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.

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 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.

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.

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.

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.

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.

Preoperative sizing of hip hemiarthroplasties to accurately estimate head size from non- standardised pelvic radiographs: Can it be done?

BACKGROUND: Preoperative sizing of implants for hip fracture patients requiring a hemiarthroplasty is difficult due to non-standardised radiographs, absence of sizing marker, variable patient position and body habitus. We investigated whether a simple tool could help predict femoral head size, allowing surgeons to safely proceed with surgery when implant stocks are limited, and to potentially improve theatre efficiency. METHODS: Three independent reviewers measured the maximum width of the contralateral (intact) femoral head using PACS software in 50 cases of intracapsular hip fracture. This was linearly regressed on actual implant size to calculate the average magnification coefficient. Inter- and intra-rater reliability were evaluated using intraclass correlation coefficients (ICC). RESULTS: The best fitting magnification constant was 118% (95% confidence interval 16.0-19.7%), which achieved a mean error of 1.7 mm. Prediction accuracy was significantly improved by allowing a constant (intercept) as a second parameter in the regression model (p = 0.01), which achieved a mean error of just 1.4 mm from the implant used. The inclusion of the constant reduces errors at the upper and lower extremes of head sizes. ICCs for inter- and intra-rather agreement were 0.94 and 0.98 respectively. CONCLUSION(S): We have shown that hip hemiarthroplasty head sizes can be reliably and accurately predicted from non-standardised pre-operative radiographs. We have devised a method which can easily be adopted by other centres and tailored to the characteristics of their radiology department.

The risk of revision after total hip arthroplasty in young patients depends on surgical approach, femoral head size and bearing type; an analysis of 19,682 operations in the Dutch arthroplasty register.

BACKGROUND: Total hip arthroplasty (THA) is used increasingly in younger patients. There is little knowledge about the effect of THA characteristics on risk of revision, especially in young patients. Therefore, we studied the influence of both patient-related and surgical factors on the risk of revision using data from the Dutch Arthroplasty Registry (LROI). METHODS: All patients younger than 55 years with a primary THA implanted in the Netherlands between 2007 and 2017 were selected (n = 19,682). The covariates age, sex, primary diagnosis, ASA-classification, surgical approach, fixation method, bearing type, head size and year of surgery were entered into Cox proportional hazards models to calculate hazard ratios for the risk of revision. RESULTS: The overall 5-year survival of primary THA was 95.3% (95% CI, 94.9-95.6). Use of the anterior approach resulted in a lower risk of revision than the use of the posterolateral approach (HR: 0.66, 95% CI: 0.47-0.92). THAs with a head diameter ≥ 38 mm had a higher risk of revision (HR: 1.90, 95% CI: 1.33-2.72) than THAs with 32 mm heads. Use of MoM bearings resulted in an increased risk when compared to C-PE (HR: 1.76, 95% CI: 1.27-2.43). CONCLUSION: The risk of revision in patients younger than 55 years depends on surgical approach, head size and bearing type. The anterior approach resulted in a decreased risk of revision, whereas use of ≥38 mm heads and MoM bearings resulted in an increased risk of revision for any reason.

Acetabular erosion following bipolar hemiarthroplasty: A Role for the size of femoral head?

INTRODUCTION: Femoral neck fractures are the most frequent fractures in the elderly and hemiarthroplasty is the treatment of choice. The objective of this study is to identify predictive factors of acetabular erosion after bipolar hemiarthroplasty in a mobile independent population during a follow-up of ten years. MATERIALS AND METHODS: This multicenter study started in 1997 ending in 2007. Data were prospectively collected and retrospectively analyzed. Inclusion criteria were: age > 60 and < 85 years, BMI < 35, normal Abbreviated MiniMental Test score, ability to walk 0.8 km and live independently, non-pathological fracture, hip with no or minimal osteoarthritic changes, and availability of clinical and radiological follow-up. For each Patient were recorded: demographic data, comorbidities, time from fracture to surgery, characteristics of the implant, duration of surgery. Patients included underwent clinical and radiological follow-up at a minimum of ten years. RESULTS: Overall, 209 Patients met inclusion criteria. A press-fit implant was performed in 172 subjects; in contrast a cemented prosthesis was implanted in 37 patients. Nineteen patients underwent implant revision to total hip arthroplasty for acetabular erosion and pain. Classification of X-ray using Baker criteria showed a grade 0 in 54.5%, a grade 1 in 19.6%, a grade 2 in 18.1% and a grade 3 in 7.6%. Multivariate analysis revealed that the size of the femoral head (FH) was the only predictive factor of a higher risk of acetabular erosion. The Kaplan-Meier survival curve verified the risk of implant revision in Group 1 (FH sized > 48 mm) and Group 2 (FH sized < 48 mm). The probability of implant revision for acetabular erosion at ten years from surgery were 5.5% in Group 1 and 15.6% in Group 2. CONCLUSION: In bipolar hemiarthroplasty smaller head size lead to a polar wear implying a higher risk of acetabular erosion and migration; in our population this risk was consistent with the use of implant head < 48 mm diameter. Considering the absolute risk of a smaller FH size, the surgeon must evaluate the accuracy of measurement of the caliber, since as reported in previous studies, it can significantly underestimate the size.

Surgically Relevant Morphological Parameters of Proximal Human Femur: A Statistical Analysis Based on 3D Reconstruction of CT Data.

OBJECTIVES: Recently, more accurate description of the femoral geometry has become of interest to engineers and orthopedic surgeons. However, an appropriate database is lacking. Therefore, the aim of this study is to present morphological parameters and their correlations, which are relevant for medical issues such as impingement after total hip replacement, as well as for implant design and the etiology of hip fractures. METHODS: We investigated 12 well-known morphological parameters of the femur in 169 healthy human subjects through evaluation of 3D-reconstructed CT scans. Pearson's coefficients of correlations were calculated using a statistical t-test method for each pair of parameters. RESULTS: The mean, maximum, minimum, median, and standard deviation values are reported for all parameters. Histograms showing the distribution of each morphological parameter are also presented. It is shown that absolute and horizontal offsets, total femur length, and NCVD parameters are normally distributed, but NCDF and NCDS are not. Furthermore, an inter-correlation matrix was reported to reveal statistical correlations between these parameters. The strongest positive correlation existed between absolute offset (OSA) and horizontal offset (OSH), while the least positive correlation was found between NCDF and total femur length (TFL), and also between NCDS and NCDF. Anteversion angle (ATA) and OSA showed the least negative correlation. However, the strongest negative correlation was found between neck-shaft angle (NSA) and greater trochanter height (GTH), as well as between OSA and NCVD. CONCLUSIONS: Comprehending patients' native bone morphology, including the variations and correlations, is essential for orthopedic surgeons to undertake preoperative planning and surgery as well as to appropriately design medical devices. Thus, more population-based detailed databases are necessary. We investigated an extensive set of proximal femoral morphology parameters using a statistically standardized method to expand the existing knowledge. The results of our study can be used for diverse medical and biomechanical purposes.

Does oversizing an uncemented cup increase post-operative pain in primary total hip arthroplasty?

INTRODUCTION: It has been suggested that one of the factors related to persistent post-operative pain following total hip arthroplasty (THA) is to over sizing of the acetabular component. In order to investigate this potential issue, we retrospectively analysed a series of consecutive uncemented THA. We assessed the incidence of persistent post-operative pain and the size difference between the implanted acetabular component and the native femoral head. METHODS: A total of 265 consecutive THAs were retrospectively identified. Standardised pre-operative radiographs were analysed using validated techniques to determine the native femoral head diameter. Post-operative standardised radiographs were reviewed and the acetabular orientation determined. Patients were sent postal questionnaires regarding their outcome and level of pain. RESULTS: Questionnaires were returned by 169 patients (189 hips, 71% response rate). A total of 17 were excluded due to inadequate radiographs., leaving 172 THA in the study group. The mean native femoral head (NFH) size was 47 mm. The most common implanted acetabular component size was 52 mm. The mean difference in cup to NFH diameter (delta) was 5.7 mm (range - 6.1 to 15.4 mm; 95% CI 5.3-6.2 mm). A delta of > 6 mm was found to be significant for predicting persistent post-operative pain (RR = 1.81; 95% CI 1.1-3.1; P = 0.027). CONCLUSION: Our study confirms that a delta of > 6 mm is associated with an increased risk of persistent post-operative pain following THA. We recommend pre-operative templating in all uncemented THA to ensure the planned acetabular component is no more than 6 mm larger than the NFH diameter.

The Hip Morphology Changes with Ageing in Asian Population.

OBJECTIVES: This study aims to determine the changing in hip anatomy parameters with age and reveals the reason for the extorsion of lower extremity in the aged. DESIGN: Retrospective study. PARTICIPANTS: One hundred and forty patients who had received imaging check of the femur and acetabulum between October 2013 and October 2016 were included in this study. MAIN OUTCOME MEASURES: The femoral neck torsion angle (FNTA), neck-shaft angle (NSA), and acetabular anteversion angle (AVA) were measured by an experienced orthopedic surgeon. All the patients' demographic and physical characteristics including age, sex, body laterality, height, and weight were recorded. The Student t-test, two-way ANOVA, Pearson correlation, and multiple linear regression were used for the statistical analysis. RESULTS: The mean age for male and female was 45.01±15.38 and 49.30±17.63 years, respectively. Outcomes revealed that the NSA on the right side of the body, 133.46±4.46° in male and 134.36±4.71° in female, was statistically higher than the left side. Female FNTA had significantly higher values than male (P<0.01). Two-way ANOVA reveals that FNTA and AVA were correlated with age (P<0.05) but not weight, height, or BMI. NSA was correlated with age, weight, and BMI (P<0.05) but not height. Multiple linear regression analysis showed that only age made an independent contribution to NSA. CONCLUSIONS: The NSA and FNTA of Asian population may have an obvious decrease whereas AVA increases with ageing, which reveals the reason for the extorsion of lower extremity with elderly. During hip-related surgery in elderly patients, more attention should be paid to these lower extremity anatomic changes.

Accuracy analysis of computer-assisted surgery for femoral trochanteric fracture using a fluoroscopic navigation system: Stryker ADAPT® system.

PURPOSE: ADAPT is a fluoroscopic computer-assisted surgery system which intraoperatively shows the distance from the tip of the screw to the surface of the femoral head, tip-to-head-surface distance (TSD), and the tip-apex distance (TAD) advocated by Baumgaertner et al. The study evaluated the accuracy of ADAPT. PATIENTS AND METHODS: A total of 55 patients operated with ADAPT between August 2016 and March 2017 were included as subjects. TSD and TAD were measured postoperatively using computed tomography (CT) and X-rays. The intraclass correlation coefficient (ICC) was checked in advance. The error was defined as the difference between postoperative and intraoperative measurement values of ADAPT. Summary statistics, root mean square errors (RMSEs), and correlations were evaluated. RESULTS: ICC was 0.94 [95% CI: 0.90-0.96] in TSD and 0.99 [95% CI: 0.98-0.99] in TAD. The error was -0.35 mm (-1.83 mm to 1.12 mm) in TSD and +0.63 mm (-5.65 mm to 4.59 mm) in TAD. RMSE was 0.63 mm in TSD and 1.53 mm in TAD. Pearson's correlation coefficient was 0.79 [95% CI: 0.66-0.87] in TSD and 0.83 [95% CI: 0.72-0.89] in TAD. There were no adverse events with ADAPT use. CONCLUSION: ADAPT is highly accurate and useful in guiding surgeons in properly positioning the screws.

Acetabular-epiphyseal angle and hip dislocation in cerebral palsy: a preliminary study. / Ángulo acetábulo-epifisario y luxación de cadera en la parálisis cerebral: Estudio preliminar.

OBJECTIVE: To relate, in non-ambulatory subjects with palsy, Reimers' migration percentage with standardized radiological measurements, including the acetabular-epiphyseal angle. METHOD: Descriptive, observational and transversal study of 15 individuals with cerebral palsy at levels IV and V of the Gross Motor Function Classification System, aged between 3 and 9 years. Radiological measurements of the acetabular index, Hilgenreiner's epiphyseal angle, acetabular-epiphyseal angle, neck-shaft angle and Reimers' migration percentage of each of the hips were performed. RESULTS: Correlations between acetabular index, epiphyseal angle and acetabular-epiphyseal angle were obtained with respect to the Reimers migration percentage. For hips with a migration rate of 15% or less, a positive correlation was observed between acetabular and epiphyseal angles. CONCLUSIONS: In our population, the measurement between acetabular and epiphyseal inclination represents the highest association with the hip migration percentage.

Fused micro-computed tomography (µCT) and histological images of bone specimens.

OBJECTIVES: To describe a stepwise process to obtain fused images from micro-computed tomography (µCT) and histological images of bone specimens. MATERIAL AND METHODS: Four surgically resected human femoral heads from four patients who had total hip replacement were imaged at a spatial resolution of 12-microns by using µCT. Histological sections of four focal bone lesions including bone cyst in osteoarthritis (n=2) and subchondral bone plate fracture in osteonecrosis (n=2) were prepared and digitized. µCT images were reformatted and adjusted to match the histological images using a landmark-based visual co-registration. Fused µCT and histological images were displayed in a cine-loop video mode with a gradual transition from one image to the other. RESULTS: µCT images of the four focal bone lesions could be successfully fused with the corresponding histological images with a near perfect match of the bone trabeculae. CONCLUSION: We present a stepwise process to obtain fused images from histological and reformatted µCT images of human femoral heads.