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 Diversity in Femur bones: Understanding the Morphological Variability for Surgical and Prosthetic Applications / Diversidad Anatómica en Huesos Fémur: Comprensión de la Variabilidad Morfológica para Aplicaciones Quirúrgicas y Protésicas

SUMMARY: The femur, the body's longest bone, plays a critical role in orthopaedics and radiology. Understanding its anatomy, particularly the neck-shaft angle (NSA), is vital for diagnosing bone issues and designing hip implants. While some Asian populations' femur measurements have been studied, there is a research gap concerning Sri Lankans. This study aimed to fill this gap by examining the proximal femur's anatomy in the Sri Lankan population. We analysed 45 adult human femurs (26 right, 19 left) of unknown sex, ethically sourced from the University of Sri Jayewardenepura. Femurs with fractures or pathologies were excluded. Precise measurements were recorded using digital vernier callipers, with millimetre accuracy. Parameters included mean femoral length, vertical and transverse femoral head diameters, neck axis and neck length. Each measurement was taken three times to minimize subjectivity. Right femurs had a mean length of 42.8 mm (SD±2.64), while left femurs measured 43.53 mm (SD±3.27). Mean NSA was 125.78º (SD±4.45) for left femurs and 127.59º (SD±2.06) for right. Mean femoral head diameters were 4.09mm (SD±0.30) (right) and 4.12mm (SD±0.31) (left). Mean anterior neck lengths of the right and left were 2.61 (SD±0.54) and 2.71(SD±0.50) respectively. Comparing our findings with other Asian populations highlighted significant variations in femur measurements. These discrepancies emphasize the need for population-specific data for orthopaedic interventions and raise questions about the suitability of imported prosthetics. Differences in femur length, neck length, and NSA between sides suggest potential challenges in using implants designed for one side on the other. This study underscores the necessity of population-specific data in orthopaedics, as femur measurements differ even among Asian populations. Further research and statistical analysis are essential for tailoring orthopaedic solutions to individual populations. The findings also suggest a potential need for locally manufactured prosthetics to better suit the Sri Lankan population.

El fémur, el hueso más largo del cuerpo, desempeña un papel fundamental en ortopedia y radiología. Comprender su anatomía, en particular el ángulo cuello-diáfisis (NSA), es vital para diagnosticar problemas óseos y diseñar implantes de cadera. Si bien se han estudiado las medidas del fémur de algunas poblaciones asiáticas, existe un vacío en la investigación sobre los habitantes de Sri Lanka. Este estudio tuvo como objetivo examinar la anatomía del fémur proximal en la población de Sri Lanka. Analizamos 45 fémures humanos adultos (26 derechos, 19 izquierdos) de sexo desconocido, obtenidos éticamente de la Universidad de Sri Jayewardenepura. Se excluyeron fémures con fracturas o patologías. Se registraron mediciones precisas utilizando calibradores vernier digitales, con precisión milimétrica. Los parámetros incluyeron la longitud femoral media, los diámetros vertical y transversal de la cabeza femoral, el eje del cuello y la longitud del cuello. Cada medición se tomó tres veces para minimizar la subjetividad. Los fémures derechos tuvieron una longitud media de 42,8 mm (DE ± 2,64), mientras que los fémures izquierdos midieron 43,53 mm (DE ± 3,27). La NSA media fue de 125,78º (DE±4,45) para el fémur izquierdo y de 127,59º (DE±2,06) para el derecho. Los diámetros medios de la cabeza femoral fueron 4,09 mm (DE ± 0,30) (derecha) y 4,12 mm (DE ± 0,31) (izquierda). Las longitudes medias del cuello anterior de la derecha y la izquierda fueron 2,61 (DE ± 0,54) y 2,71 (DE ± 0,50) respectivamente. La comparación de nuestros hallazgos con otras poblaciones asiáticas destacó variaciones significativas en las medidas del fémur. Estas discrepancias enfatizan la necesidad de datos específicos de la población para las intervenciones ortopédicas y plantean dudas sobre la idoneidad de las prótesis importadas. Las diferencias en la longitud del fémur, la longitud del cuello y la NSA entre lados sugieren posibles desafíos al utilizar implantes diseñados para un lado en el otro. Este estudio subraya la necesidad de datos específicos de la población en ortopedia, ya que las mediciones del fémur difieren incluso entre las poblaciones asiáticas. Es esencial realizar más investigaciones y análisis estadísticos para adaptar las soluciones ortopédicas a poblaciones individuales. Los hallazgos también sugieren una posible necesidad de prótesis fabricadas localmente para adaptarse mejor a la población de Sri Lanka.

Análisis Morfológico y Biométrico de la Fóvea de la Cabeza del Fémur / Morphological and Biometric Analysis of the Fovea for Ligament of Head of Femur

En la literatura actual se encuentra escasa información referente a la fóvea de la cabeza del fémur (fóvea de la cabeza del hueso fémur). Este estudio tuvo como propósito recolectar datos morfológicos y biométricos respecto a la fóvea de la cabeza del fémur y reconocer variaciones que podrían ser de utilidad en las diversas patologías de la región. Se utilizaron 46 huesos fémures humanos pertenecientes al Departamento de Ciencias Básicas de la Universidad de La Frontera, Chile. Para la medición de datos se utilizó material ad hoc y los datos fueron analizados el programa Excel y los softwares ImageJ e Image Pro Plus. La longitud promedio de los huesos fémures fue de 43,8 ± 2,9 cm; el ángulo de torsión del cuello fue de 23,0 ± 2,0°. En el 100 % de las muestras se observó una fóvea en el cuadrante posteroinferior de la cabeza del fémur. El área promedio de la fóvea de la cabeza del fémur fue de 1,51 ± 0,7 cm2. El perímetro fue de 4,72 ± 1,0 cm; la forma de la fóvea fue: 60,9% ovalada, 23,9% triangular y 15,2 % circular, teniendo como base la fórmula derivada del índice craneal, dejando la fórmula como feret mínimo/feret máximo, con el cual los valores mayores a 0,8 se clasificaban como circulares y los menores como ovalados. Conocer la ubicación de la fóvea de la cabeza del fémur adquiere implicancia médica, ya que una fóvea en posición anormalmente alta, en imágenes radiológicas, es un indicador de displasia pélvica. La importancia de las variaciones de la fóvea de la cabeza del fémur debe ser más investigadas para una correcta comprensión de las patologías que afectan a la cabeza femoral.

SUMMARY: In the current literature there is little information regarding the fovea for ligament of head of femur. The aim of this study was to collect morphological and biometric data regarding the fovea for ligament of head of femur and recognize variations that could be useful in the various pathologies of the region. Forty six human femur bones belonging to the Department of Basic Sciences of the University of La Frontera, Chile were used. For data measurement, ad hoc material was used and the data were analyzed with the Excel program and the ImageJ and Image Pro Plus software. The average length of the femur bones was 43.8 ± 2.9 cm; the neck torsion angle was 23.0 ± 2.0°. In 100% of the samples, a fovea was observed in the posteroinferior quadrant of the head of femur. The average area of the fovea for ligament of head of femur was 1.51 ± 0.7 cm3. The perimeter was 4.72 ± 1.0 cm; The shape of the fovea was: 60.9% oval, 23.9% triangular and 15.2% circular, based on the formula derived from the cranial index, leaving the formula as minimum feret/maximum feret, with which the values greater than 0.8 were classified as circular and those less as oval. Knowing the location of the fovea for ligament of head of femur acquires medical implications, since a fovea in an abnormally high position, in radiological images, is an indicator of pelvic dysplasia. The importance of variations in the fovea for ligament of head of femur must be further investigated for a correct understanding of the pathologies that affect the femoral head.

Evolution of posture in amniotes-Diving into the trabecular architecture of the femoral head.

Extant amniotes show remarkable postural diversity. Broadly speaking, limbs with erect (strongly adducted, more vertically oriented) posture are found in mammals that are particularly heavy (graviportal) or show good running skills (cursorial), while crouched (highly flexed) limbs are found in taxa with more generalized locomotion. In Reptilia, crocodylians have a "semi-erect" (somewhat adducted) posture, birds have more crouched limbs and lepidosaurs have sprawling (well-abducted) limbs. Both synapsids and reptiles underwent a postural transition from sprawling to more erect limbs during the Mesozoic Era. In Reptilia, this postural change is prominent among archosauriforms in the Triassic Period. However, limb posture in many key Triassic taxa remains poorly known. In Synapsida, the chronology of this transition is less clear, and competing hypotheses exist. On land, the limb bones are subject to various stresses related to body support that partly shape their external and internal morphology. Indeed, bone trabeculae (lattice-like bony struts that form the spongy bone tissue) tend to orient themselves along lines of force. Here, we study the link between femoral posture and the femoral trabecular architecture using phylogenetic generalized least squares. We show that microanatomical parameters measured on bone cubes extracted from the femoral head of a sample of amniote femora depend strongly on body mass, but not on femoral posture or lifestyle. We reconstruct ancestral states of femoral posture and various microanatomical parameters to study the "sprawling-to-erect" transition in reptiles and synapsids, and obtain conflicting results. We tentatively infer femoral posture in several hypothetical ancestors using phylogenetic flexible discriminant analysis from maximum likelihood estimates of the microanatomical parameters. In general, the trabecular network of the femoral head is not a good indicator of femoral posture. However, ancestral state reconstruction methods hold great promise for advancing our understanding of the evolution of posture in amniotes.

Anatomical features of the proximal femur in the Turkish population / Características anatómicas del fémur proximal en la población turca

SUMMARY: Different populations have different genetic traits, and this causes various anatomical features to emerge. Orthopedic implants used in Turkey are generally of Western origin, and these implants are designed based on the anatomical features of Western populations. This study aimed to evaluate the compatibility of existing implants for the Turkish population by revealing the anatomical features of the proximal femurs of individuals from the Turkish population while also constituting a helpful source of data on newly developed implants. A total of 1920 proximal femurs of 960 patients were evaluated via images obtained by Computer Tomography. Twenty patients (10 females and 10 males) for each age within the age range of 18-65 years were included. Femoral head diameter, femoral neck width, femoral neck length, medullary canal width, and collodiaphyseal angle were measured. The right and left femoral head diameter was 46.46±3.84 mm, 46.50 ±3.85 mm respectively. The right and left femoral neck width was 30.63±3.4 mm, 30.85±3.29 mm respectively. The neck length was 94.62±8.33 mm for the right proximal femur, it was 94.75±8.19 mm for the left. The width of the medullary canal was 15.46±2.25 mm for the right proximal femur and 15.53±2.20 mm for the left. The right and left hips, the collodiaphyseal angles were 133.06±2.39° and 133.13±2.36°. Anatomical features of the proximal femur vary according to age, sex, and race. This study may be used as an important resource for the evaluation of patients' compatibility with existing implants and for the design of new implants.

Diferentes poblaciones tienen diferentes rasgos genéticos, y esto hace que surjan varias características anatómicas. Los implantes ortopédicos utilizados en Turquía son generalmente de origen occidental y estos implantes están diseñados en función de las características anatómicas de estas poblaciones. Este estudio tuvo como objetivo evaluar la compatibilidad de los implantes existentes para la población turca al revelar las características anatómicas de las epífisis proximales de fémures de individuos de la población turca y, al mismo tiempo, constituir una fuente útil de datos sobre implantes recientemente desarrollados. Se evaluaron un total de 1920 fémures proximales de 960 pacientes mediante imágenes obtenidas por tomografía computarizada. Se incluyeron veinte pacientes (10 mujeres y 10 hombres) para cada edad dentro del rango de edad de 18 a 65 años. Se midió el diámetro de la cabeza femoral, el ancho del cuello femoral, la longitud del cuello femoral, el ancho del canal medular y el ángulo colodiafisario. El diámetro de la cabeza femoral derecha e izquierda fue de 46,46 ± 3,84 mm, 46,50 ± 3,85 mm, respectivamente. La anchura del cuello femoral derecho e izquierdo fue de 30,63±3,4 mm, 30,85±3,29 mm, respectivamente. La longitud del cuello fue de 94,62±8,33 mm para el fémur derecho, fue de 94,75±8,19 mm, para el izquierdo. El ancho del canal medular fue de 15,46±2,25 mm para el fémur derecho y de 15,53±2,20 mm para el izquierdo. Las caderas derecha e izquierda, los ángulos colodiafisarios fueron 133,06±2,39° y 133,13±2,36°. Las características anatómicas de la epífisis proximal del fémur varían según la edad, el sexo y la raza. Este estudio puede utilizarse como un recurso importante para la evaluación de la compatibilidad de los pacientes con los implantes existentes y para el diseño de nuevos implantes.

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.

Establishing reference values for the pubofemoral distance in normal infant medial hips by ultrasound.

BACKGROUND: Measuring the pubofemoral distance (PFD) is important for evaluating the effectiveness of hip reduction in the treatment of developmental dysplasia of the hip (DDH). However, reference PFD values have not been established in normal infants. PURPOSE: To investigate variations in PFD values measured in normal infant medial hips stratified by age, laterality, and gender. MATERIAL AND METHODS: A total of 240 infants diagnosed with Graf type Ia and/or Graf type Ib hips by ultrasonography were stratified into eight age groups: 0-1 month; 1-2 months; 2-3 months; 3-4 months; 4-5 months; 5-6 months; 6-7 months; and 7-12 months. The bilateral medial hips were scanned with transinguinal ultrasound. The PFD was defined as the distance between the lateral edge of the superior ramus of pubic bone and the medial edge of the femoral head. Inter-observer reproducibility was assessed. RESULTS: Among the 240 infants, there were 371 Graf type Ia hips and 109 Graf type Ib hips. Mean ± SD bilateral PFD values of eight groups were measured separately. There were no significant differences in mean PFD values for left or right hips (t = 0.946, P = 0.345) or mean bilateral PFD values in male and female infants (t = 1.445, P = 0.149). Mean PFD values increased linearly with age (left: r = 0.680, P < 0.0001; right: r = 0.682, P < 0.0001). Inter-observer reproducibility was excellent. CONCLUSION: This study established reference PFD values from the medial hip in infants aged 0-12 months. PFD values increased with age, but were not significantly influenced by laterality or gender. These data provide detailed information that can support follow-up of infants treated for DDH.

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.

Trabecular bone in domestic dogs and wolves: Implications for understanding human self-domestication.

The process of domestication is complex and results in significant morphological, cognitive, and physiological changes. In canids, some of the traits indicative of domestication of domestic dogs compared to their wild counterparts the wolves are prosociality toward humans, reduced stress hormone levels, and reduced cranial capacity. Research suggests that selection for prosociality among dogs resulted in morphological changes such as reduction in cranial capacity, juvenilization of the face, and overall gracile morphology. Interestingly, similar features have been described in modern humans compared to extinct species of Homo, for example, Neanderthals. Therefore, the human self-domestication hypothesis has been proposed to partially explain the gracile modern human skeleton. Specifically, that as modern humans settled in communities, there was increased selection for prosociality (intergroup cooperation); and one of the by-products of this selection was the evolution of a gracile skeleton, including a slight reduction in cranial capacity, reduced brow ridge and tooth size, and low trabecular bone fraction (TBF). However, TBF variation has not been tested between domestic dogs and wolves, who underwent self-domestication. Thus, this study tests the hypothesis that dogs have low TBF as a consequence of domestication compared to their wild counterparts, the wolves, by comparing TBF in the hindlimbs-proximal femur and distal tibia- of the two species. Wilcoxon rank sum tests show that dogs have lower TBF values than wolves in both elements. These preliminary results add to the literature documenting changes in self-domesticated species and provide a potential analog to further the understanding of self-domestication.

The Effect of Resection Size in the Treatment of Cam-Type Femoroacetabular Impingement in the Typical Patient With Hip Arthroscopy: A Biomechanical Analysis.

BACKGROUND: Arthroscopic osteochondroplasty may improve range of motion and relieve pain in patients with symptomatic hip impingement. Femoral neck fracture is a risk of this procedure because of the weakening of the proximal femur. To our knowledge, there are no biomechanical studies in young human cadaveric bone evaluating the effect of osteochondroplasty on femoral neck strength. PURPOSE/HYPOTHESIS: The purpose was to evaluate loads to fracture in young human cadavers after resection depths of 25% and 40% at the head-neck junction. We hypothesized that both depths will maintain ultimate loads to failure above previously published loads, as well as above physiologic weightbearing loads. STUDY DESIGN: Descriptive laboratory study. METHODS: Cadaveric proximal femoral specimens (6 matched pairs, under the age of 47 years) were divided into 2 groups: 25% or 40% of the diameter at the head-neck junction was resected. The length of the resection was 2 cm and the width of the resection was determined by the length of the anterolateral quadrant at the head-neck junction in all cases. A compressive load was applied directly to the femoral head. Peak load, stiffness, and energy to fracture were compared between groups. RESULTS: The average peak load to fracture after 25% resection (7347 N) was significantly higher than after the 40% resection (5892 N) (P = .010). The average energy to fracture was also significantly higher in the 25% resection group (30.2 J vs 19.2 J; P = .007). The average stiffness was higher in the 25% group, although not statistically significant (P = .737). CONCLUSION: Resection depths of 25% and 40% at the anterolateral quadrant of the femoral head-neck junction may be safe at previously described functional loads such as standing and walking in the age range more typically seen in patients undergoing hip arthroscopy. Loads to fracture were significantly higher than previously reported using older cadaveric specimens. CLINICAL RELEVANCE: Currently, most surgeons limit weightbearing after femoral osteochondroplasty in part because of risk of femoral neck fracture. Given the higher observed loads to fracture, young patients could possibly bear weight sooner after surgery, although postoperative protocols should be individualized based on patient age, weight, bone density, amount of bone resected, concomitant procedures, and potential compliance with activity restrictions.

The morphometry, localization, and shape types of the fovea capitis femoris, and their relationship with the femoral head parameters.

PURPOSE: The aim of this study was to investigate the morphometric properties of the fovea capitis femoris (FCF) and its localization on the femoral head, the shape types, and the relationship with the femoral head parameters. METHODS: This study was performed on 146 dry femora. The morphological and morphometric properties were evaluated on dry bones and digital images of these bones. Some of the FCF and femoral head parameters were measured with a caliper on dry bones while others were measured using ImageJ software on digital images. RESULTS: The most common localization type was the Type 2 localization and the shape type was the oval type. The FCF sizes [except depth of the FCF (DFCF)] were found to be smaller in the Type 1 localization. The femoral neck shaft angle (NSA) was found to be greater in the triangular type than the round (or circular) type on the left side and in all cases. The vertical diameter of the femoral head (FHD-V), the anteroposterior diameter of the femoral head (FHD-AP), and the area of the femoral head (AREAHOF) values were greater in the triangular types than in the oval types in all cases. There was no relationship between the localization types and the shape types of the FCF. CONCLUSION: Results showed that the morphometric properties, localization, and shape types of the FCF were related to some femoral head parameters. It is thought that our findings contributed to orthopedic and radiological applications and anthropological sciences.

Estimation of Femoral Head Size from Palpable Bony Prominences of the Femur.

BACKGROUND: Proximal femoral surgeries involving femoral head replacement are common procedures worldwide. In these patients, the femoral heads are replaced with femoral head prosthetic implants. Pre-operative planning to determine the likely size of the prosthetic implant is important. Estimation from radiographs is the commonest method being used but this is fraught with problems. This study, therefore, developed an alternative method that can be used to estimate the femoral head size prior to hemiarthroplasty. MATERIALS AND METHODS: This was a prospective descriptive study that involved measurements of parts of femoral bone. Forty-eight adult femoral bones were measured. Measurements taken were the femoral head size (FH), the femoral bone maximum length (ML), the trochanteric length of the femur (TL), and the distal femoral breadth (DFB) of the femur. All measurements obtained were recorded and were analyzed using STATA version 13 (StataCorp, Texas, USA). RESULTS: The maximum length of the femora ranged from 42.1 cm to 51.5 cm. The trochanteric length ranged from 39 cm to 48.3 cm. The distal femoral breadth ranged from 53.8 mm to 92.3 mm. The femoral head size ranged from 39 mm to 55 mm with a mean value of 46.6 ± 2.9 mm. An equation was generated using the trochanteric length. Femoral head size = 16 + 0.7(trochanteric length in centimeter) ± 5 mm. This will provide a range of possible femoral head prostheses that should be made available for the surgery. CONCLUSION: This study generated an alternate method to be used during the pre-operative planning of a femoral head replacement surgery. It provides the possible range of prosthetic implants sizes to be made available for such surgeries. The trochanteric length can be easily measured. The method described will be of great benefit in middle and low income countries where prosthetic implants are not usually stocked within the hospital.

Differences between race and sex in measures of hip morphology: a population-based comparative study.

OBJECTIVE: This paper aims to (i) identify differences in measures of hip morphology between four racial groups using anteroposterior (AP) hip x-rays, and (ii) examine whether these differences vary by sex. METHODS: 912 hip x-rays (456 individuals) from four racial groups (European Caucasians, American Caucasians, African Americans and Chinese) were obtained. Males and females (45-75 years) with no radiographic hip OA (Kellgren and Lawrence < Grade 2 or Croft < Grade 1) were included. Eleven features of hip joint morphology were analysed. Linear regression with generalised estimating equations (GEE) was used to determine race and sex differences in hip morphology. Post-hoc Bonferroni procedure was used to adjust for multiple comparisons. RESULTS: The final analysis included 875 hips. Chinese hips showed significant differences for the majority of measures to other racial groups. Chinese were characterised by more shallow and narrow acetabular sockets, reduced femoral head coverage, smaller femoral head diameter, and a lesser angle of alignment between the femoral neck and shaft. Variation was found between other racial groups, but with few statistically significant differences. The average of lateral centre edge angle, minimum neck width and neck length differed between race and sex (p-value for interaction < 0.05). CONCLUSIONS: Significant differences were found in measures of morphology between Chinese hips compared to African Americans or Caucasian groups; these may explain variation in hip OA prevalence rates between these groups and the lower rate of hip OA in Chinese. Sex differences were also identified, which may further explain male-female prevalence differences for OA.

Validation of two methods to measure posterior tilt in femoral neck fractures.

INTRODUCTION: Posterior tilt of the femoral head in femoral neck fractures (FNF) may influence stability of the fracture and may therefore affect the treatment outcome. Posterior tilt can be measured with different methods. The Lateral Garden Angle (LGA) has been used for this purpose for decades and more recently the Posterior Tilt Measurement (PTM) was introduced. Despite the fact that both methods (LGA and PTM) are used in multiple studies, they have never been compared for reliability in a direct study. The aim of this study is to analyze the intra and inter observer reliability of the LGA described by Garden and the PTM according to Palm. METHODS: Four observers measured the posterior tilt on the radiographs of 50 FNF two times with both methods. Intra and inter observer reliability were determined for the LGA and the PTM. RESULTS: The intra observer reliability for both methods is substantial with an intra class coefficient of 0.75. The inter observer reliability of the PTM is also substantial with an intra class coefficient of 0.75 compared to a moderate reliability of the LGA with an intraclass coefficient of 0.60. CONCLUSION: Based on our results we believe the LGA and the PTM are both reliable methods to measure posterior tilt. Yet the Posterior Tilt Measurement seems to have a better inter observer reliability and therefore has a slight preference over the Lateral Garden Angle.

The influence of an extra-articular implant on bone remodelling of the knee joint.

Bone remodelling is a crucial feature of maintaining healthy bones. The loading conditions on the bones are one of the key aspects which affect the bone remodelling cycle. Many implants, such as hip and knee implants, affect the natural loading conditions and hence influence bone remodelling. Theoretical and numerical methods, such as adaptive bone remodelling, can be used to investigate how an implant affects bone mineral density (BMD). This research aimed to study the influence of an extra-articular implant on bone remodelling of the knee joint using adaptive bone remodelling. Initially, a finite element (FE) model of the knee joint was created. A user-defined material subroutine was developed to generate a heterogeneous BMD distribution in the FE model. The heterogeneous density was then assigned to the knee model with the implant in order to investigate how the implant would affect BMD of the knee joint, five years postoperatively. It was observed that in the medial compartments of the femur and tibia, bone mineral density increased by approximately 3.4% and 4.1%, respectively, and the density for the fixation holes of both bones increased by around 2.2%. From these results, it is concluded that implanting of this load-sharing device does not result in significantly adverse BMD changes in the femur and tibia.

Digital templating without a calibration marker is accurate at predicting implant size for hip hemiarthroplasty.

INTRODUCTION: This study aims to assess the accuracy of digital templating for hip hemiarthroplasty using radiographs without calibration. METHODS: Two independent, blinded observers retrospectively utilised digital software to template 50 consecutive patients who had hip hemiarthroplasty. The templated parameters (head size, offset and stem size) derived from pre-operative radiographs were compared to the actual prosthetic sizes used intra-operatively. Inter and intra-observer variabilities were calculated. RESULTS: Both observers correctly templated the offset and head size (± 2 mm) used in 90% (n = 45) of cases. The femoral stem size (± 1 size) was correctly predicted by templating in over 84% of the cases (n = 42). Inter-observer agreement was excellent for femoral head size with an intra-class correlation coefficients (ICC) of 0.94, substantial for offset (k = 0.7) but only fair for stem size (k = 0.27). ICC values comparing the actual prostheses inserted with the template values were excellent for head size (ICC = 0.96), substantial to near perfect for offset (k = 0.78, 0.85) and fair to moderate (k = 0.24, 0.45) for stem size. CONCLUSION: Digital templating of radiographs without calibration can be used to accurately and reliably predict femoral head size and offset at a set magnification of 120%. Femoral stem size, however, is more difficult to template adequately on pre-operative radiographs without calibration.

Smaller Epiphyseal Tubercle and Larger Peripheral Cupping in Slipped Capital Femoral Epiphysis Compared with Healthy Hips: A 3-Dimensional Computed Tomography Study.

BACKGROUND: The inner surface of the capital femoral epiphysis is important for growth plate stability. However, abnormalities of epiphyseal morphology associated with the pathogenesis of slipped capital femoral epiphysis (SCFE) remain poorly understood. This study compares the 3-dimensional anatomy of the epiphyseal tubercle and peripheral cupping in hips with SCFE and normal hips. METHODS: We created 3-dimensional models of the capital femoral epiphysis with use of computed tomography (CT) imaging from 51 patients with SCFE and 80 subjects without hip symptoms who underwent CT because of abdominal pain. The height, width, and length of the epiphyseal tubercle and the peripheral cupping were measured and normalized by the epiphyseal diameter and presented as a percentage. We used analysis of variance for the comparison of the measurements between SCFE and control hips after adjusting for age and sex. RESULTS: Compared with normal hips, hips with mild SCFE had smaller mean epiphyseal tubercle height (0.9% ± 0.9% compared with 4.4% ± 0.4%; p = 0.006) and length (32.3% ± 1.8% compared with 43.7% ± 0.8%; p < 0.001). The mean epiphyseal tubercle height was also smaller in hips with moderate (0.6% ± 0.9%; p = 0.004) and severe SCFE (0.3% ± 0.8%; p < 0.001) compared with normal hips. No differences were observed for measurements of epiphyseal tubercle height and length between SCFE subgroups. The mean peripheral cupping was larger in hips with mild (16.3% ± 1.0%; p < 0.001), moderate (16.4% ± 1.1%; p < 0.001), and severe SCFE (18.9% ± 0.9%; p < 0.001) overall and when assessed individually in all regions compared with normal hips (10.6% ± 0.5%). CONCLUSIONS: Hips with SCFE have a smaller epiphyseal tubercle and larger peripheral cupping compared with healthy hips. A smaller epiphyseal tubercle may be a predisposing morphologic factor or a consequence of the increased shearing stress across the physis secondary to the slip. Increased peripheral growth may be an adaptive response to instability as other stabilizers (i.e., epiphyseal tubercle and anterior periosteum) become compromised with slip progression. Future studies are necessary to determine the biomechanical basis of our morphologic findings.

The neck-shaft angle: an update on reference values and associated factors.

Background and purpose - The neck-shaft angle (NSA) is valuable for diagnostics and therapy of the hip, but current reference values derive mostly from studies on anatomic specimens, small cohorts, or are hospital-based. Moreover, associated factors such as age, sex, or anthropometric data have rarely been considered. Therefore, we determined associated factors for NSA and reassessed the historical reference values in a general adult population.Methods - NSAs on both sides of 3,226 volunteers from the population-based Study of Health in Pomerania (SHIP) were measured with MRI. SHIP drew a representative sample of the population of Pomerania (northeastern Germany). NSAs were compared with sex, age, and anthropometric data by bivariable linear regression models. Reference values were assessed by quantile regressions for 2.5th and 97.5th percentiles.Results - The mean NSA was 127° (SD 7), while men had a lower NSA than women (95% confidence interval [CI] 0.4°-1.4°). The reference range was 114°-140°. Age was inversely associated with NSA (CI -0.2 to -0.1). Body height was positively associated with the NSA, while BMI and waist circumference showed a negative association. There was no association between body weight and NSA.Interpretation - The historical lower limit of 120° might be too high, so the radiological prevalence of hip pathology might have been overestimated. The previously reported influence of age, sex, and body height on the NSA has been confirmed.

Total cross-sectional area of the femoral neck nutrient foramina measured to assess arterial vascular beds in the femoral head.

BACKGROUND: A detailed understanding of the blood supply to the femoral head is required to plan the surgery in the femoral neck and head area. However, information about the blood vessel networks in the femoral head is inadequate. METHODS: The surface of the femoral neck of 100 dry cadaveric adult femur specimens was scanned using a 3D scanner. The scanning distance was 200 mm, precision 0.01 mm, and measuring point 0.04 mm. The images were acquired at a resolution of 1,310,000 pixels. Digital imaging data were recorded from the femoral neck surface. The diameters of the nutrient foramina of the superior, inferior and anterior retinacular arteries, and the ligamentum teres arteries were determined and divided into five groups. RESULTS: The mean cumulative cross-sectional area of the nutrient foramina was as follows: canals of the superior, inferior, anterior, and ligamentum retinacular arteries were 15.59 mm2, 3.63 mm2, 4.32 mm2, and 1.58 mm2, respectively. Next, we analyzed the canals of the superior, inferior, anterior and ligamentum retinacular arteries, respectively, via 3D scanner. We found that the canals of the superior retinacular arteries appear to supply more blood to the femoral head than the canals of the other three types of arteries. CONCLUSIONS: Our results demonstrated that surgeries of the femoral neck and femoral head will be improved with prior 3D scanning and lead to better outcomes in surgeries involving the hip area.