Measurement Of Femoral Anteversion Research Articles

A New Method to Predict Postoperative Stem Anteversion in Total Hip Arthroplasty for Developmental Dysplasia of the Hip.

Preoperative evaluation of femoral anteversion to predict postoperative stem anteversion aids the selection of an appropriate prosthesis and optimizes the combined anteversion in total hip arthroplasty (THA) for developmental dysplasia of the hip (DDH). The conventional prediction methods are based on the femoral anteversion measurement at the location of the femoral head and/or neck. However, varied differences between femoral anteversion and postoperative stem anteversion were demonstrated. This study investigated the predictive role of a new method based on the principle of sagittal three-point fixation. From January 2017 to December 2018, a total of 133 DDH hips that underwent THA were retrospectively analyzed. There were 76 Crowe type I, 27 type II, and 30 type III hips. The single-wedge stem was used in 49 hips, and the double-wedge stem was used in 84 hips. Preoperative native femoral anteversion at the femoral head-neck junction, anterior cortex anteversion at 2 levels of the lesser trochanter, posterior cortex anteversion at 5 levels of the femoral neck, and postoperative stem anteversion were measured using two-dimensional computed tomography. Predictive anteversion by the new method was calculated as the average anteversion formed by the anterior cortex at the lesser trochanter and the posterior cortex at the femoral neck. For hips with different neck heights, different Crowe types, different stem types, or different femoral anteversions, native femoral anteversion showed widely varied differences and correlations with stem anteversion, with differences ranging from -1.27 ± 8.33° to -13.67 ± 9.47° and correlations ranging from 0.122 (p = 0.705, no correlation) to 0.813. Predictive anteversion formed by the anterior cortex at the lesser trochanter proximal base and posterior cortex 10 mm above the lesser trochanter proximal base showed no significant difference with stem anteversion, with less varied differences (0.92 ± 7.52°) and good to excellent correlations (r = 0.826). Adopting our new method, predictive anteversion, measured as the average anteversion of the anterior cortex at the lesser trochanter proximal base and posterior cortex 10 mm above the lesser trochanter proximal base, predicted postoperative stem anteversion more reliably than native femoral anteversion.

The conundrum in the measurement of femoral anteversion for young adults with hip pathology.

The conundrum in the measurement of femoral anteversion for young adults with hip pathology.

Reliability and validity of a mobile application for femoral anteversion measurement in adult patients

BackgroundFemoral torsion is primarily measured by computed tomography (CT), which has cost and radiation exposure concerns. Recently, femoral anteversion measurement by a simple radiograph-based mobile application was developed for patients with cerebral palsy. This study aimed to validate the use of a mobile application that can reconstruct a three-dimensional model of the femur from conventional radiographs for adults.MethodsMedical records of 76 patients undergoing conventional femur anteroposterior/lateral radiography and femur CT were reviewed. To measure femoral anteversion on the reconstructed 3-dimensional images from both the mobile application and CT, we drew a line which connects the posterior margins of each femoral condyle and another line which passes through the center of the femoral head and the midpoint of the femoral neck. After the reliability test, a single examiner measured femoral anteversion on the mobile application and CT. Pearson’s correlation analysis was used to assess the correlation between anteversion on the mobile application and CT.ResultsFemoral anteversion measured on both CT and the mobile application showed excellent reliability (intraclass correlation coefficients: 0.808–0.910). The correlation coefficient between femoral anteversion measured using CT and the mobile application was 0.933 (p < 0.001). The correlation of femoral anteversion between CT and the mobile application was relatively higher in the absence of metallic implants (correlation coefficient: 0.963, p < 0.001) than in the presence of metallic implants (correlation coefficient: 0.878, p < 0.001).ConclusionsUsing two simple radiographs, the mobile application showed excellent validity and reliability for femoral anteversion measurement in adults as compared to CT. With the high accessibility and cost-effectiveness of this mobile application, femoral torsion measurement might be easily performed with simple radiography in clinical settings in the near future.

Using the Axial Oblique View of Computed Tomography (CT) in Evaluating Femoral Anteversion: A Comparative Cadaveric Study.

Twenty-five cadaveric adult femora’s anteversion angles were measured to develop a highly efficient and reproducible femoral anteversion measurement method using computed tomography (CT). Digital photography captured the proximal femur’s two reference lines, head-to-neck (H-N) and head-to-greater trochanter (H-G). Six reference lines (A/B in transverse section; C, axial oblique section; D/E, conventional 3D reconstruction; and M, volumetric 3D reconstruction) from CT scans were used. The posterior condylar line was used as a distal femoral reference. As measured with the H-N and H-G lines, the anteversion means were 10.43° and 19.50°, respectively. Gross anteversion measured with the H-G line had less interobserver bias (ICC; H-N = 0.956, H-G = 0.982). The 2D transverse and volumetric 3D CT sections’ B/M lines were consistent with the H-N line (p: B = 0.925, M = 0.122) and the 2D axial oblique section’s C line was consistent with the H-G line (p < 0.1). The D/E lines differed significantly from the actual gross images (p < 0.05). Among several CT scan femoral anteversion measurement methods, the novel anteversion angle measurement method using CT scans’ axial oblique section was approximated with actual gross femoral anteversion angle from the femoral head to the greater trochanter.

Femoral Torsion in CT: Why We Should Add Some Trigonometry

Purpose: In our department, we routinely perform Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) of the lower extremity to assess femoral torsion for preoperative planning prior correcting osteotomies. It might be difficult to assess the FA, because on axial images the depicted part of the femoral neck is too short to allow correct alignment of the axis of the femoral neck. Measurements can also be performed on oblique axial images with improvement of depiction of the femoral neck but are smaller than those of measurements on axial images, due to the fact that images depend on rules of trigonometry. The aim is to provide a trigonometrical formula to calculate the value for FA, allowing precise assessment of femoral anteversion on oblique axial images similar to those on axial images. Materials and Methods: Trigonometrical transformation is performed in three steps. Initial measurement of femoral anteversion on oblique images is transformed via a corresponding rectangular triangle from coronal images to calculated femoral anteversion on axial images. Results: The first triangle is labelled with a1, b1, c1 for the sides and alpha1, beta1for the angles. Second and third triangle is labelled correspondingly. Length of both cathetus a1 and b1 are calculated as follows: cathetus a1=sin alpha1*c1 and cathetus b1=cos alpha 1*c1. Cathetus b2 is calculated as follows: b2=cos alpha2*c2. alpha3=tan-1 (a3/b3). Initial calculation of angle alpha3=tan-1 (a3/b3)=tan-1 (a1/b2), with a3=a1=sin alpha1*c1 and b3=b2=cos alpha2*b1*c, with b1=cos alpha1*c1 and b3=cos alpha2*cos alpha1*c1². The final formula is then: alpha3=tan-1 ((sin alpha1*c1)/(cos alpha²*cos alpha1*c12)) = tan-1 ((sin alpha1/(alpha2*cos alpha1*c1)) Conclusion: In this study we can provide a formula: alpha3=tan-1 ((sin alpha1/(cos alpha2*cos alpha1*c1)), which allows to calculate the femoral anteversion for true axial reconstructed images with the increased accuracy of measurements on oblique images and the ability to use the already known reference values from the literature.

Femoral Version in Hip Arthroscopy: Does it Matter?

Femoral version is extremely variable between patients presenting with femoroacetabular impingement (FAI). Careful and routine measurement of femoral anteversion is essential in comprehensive preoperative planning. In general, low degrees of femoral version can lead to anterior impingement (especially on the subspine and distal medial femoral neck). High degrees of anteversion can be seen in the setting of acetabular dysplasia and can lead to anterior hip instability and or posterior impingement. In this article, the authors will discuss the role of routine femoral version management for optimal outcomes after hip arthroscopy for FAI.

Analysis of Computed Tomography-Based Technique for Measuring Femoral Anteversion: Implications for Measuring Rotation After Femoral Intramedullary Nail Insertion.

To assess the reliability of the current computed tomography (CT)-based technique for determining femoral anteversion and quantify the prevalence and magnitude of side-to-side differences. Cross-sectional cohort study. Academic trauma center. We reviewed CT scans from 120 patients with bilateral full-length axial cuts of both femurs. Two hundred forty femurs with no fractures or other identifying features in their femora were included. Ten unique data sets were created to measure anteversion of the left and right sides. Intraobserver and interobserver reliability were calculated using intraclass correlation coefficients (ICCs) and pooled absolute differences. The mean absolute difference between the sides was determined using a fixed-effects model. Interobserver reliability was high (ICC: 0.85, 95% confidence interval [CI]: 0.83-0.88). The pooled mean absolute magnitude of variation between reviewers was small at 1.6 degrees (95% CI: 1.4-1.8 degrees) per scan. The intraobserver reproducibility was high (ICC: 0.91, 95% CI: 0.88-0.93) with a mean error of 2.7 degrees (95% CI: 2.2-3.1 degrees) per repeat viewing of the same scan by the same person. The magnitude of side-to-side variation was 2.0 degrees (95% CI: 1.5-2.6 degrees). Twenty-one subjects (18%, 95% CI: 12%-25%) had a mean side-to-side calculated femoral anteversion difference of ≥10 degrees, whereas 6 (5%, 95% CI: 2-10) subjects had a calculated mean side-to-side difference of ≥15 degrees. CT based femoral anteversion measurement techniques demonstrate good precision. Only 1 in 20 patients had side-to-side differences of 15 degrees or more.

An experimental study to evaluate a new radiographic method for measuring femoral anteversion

Introduction: The measurement of femoral anteversion has been a subject of interest and debate. Femoral anteversion is defined as the angle formed by the bicondylar plane and a plane passing through the center of the neck and femoral head. The angle of anteversion in humans exhibit a wide range (-25o to 40o) with the mean varying from 8o to 25o. Many methods for measuring femoral anteversion have been proposed each with its own merits and demerits. Our aim was to evaluate the validity of the Parallax method for measuring femoral anteversion and compare the results with Direct measurement and Biplane radiography - the method of Ogata et al. Materials and Methods: This is a Prospective study conducted at our institute with a total of 50 dried femur specimens obtained from the department of anatomy. Bones with obvious deformities in the proximal portion were excluded from the study. The anteversion angle was calculated by three methods: 1. Direct measurement – taken as the reference value against which the values of the other two methods can be compared. 2. Parallax method 3. Biplane radiography – the method of Kosuke Ogata et al. Results: Considering direct measurement of anteversion by the Kingsley-Olmsted method as the most accurate method, the mean anteversion was found to be 11.235o, Range: -12o to 37o. 5(10%) femurs were retroverted. 3(6%) were in neutral version. 32(64%) were in the range 1o to 20o of anteversion. 10(20%) femurs showed anteversion more than 20o. Conclusion: The parallax method is comparable to biplanar radiography in terms of safety, availability, cost and accuracy. The patient can lie with the hips extended and in neutral rotation and the radiographs can be taken. Therefore the “Parallax Method” seems to be a viable alternative to the biplanar method especially in complicated and difficult situations.

Development and Validation of a Mobile Application for Measuring Femoral Anteversion in Patients With Cerebral Palsy.

Computed tomography (CT) provides benefits for 3-dimensional (3D) visualization of femur deformities. However, the potential adverse effects of radiation exposure have become a concern. Consequently, a biplanar imaging system EOS has been proposed to enable reconstruction of the 3D model of the femur. However, this system requires a calibrated apparatus, the cost of which is high, and the area occupied by it is substantial. The purpose of this study was to develop a mobile application that included a new method of 3D reconstruction of the femur from conventional radiographic images and to evaluate the validity and reliability of mobile the application when measuring femoral anteversion. The statistical shape model, graph-cut algorithm, and iterative Perspective-n-Point algorithm were utilized to develop the application. The anteroposterior and lateral images of a femur can be input using the embedded camera or by file transfer, and the touch interface aids accurate contouring of the femur. Regarding validation, the CT scans and conventional radiographic images of 36 patients with cerebral palsy were used. To evaluate concurrent validity, the femoral anteversion measurements on the images reconstructed from the mobile application were compared with those from the 3D CT images. Three clinicians assessed interobserver reliability. The mobile application, which reconstructs the 3D image from conventional radiographs, was successfully developed. Regarding concurrent validity, the correlation coefficient between femoral anteversion measured using 3D CT and the mobile application was 0.968 (P<0.001). In terms of interobserver reliability, the intraclass correlation coefficient among the 3 clinicians was 0.953. The measurement of femoral anteversion with the mobile application showed excellent concurrent validity and reliability in patients with cerebral palsy. The proposed mobile application can be used with conventional radiographs and does not require additional apparatus. It can be used as a convenient technique in hospitals that cannot afford a CT machine or an EOS system. Level III-diagnostic.

A Validated Single-View Radiographic Alternative to Computed Tomography for the Measurement of Femoral Anteversion: A Method-Comparison Study

BackgroundAlthough preoperative templating in total hip arthroplasty is helpful to ensure appropriate component position, there is no single-view radiographic method to determine femoral anteversion (FA) preoperatively. The aim of the present study was to validate the use of radiographic measurement of FA using a modified Budin view. MethodsThis prospective study reports on 105 limbs from 65 patients. Computed tomography (CT) scans and radiographs were obtained to measure native FA. Radiographs were obtained using the modified Budin protocol with 90° flexion at the knee and 90° flexion and 30° abduction at the hip. Pearson correlation analyses, paired-samples t-test, and Bland-Altman plots were performed to assess correlation and agreement between methods. Data were grouped into subsets based on CT-derived FA in 5° intervals. Groups included all limbs, FA < 35°, FA < 30°, and FA < 25°. ResultsFor all limbs, Bland-Altman analysis revealed a fixed bias (mean bias, −0.8°; 95% confidence interval, −1.4° to −0.2°) and showed that radiographic methods underestimated FA. Subset analyses were performed and revealed excellent correlation between CT and radiographic measurements for all subgroups (r = 0.97, P < .001). Paired-samples t-tests revealed no significant difference between methodologies for any of the subgroups. Radiographic and CT methods showed excellent agreement, and the bias between methods was within 0.5° for all subgroups. There was no fixed bias and thus no systematic difference in methods within any of the subgroup analyses. ConclusionRadiographic measurement of FA using a modified Budin view is a valid and reliable technique.

Three‐dimensional reconstruction and femoral anteversion measurement of uncalibrated biplanar radiographic images in patients with cerebral palsy

Three‐dimensional reconstruction and femoral anteversion measurement of uncalibrated biplanar radiographic images in patients with cerebral palsy

Magnetic Resonance Three-dimensional Cube Technique in the Measurement of Piglet Femoral Anteversion

Background:The accurate measurement of the femoral anteversion (FA) angle is always a topic of much debate in the orthopedic surgery and radiology research. We aimed to explore a new FA measurement method to acquire accurate results without radiation damage using piglet model.Methods:A total of thirty piglets were assigned to two groups based on the age. Bilateral femora were imaged with 3.0-T magnetic resonance (MR) and 64-slice computed tomography (CT) examinations on all piglets. FA was measured on MR-three-dimensional (3D) postprocessing software with a four-step method: initial validation of the femoral condylar axis, validation of the condylar plane, validation of the femoral neck axis, and line-plane angle measurement of FA. After MR and CT examinations, all piglets were sacrificed and their degree of FA was measured using their excised, dried femora. MR, CT, and dried-femur measurement results were analyzed statistically; MR and CT measurements were compared for accuracy against each other and against the gold standard dried femur measurement.Results:In both groups, the mean FA value measured by MR was lower than that measured by CT. A statistically significant difference was observed between CT- and dried-femur measurements but not between MR- and dried-femur measurements. A higher correlation (0.783 vs. 0.408) and a higher consistency (0.863 vs. 0.578) with dried-femur measurement results were seen for MR measurements than CT measurements in the 1-week age group. However, in the 8-week age group, similar correlations (0.707 vs. 0.669) and consistencies (0.864 vs. 0.821) were observed.Conclusions:Noninvasive MR-3D-Cube reconstruction was able to accurately measure FA in piglets. Particularly in the 1-week age group with a larger proportion of cartilaginous structures, the correlation and consistency between MR- and dried-femur measurement results were higher than those between CT- and dried-femur measurements, suggesting that MR may be a new useful examination tool for FA-related diseases in children.

Bone marrow segmentation based on a combined consideration of transverse relaxation processes and Dixon oscillations.

The aim of this study was to demonstrate that gradient-echo sampling of single spin echoes can be used to isolate the signal from trabecular bone marrow, with high-quality segmentation and surface reconstructions resulting from the application of simple post-processing strategies. Theoretical expressions of the time-domain single-spin-echo signal were used to simulate signals from bone marrow, non-bone fatty deposits and muscle. These simulations were compared with and used to interpret signals obtained by the application of the gradient-echo sampling of a spin-echo sequence to image the knee and surrounding tissues at 1.5 T. Trabecular bone marrow has a much higher reversible transverse relaxation rate than surrounding non-bone fatty deposits and other musculoskeletal tissues. This observation, combined with a choice of gradient-echo spacing that accentuates Dixon-type oscillations from chemical-shift interference effects, enabled the isolation of bone marrow signal from surrounding tissues through the use of simple image subtraction and thresholding. Three-dimensional renderings of the marrow surface were then readily generated with this approach - renderings that may prove useful for bone morphology assessment, e.g. for the measurement of femoral anteversion. In conclusion, understanding the behavior of signals from bone marrow and surrounding tissue as a function of time through a spin echo facilitates the segmentation and reconstruction of bone marrow surfaces using straightforward post-processing strategies that are typically available on modern radiology workstations.

Measuring physiological and pathological femoral anteversion using a biplanar low-dose X-ray system: validity, reliability, and discriminative ability in cerebral palsy.

The aims of this study were to evaluate the concurrent validity and reliability of a low-dose biplanar X-ray system (Ld-BPR) for the measurement of femoral anteversion (FA) by comparing Ld-BPR-based three-dimensional measures with CT-scan-based measures and to assess the discriminative ability of this method in children with cerebral palsy. Fifty dry femora were scanned using both a CT scan and the Ld-BPR system. Ten femora were artificially modified to mimic a range of anteversion from -30° to +60° and scanned by both modalities. FA was quantified using the images from both modalities and statistically compared for concurrent validity. Intra- and inter-observer reliability of the Ld-BPR system was also determined. Further, Ld-BPR data from 16 hemiplegic and 22 diplegic children were analyzed for its discriminative ability. The concurrent validity between the Ld-BPR and CT-scan measures was excellent (R (2) = 0.83-0.84) and no significant differences were found. The intra- and inter-trial reliability were excellent (ICCs = 0.98 and 0.97) with limits of agreement of (-2.28°; +2.65°) and (-2.76°; +3.38°) respectively. Further, no significant effects of angle or method were found in the sample of modified femora. Ld-BPR measures for FA were significantly different between healthy and impaired femora. The excellent concurrent validity with the CT scan modality, the excellent reliability, and the ability to discriminate pathological conditions evaluated by this study make this radiological method suitable for a validated use across hospitals and research institutes.

Utility of Preoperative Femoral Neck Geometry in Predicting Femoral Stem Anteversion

This study investigated the relationships between the preoperative femoral anteversions and the femoral stem anteversion using CT scans and CT-based 3D models to determine whether any preoperative anteversion measurement correlates with the postoperative stem anteversion. Pre-operative and post-operative CT scans of 19 hips with THAs were evaluated. Five preoperative anatomical femoral anteversion measurements (CT-Head, CT-Below Head, CT-Neck, 3D-Head, and 3D-Neck) were compared with the postoperative femoral stem anteversion. The preoperative CT-Neck anteversion measurement was most correlated with the postoperative stem anteversion (r=0.761, P=0.002) with the narrowest ranges of the differences (−10.2° to 11.0°). The preoperative anteversions using the femoral neck geometry from CT scans can be used for the estimation of the postoperative femoral stem anteversion in THA.

Effect of Femoral Anteversion on Clinical Outcomes After Hip Arthroscopy

To compare the clinical outcomes after hip arthroscopy of patients with femoral retroversion, normal femoral version, and excessive femoral anteversion. Patients who underwent primary hip arthroscopy from August 2008 to April 2011 and underwent femoral anteversion measurement by magnetic resonance imaging/magnetic resonance arthrogram were included. The patients were divided into 3 groups: retroversion, normal version, and excessive anteversion. The normal-version group was considered to have a value within 1 SD of the mean femoral version value. Four patient-reported outcome scores and the visual analog pain score were prospectively collected with analysis performed retrospectively. Two hundred seventy-eight patients met the inclusion criteria. Among these patients, mean anteversion was 8.2° ± 9.3°, creating a retroversion group defined as -2° or less and an anteversion group defined as 18° or greater. There were 25 patients in the retroversion group, 219 in the normal-version group, and 34 in the excessive-anteversion group. Most labral tears were noted in the 12- to 2-o'clock range, with the main difference at the anterior 3-o'clock position, where the excessive-anteversion group showed a lower incidence of tearing (30%) than the retroversion group (73%) and normal-anteversion group (78%). Postoperatively, there was a statistically significant improvement from preoperative scores in all 3 groups and for all scores (P < .001). When the postoperative scores were compared for the 3 groups, although all scores were higher in the retroversion group than in the other 2 groups, this was not statistically significant and there were no significant differences in scores among the 3 groups (modified Harris Hip Score, P = .104; Non-Arthritic Hip Score, P = .177; Hip Outcome Score-Activities of Daily Living, P = .152; Hip Outcome Score-Sport-Specific Subscale, P = .276; visual analog scale score, P = .508). On the basis of patient-reported outcome scores without accounting for diagnoses and treatments, the amount of femoral anteversion does not appear to affect the clinical outcomes after hip arthroscopy. Level III, retrospective comparative study.

Validation of the femoral anteversion measurement method used in imageless navigation

Total hip arthroplasty restores lost mobility to patients suffering from osteoarthritis and acute trauma. In recent years, navigated surgery has been used to control prosthetic component placement. Furthermore, there has been increasing research on what constitutes correct placement. This has resulted in the definition of a safe-zone for acetabular cup orientation. However, there is less definition with regard to femoral anteversion and how it should be measured. This study assesses the validity of the femoral anteversion measurement method used in imageless navigation, with particular attention to how the neutral rotation of the femur is defined. CT and gait analysis methodologies are used to validate the reference which defines this neutral rotation, i.e., the ankle epicondyle piriformis (AEP) plane. The findings of this study indicate that the posterior condylar axis is a reliable reference for defining the neutral rotation of the femur. In imageless navigation, when these landmarks are not accessible, the AEP plane provides a useful surrogate to the condylar axis, providing a reliable baseline for femoral anteversion measurement.

Femoral Anteversion in the Hip: Comparison of Measurement by Computed Tomography, Magnetic Resonance Imaging, and Physical Examination

The purpose of this study was to evaluate the correlation between computed tomography (CT) and magnetic resonance imaging (MRI) measurements of femoral anteversion, as well as the relation of anteversion with physical examination and radiographic findings. Preoperative CT and MRI measurements of anteversion along with clinical examination were performed on 129 consecutive hips before hip arthroscopy for nonarthritic hip injuries. All anteversion measurements were performed by 2 musculoskeletal radiologists. The radiographic findings and physical examination findings were analyzed for statistically significant correlations. For statistical analysis purposes, the patients were divided into 3 groups according to the mean CT anteversion measurement: group I (low), less than 10°; group II (medium), 10° to 22°; and group III (high), greater than 22°. High interobserver correlation was found for femoral anteversion measurement by CT and MRI (r = 0.95 and r = 0.86, respectively; P < .0001 for both). CT and MRI measurements showed high correlation with each other (r = 0.80, P < .0001). However, in 96% of the cases, the CT measurement was larger, with a mean difference of 8.9° (range, -37° to 1.5°). A significant correlation coefficient was found between internal rotation and anteversion angles as measured by CT (r = 0.36, P < .0001). However, no correlation was found with other hip movement measurements. Abnormal femoral acetabular bony architecture of the hip was found in 64% of the patients; isolated cam impingement was more prevalent in group I, whereas isolated pincer impingement was more prevalent in group III (P = .01). Although high correlation was found between anteversion angle measurements by CT and MRI, significant discrepancies in the absolute anteversion number between the 2 techniques suggest that they may not be interchangeable. Furthermore, CT was found to have higher interobserver reliability than MRI. There was a significant correlation between CT and examination of internal rotation of the hip. Clinically, the findings of the study show that the diagnosis of excessive femoral anteversion or retroversion should have different thresholds according to MRI and CT measurements; moreover, the diagnosis should not rely exclusively on either examination or radiologic criteria. Level III, retrospective comparative study.

Accuracy of measurement of femoral anteversion in femoral shaft fractures using a computer imaging software: a cadaveric study

Rotational malalignment after intramedullary nailing of femoral fractures remains an unresolved problem. Various techniques have been described to address this problem, with limited success. In this cadaveric study, we describe the determination of the femoral anteversion (FAV) angle utilizing a new imaging software program which allows us to generate and manipulate reformatted virtual images from standard DICOM (Digital Imaging and Communications in Medicine) images. Eleven intact femoral specimens were scanned by CT before and after fracture induction in standardized fashion. The obtained DICOM image datasets were uploaded to the new software tool. From this, we obtained reformatted virtual fracture fragment images, which enabled us to reconstruct the femoral anatomy and determine FAV measurements. We then compared FAV measurements before and after fracture induction to determine if there were any statistically significant differences. Fracture induction generated 5 AO type A and 6 AO type B fractures. In the specimens prior to fracture induction, we were able to determine the mean FAV to be 17.94° ± 4.48°. Additionally, analysis of the fractured femoral specimens revealed the new mean FAV to be 16.26° ± 4.83°. Statistical analysis of these two measurement groups did not demonstrate statistical significance. When a sub-analysis was performed of the FAV measurements between the two different AO fracture types, there also were no statistically significant differences. Through new imaging software that allows us to reformat standard DICOM images and generate virtual fracture fragments, we were able to determine the appropriate FAV. We feel that this technique can potentially be integrated into the imaging algorithm for femoral shaft fractures in the future, and can potentially optimize clinical outcomes by allowing the orthopaedic surgeon to determine precisely the appropriate native FAV.

Patellofemoral Disorders

Background:The contribution of lower limb rotational malalignment to patellofemoral pain and instability has been well recognized. The purpose of the present study is to review the role of computed tomography (CT) and magnetic resonance imaging (MRI) in assessment of abnormal rotational alignment of lower limb.Evidence Acquisition:An analysis of all available literature in the English language through 2010 was performed to provide data on a comparison between MRI and CT—specifically, the techniques and normative values used to determine abnormal lower limb alignment.Results:CT and MRI are highly accurate in defining abnormal alignment of the lower limb. Determination of axis of femoral anteversion in proximal femur has been the subject of debate in the literature. The determination of distal femoral condylar axis, proximal tibial axis and distal tibial axis are less controversial.Conclusions:CT and MRI are both used for assessing the rotational abnormalities of the femur and tibia during evaluation for patellofemoral disorders. MRI has an advantage over CT because femoral anteversion measurements are more accurate and ionizing radiation is avoided. A standardized protocol defining the level and axes for measurement of femoral and tibial alignment indices should be used to maintain consistency in measurements.