False-Profile Radiograph Sourcil-Edge and Bone-Edge Measurements Correlate to Different Weightbearing Regions of the Acetabulum: A 3-Dimensional Analysis.

BACKGROUND: The acetabular sourcil is commonly interpreted as a reliable radiographic representation of the weightbearing dome of the acetabulum, despite limited modern data. Assessment of weightbearing acetabular coverage has been described using both the sourcil edge and bone edge as anatomic landmarks, leading to confusion and potential misguidance in surgical decision-making and thus compromised patient outcomes. PURPOSE/HYPOTHESIS: The purpose of this study was to characterize the 3-dimensional (3D) anatomic correlates of the sourcil-edge and bone-edge radiographic measurements on false-profile radiographs. It was hypothesized that the sourcil edge would represent anterolateral coverage and the bone edge would represent anterior coverage. STUDY DESIGN: Descriptive laboratory study. METHODS: A total of 80 hips were grouped by large or small differences between bone-edge and sourcil-edge anterior center-edge angles, based on upper and lower quartiles of discrepancy. Three-dimensional surface mesh models and digitally reconstructed radiographs were generated from hip computed tomography scans. Sourcil-edge and bone-edge anterior center-edge angles were identified on digitally reconstructed radiographs and registered to the 3D models with fiducial markers. Intersections of bone-edge and sourcil-edge projection lines with the acetabular rim were obtained from the 3D models. RESULTS: The bone-edge and sourcil-edge projections intersected the acetabular rim at clockface means of 2:05 ± 0:22 and 1:12 ± 0:25, respectively. The 3D models consistently demonstrated that, in both large- and small-discrepancy groups, the sourcil edge corresponded to the acetabular area just posterior to the anterior inferior iliac spine (AIIS) projection, and the bone edge corresponded to the weightbearing region inferior to the AIIS. Additionally, in large-discrepancy hips, the bone edge corresponded to more prominent acetabular coverage in the region inferomedial to the AIIS when compared with the small-discrepancy hips. CONCLUSION: On false-profile radiographs, the sourcil edge corresponds to superior femoral head coverage, and the bone edge corresponds to anterosuperior coverage. Radiographs with a large discrepancy between sourcil-edge and bone-edge measurements demonstrate acetabular rim prominence in the region of the AIIS. CLINICAL RELEVANCE: Characterizing the anatomic weightbearing regions of the acetabulum represented on false-profile radiographs facilitates improved clinical and intraoperative decision-making in hip preservation surgery, including acetabuloplasty and periacetabular osteotomy.

Evaluation of the superior pubic ramus and supra acetabular corridors using statistical shape modelling.

INTRODUCTION: The incidence of osteoporotic pelvic fractures is increasing. The broken anterior pelvic ring is preferentially fixed with long intramedullary screws, which require a good understanding of the patient-specific anatomy to prevent joint perforation. The aim of this study was to assess the variability of the superior pubic ramus and the supra acetabular corridors' length and width using statistical shape modelling. MATERIALS AND METHODS: A male and female statistical shape model was made based on 59 forensic CT scans. For the superior pubic ramus and the supra acetabular corridor the longest and widest completely fitting cylinder was created for the first 5 principal components (PC) of both models, male and female pelvises separately. RESULTS: A total of 59 pelvises were included in this study of which 36 male and 23 female. The first 5 principal components explained 75% and 79% of the pelvic variation in males and females, respectively. Within 3 PCs of the female statistical shape model (SSM) a superior pubic ramus corridor of < 7.3 mm was found, 5.5 mm being the narrowest linear corridor measured. Both corridors in all PCs of the male SSM measured > 7.3 mm. CONCLUSION: Within females a 7.3 mm and 6.5 mm screw won't always fit in the superior pubic ramus corridor, especially if a flat sacrum, a small pelvis or a wide subpubic angle are present. The supra acetabular corridor did not seem to have sex-specific differences. In the supra-acetabular corridor there was always enough space to accommodate a 7.3 mm screw, both in males and females.

Intraoperative live measurement of femoral head size for acetabular cup sizing: simple, accurate, and green!

PURPOSE: Templating is the first step in achieving a successful total hip arthroplasty. We hypothesize that native head size is highly correlated with implanted cup size. Therefore, the purpose of this study is to look for a correlation between sizes of the intra-operative measurement of the femoral head and the implanted cup. METHODS: This is a monocentric observational study conducted from December 2018 till January 2023. All patients admitted for a primary total hip arthroplasty were included and retrospectively reviewed. Intra-operative femoral head measurement, radiographic femoral head diameter, templated (planned) cup size, and definitive implanted cup size were recorded. RESULTS: The sample included 154 patients (85 female and 69 males) with a mean age of 66.2 ± 10.4 years. There were 157 THA cases; 82 on the right side and 75 on the left side. The native head size and acetate template on digital radiographs were the most significantly positively correlated with cup size (P < 0.0001) while the radiological head size was significantly negatively correlated with cup size (P = 0.009). The implanted cup was on average 2 ± 2 mm bigger than the native head size measured intra-operatively. CONCLUSION: The native femoral head diameter measured intra-operatively is a simple and reliable tool to help the surgeons choose the proper size of the acetabular cup, preventing complications during surgery hence optimizing results post operatively. This technique would contribute to a more ecofriendly orthopaedic reconstructive surgery.

Anatomical study of the modified direct posterior gluteal splitting approach for acetabular fractures.

BACKGROUND: In this study, we investigated the area that can be addressed with an approach in which the skin incision is made directly above the dorsal column with Thiel cadaveric specimens. METHODS: Six Thiel cadaveric specimens were prepared. A skin incision was made directly above the dorsal column. The accessible proximal end from the proximal part of the greater sciatic notch to the gluteal ridge and the accessible distal end of the ischium were marked with a flat chisel. A molded 8-hole reconstruction plate was placed from the base of the ischium toward the gluteal ridge and fixed with 3 screws proximally and 2 screws distally. The length of the skin incision and the distance from each reference point on the bone to the reachable markings were assessed after the muscles were removed. RESULTS: Mean skin incision length was 9.3 ± 0.7 (range, 8.0-10.0) cm. In 3 of 6 cases, proximal screws were inserted through different spaces between muscle fibers. In all cases, we were able to reach at least the greater sciatic notch, the gluteal ridge at the level of superior border of the acetabulum, and the base of the ischial tuberosity. In all cases, an 8-hole plate could be placed from the gluteal ridge to the base of the ischium. There were no superior gluteal artery or sciatic nerve injuries in any of the cases. CONCLUSION: We anatomically investigated the area that can be addressed with an approach in which the skin incision was made directly above the dorsal column. In all cases, we were able to access the areas needed to reduce the fracture and place the plates necessary to stabilize the fracture through a 9.3 ± 0.7 cm skin incision. This approach can be a useful minimally invasive posterior approach for acetabular fractures.

An anatomic consideration of the femoral nerve during direct anterior hip approach: A cadaveric study.

PURPOSE: This study aimed to investigate the distance and correlation between the anatomy of the anterior side of the hip joint and the femoral nerve. METHODS: Using ten fresh-frozen cadavers with twenty hip joints. We dissected and marked the femoral nerve in the inguinal area. Employing the direct anterior approach, we identified and marked study points, including the superior and inferior points of the anterior rim of the acetabulum, » point, half point, and ¾ point along an imagined line connecting the formers, the inferomedial and mid aspect of the femoral neck, and the soft spot. Coronal plane measurements gauged the distance between these points and the femoral nerve. The collected data were analyzed to assess the distance and correlation. RESULTS: In the coronal plane, the median distance between the inferior point of the anterior rim of the acetabulum and the femoral nerve was 0 millimeters (interquartile range [IQR] 0-0). Likewise, the median distance between the mid aspect of the medial side of the femoral neck and the femoral nerve was 0 millimeters (IQR 0-0). Additionally, the mean distance between the soft spot and the femoral nerve was 1.18 cm (SD 0.63). CONCLUSION: Surgeons approaching the hip joint via the direct anterior approach should be cautious at the inferior point of the anterior rim of the acetabulum and the mid aspect of the femoral neck. The soft spot at the anterior rim of the acetabulum remains safe from direct injury when surgeons use the correct technique during anterior retractor insertion.

Anatomy of the iliopsoas notch and its relationship with morphology of the proximal femur.

PURPOSE: Discrepancy between the morphology of the acetabular margin and the design of hemispheric acetabular cups used in total hip arthroplasty may produce postoperative hip pain due to an iliopsoas impingement at the iliopsoas notch. This study aimed to determine the anatomical features of the iliopsoas notch in the Central European sample, and to test whether the morphology of the proximal femur affects the size of the iliopsoas notch. METHODS: The sample was composed of 40 matched pairs of dry hip bones and corresponding femora. The depth and length of the iliopsoas notch were measured and correlated with the available demographic data. The anthropometric parameters of the proximal femur were calculated using image-analysis software, and their association with the measurements of the iliopsoas notch was tested. RESULTS: The iliopsoas notch was present in all specimens and featured four morphological configurations: curved (61.3%), angular (16.2%), irregular (16.2%), and straight (6.3%). Its size was found to be larger in males (P = 0.014 for depth, P < 0.001 for length). No significant difference existed between the sides. The height and age of the specimens did not correlate with the size of the iliopsoas notch. Furthermore, neither the femoral neck version, the lesser trochanteric version, nor the angle between the neck of the femur and the lesser trochanter influenced the dimensions of the iliopsoas notch. CONCLUSION: The iliopsoas notch is a consistent landmark of the acetabulum, although its anatomical appearance is widely variable. The iliopsoas notch arrangement cannot be predicted perioperatively based on the morphology of the proximal femur. The various shapes and sex-related differences detected in this study could be used for designing new hip implants or could be utilized during cup positioning in total hip arthroplasty.

Defining the Borderline Dysplastic Hip: High Variability in Acetabular Coverage and Femoral Morphology on Low-Dose Computed Tomography.

BACKGROUND: Borderline acetabular dysplasia is commonly radiographically defined as a lateral center-edge angle (LCEA) of 20° to 25°. While the variability of plain radiographic assessment of this population has been reported, an understanding of the variability of 3-dimensional (3D) hip morphology remains to be better defined. PURPOSE: To investigate the variability of 3D hip morphology present on low-dose computed tomography (CT) in the setting of symptomatic borderline acetabular dysplasia and to determine if plain radiographic parameters correlate with 3D coverage. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: A total of 70 consecutive hips with borderline acetabular dysplasia undergoing hip preservation surgery were included in the current study. Plain radiographic evaluation included LCEA, acetabular inclination, anterior center-edge angle (ACEA), anterior wall index (AWI), posterior wall index (PWI), and alpha angles on anteroposterior, 45° Dunn, and frog-leg views. All patients underwent low-dose pelvic CT for preoperative planning, which allowed detailed characterization of 3D morphology relative to normative data. Acetabular morphology was assessed with radial acetabular coverage (RAC) calculated according to standardized clockface positions from 8:00 (posterior) to 4:00 (anterior). Coverages at 10:00, 12:00, and 2:00 were classified as normal, undercoverage, or overcoverage relative to 1 SD from the mean of normative RAC values. Femoral morphology was assessed with femoral version, alpha angle (measured at 1:00 increments), and maximum alpha angle. Correlation was assessed with the Pearson correlation coefficient (r). RESULTS: Lateral coverage (12:00 RAC) was deficient in 74.1% of hips with borderline dysplasia. Anterior coverage (2:00 RAC) was highly variable, with 17.1% undercoverage, 72.9% normal, and 10.0% overcoverage. Posterior coverage (10:00 RAC) was also highly variable, with 30.0% undercoverage, 62.9% normal, and 7.1% overcoverage. The 3 most common patterns of coverage were isolated lateral undercoverage (31.4%), normal coverage (18.6%), and combined lateral and posterior undercoverage (17.1%). The mean femoral version was 19.7°± 10.6° (range, -4° to 59°), with 47.1% of hips having increased femoral version (>20°). The mean maximum alpha angle was 57.2° (range, 43°-81°), with 48.6% of hips having an alpha angle ≥ 55°. The ACEA and AWI were poorly correlated with radial anterior coverage (r = 0.059 and 0.311, respectively), while the PWI was strongly correlated with radial posterior coverage (r = 0.774). CONCLUSION: Patients with borderline acetabular dysplasia demonstrate highly variable 3D deformities, including anterior, lateral, and posterior acetabular coverage; femoral version; and alpha angle. Plain radiographic assessments of anterior coverage are poorly correlated with anterior 3D coverage on low-dose CT.

Inter-population differences in acetabular senescence: relevance in age-at-death estimation.

Since investigation of the timing of the skeletal traits among the acetabula of different populations is lacking, this study aims to evaluate the relevance of geographical origin in the acetabulum aging process and in the usability of the SanMillán-Rissech aging method. The acetabula of 826 European North Americans derived from the Bass Collection (USA) have been analyzed and compared with 611 Portuguese acetabula from the Luis Lopes Collection (Portugal) applying the most updated acetabular age estimation technique (2017). After evaluating and comparing the acetabular aging rates between both populations by Mann-Whitney U tests, the inaccuracy values (bias and absolute error) were analyzed and compared using population-specific reference samples and using references differing in geographical origin by Wilcoxon tests. In general terms, the North Americans age faster than the Portuguese, especially the females, reaching the consecutive acetabular stages at younger ages. Regarding the SanMillán-Rissech method accuracy, using population-specific reference samples produces, as a general rule, better outcomes. In addition, an exhaustive meta-analysis of inaccuracy values has demonstrated that this method provides better estimation values than pubic symphysis and auricular surfaces regardless of the geographic coherence of the reference sample. These inter-population skeletal differences are derived from different factors than age, highlighting the impact of both biological and social background on age estimation. A thorough analysis of the skeletal age-based timing becomes essential to understanding, deciphering and being able to minimize bias and potential inaccuracy or even counteract them when applying the age estimation methods to different populations.

The importance of acetabular morphometry in determining hip dysplasia / Importancia de la morfometría acetabular en la determinación de la displasia de cadera

SUMMARY: The aim of this study was to evaluate the relation between acetabulum morphological measurements and present the reference values of the acetabulum. The study had a retrospective design and was conducted with 234 healthy subjects (108 females; 126 males) aged 18-53 years over a period of 4 years from 2018 to 2022. Eleven measurements including the center- edge angle (CEA), acetabular angle (AA), acetabular depth (AD), acetabular width (AW), dept to width ratio (ADWR), Extrusion A (EA)-B (EB), Extrusion index (EI), the lateral subluxation (LS), peak to edge distance (PED), and roof obliquity (RO) were taken. The p<0.05 value was considered significant. A significant difference was found in CEA, AA, EB, LS, and RO values, while there was no significance in the AD, AW, ADWR, EI, and PED measurements in comparison with acetabular morphometry according to gender. Also, in the evaluation of acetabulum to age-related changes, there was a significant difference in values of the CEA, AA, AD, AW, ADWR, LS, and PED from decades 1 to 5. The knowledge of radiological acetabulum findings is paramount for the diagnosis of hip dysplasia and may be useful for prosthesis, orthopedic and forensic experts. Also, the most interesting finding was that ADWR increased based on age in a directly proportional trend. The most apparent change based on age was seen in CEA (between decades 3-4), LS (decades 1-5), PED (decades 2-4), AD, and AW (decades 2-5).

El objetivo de este estudio fue evaluar la relación entre las medidas morfológicas del acetábulo y presentar sus valores de referencia. El estudio tuvo un diseño retrospectivo y se realizó con 234 sujetos sanos (108 mujeres; 126 hombres) de 18 a 53 años de edad durante un período de 4 años, desde 2018 hasta 2022. Once mediciones que incluyeron el ángulo centro-margen (ACM), ángulo acetabular (AA), profundidad acetabular (PA), ancho acetabular (AC), relación de profundidad y ancho (RPAC), extrusión A (EA)-B (EB), índice de extrusión (IE), subluxación lateral (SL). Se midió la distancia al margen (DAM) y la oblicuidad del techo (OT). Se consideró significativo el valor de p<0,05. Se encontró una diferencia significativa en los valores de ACM, AA, EB, SL y OT, mientras que no hubo significación en las medidas de AA, AC, RPAC, IE y DAM en comparación con la morfometría acetabular según el sexo. Además, en la evaluación del acetábulo respecto a los cambios relacionados con la edad, hubo una diferencia significativa en los valores de ACM, AA, PA, AC, RPAC, SL y DAM de las décadas 1 a 5. El conocimiento de los hallazgos radiológicos del acetábulo es primordial para el diagnóstico de displasia de cadera y puede ser útil para expertos en prótesis, ortopedia y medicina forense. Además, el hallazgo más interesante fue que RPAC aumentó según la edad en una tendencia directamente proporcional. El cambio más aparente según la edad se observó en ACM (entre las décadas 3 y 4), LS (décadas 1 a 5), DAM (décadas 2 a 4), PA y AC (décadas 2 a 5).

Applicability of the Calce method for age estimation in an Indian population: A clinical CT-based study.

Age estimation is one of the prerequisites of human identification. Age-progressive changes in the pelvis offer useful evidence for forensic age estimation across all age groups. The acetabulum presents as a durable and taphonomic degradation resistant age marker, and, can be employed for analysing age-progressive changes described by Calce. The present study aimed at determining the applicability of the Calce method for age estimation in an Indian population based on a computed tomographic examination of the acetabulum. Additionally, different morphological features defined by Calce were evaluated to identify the feature which contributes most towards the process of age estimation. CT images obtained from clinically undertaken examinations of individuals aged 17 years and above were scrutinized according to the features defined within the Calce method. No statistically significant bilateral or sex differences were observed. An overall accuracy of 76.66% was observed on applying the Calce method to an Indian population, with lower accuracy percentages for individuals aged 40 years and above. The associated overall inaccuracy and bias were found to be 9.45 and 8.88 years, respectively. Within the various features, acetabular groove was found to contribute most towards the overall accuracy, and apex growth the least. Considering this weighted proportion, population specific models should be derived to render greater applicability to the method for age estimation.

Computed tomographic evaluation of the acetabulum for age estimation in an Indian population using principal component analysis and regression models.

The acetabulum presents as a well-preserved evidence, resistant to taphonomic degradation changes and can thus aid in the age estimation process. A CT-based examination of the acetabulum can further help simplify the process of age estimation by overcoming the time-consuming process of maceration and by doing away with the interference resulting from tissue remnants. The aim of the present study was to evaluate the role of the acetabulum for age estimation in an Indian population through a CT-based examination, using principal component analysis and regression models. CT images of 400 individuals aged 10 years and above were evaluated according to the features defined in the San-Millán-Rissech method of age estimation. Five of the seven morphological features defined by San-Millán-Rissech were appreciable on CT scans, and, to enable further statistical analysis, a cumulative score was computed using these five features. A significant correlation of 0.835 and 0.830 for the right and left acetabulum, respectively, was obtained between computed cumulative scores and chronological age of individuals. No significant sex differences were observed in the scoring of different age-related morphological changes. Regression models were generated using individual features and cumulative scores. Regression models derived using the cumulative score yielded inaccuracy values of 9.67 years for the right acetabulum and 9.15 years for the left acetabulum. Inaccuracy and bias values were computed for each individual feature, as well as for each decade, using mean point ages established within the original study. Amongst the various features, acetabular rim porosity was seen to have the lowest values of inaccuracy (11.50 years) and bias (2.32 years) and activity on outer edge of acetabular fossa the highest (inaccuracy and bias values of 22.36 years and 21.50 years, respectively). Taking into consideration this differential contribution towards age estimation, weighted coefficients and mean point ages for different morphological features were determined using principal component analysis. Subsequently, summary age models were generated from the obtained weighted coefficients and mean age values. Summary age models derived in the present study yield lower estimates of inaccuracy of 7.60 years for the right acetabulum and 7.82 years for the left acetabulum. While regression models derived in the present study allow for age estimation using even a single appreciable feature, summary age models take into account the contribution of each feature and generate more accurate estimates of age. Both statistical computations yield reduced error rates and thus can render greater applicability to the acetabulum in forensic age estimation.

Acetabular morphological variation in Asian patients with femoral neck fracture: A three-dimensional CT-based study.

AIMS: The acetabular morphology varies greatly among individuals, and hypoplasia is more common in Asia than in Europe. Dislocation after bipolar hip arthroplasty (BHA) for femoral neck fracture occurs at a constant rate, and is affected by the acetabular morphology. This study aimed to clarify individual differences in the acetabula of Asian patients with displaced femoral neck fractures. PATIENTS AND METHODS: Fifty patients with displaced femoral neck fractures were assessed (50 fractured hips, 50 non-fractured hips). On CT corrected by the anterior pelvic plane, the 100 hips were assessed regarding acetabular coverage (six parameters), acetabular depth (two parameters), and acetabular opening angle (four parameters). Additional parameters related to the fracture and sex were examined. The percentile of each parameter was shown for all hips. RESULTS: There was no patient with hip dysplasia defined as superior acetabular sector angle (SASA) less than 110° Compared with men, women had a significantly smaller anterior acetabular sector angle (AASA) (p = 0.016), and significantly larger acetabular inclination angle (p = 0.006) and acetabular index angle (p = 0.034). In the group with a normal SASA, seven hips (7.3%) had an anterior wall defect (AASA<50°) and five hips (5.2%) had a posterior wall defect (posterior acetabular sector angle<90°). CONCLUSION: Older adults with femoral neck fractures can have anterior wall and posterior wall defects, even if their SASA is normal. Hidden acetabular dysplasia may be related to post-BHA dislocation. So, our results suggest that is important to accurately evaluate the acetabulum of patients with femoral neck fracture before surgery.

CT-based evaluation of the acetabulum for age estimation in an Indian population.

Age estimation constitutes an important aspect of forensic research, investigation and human identification. For the purpose of age estimation, various markers within the skeletal framework are employed. Degenerative morphological changes in the skeleton can be used for age estimation in adults. Amongst the various bones, age-progressive changes in the innominate bone are of particular significance in age estimation. Within the pelvis, the acetabulum presents as a durable and well-preserved evidence, characteristic manifestations of which can be employed for age estimation. The present study aimed at a CT-based evaluation of acetabular changes for the purpose of age estimation in an Indian population. CT images of 250 individuals aged 10-88 years were scrutinized according to the features defined in the Calce method of acetabular age estimation. Scores were allotted to the various features and a cumulative score was calculated. No significant bilateral and sex differences were observed. Significant correlation was obtained between the scores for these defined characteristics and the chronological age of individuals. Population-specific regression models were generated for age estimation. The scoring method devised in the present research requires further validation as it represents a new tool for age estimation in medico-legal cases.

Arthroscopic acetabular labrum suture.

It is essential to be aware of the anatomy and biomechanics of the acetabular labrum in order to understand why it should be conserved. Vascularization comes from the capsule and also from the bone. The joint side contains numerous nerve endings, which explains why labral lesions are painful. It is involved in joint stabilization by maintaining a negative pressure inside the joint able to resist distraction. It acts as a seal. There are two main suture techniques: trans- and peri-labral. Translabral suture is better suited to a wide and solid labrum free of degenerative lesions. Both techniques should be known, and may be associated. Results are comparable. It is essential to manage the underlying pathology responsible for the labral lesion. Joint degeneration is associated with poor prognosis. It needs to be recognized and discussed with the patient, to avoid unrealistic expectations.

Measuring the Acetabular Index: An Accurate and Reliable Alternative Method of Measurement.

OBJECTIVE. In children (4 months to 8 years old), radiographic measurements of the acetabular index are the preferred method to assess developmental hip dysplasia. However, the acetabular index has been criticized as having variable reliability owing to difficulty identifying the correct anatomic landmarks. An alternative method of measuring the acetabular index using the ischium is being proposed to avoid the variability of the triradiate cartilage line as a reference point. With the alternative method, the acetabular index is derived by measuring the angle between a line connecting the ischial tuberosi-ties and a line connecting the inferomedial and superolateral edges of the acetabulum. The purpose of this study was to evaluate the accuracy and reliability of this alternative method of measuring the acetabular index compared with the traditional method. MATERIALS AND METHODS. Children 4 months to 8 years old who presented for evaluation of developmental dysplasia of the hip were included. Two physicians, each using both the traditional and the alternative method, measured acetabular indexes on all radiographs. Accuracy was defined as mean absolute error less than 6°. Reliability was calculated by means of intraclass correlation coefficient (ICC). RESULTS. Pelvic radiographs of 40 children (324 hips) were included. The mean age was 23.7 months (range, 4-96 months) and mean acetabular index was 24.2° (range, 8-50°). The alternative method was associated with mean absolute error of 2.50°, which is significantly below the threshold of 6° (t < 0.001). Intrarater reliability for the traditional method was high (ICC, 0.81) and for the alternative method was very high (ICC, 0.92). Interrater reliability for the traditional method was high (ICC, 0.89) and for the alternative method was very high (ICC, 0.91). CONCLUSION. Measuring the acetabular index using the alternative method has very high accuracy and intrarater and interrater reliability.

Age estimation based on the acetabulum using global illumination rendering with computed tomography.

INTRODUCTION: The acetabulum has been reported as a reliable age estimation marker. However, analyzing its morphological changes can be challenging using computed tomography (CT) imaging. Newly introduced global illumination rendering (GIR) applied to CT can improve the visualization of the fine details and thus the method's performance. This study aimed to analyze age estimation using morphological features of the acetabulum using GIR applied to CT. METHODS: We collected 200 postmortem CT scans. A segmentation of the acetabular joint was initially done. Then, three-dimensional (3D) reconstruction of the images was performed using GIR. These images were saved and then analyzed by two operators based on the three morphological criteria described in the Rougé-Maillart method. Reproducibility was assessed by intraclass correlation (ICC). Age estimation was assessed by multiple linear regression. RESULTS: The sample was composed of 155 males and 45 females, with a mean age of 50 ± 18.3 years old. We observed high agreement in both the inter-observer and intra-observer reproducibility for the three variables (ICC of 75.6 to 90.8% and 89.3 to 95.8%, respectively) and the total score (ICC of 93.5% and 95%, respectively). The three variables, as well as the total score, were significantly correlated with age groups. The total score showed a prediction rate higher than 85% for ages under 40 and over 70 years old. We identified three models with two validated models with an adjusted R2 of 85.6% and 84.8%, respectively; a standard error of 0.688 and 0.706, respectively; and a good correlation of all variables and no inter-correlation. The first validated model included the three morphological criteria scores, and the second model was based on the total score. CONCLUSION: GIR applied to CT provides photorealistic images that can be useful for forensic imaging intended for age estimation based on morphological methods.

The relationship between pelvic incidence and anatomical acetabular anteversion in female Japanese patients with hip osteoarthritis: a retrospective iconographic study.

PURPOSE: This study aimed (1) to investigate the relationship between pelvic incidence (PI) and the anatomical acetabular anteversion (AA) relative to the spino-pelvic tilt (SPT) plane (anatomical AASPT), relative to the anterior pelvic plane (anatomical AAAPP), and functional standing AA; and (2) to compare AA and the sagittal spino-pelvic parameters of lumbo-pelvic complex types 1 (PI ≤ 30°) and 2 (PI > 30°), in Japanese females with hip osteoarthritis. METHODS: We conducted a retrospective study on 110 Japanese females with unilateral hip osteoarthritis. PI, standing lumbar lordosis (LL), standing SPT, anatomical AASPT, anatomical AAAPP, and functional standing AA were measured and calculated using radiographs and computed tomography. The PI-LL difference was defined as the mathematical difference between the PI and standing LL angles. Pearson's correlation test was used to measure the relationship between the PI and AA. Student's t test was used to compare spino-pelvic parameters between lumbo-pelvic complex type 1 (n = 24) and type 2 (n = 86). RESULTS: There was a significant relationship between the PI and anatomical AASPT (r = -0.532, p < 0.001), but no significant relationship between the PI and anatomical AAAPP (r = -0.021, p = 0.824) or functional standing AA (r = 0.104, p = 0.299). Lumbo-pelvic complex type 1 had a higher anatomical AASPT (22.4° ± 9.1° vs. 5.4° ± 15.1°, p < 0.001), similar anatomical AAAPP (15.0° ± 10.6° vs. 15.1° ± 15.3°, p = 0.981) and functional standing AA (12.4° ± 8.0° vs. 15.0° ± 14.1°, p = 0.254), a lower standing SPT (- 14.3° ± 11.0° vs. 13.7° ± 12.6°, p < 0.001), and a lower PI-LL difference (- 14.4° ± 18.5° vs. 6.4° ± 17.1°, p < 0.001) in comparison to lumbo-pelvic complex type 2. CONCLUSION: Our findings will help to improve the understanding of hip anatomy and its relationship with the standing spino-pelvic alignment in Japanese females with hip osteoarthritis.

Morphological consistency of bilateral hip joints in adults based on the X-ray and CT data.

PURPOSE: The application of the anatomical parameters of the contralateral hip joint to guide the preoperative template of the affected side relies on the bilateral hip symmetry. We investigated the bilateral hip symmetry and range of anatomical variations by measurement and comparison of bilateral hip anatomical parameters. METHODS: This study included 224 patients (448 hips) who were diagnosed with osteoarthritis (OA) and avascular necrosis (AVN) of the femur head, and underwent bilateral primary total hip arthroplasty (THA) in our hospital from January 2012 to August 2020. Imaging data included 224 patients X-ray and 30 CT data at the end of the cohort. Anatomical parameters, including the acetabular abduction angle and trochanteric height, were measured using the Noble method. Postoperative measurements included stem size, difference of leg length and offset. RESULTS: Except for the isthmus width, there were no significant differences in the anatomical morphology of the hip joint. Among the demographic factors, there was a correlation between body weight and NSA. Among various anatomical parameters, a correlation was present between medullary cavity widths of T + 20, T, and T - 20. The difference in the use of stem size is not due to the morphological difference of bilateral medullary cavity, but due to the different of 1- or 2-stage surgery. CONCLUSION: Bilateral symmetry was present among the patients with normal morphology of the hip medullary cavity, theoretically confirming the feasibility of structural reconstruction of the hip joint using the hip joint on the uninjured side. Additionally, the difference in the morphology of the hip medullary cavity is not present in a single plane but is synergistically affected by multiple adjacent planes.

The effect of pelvic tilt on three-dimensional coverage of the femoral head: A computational simulation study using patient-specific anatomy.

Improved understanding of how three-dimensional (3D) femoral head coverage changes as the pelvic sagittal inclination (PSI) is altered would advance clinical diagnosis of hip pathoanatomy. Herein, we applied computer modeling of 3D computed tomography reconstructions of the pelvis and proximal femur to quantify relationships between the PSI and regional 3D femoral head coverage. Eleven healthy, young adult participants with typically developed hip anatomy were analyzed. The orientation of the pelvis was altered to define a PSI of -30° to 30° at 1° increments. Hip adduction and rotation were fixed in a standing position, which was measured by direct in vivo imaging of the pelvis and femur bones using dual fluoroscopy. Femoral head coverage was quantified in the anterior, superior, posterior, and inferior regions for each PSI position. Change in coverage was largest in the anterior region (29.8%) and smallest in the superior region (6.5%). Coverage increased linearly in the anterior region as the PSI increased, while a linear decrease was found in the posterior region and the inferior region (all p < .001). The slopes of the regression line for these regions were 0.513, -0.316, and -0.255, respectively. For the superior region, coverage increased when the PSI was altered from -30° to 5° and decreased when the PSI was larger than 5°. Overall, a 1° increase in PSI resulted in an increase of 0.5% in anterior coverage and a decrease of 0.3% in posterior coverage. Our findings provide baseline data that improve understanding of the effect of PSI on femoral coverage.

Acetabular Bone Defect in Total Hip Arthroplasty for Crowe II or III Developmental Dysplasia of the Hip: A Finite Element Study.

BACKGROUND: The purpose of this study was to establish the finite element analysis (FEA) model of acetabular bone defect in Crowe type II or III developmental dysplasia of the hip (DDH), which could evaluate the stability of the acetabular cup with different types of bone defects, different diameters of femoral ceramic heads, and the use of screws and analyze the stress distribution of screws. METHODS: The FEA model was based on the CT scan of a female patient without any acetabular bone defect. The model of acetabular bone defect in total hip arthroplasty for Crowe II or III DDH was made by the increasing superolateral bone defect area of the acetabular cup. Point A was located in the most medial part of the acetabular bone defect. A 52 mm PINNACLE cup with POROCOAT Porous coating was implanted, and two screws (the lengths were 25 mm and 40 mm) were implanted to fix the acetabular cup. The stability of the acetabular cup and the von Mises stress of point A and screws were analyzed by a single-legged stance loading applied in 1948 N (normal working). The different diameters of the femoral ceramic head (28 mm, 32 mm, and 36 mm) were also analyzed. RESULTS: The von Mises stress of point A was gradually increased with the increasing uncoverage values. When the uncoverage values exceeded 24.5%, the von Mises stress of point A without screws increased significantly, leading to instability of the cup. Screws could effectively reduce the von Mises stress of point A with uncoverage values of more than 24.5%. However, the peak von Mises stress in the screws with the uncoverage values that exceeded 24.5% was considerably increased. The diameter of the femoral ceramic head had no significant effect on the von Mises stress and the stability of the acetabular cup. CONCLUSIONS: We recommend that uncoverage values of less than 24.5% with or without screw is safe for patients with Crowe II or III DDH.