Femoral Torsion Angle Research Articles

Three dimensional CT analysis of the change in rotational alignment in double level osteotomy after double level osteotomy performed for varus osteoarthritic knees

PurposeTo analyze the change in rotational alignment caused by double level osteotomy (DLO) based on comparative three-dimensional image analysis of pre- and postoperative CT images. MethodsPre- and postoperative CT examination of the lower extremities were performed with informed consent for 39 consecutive knees undergoing DLO for varus knee deformity. The DLO procedure consisted of closed wedge distal femoral osteotomy (CWDFO) and open wedge high tibial osteotomy (OWHTO). Among those cases, 20 knees complicated with hinge fracture at the osteotomy site were excluded from the analysis to eliminate a confounding factor affecting the results. Consequently, data obtained from 19 knees were subjected to the study analysis while osteotomies with hinge fractures complications were excluded from the study. In the three-dimensional CT image analysis of axial plane images, femoral torsion (the angle between midline along the femoral neck axis and the tangent of the posterior edges of the medial/lateral femoral condyles) and tibial torsion (the angle between the tangent of the posterior edges of the medial/lateral tibial condyles and the transmalleolar axis) were measured. The torsion angle was measured in each of the femurs and the tibias on both pre- and postoperative CT axial images, and the change induced by the osteotomy was calculated and statistically(using Wilcoxon signed-rank test) compared. ResultsThe mean pre- and postoperative femoral torsion (anteversion) angles were 29.3° and 31.4° with a significant postoperative increase in internal rotation of the bony segment distal to the osteotomy(P = 0.002). On the tibial side, the mean pre- and postoperative torsion angles were 26.5° and 25.7°, indicating no significant postoperative change(P = 0.199)（NS）. ConclusionsThis study showed that the DLO procedure (combining CWDFO and OWHTO) increased torsion (anteversion) of the femur by 2.1° on average while inducing no significant rotational change on the tibial side.

Ischiofemoral Impingement Syndrome: Effect of Morphological Variations on the Diagnosis.

The purpose of this study is to clarify which morphologic variations of the hip on MRI are associated with the development of ischiofemoral impingement. Hip MRIs of patients who have been referred to our department between 2016-2017 were retrospectively reviewed and assessed for pathological signal changes in the quadratus femoris muscle and ipsilateral hip or buttock pain. After assessment, ischial angle, inclination angle, ischiofemoral space, quadratus femoris space, intertuberous distances and femur neck angle, femoral torsion angle and knee angle were measured and compared in 37 hips of 20 patients and 56 hips of 28 age-gender matched control subjects. There were statistically significant differences between the patient and control groups in all MRI parameters except for intertuberous distances (p<0.05). Quadratus femoris space (p<0.001) and ischiofemoral space (p<0.001) were significantly lower and femoral torsion angle (p=0.02), femur neck angle (p=0.001), ischial angle (p=0.01) and inclination angle (p=0.03) values were significantly higher in patients compared with the control group. Decreased ischiofemoral space and quadratus femoris space, increased femoral torsion angle, femur neck angle, ischial angle and inclination angle are found to be associated with IFI on MRI. These pelvic anatomical variations may predispose to ischiofemoral impingement and should be kept in mind for patients with hip pain.

Characteristics of Femoral Torsion Angles and Relationships Between Femoral Torsion Angles and Hip Rotational Motion Variables in Adult Baseball Players

Background:Abnormalities in hip rotational motion (HRM) are risk factors for throwing injuries. To evaluate hip rotational motion, it is necessary to assess the torsion angle. However, no studies have investigated the femoral torsion angle (FTA) in baseball players.Purpose:To investigate differences in hip FTA of adult baseball players through use of ultrasonography to evaluate the relationship between the FTA and HRM.Study Design:Cross-sectional study; Level of evidence, 3.Methods:A total of 149 elite male baseball players (mean age, 20.0 ± 1.8 years; 64 pitchers, 85 position players) were enrolled in this study. Ultrasonographic assessment of FTA was performed based on the tilting angles of the anterior surface of the femoral neck and condylar axis. The hip internal rotation (HIR) and hip external rotation (HER) were assessed at 0° and 90° of flexion. Data related to FTA and HRM were compared between hips and between pitchers and position players.Results:No significant difference was observed in the FTAs between hips for any player (lead hip, 20.5° ± 9.2°; trail hip, 19.6° ± 9.8°; P = .276). No significant difference was observed in FTAs of both hips between pitchers and position players (lead hip, 20.1° ± 9.4° and 20.9° ± 9.0°, respectively, P = .957; trail hip, 19.5° ± 9.8° and 19.7° ± 9.8°, P = .999). In terms of HER in 90° of hip flexion in both hips, significant differences were observed in HRM variables between pitchers and position players (lead hip, 33.0° ± 8.9° and 37.5° ± 9.8°, respectively, P = .024; trail hip, 35.6° ± 9.6° and 40.4° ± 10.2°, P = .035). Linear regression analysis revealed a significant agreement between the FTA and HIR at both 0° (R = 0.298, P < .001) and 90° of hip flexion (R = 0.279, P < .001).Conclusion:Our findings indicated that FTAs were not different between the hips of elite baseball players. Abnormalities of the HRM are not caused by differences in the FTA but rather involve soft tissue tightness around the hip area or other bony morphologic factors in the hip joint.

The Effect of Modality and Landmark Selection on MRI and CT Femoral Torsion Angles.

Background Assessment of femoral torsion at preoperative hip imaging is commonly recommended. However, it is unclear whether MRI is as accurate as CT and how different methods affect femoral torsion measurements. Purpose To compare MRI- and CT-based assessment of femoral torsion by using four commonly used measurement methods in terms of agreement, reproducibility, and reliability and to compare femoral torsion angles between the four different measurement methods. Materials and Methods This retrospective study evaluated patients with hip pain who underwent CT and 3-T MRI of the hip including sequences of the pelvis and distal condyles between May 2017 and June 2018. The four measurement methods differed regarding the landmark levels for the proximal femoral reference axis and included measurements at the level of the greater trochanter, femoral neck, base of the femoral neck, and level of the lesser trochanter. Intraclass correlation coefficients (ICCs) were calculated, and Bland-Altman analysis was performed. Results Forty-five patients (mean age ± standard deviation, 19 years ± 5; 27 female) and 57 hips were evaluated. Inter- and intrarater reliability were excellent for each of the four CT- and MRI-based measurement methods (ICC range, 0.97-0.99). Mean difference between CT- and MRI-based measurement ranged from 0.3° ± 3.4 (P = .58) to 2.1° ± 4.1 (P < .001). Differences between CT and MRI were within the corresponding ICC variation for all four measurement methods. Mean torsion angles were greater by 17.6° for CT and 18.7° for MRI (all P < .001) between the most proximal to the most distal measurement methods. Conclusion MRI- and CT-based femoral torsion measurements showed high agreement and comparable reliability and reproducibility but were dependent on the level of selected landmarks used to define the proximal reference axis. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Zoga in this issue.

Three-dimensional morphological analysis of the femoral neck torsion angle\u2014an anatomical study

BackgroundThe femoral neck torsion angle (FNTA) is an important but often neglected parameter in assessments of the anatomical morphology of the femoral neck, which is often confused with the femoral neck anteversion angle (FNAA) in the current literature. Currently, the measurement methods reported in the literature all adopt the naked eye or two-dimensional (2D) visualization method, and the measurement parameters and details are not clearly defined. The objection of this research was to provide a reliable 3D method for determining the femoral neck axis, to improve the measurement method of the FNTA, and to analyze the anatomical and clinical significance of the results.MethodsComputed tomography (CT) data of 200 patients who received a lower extremity CT angiography examination were selected, and the bilateral femurs were reconstructed with three dimensional CT (3D CT). First, the 3D axis of the femoral neck was built. Second, the long axis of the cross section the femoral neck isthmus (FNI) and femoral neck basilar part (FNB) were confirmed by the “inertia axes” method, and the plane consisting of the long axis of the cross-section and the center of the femoral head was defined as the long axial plane. Third, the coronal plane of the proximal femur was determined through the long axis of the proximal femur and the femoral coronal. Finally, the FNTAs (the angles between the long axial planes and the coronal plane of the proximal femur) of FNI and FNB were measured. The size of FNTA was compared between the sexes and sides and different locations, the correlation between the parameters and age, height, and weight were evaluated.ResultsThe difference in FNTA was statistically significant between the isthmus and the basilar part (isthmus 30.58 ± 8.90° vs. basilar part 23.79 ± 3.98°; p < 0.01). Significant difference in the FNTA was observed between the sexes (males 31.99 ± 9.25° vs. females 27.49 ± 7.19°; p < 0.01). The increase in FNTA from the basilar part to the isthmus was 6.79 ± 8.06°, and the male (7.87 ± 8.57°) was greater than the female (4.44 ± 6.23°, p < 0.01). However, no significant difference in the values was observed between sides. Height exerted the greatest effect on the FNTA according to the correlation analysis (r = 0.255, p< 0.001).ConclusionsThis study found a reliable 3D method for the determination of the femoral neck axis improved the measurement method of the FTNTA and made it more accurate and repeatable. The results provided a methodological basis and theoretical support for the research and development of internal fixation device for femoral neck fracture and the spatial configuration of implants in treatment. And the optimal opening point of the femoral medullary cavity was recommended to locate at the posterior position of the top of the femoral neck cross-section during hip replacement.

Femoral derotational osteotomy level does not effect resulting torsion

PurposeThe purpose of this study was to assess the effect on femoral torsion by rotational osteotomies at three different levels as measured in 3D using both the mechanical and the anatomic axes.MethodsTen cadaveric lower extremities underwent femoral osteotomies perpendicular to the anatomic axis (AA) at three levels: subtrochanteric, mid-diaphyseal and supracondylar. Parallel pins were placed, one in each femur segment. Computed tomography (CT) was acquired in post-osteotomies neutral position, then post-external rotation of the femur at each osteotomy level. Femurs were returned to neutral rotation between imaging exams. Using 3D CT reconstructions, custom software calculated femoral torsion (angle between the femoral neck axis and the posterior condylar axis in the transverse plane) and pin angle between segments, reoriented to both the mechanical axis (MA) and the AA. Pin angle and torsion change were compared for the three osteotomy locations (regression analysis and ANOVA performed).ResultsTwo specimens were omitted (inadequate imaging); the remaining eight donors were 55–90 years old (mean: 64 ± 15 years), CT confirmed no bony defects. All three levels of osteotomy demonstrated significant correlations between the amount of rotation at the osteotomy (pin angle change) and the resulting change in femoral torsion (R square range 0.658–0.847). No significant differences were found between osteotomy level in torsion (MA:p = 0.285, AA:p = 0.156) or in pin angle (MA:p = 0.756, AA:p = 0.753).ConclusionsPerforming a corrective rotational osteotomy orthogonal to the AA achieves the desired effect on MA regardless of location. This suggests that a surgeon’s osteotomy level choice may be based on other risks/benefits of the various techniques.

Application of three-dimensional reconstruction to improve the preoperative measurement accuracy and applicability of femoral neck torsion angle.

Conventional methods have limitations in measuring femoral neck torsion angle (FNTA) of patients with femoral deformities. A new method of three-dimensional (3D) reconstruction technology based on computer tomography (CT) was proposed to enhance measurement accuracy and applicability in this study.Bilateral FNTA of 50 developmental dysplasia of the hip (DDH) patients (DDH group) and 81 volunteers (normal group) were measured by Mimics software based on CT data with the marker lines determined by centerline and curvature. Each FNTA was measured by observer A and observer B for twice separately. 50 DDH patients were classified into 3 groups (group I, II, III) according to Hartofilakidis classification. The statistical analysis of the differences was made among the measurements of the FNTA.The FNTA values were 27.56° ± 12.48° in DDH group and 21.22° ± 8.14° in normal group with significant difference (t = 4.516, P < .001). The FNTA values were 24.53° ± 2.40° in group I, 29.78° ± 1.83° in group II and 39.08° ± 3.13° in group III, with significant difference (F = 7.568, P = .001).The accuracy, reliability and applicable scope of FNTA measurement can be improved by 3D reconstruction in clinical practice. The applicable scope of this method included normal people and patients with femoral deformities. The FNTA of DDH patients is significantly larger than normal volunteers with a positive correlation between the severity of classification. This study will also provide references for preoperative design of Chinese population.

Ultrasonographic Assessment of Femoral Torsion Angle Based on Tilting Angles of Femoral Neck and Condylar Axis

Femoral anteversion has been assessed with ultrasound using femoral neck tilting angle (FN-TA); however, femoral torsion angle (FTA), which is defined using FN-TA and condylar axis tilting angle, has not been assessed with ultrasound. This study aimed to establish the ultrasonographic assessment of FTA (US-FTA) by comparing data obtained through US-FTA and computed tomography (CT). Twenty-one patients (age range, 38–82 y) with 21 intact hips were included. In the US-FTA, the femoral head and anterior tubercle of the greater trochanter were used as bony landmarks. The intra-rater and inter-rater reliabilities and standard error of measurement (SEM) of US-FTA were 0.994 (SEM 0.93) and 0.994 (SEM 0.94), respectively. A strong agreement was found between FTA variables obtained with ultrasound and CT (R = 0.939, p < 0.001). Ultrasound is useful and can be a valid alternative to CT for the evaluation of the femoral torsion angle without radiation exposure.

Patella alignment abnormality in patients with developmental dysplasia of the hip.

The purpose of this study was to assess the influence of developmental dysplasia of the hip (DDH) on patella alignment. The radiographic data of all the patients who met the inclusion criteria from January 2015 to July 2017 were reviewed, including the quadriceps angle (QA), patellar lateral tilt (PTA), sulcus angle (SA), lateral shift of patella (LSP), and lower limbs alignment. The patients were divided into three groups in accordance with lateral center-edge angle (LCE) and femoral neck torsion angle (FNTA): group A (LCE > 25° and FNTA < 40°), group B (LCE < 20° and FNTA < 40°), and group C (LCE < 20° and FNTA > 40°). One hundred thirty-eight patients with 230 hips (115 females and 23 males) were recruited with an average age of 22 years. There were significant differences between group A and group C as well as group B and group C in QA, SA, PTA, LSP, and lower limbs alignment (p < 0.01). There were no differences in SA, PTA, LSP, and lower limbs alignment (p >0.05) and significant differences in QA (p < 0.01) between group B and group C. The "Pearson's" correlation analysis of the data in total of group B and group C showed that FNTA and LCE and QA and LCE were negatively correlated, whereas FNTA and QA, PTA, SA, and lower limbs alignment as well as SA, PTA, and lower limbs alignment were positively correlated. Patients with DDH not only have hip joint change, but also have the patella alignment abnormality, which may lead to patella instability. In the clinic, we should pay attention to the hip development of the patella instability patients for excluding DDH. Level of Evidence: Prognostic level III.

Accuracy of patient-specific three-dimensional-printed osteotomy and reduction guides for distal femoral osteotomy in dogs with medial patella luxation.

To compare precorrectional and postcorrectional femoral alignment following distal femoral osteotomy using patient-specific 3-dimensional (3D)-printed osteotomy and reduction guides in vivo and ex vivo. Prospective study. Ten client-owned dogs and matching 3D-printed plastic bone models. Distal femoral osteotomy was performed via a standard approach using osteotomy and reduction guides developed with computer-aided design software prior to 3D-printing. Femoral osteotomy and reduction was also performed on 3D-printed models of each femur with identical reprinted guides. Femoral varus angle (FVA) and femoral torsion angle (FTA) were measured on postoperative computed tomographic images by 3 observers. In vivo, the mean difference between target and achieved postoperative was 2.29° (±2.29°, P = .0076) for the FVA, and 1.67° (±2.08°, P = .300) for the FTA. Ex vivo, the mean difference between target and achieved postoperative was 0.29° (±1.50°, P = .813) for the FVA, and -2.33° (±3.21°, P = .336) for the FTA. Intraobserver intraclass correlation coefficients (ICC; 0.736-0.998) and interobserver ICC (0.829 to 0.996) were consistent with an excellent agreement. Use of 3D-printed osteotomy and reduction guides allowed accurate correction of FTA in vivo and both FVA and FTA ex vivo. Use of 3D-printed osteotomy and reduction guides may improve the accuracy of correction of femoral alignment but warrant further evaluation of surgical time, perioperative complications, and patient outcomes compared with conventional techniques.

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.

What Is the Association between an Anteriorly Tilted Pelvis and Trendelenburg Gait?

Lower back pain (LBP) is a widespread, painful medical condition that has been plaguing society for many years. Present conservative rehabilitation focus is on lumbo-pelvic hip stability exercises in individual planes. However, a functional integrative rehabilitative approach addressing lumbo-pelvic misalignment in the sagittal (anteriorly tilted pelvis) and frontal (Trendelenburg gait) planes has not been presented. The aforementioned patho-biomechanical conditions and their management are often discussed estranged from each other rather than functionally integrated. This paper serves as a short communication which discusses the lumbo-pelvic anatomy, identifies the anatomical and biomechanical associations between the anteriorly tilted pelvic and Trendelenburg gait. Through an analysis of relevant literature, recommendations were made on the improvement of flexibility of the hip flexors, taut iliofemoral and pubofemoral ligaments to resolve the primary abnormal force-couple, with improved flexibility of the erector spinae and quadratus lumborum to resolve the secondary abnormal force-couple. In addition, improved flexibility of the hip flexors should coincide with closed-kinetic chain concentric strengthening of the ipsi-lateral hip abductors and contralateral external obliques. Patient education is also needed for self-re-alignment of the lower extremity to a neutral position and neutral foot stance. Biokineticists/exercise therapists should also review the patient’s gait biomechanics to determine whether sartorius synergistic dominance is in play. In conclusion, the association between an anteriorly tilted pelvis and Trendelenburg gait, is in regard to taut anterior acetabulofemoral ligaments and femoral retroversion torsion angle that is both preceded and followed by the biomechanical influence of various anatomical structures. These anatomical and biomechanical factors must be evaluated by the biokineticists/exercise therapists before prescribing a rehabilitative programme to ensure successful rehabilitation of lumbo-pelvic hip complex.

Automated computation of femoral angles in dogs from three-dimensional computed tomography reconstructions: Comparison with manual techniques

The aim of this ex vivo study was to test a novel three-dimensional (3D) automated computer-aided design (CAD) method (aCAD) for the computation of femoral angles in dogs from 3D reconstructions of computed tomography (CT) images. The repeatability and reproducibility of three manual radiography, manual CT reconstructions and the aCAD method for the measurement of three femoral angles were evaluated: (1) anatomical lateral distal femoral angle (aLDFA); (2) femoral neck angle (FNA); and (3) femoral torsion angle (FTA). Femoral angles of 22 femurs obtained from 16 cadavers were measured by three blinded observers. Measurements were repeated three times by each observer for each diagnostic technique. Femoral angle measurements were analysed using a mixed effects linear model for repeated measures to determine the levels of intra-observer agreement (repeatability) and inter-observer agreement (reproducibility). Repeatability and reproducibility of measurements using the aCAD method were excellent (intra-class coefficients, ICCs≥0.98) for all three angles assessed. Manual radiography and CT exhibited excellent agreement for the aLDFA measurement (ICCs≥0.90). However, FNA repeatability and reproducibility were poor (ICCs<0.8), whereas FTA measurement showed slightly higher ICCs values, except for the radiographic reproducibility, which was poor (ICCs<0.8). The computation of the 3D aCAD method provided the highest repeatability and reproducibility among the tested methodologies.

Femoral Torsion: Impact of Femur Position on CT and Stereoradiography Measurements.

The purpose of this study is to evaluate stereoradiographic measurements of femoral torsion with different femoral positions, in comparison with CT measurements, with use of the current standard axial-slice technique. We hypothesize that CT measurements vary with femoral spatial positioning because of the resulting projection onto the CT plane, whereas stereoradiographic measurements, which are derived from a 3D reconstruction of the femur, remain constant. Both in vitro and in vivo studies were conducted. CT and stereoradiographic examinations were performed using 30 dry femurs in the following six femoral positions: neutral position (with the femoral mechanical axis aligned with the longitudinal axis of the CT scanner or stereoradiography system), 10° of abduction, 10° of adduction, 5° of flexion, 10° of flexion, and 5° of extension. The impact of femoral position on torsion measurement was assessed using paired t tests. In addition, 18 patients (mean [± SD] age, 42.3 ± 19.9 years) who underwent both CT and stereoradiography examinations were retrospectively assessed. The correlation between femoral positioning and torsion measurement was determined using the Pearson correlation coefficient. Flexion and extension statistically significantly affected CT measurement of femoral torsion (p < 0.01) but not stereoradiography measurement (p > 0.21). A strong correlation existed between hip flexion and the difference between femoral torsion measured by CT and stereoradiography (r = -0.80). The accuracy of femoral torsion determined by axial CT depends on the position of the femur. Hip flexion significantly reduced the femoral torsion angle measured by CT. Conversely, the accuracy of stereoradiography was independent of femur positioning. Thus, stereoradiography is preferable to CT for accurate measurement of femoral torsion, while it also substantially reduces the radiation dose.

Computation of Femoral Canine Morphometric Parameters in Three-Dimensional Geometrical Models.

To define and validate a method for the measurement of 3-dimensional (3D) morphometric parameters in polygonal mesh models of canine femora. Ex vivo/computerized model. Sixteen femora from 8 medium to large-breed canine cadavers (mean body weight 28.3 kg, mean age 5.3 years). Femora were measured with a 3D scanner, obtaining 3D meshes. A computer-aided design-based (CAD) software tool was purposely developed, which allowed automatic calculation of morphometric parameters on a mesh model. Anatomic and mechanical lateral proximal femoral angles (aLPFA and mLPFA), anatomic and mechanical lateral distal femoral angles (aLDFA and mLDFA), femoral neck angle (FNA), femoral torsion angle (FTA), and femoral varus angle (FVA) were measured in 3D space. Angles were also measured onto projected planes and radiographic images. Mean (SD) femoral angles (degrees) measured in 3D space were: aLPFA 115.2 (3.9), mLPFA 105.5 (4.2), aLDFA 88.6 (4.5), mLDFA 93.4 (3.9), FNA 129.6 (4.3), FTA 45 (4.5), and FVA -1.4 (4.5). Onto projection planes, aLPFA was 103.7 (5.9), mLPFA 98.4 (5.3), aLDFA 88.3 (5.5), mLDFA 93.6 (4.2), FNA 132.1 (3.5), FTA 19.1 (5.7), and FVA -1.7 (5.5). With radiographic imaging, aLPFA was 109.6 (5.9), mLPFA 105.3 (5.2), aLDFA 92.6 (3.8), mLDFA 96.9 (2.9), FNA 120.2 (8.0), FTA 30.2 (5.7), and FVA 2.6 (3.8). The proposed method gives reliable and consistent information about 3D bone conformation. Results are obtained automatically and depend only on femur morphology, avoiding any operator-related bias. Angles in 3D space are different from those measured with standard radiographic methods, mainly due to the different definition of femoral axes.

Determination of Femoral Neck Angle and Torsion Angle Utilizing a Novel Three-Dimensional Modeling and Analytical Technology Based on CT Datasets.

IntroductionExact knowledge of femoral neck inclination and torsion angles is important in recognizing, understanding and treating pathologic conditions in the hip joint. However, published results vary widely between different studies, which indicates that there are persistent difficulties in carrying out exact measurements.MethodsA three dimensional modeling and analytical technology was used for the analysis of 1070 CT datasets of skeletally mature femurs. Individual femoral neck angles and torsion angles were precisely computed, in order to establish whether gender, age, body mass index and ethnicity influence femoral neck angles and torsion angles.ResultsThe median femoral neck angle was 122.2° (range 100.1–146.2°, IQR 117.9–125.6°). There are significant gender (female 123.0° vs. male 121.5°; p = 0.007) and ethnic (Asian 123.2° vs. Caucasian 121.9°; p = 0.0009) differences. The median femoral torsion angle was 14.2° (-23.6–48.7°, IQR 7.4–20.4°). There are significant gender differences (female 16.4° vs. male 12.1°; p = 0.0001). Femoral retroversion was found in 7.8% of the subjects.ConclusionPrecise femoral neck and torsion angles were obtained in over one thousand cases. Systematic deviations in measurement due to human error were eliminated by using automated high accuracy morphometric analysis. Small but significant gender and ethnic differences were found in femoral neck and torsion angles.

Differences in anatomical parameters between the affected and unaffected hip in patients with bilateral cam-type deformities

BackgroundIt is still unclear why many individuals with bilateral cam deformities demonstrate only unilateral symptoms of femoroacetabular impingement, thus symptoms may be attributed to additional anatomical parameters. The purpose was to examine patients with bilateral cam deformities, with unilateral symptoms, and compare anatomical hip joint parameters between their affected (symptomatic) hip and their contralateral, unaffected (asymptomatic) hip. MethodsTwenty participants (n=20) with unilateral symptoms, but bilateral cam deformities, underwent CT imaging to measure their affected and unaffected hip's: axial and radial alpha angles, femoral head–neck offset, femoral neck-shaft angle, medial proximal femoral angle, femoral torsion, acetabular version, center-edge angle; and a physical examination (hip flexion, straight-leg raise, internal rotation, external rotation) to ascertain clinical signs. FindingsThe affected hips demonstrated limited motions during physical examination, compared with unaffected hips (effect size=0.550 to 0.955). The affected hips had significantly lower femoral neck-shaft angles (mean 125° (SD 3)) and lower medial proximal femoral angles (mean 79° (SD 4)), compared with the unaffected hips (mean 127° (SD 3), P=0.001, effect size=0.922; and mean 81° (SD 4), P=0.011, effect size=0.632; respectively). There were no differences in cam deformity parameters (axial and radial alpha angles, femoral head–neck offset), femoral torsion, acetabular version, and center-edge angle, between affected and unaffected hips. InterpretationA decreased femoral neck-shaft angle or medial proximal femoral angle can be implemented as a diagnostic predictor, to determine which hip may be at a greater risk of developing early symptoms.

Total Limb Rotation after Unilateral Total Knee Arthroplasty: Side-to-Side Discrepancy.

Total limb rotation, an important anatomical feature of the lower limb, is defined as any rotation of the lower limb on its longitudinal axis. The aim of the present study was to evaluate the discrepancies of rotational profiles of total limb between nonoperated and operated limb following unilateral total knee arthroplasty. We conducted an analysis of the computed tomography (CT) data from 32 patients undergoing primary unilateral total knee arthroplasty. Using these CT scan, rotational profiles of total limb, such as femoral neck anteversion angle expressed as femoral torsion angle (FTA), tibial torsion angle (TTA), knee joint rotation angle (KJRA), and total limb rotation (TLR) were measured. There were significant discrepancies of FTA and KJRA between operated and nonoperated limb following unilateral total knee arthroplasty. The mean difference of operated and nonoperated side for FTA and KJRA were -6.51 ± 11.88 degrees (p = 0.0041) and -6.83 ± 5.04 degrees (p < 0.001), respectively. However, there were no significant discrepancies of TLR, TTA. These results are due to the compensation effect of KJRA. However, excessive external rotation of the femoral component beyond the compensation effect of prosthetic knee joint can lead to a total limb rotational discrepancy in patient undergoing unilateral total knee arthroplasty.

Measuring femoral neck torsion angle using femoral neck oblique axial computed tomography reconstruction.

To propose a novel method for measuring the femoral neck torsion angle (FNTA) with femoral neck oblique axial computed tomography (CT) reconstruction. Fifty-five patients (24 females, 31 males; mean age 48.8years [range, 20-91years]) were included in the study. CT scans were performed on the left femurs of 27 patients and the right femurs of the remaining 28 patients. The images were analyzed independently by two observers using oblique axial femoral neck CT reconstruction. Intra-observer and inter-observer agreement was calculated as intraclass correlation coefficient (ICC). FNTA can be measured with high intra-observer (ICC = 0.961) and high inter-observer (ICC = 0.982) agreement. Mean FNTA was slightly larger in women than in men, and the mean left FNTA was slightly larger than the right, but neither difference was statistically significant. Femoral neck oblique axial CT reconstruction can be used to obtain accurate measurement of FNTA with good reproducibility. No significant differences were found in FNTA between sexes or sides.

Comparative Analysis of Lower Limb Alignments in Healthy Subjects and Subjects with Back Pain

The objective of the present study was to comparatively analyze the clinical status of the lower limbs in healthy subjects and subjects with back pain. Forty three (43) male and female subjects with average age of 36.91± 3.97 were selected as the statistical sample of the study. This population was recognized intelligently by utilizing the Nordic Musculoskeletal Questionnaire (NMQ). Furthermore, the NMQ was used to designate 43 male and female subjects with average age of 37.88 ± 4.12 and similar anthropometric characteristics with the statistical population as the research control sample. In the next phase, tibial torsion and femoral torsion angles were measured using a goniometer. Foot typicality was designated using a foot arch index while intercondylar and intermalleolar distances were measured using a clinical caliper. The results depict that the size of the foot arch is steeper in people with back pains compared to those with flat foot arch (p<0.05). It also indicates that there is no significant correlation between the tibia, femur torsion, knee condition of the healthy subjects and subjects with back pain. Therefore, it is deduced that steep foot arch can be a key component in the generation of back pains.