomes, remain poorly investigated. This study sought to assess the morphology of the femur and acetabulum, and to investigate the discriminative ability of femoral anteversion (FA), acetabular anteversion (AA), and combined anteversion (CA) on the selection of femoral modular stem in dysplastic hips. Retrospective data were collected from multiple centers on a total of 230 cases who underwent THA due to DDH from January 1, 2020, to March 1, 2023. There were 46 males and 184 females, with an average age of 51.57 ± 14.87. Patients were stratified according to Crowe and Eftekhar classifications. FA, AA, and CA were measured using computed tomography (CT). The distribution of these indices in different grades of dysplastic hips was compared, and the correlation between these indices and the selection of femoral modular stem was analyzed. Receiver operating characteristic (ROC) and likelihood statistics were performed to investigate the discriminating and predictive value of each index in selecting modular stem. Two hundred and thirty hips were included in the study. FA increased as the subluxation percentage increased: type I, 21.5°; type II, 28.6°; type III, 34.9°; and type IV, 39.7°. AA was smaller in type I (16.9°) and higher in types II, III, and IV (18.9-22.6°). The area under the curve for the modular stem was 0.87 for FA, 0.86 for CA, and 0.65 for AA. The optimal cutoff values were FA > 32.6°, CA > 50.7°, and AA > 23.3°. Excessive AA and femoral anteversion FA were observed in Crowe types II, III, and IV cases. FA and CA demonstrated strong discriminative ability and predictive value in the selection of a modular stem. The best cutoff values were ≥32.6° for FA and ≥50.7° for CA in discriminating the use of modular stem. Surgeons may contemplate the use of a modular stem when the preoperative evaluation approaches the cutoff value.

Polyethylene liner dissociation in total hip arthroplasty: a retrospective case–control study on a single implant design

BackgroundModular acetabular components for total hip arthroplasty (THA) provide intraoperative flexibility; however, polyethylene liner dissociation may occur. This study aimed to examine the incidence and causes of liner dissociation associated with a specific acetabular component design at a single centre.Materials and methodsA retrospective analysis of 7027 patients who underwent primary THA was performed to identify isolated liner dislocations. Patient demographics, clinical presentations, surgical and implant details, and both radiographic and computed tomography (CT) findings were analysed. Patients with liner dislocation were matched to a control group via 2:1 propensity score matching, and a logistic regression analysis was employed to identify associated risk factors.ResultsA total of 32 patients (0.45%) experienced liner dislocation at a mean 71.47 ± 60.10 months post surgery. Significant factors contributing to dislocations included the use of a conventional compared with a highly crosslinked polyethylene component (p = 0.049) and screw fixation (p = 0.028). Radiographic and CT analysis highlighted the importance of proper component orientation, revealing that patients experiencing dislocations demonstrated significantly lower acetabular cup anteversion angles (p = 0.001) compared with the control group. Impingement and malposition, identified in 41% and 47% of the cases, respectively, further underscored the multifactorial nature of dislocation risks.ConclusionsWhile the overall rate of polyethylene liner dislocation was low, the findings of this study highlight the importance of appropriate cup placement to decrease the risk of dissociation. It further substantiates the influence of impingement and malposition in liner displacement, with increased mechanical stress exerted on the locking mechanism under adverse conditions and the potential risk increase due to screw placement.

Increased combined anteversion is associated with larger posterior acetabular rim ossification in patients with femoroacetabular impingement syndrome.

(1) To determine the prevalence, magnitude and distribution pattern of acetabular rim ossification in patients with femoroacetabular impingement syndrome (FAIS) and (2) to determine the association between acetabular rim ossification and rotational abnormalities of the hip. Patients underwent hip arthroscopic surgery for FAIS at our institute between January 2021 and May 2022 were retrospectively reviewed. Patients were included if preoperative computed tomography (CT) images of the operated hip and ipsilateral distal femur were available for the measurement of femoral and acetabular anteversion. The presence and size of acetabular rim ossification were evaluated on coronal CT sections for the superior half of the acetabulum on each clockface location. The associations between acetabular rim ossification and radiographic parameters of hip rotational morphology were examined. A total of 214 hips were included. Acetabular rim ossification was found in 167 hips (78%) and the most common locations were 10 and 11 o'clock. Patients presenting with acetabular rim ossification had a mean size of 4.6 ± 1.6 mm. It was the largest at 9 o'clock position (4.9 ± 2.2 mm), with a decreasing trend in size from posterior to anterior. Logistics regression analysis found age was associated with the occurrence of posterior ossification (p = 0.002). Linear regression analysis found age (p = 0.049) and male sex (p < 0.001) were significantly correlated with the size of ossification. Patients with increased cranial combined anteversion had larger posterior ossification than patients with normal and decreased cranial combined anteversion (4.2 ± 2.9 vs. 3.1 ± 2.5 mm, p = 0.016; 4.2 ± 2.9 vs. 2.5 ± 2.4 mm, p = 0.005). Increased combined anteversion is associated with greater posterior acetabular rim ossification. The presence and size of acetabular rim ossification are positively associated with older age and male sex. Level III.