Variations of relative anteversion of the femoral neck during walking

Based on the geometric model developed by Netter [11], we determined the different positions of the femoral neck during monopodal support in walking in relation to a fixed frontal plane of reference (relative anteversion). This “relative anteversion” ranges on average from 24° of retroversion at the beginning of support to 15° of anterversion at the end if loading. We then studied the relations possibly existing between relative anteversion and acetabular orientation on the one hand, and the orientation of the resultant of the articular stresses on the other (both being variables during monopodal support in walking). The results showed that relative anteversion is well correlated with variations of position of the acetabulum since, at most, the deviation between the respective axes did not exceed the anatomic deviation due to absolute anteversion of the femoral neck and acetabulum. Lastly, analysis of the relations obtained with the orientation of the resultant of the articular stresses allowed a better comprehension of the functional distribution of forces.     

应用三维重建测量股骨颈前倾角的计算机方法研究

目的寻求一种测量结果更符合真实前倾角值的测量方法。方法应用计算机重建股骨CT断层图像获得三维模型,将股骨头拟合成球体以确定股骨头中心;然后截取股骨颈区域并重新分割为断层图像,测量每层的体积进行比较以确定股骨颈峡部,从而确定股骨颈中心;经三维模型表面直接选取内、外髁。结果股骨头中心、股骨颈中心的连线即为颈轴线,内、外髁的连线即为髁状轴,根据Billing对前倾角的定义,两线所形成的夹角即为前倾角。结论该研究符合定义法测量,故测量结果更为可信。     

Variation in femoral anteversion

Variation in femoral anteversion in an adult African skeletal population is examined in this study. Variation is measured in reference to population, gender, and side of the extremity (right vs. left). This study demonstrates greater average anteversion (19°) and a significant right-left variation (21 vs. 17) when compared to previously reported Caucasian and Oriental populations. The increased anteversion complements previous reports documenting morphologic differences between populations in length and width of the femur. This study documents a variation in femoral anteversion not appreciated in earlier studies that may be clinically useful in the assessment and correction of “abnormal” anteversion. © 1994 Wiley-Liss, Inc.     

Comparison of four methods for measuring femoral anteversion

This study evaluates the most valid and reproducible method for directly measuring anteversion (torsion) in dried femora using a commercially available measuring machine. Each femur was placed horizontally on the surface of the machine and readings were obtained from the head, the shaft distal to the lesser trochanter, and the distal end. Using computer software, four different anteversion angles were calculated: the center head-neck line to the retrocondylar line (Method 1); the center head-neck line to the transcondylar line (Method 2); the anterior head-trochanter line to the retrocondylar line (Method 3); and the anterior head-trochanter line to the transcondylar line (Method 4). The methods were applied to 20 femora, which were measured twice by one observer. The most reproducible method of measuring femoral anteversion uses the bone surfaces on the anterior aspect of the head and greater trochanter and on the posterior aspect of the condyles (Method 3.95% confidence limits of ± 0.4°). The other methods are shown to be reproducible to ±2.4°, ±3.3° and ±1.7° (Methods 1, 2, and 4, respectively, 95% confidence limits). Conversion factors between the different methods are: 12.5° + 0.8 x (anteversion angle) to change each of Method 2 to Method 1 and Method 4 to Method 3; and 8° + 0.7 x (anteversion angle) to change each of Method 1 to Method 3 and Method 2 to Method 4 (correct to within ±3°). © 1993 Wiley-Liss, Inc.     

激光投射法测量股骨颈扭转角及前倾角

目的通过裸骨观察及设计激光投射法测量股骨颈扭转角及前倾角,探讨激光投射法测量的可行性。方法裸骨观察描述股骨颈扭转角及前倾角,设计股骨颈扭转角前倾角测量装置,分两次用激光投射法测量60个股骨标本,对测定值进行统计学分析,并作左右两侧比较。结果对裸骨标本直接观察可以看出股骨颈扭转角与前倾角区别,采用激光投射法分两次测量所得数据差异无显著意义(统计学把握度为100%,P0.05)。测定股骨颈前倾角左侧13.58°±6.55°,右侧12.15°±5.83°;股骨颈扭转角左侧18.50°±7.38°,右侧19.08°±8.59°,双侧两角度差异无显著性(P0.05)。结论激光投射法是测量股骨颈扭转角及前倾角有效的方法,具有良好的可重复性。     

Measurement of femoral neck anteversion in 3D. Part 2:3D modelling method

Femoral neck anteversion is the torsion of the femoral head with reference to the distal femur. Conventional methods that use cross-sectional computed tomography (CT), magnetic resonance or ultrasound images to estimate femoral anteversion have met with several problems owing to the complex three-dimensional (3D) structure of the femur. A 3D imaging method has been developed that virtually measures femoral anteversion on the 3D computer space with continuous CT slices; this 3D method provides more accurate and reliable results than conventional 2D CT measurements. A 3D modelling method is devised for the measurement of femoral neck anteversion. This method has advantages over the 3D imaging method, such as shorter processing time, reduced number of slices and an objective result compared with the 3D imaging method. The results of the 3D modelling method are compared with the conventional CT methods (2D CT method and 3D imaging method) using 20 dried femurs.     

Measurement of femoral neck anteversion in 3D. Part 1: 3D imaging method

Femoral neck anteversion is the torsion of the femoral head with reference to the distal femur. Conventional methods that use cross-sectional computed tomography (CT), magnetic resonance or ultrasound images to estimate femoral anteversion have met with several problems owing to the complex, three-dimensional (3D) structure of the femur. These problems include not only the difficulty of defining the direction of the femoral neck axis and condylar line but also the dependency upon patient positioning. In particular, the femoral neck axis, the direction of the femoral head, known as the major source of error, is difficult to determine from either a single or several two-dimensional (2D) cross-sectional images. A new method has been devised for the measurement of femoral anteversion using the 3D imaging technique. 3D reconstructed CT images from the femoral head and trochanter to the distal femur are used to measure the anteversion. It is necessary to remove the soft tissue from the CT images and extract just the bone part. Then, the femoral anteversion is measured from a computer-rendered femur image. The 3D imaging method is compared with both the conventional 2D method and the physical method using 20 dried femurs. For the physical method, which is used as a reference value, a special apparatus is devised. The average difference between the results of the physical method and those of the 2D CT method is 5.33°. The average difference between the results of the physical method and those of the 3D imaging method is 0.45°. Seventy-four patients, who suffer from toe-in-gait disease, are tested to compare the 3D imaging method with the conventional 2D CT method. The average difference between the 2D and 3D methods is 8.6°, and the standard is 7.43°. This method provides a very accurate and reliable measurement of femoral anteversion, as it is virtually equivalent to the direct measurement of bisected dried femur in vitro.     

Biomechanics of the hip: forces exerted during walking

Summary Since the work of Pauwels, the forces exerted on the coxofemoral joint during walking have been studied either in different spatial planes (frontal, sagittal and horizontal) or by three-dimensional spatial analysis. Starting from the findings of our own studies, our aim was to compare the two methods of analysis (two-dimensional and three-dimensional) in order to provide a better understanding of the benefits and limitations of each method. In pursuit of this aim, we studied the pressure forces exerted on the coxofemoral joint, using a geometric plane technique following a method similar to that of Pauwels [20], and with a three-dimensional modelling technique using the finite element method. The material, taken from the published literature, was the same in both our studies. The results are expressed in terms of the size and orientation of the pressure force exerted on the coxofemoral joint during the monopodal weightbearing phase of walking. A comparison of these two methods of analysis clearly demonstrates the simplicity of two-dimensional analysis (which must incorporate as a minimum the frontal plane and the sagittal plane) and the richness of the three-dimensional analysis. The latter method, by appropriate manipulation of the information obtained, provides a starting point for computer simulations performed with the aim of testing a biomechanical or therapeutic hypothesis.

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Biomécanique de la hanche : les sollicitations à la marche

Résumé Depuis Pauwels, les sollicitations exercées sur l'articulation coxofémorale au cours de la marche ont été étudiées soit dans les différents plans de l'espace (frontal, sagittal et horizontal), soit par des analyses spatiales tridimensionnelles. A partir d'études personnelles, nous avons voulu comparer ces deux méthodes d'analyse (bidimensionnelle et tridimensionnelle) afin de dégager au mieux les apports et les limites de chacune. Pour cela, nous avons étudié les sollicitations en pression s'exerçant sur l'articulation coxofémorale, d'une part selon une étude géométrique plane dont la méthodologie s'apparente à celle de Pauwels [20], d'autre part selon une modélisation tridimensionnelle par la méthode des éléments finis. Le matériel, emprunté à la littérature, est commun à nos deux études. Les résultats intéressent l'intensité et l'orientation de la force en pression exercée sur l'articulation coxofémorale pendant la phase d'appui monopodal de la marche. La comparaison des deux types d'analyse met en valeur la simplicité de l'analyse bidimensionnelle (qui doit combiner le plan frontal et le plan sagittal au minimum) et la richesse de l'analyse tridimensionnelle qui, par la manipulation des informations obtenues, ouvre sur les simulations informatiques, en vue de tester une hypothèse biomécanique ou thérapeutique.

     

A novel method for quantifying femoral neck anteversion: A case study in extinct and extant sloths

Extinct sloths represent a wide range of morphological, locomotor, and body size variation. Researchers have examined femoral neck angle in two dimensions to hypothesize locomotor behaviors in this group; however, this measure does not account for femoral neck anteversion. Here, we present a new method for quantifying femoral neck anteversion angle, in addition to femoral neck angle, to capture the 3D position of the femoral head/neck. Femora of extant (n = 21; Bradypus and Choloepus) and extinct (n = 49; Acratocnus, Megalocnus, Neocnus, and Parocnus) sloths were surface scanned and their surface models used to calculate three angles of femoral neck anteversion and femoral neck angle. Femoral neck anteversion was calculated as the angle between the femoral neck axis and the geometric axis of the femoral condyles (GA), the 35% cross section axis, and a trochanter axis. Femoral neck angle was calculated as the angle between the femoral neck and shaft axes. Genera were compared using ANOVAs with post hoc multiple comparisons for each angle. Femoral neck angle and femoral neck anteversion relative to the cross section were also analyzed. Significant differences among genera exist for all angles, (p < .001) but not all angles separate all genera. Femoral neck and anteversion angles typically yield different results, demonstrating the utility of analyzing both angles. The GA and cross section angles are highly correlated in sloths, with the exception of comparisons among Megalocnus, Parocnus, and Neocnus, suggesting morphological variation in the distal femur. While this method was applied to sloths, it has broad applicability to mammalian groups.     

单次曝光改良Budin位X线片测量髋关节发育不良患者股骨前倾角的临床应用

目的 探讨单次曝光改良Budin位X线片测量髋关节发育不良(DDH)患者股骨前倾角(FA)的临床可行性。方法 前瞻性对照研究。纳入2018年6-12月解放军总医院第四医学中心关节外科拟行保髋治疗的22例DDH患者,其中男3例、女19例,年龄(25.8±7.2)岁。患者术前均行双侧髋关节改良Budin位X线摄片及CT扫描。在改良Budin位X线片上测量术前FA值,在CT影像上分别通过Yoshioka法和Suh法测量术前FA值。采用配对t检验,分别比较改良Budin位X线测量与CT扫描Yoshioka法和Suh法FA测量值的差异;分析Budin位X线片上FA测量结果与CT片上两种测量方法所测结果的相关性;采用组内相关系数(ICC),对改良Budin位X线FA测量值进行观察者自身及观察者间一致性检验。结果 在改良Budin位X线片上观察者自身ICC为0.984,观察者间ICC为0.972,均有良好的一致性。改良Budin位X线片FA测量值为22.05°±12.29°,CT片上Yoshioka法和Suh法FA测量值分别为23.42°±14.64°和24.44°±14.53°,X线测量与后两者比较差异均无统计学意义(t=0.473、0.832, P值均>0.05)。相关性分析结果显示,改良Budin位X线测量与CT片上Yoshioka法和Suh法两种测量法的测量结果间相关性好(r=0.962、0.972, P值均<0.05)。结论 拟接受保髋治疗的DDH患者可以应用单次曝光改良Budin位X线片对术前股骨前倾角进行评估。     

大龄髋脱位儿童股骨颈前倾角变化与骨骺应力的有限元分析研究

目的运用有限元分析方法,对正常及发育性髋关节发育不良(DDH)儿童股骨头近端骨骺生长板同承力情况下横断面的应力进行研究,为股骨近端截骨矫形手术提供理论依据。方法按照Tonnis分型选取40例DDH大龄儿童,其中男性11例,女性29例;年龄8～12岁,平均年龄10.14岁。分为半脱位及全脱位组。20例非DDH儿童作为正常对照组,其中男性11例,女性9例;年龄8～12岁,平均年龄10.10岁。通过二维CT技术测定各组股骨颈前倾角,通过有限元分析软件分析股骨头近端骨骺生长板在横断面上的应力情况。结果正常对照组股骨头近端骨骺生长板横断面上前内侧及后外侧的切应力和静压力相当。半脱位组及全脱位组股骨头近端骨骺生长板横断面上前内侧静压力大于后外侧,而前内侧的切应力小于后外侧。股骨颈前倾角与前后两侧静压力差呈正相关,与前后两侧切应力差呈负相关。结论 DDH大龄儿童的股骨颈前倾角随生长发育而增大。传统的股骨近端旋转截骨术在纠正发育性髋脱位儿童股骨骨骺异常应力,保证正常的头臼关系中有重要的临床意义。     

构建股骨3D数字化模型提出一种新的股骨颈前倾角测量方法

背景:全髋关节置换过程中假体置入的准确性非常重要,经典股骨颈前倾角术中运用时需转化为骨性标志的相对位置,全髋关节置换或翻修术中相关骨性标志可能缺失,希望提出一种新型股骨颈前倾角的测量方法,方便术中加以运用,提高假体置入准确性.目的:通过股骨3D数字化模型,提出一种新的股骨颈前倾测量方法,结合经典股骨颈前倾角为复杂性人工...     

Theoretical study of the decrease in the femoral neck anteversion during growth

This theoretical analysis tries to explain the decrease of the femoral neck anteversion during growth according to well-established concepts. In the frontal plane, it was demonstrated that the capital epiphyseal plate inclination allows the plate to remain perpendicular to the resultant force applied to the hip during gait. In the transversal plane, the projection of this force varies from -24 degrees, outwards and forwards (heel strike), to 20 degrees, outwards and backwards (toe off). A mathematical formula calculates the instantaneous coordinates of the plate in this plane during gait. This kinematic study points out that the physiological value of the capital epiphyseal plate anteversion at the end of the growth is theoretically the ideal value to obtain in the transversal or horizontal plane a perpendicular relation between the orientation of this plate and the projection of the resultant force during walking.     

肉眼直观区别股骨颈扭转角与前倾角

目的探讨肉眼直观下描述股骨颈扭转角及前倾角的区别,并分析其差异的临床意义。方法在股骨冠状面平面,分别从6点钟、12点钟、1∶30点钟、3点钟和4∶30点钟位置观察干燥完整的股骨标本(60根),在照片上分别确定股骨头颈轴线、股骨冠状面、股骨颈截面最长径及股骨上段冠状面,画图描述股骨颈扭转角与前倾角,分析这两个角度的区别。结果股骨颈前倾角是股骨头颈轴线与股骨冠状面的夹角,是线与面的关系,角尖朝内,在6点钟、12点钟、1∶30点钟、3点钟和4∶30点钟位均可观察到;股骨颈扭转角是股骨颈椭圆截面最长径线构成的面与股骨(上段)冠状面的夹角,是面与面的关系,角尖朝后,仅在12点钟、1∶30点钟、3点钟位可以观察到。1∶30钟位是显示股骨颈扭转角和前倾角区别的最佳位置。结论股骨颈前倾角和扭转角是共同基于股骨冠状面,分别与股骨头颈轴线、股骨颈截面最长径线构成的面,组成的两个不同角度参数。非立体观察是混淆股骨颈扭转角与前倾角的重要原因。前倾角决定内固定螺钉及股骨假体的方向,扭转角对内固定螺钉进钉点及股骨髓腔开口位置有参考价值。     

Characteristics of instructed and uninstructed interpersonal coordination while walking side-by-side

We examined how people synchronize their leg movements while walking side-by-side on a treadmill. Walker pairs were either instructed to synchronize their steps in in-phase or in antiphase or received no coordination instructions. Frequency and phase analysis revealed that instructed in-phase and antiphase coordination were equally stable and independent of walking speed and the difference in individually preferred stride frequencies. Without instruction we found episodes of frequency locking in three pairs and episodes of phase locking in four pairs, albeit not always at (or near) 0 degrees or 180 degrees. Again, we found no difference in the stability of in-phase and antiphase coordination and no systematic effects of walking speed and the difference in individually preferred stride frequencies. These results suggest that the Haken-Kelso-Bunz model for rhythmic interlimb coordination does not apply to interpersonal coordination during gait in a straightforward manner. When the typically involved parameter constraints are relaxed, however, this model may largely account for the observed dynamical characteristics.     

Functional anteversion of the femur in healthy children and its measurement

In this paper, we introduce the concept of functional anteversion of the femur and its positional change. It emerged from studies using B-mode and real-time ultrasound to determine femoral anteversion in two knee positions. Twenty healthy children were scanned at the hips whilst lying supine with knees extended and then with the knees flexed to about 90°. The “anteversion” angle between the head-trochanter line and the horizontal measured with knees extended and feet together is determined by three factors: 1) anatomical femoral anteversion, 2) femoro-tibial rotation at the knee, and 3) tibial torsion. This is one type of “functional anteversion” of the femur. The best reproducibility for functional femoral anteversion was obtained by scanning with real-time ultrasound and the knees extended (95% confidence limits within ± 2.8°); the use of B-mode ultrasound in the knees-extended position is significantly less reproducible (95% confidence limits within ± 6.1°). In the flexed-knee position, the reproducibility is similar with both B-mode and real-time ultrasound (± 2.6–3.5°). Both positions have limitations in attempts to measure anatomical femoral anteversion by ultrasound. The functional femoral anteversion angle measured by B-mode and real-time ultrasound is significantly larger (by 9–10°) with the knees flexed than with the knees extended. This positional change of measured femoral anteversion involving axial rotation at the hip is attributed mainly to 1) lateral rotation (unlocking) of the femur at the knee during flexion from the fully extended position and 2) any lateral tibial torsion which rotates the femur nedially in the knees-extended position with the feet vertical. The considerable individual variation and asymmetry of this axial rotational change may have relevance to the etiology of certain clinical disorders of the spine, hip, and knee joints. © 1993 Wiley-Liss, Inc.     

Angular momentum synergies during walking

We studied the coordination of body segments during treadmill walking. Specifically, we used the uncontrolled manifold hypothesis framework to quantify the segmental angular momenta (SAM) synergies that stabilize (i.e., reduce the across trials variability) the whole body angular momentum (WBAM). Seven male subjects were asked to walk over a treadmill at their comfortable walking speed. A 17-segment model, fitted to the subject’s anthropometry, was used to reconstruct their kinematics and to compute the SAM and WBAM in three dimensions. A principal component analysis was used to represent the 17 SAM by the magnitudes of the first five principal components. An index of synergy (ΔV) was used to quantify the co-variations of these principal components with respect to their effect on the WBAM. Positive values of ΔV were observed in the sagittal plane during the swing phase. They reflected the synergies among the SAM that stabilized (i.e., made reproducible from stride to stride) the WBAM. Negative values of ΔV were observed in both frontal and sagittal plane during the double support phase. They were interpreted as “anti-synergies”, i.e., a particular organization of the SAM used to adjust the WBAM. Based on these results, we demonstrated that the WBAM is a variable whose value is regulated by the CNS during walking activities, and that the nature of the WBAM control changed between swing phase and double support phase. These results can be linked with humanoid gait controls presently employed in robotics.     

Non-linear flexion relationships of the knee with the hip and ankle, and their relative postures during landing

The knee joint, together with the hip and ankle, contributes to overall shock absorption through their respective flexion motions during landing. This study sought to investigate the presence of a lower extremity coordination pattern by determining mathematical relationships that associate knee flexion angles with hip flexion and ankle dorsiflexion angles during landing phase, and to determine relative postures of the hip and ankle, with reference to the knee, and examine how these relative postures change during key events of the landing phase. Eight healthy male subjects were recruited to perform double-leg landing from 0.6-m height. Motion capture system and force-plates were used to obtain kinematics and ground reaction forces (GRF) respectively. Non-linear regression analysis was employed to determine appropriate mathematical relationships of the hip flexion and ankle dorsiflexion angles with knee flexion angles during the landing phase. Relative lower extremity postures were compared between events of initial contact, peak GRF and maximum knee flexion, using ANOVA on ranks. Our results demonstrated a lower extremity coordination pattern, whereby the knee flexion angles had strong exponential (R² = 0.92–0.99, p < 0.001) and natural logarithmic (R² = 0.85–0.97, p < 0.001) relationships with hip flexion and ankle dorsiflexion angles respectively during the landing phase. Furthermore, we found that the subjects adopted distinctly different relative lower extremity postures (p < 0.05) during peak GRF as compared to initial contact. These relative postures were further maintained till the end of the landing phase. The occurrence of these relative postures may be a reflexive mechanism for the subjects to efficiently absorb the impact imposed by the peak GRF.