The direct radiographic measurement of femoral torsion using axial tomography: technic comparison with an indirect radiographic method

Estimation of Femoral Neck Anteversion in Adults: A Comparison Between Clinical Method, Radiography, and Computed Tomography at a Tertiary-care Center in Eastern India

Introduction

Femoral anteversion is the anterior inclination of the femoral neck and head in relation to the shaft of the femur. Femoral anteversion provides torsional stability of the hip - an important clinical factor for conditions such as trauma, arthroplasty, developmental dysplasia of the hip, and Legg-Calve Perthes disease. Precise measurement is important to avoid instability in pathological conditions of the hip. Computed tomography (CT) measures the angle more accurately as compared to plain radiography and is considered the gold standard procedure for measurement. Patients are exposed to significantly more ionizing radiation in CT, especially the pediatric population, which is more susceptible.

Material and methods

A prospective study of 25 individuals was undertaken wherein the femoral anteversion angle was comparatively measured by clinical, radiographic, and CT methods.

Results

The radiological evaluation depicted mean values that were far from those of the CT evaluation as compared to the clinical evaluation.

Conclusion

The clinical method (trochanter prominence angle test) can be used to measure femoral anteversion to avoid exposure to ionizing radiation and cases where CT is unavailable.

Radiographic evaluation of femoral torsion and correlation with computed tomographic techniques in labrador retrievers with and without cranial cruciate ligament disease

OBJECTIVES

To (1) develop a technique to determine the anteversion angle (AA) of the femur on a single radiograph; (2) determine the correlation between this technique and other published radiographic and computed tomographic (CT) methods; and (3) compare the diagnostic outcome of these methods in determining the level at which femoral torsion occurred in Labrador Retrievers with cranial cruciate ligament (CCL) deficiency.

STUDY DESIGN

Cross-sectional clinical study.

ANIMALS

Mature pure-bred Labrador Retrievers (n = 30).

METHODS

Pelvic limbs (n = 28) of 14 dogs without CCL deficiency were classified as control, whereas limbs of 16 dogs (18 limbs) with CCL deficiency were considered as diseased. Femoral torsion was evaluated using radiography and CT and variables were compared among limb groups by use of a mixed-model ANOVA, with P < .05 considered significant.

RESULTS

There was a significant association between biplanar and lateral plane AAs but neither correlated with CT assessment of femoral torsion. On CT, a significant correlation was identified between overall AA and each of the distal, proximal, and femoral head trochanteric angles. Biplanar and lateral plane AAs did not differ between normal and CCL deficient limbs. On CT, overall and distal AAs were increased in CCL deficient limbs compared to control.

CONCLUSION

Biplanar determination of femoral torsion can be estimated based on a single lateral radiograph but the results will be inaccurate as only CT identified and localized the site of femoral torsion.

Validity and reliability of radiological methods to assess proximal hip geometry in children with cerebral palsy: a systematic review

AIM

The aim of this systematic review was to assess the current validity and reliability of radiological methods used to measure proximal hip geometry in children with cerebral palsy.

METHOD

A search was conducted using relevant keywords and inclusion/exclusion criteria of the MEDLINE, CINALH Plus, Embase, Web of Science, Academic Search Premier, The Cochrane Library, and PsychINFO databases.

RESULTS

The migration percentage using X-rays showed excellent reliability and concurrent validity with three-dimensional (3D) measurements from computed tomography (CT) scans. The acetabular index, measured using X-rays had good reliability but moderate concurrent validity with 3D CT measurements; 3D CT scan indexes had greater reliability. The measurement of the neck shaft angle using X-rays showed excellent concurrent validity with measurements from 3D CT scans and excellent reliability. Regarding femoral anteversion, one study found an excellent correlation between two-dimensional CT and clinical assessment and excellent reliability. Two others showed less evidence for the use of CT ultrasounds.

INTERPRETATION

Most of the X-ray-based measurements showed good to excellent metrological properties. More metrological evidence is needed for the assessment of femoral anteversion. Magnetic resonance imaging and ultrasound-based measurements have great potential although very little metrological evidence is available.

CT and MRI lower extremity torsional profile studies: measurement reproducibility

BACKGROUND

Assessment of lower extremity (LE) torsional profile using computed tomography (CT) imaging is a well-recognized imaging method that supplements the clinical examination. Magnetic resonance imaging (MRI) is another advanced imaging modality that can be used as an alternative, since there are many growing concerns of radiation exposure with traditional CT studies, particularly in the skeletally immature population.

METHODS

Sixty-two patients between the ages of 7 and 19 years were included. Thirty-four had CT and 28 had MRI for assessment of LE torsional profile. All patients had clinical evidence of torsional malalignment. CT and MR images were randomized and de-identified. Two observers measured femoral anteversion and tibial torsion based on previously published methodologies. This exercise was repeated 2 weeks later and the data were tabulated and statistical analysis was performed. Radiation exposure for the patients studied by CT was estimated.

RESULTS

The mean age of the patients was 14.4 years (range 9.5-18.9 years) and 13.8 years (range 7.3-18.9 years) for the CT and MRI groups, respectively. Inter-observer reliability for both CT and MRI studies were excellent. The intra-class correlation coefficient (ICC) for femoral anteversion and tibial torsion studied by CT and MRI for both observers at both times were excellent. The radiation exposure for CT examination averaged 0.3-0.5 mSv, compared to none with the MRI method.

CONCLUSIONS

MRI provides a reproducible method for assessing the torsional profile in children and adolescents using similar anatomic landmarks for measurements as those used on CT torsional profile. In circumstances where MRI methods are readily available (and affordable), the CT torsional profile can be replaced with MRI methods, in the current era of growing concerns of radiation hazards and increasing awareness about radiation safety.

LEVEL OF EVIDENCE

Diagnostic Level III.

Measurement of femoral torsion by ultrasound and magnetic resonance imaging: concurrent validity

BACKGROUND

Abnormal femoral torsion has been linked to osteoarthritis in the knee as well as to patellofemoral pain. Inexpensive, valid, and reliable methods for assessing femoral torsion are needed. Ultrasound (US) is a noninvasive and clinically accessible method that can be used for the assessment of bone morphology, such as femoral torsion.

OBJECTIVE

The objective of this study was to determine the concurrent validity of US for the measurement of femoral torsion with a reference method, magnetic resonance imaging (MRI).

DESIGN

Repeated measurements of femoral torsion were obtained with US and MRI in a laboratory setting.

METHODS

Twenty-eight people (4 men, 24 women; mean age=26.8 years [SD=4.0 years], mean body height=170.3 cm [SD=8.0 cm], mean body weight=64.7 kg [SD=9.8 kg]) participated in this study. T1-weighted axial oblique images of the femoral neck and epicondylar axis were acquired with a 1.5-T magnetic resonance system. Ultrasonographic measurements then were obtained by a tilting technique with a linear transducer that was 4.5 cm long and operated at a frequency of 10 MHz and a depth of 5 cm.

RESULTS

The average angles of anteversion measured by US and by MRI were 20.7 degrees (SD=11.0) and 19 degrees (SD=11.3), respectively. The reliability, reported as the intraclass correlation coefficient [ICC (2,1)], of repeated measurements of in vivo femoral torsion by US was .98. The reliability [ICC (2,1)] of magnetic resonance image analysis was .96. The standard error of the measurement for US was 2.2 degrees, and that for MRI was 1.9 degrees. The concurrent validity of US with MRI (R(2)) was .93 (r=.96).

LIMITATIONS

Obtaining measurements by US requires appropriate training before data collection.

CONCLUSIONS

Ultrasound measurement of femoral torsion has high concurrent validity with in vivo MRI and may be used when an assessment of bony morphology is needed but MRI is not available.

Femoral neck anteversion, acetabular anteversion and combined anteversion in the normal Indian adult population: A computed tomographic study

BACKGROUND

Abnormal femoral neck anteversion (FNA) and/or acetabulum anteversion (AA) have long been implicated in the etiogenesis of hip osteoarthritis (OA), developmental dysplasia of the hip (DDH), and impingement, instability and wear in total hip arthroplasty (THA). Since studies on the Indian population are sparse on this topic, the purpose of this study was to report the normal values of FNA, AA and the combined anteversion (CA= FNA+ AA) in Indian adults.

MATERIALS AND METHODS

FNA, AA and CA were prospectively measured in 172 normal hips in 86 Indian adults using standardized computed tomographic (CT) methods and this data was compared with the established Western values.

RESULTS

The median values and interquartile ranges were 8 degrees (6.5-10.0 degrees ) for FNA, 19 degrees (16.0-22.0 degrees ) for AA and 27 degrees (23.5-30.0 degrees ) for CA. AA and CA values were significantly (P<0.05) lower in males, and there was also a trend towards lower FNA in males. Although a negative correlation was observed between the FNA and AA, this was not strong and may not be clinically relevant.

CONCLUSION

When compared with the Western data, the FNA values were 3-12 degrees lower and the CA values were 3-5 degrees lower in Indian adults. The AA values were comparable, but were skewed towards the higher side. Further studies are needed to assess the clinical relevance of our basic science data in pathogenesis of OA, and to validate it in relation to hip surgeries like corrective osteotomies and THA.

Imaging in the surgical management of developmental dislocation of the hip

Although the use of ultrasound in the diagnosis and early treatment of developmental dysplasia of the hip (DDH) has reduced the number of patients diagnosed late and decreased the number of operative procedures, surgical treatment is still needed in some patients. Late cases continue to occur as a result of missing the screening examination, being normal at initial screening and missing followup. Dysplasia may persist despite appropriate nonoperative or operative treatment. Many of these patients subsequently undergo closed or open reduction and femoral or acetabular reconstruction. Ultrasound of the hips is generally used up to 6 or 8 months of age, during which time the hips are largely cartilaginous, and radiographs after that time when bony development is more complete. Options to supplement ultrasound and radiography include arthrography, computed tomography, and magnetic resonance imaging. Several advances have been made in the imaging of DDH and its complications including acetabular labral pathology and of femoroacetabular impingement (FAI). We review imaging techniques other than ultrasound used in the management of DDH.

LEVEL OF EVIDENCE

Level V, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Femoral version: definition, diagnosis, and intraoperative correction with modular femoral components

Normal femoral version contributes to the inherent stability of the hip joint. Abnormal version is found in a variety of hip diseases afflicting children and adults. At the time of reconstruction for end-stage hip disease, maintaining proper femoral version in conjunction with acetabular version allows for hip stability and unimpeded functional range of motion. In those instances where femoral version is significantly abnormal, a means of correction at time of surgery is necessary. Non-modular femoral components allow for minor adjustments in version at time of surgery. To accommodate significant versional abnormalities, the modular S-ROM (DePuy Orthopaedics Inc, Warsaw, Ind) was introduced in 1984. In a series of 156 primary S-ROM total hip arthroplasties, the ability to correct for abnormal version resulted in excellent clinical results with no incidence of hip instability and excellent range of motion.

Measurement of femoral anteversion by biplane radiography and computed tomography imaging: comparison with an anatomic reference

RATIONALE AND OBJECTIVES

The ability of biplane radiography and standard computed tomography (CT) imaging techniques to measure accurately the human femoral anteversion was evaluated and compared with an anatomic reference: the osteometric method.

METHODS

Femoral anteversion of 10 normal adult cadaveric human femora were determined using a standardized anatomic measurement method (the anatomic reference) and the 2 selected common imaging techniques (biplane radiography and CT).

RESULTS

On average, anteversion measurements using biplane radiography were 21/2 times greater in magnitude than measurements using the anatomic reference (absolute mean difference, 13.5 degrees; P = 0.004). In contrast, the discrepancy between CT and anatomic reference measurements was notably less and not statistically significant (absolute mean difference, 2.8 degrees; P = 0.351). In addition, biplane radiography demonstrated greater inter- and intrarater variability than CT imaging for repeated measurements of the same bone specimens.

CONCLUSIONS

Compared with the anatomic reference, CT imaging was an accurate and valid technique for measuring the femoral anteversion. In contrast, biplane radiography demonstrated significant inconsistencies in the measurement of this anatomic parameter.

Computed tomography for femoral and tibial torsion in children with clubfoot

Forty-seven children with 70 clubfeet had computed tomography studies performed to determine the degree of femoral, tibial, and total limb torsion in both lower limbs. The total limb torsion angle (angle between the axis of the femoral neck and the axis of the ankle), which describes the relationship between femoral and tibial torsion, was used to evaluate the whole rotational deformity of the lower limb. The children were between the ages of 2 and 10 years (mean, 5 years) at the time of the computed tomography study. The mean femoral torsion was 25 degrees in the limbs with a clubfoot and 23 degrees in the contralateral limbs of patients with a unilateral clubfoot. The mean tibial torsion was 25 degrees in the limbs with a clubfoot and 24 degrees in the contralateral limb of patients with a unilateral clubfoot. The authors observed decreases of anterior femoral torsion corresponding to increases in age, consistent with the observations made by other authors of studies of children without clubfoot. External tibial torsion increased with age, with similar values in limbs with and without clubfoot. Ten limbs (nine with clubfoot, one without clubfoot) had femoral torsion greater than the means plus one standard deviation and 12 limbs (eight with clubfoot, four without clubfoot) had tibial torsion less than the means minus one standard deviation. The authors found four limbs (all with clubfoot) in three patients with lower than the mean minus one standard deviation of the total limb torsion angle (intoeing). Overall, there was no appreciable difference in the amount of femoral or tibial torsion in limbs with and without a clubfoot.

Measuring anteversion and femoral neck-shaft angle in cerebral palsy

Femoral anteversion was measured by computed tomography (CT) in 40 children with cerebral palsy, however an accurate measurement was possible in only 59 of the 80 hips. Flat-surface measurement of anteversion was possible in 72 of 80 hips by CT, and in 36 of 40 hips by ultrasound. A high neck-shaft angle correlated with an inability to measure anteversion by CT. Measuring by ultrasound allowed subjects to be positioned in internal rotation and in this way accurate measurements of neck-shaft angles were obtained.

A symmetric axis-based method for measuring the projected femoral angle of inclination in dogs

A new, simple and more consistent method for measuring the projected angle of inclination of the canine femoral neck was devised and tested. This method, based on the principles of symmetric axis (symax) shape analysis, was compared with three other techniques currently in use. Diplomates of the ACVR or ACVS and senior veterinary students were asked to perform measurements of the angle of inclination using the four methods, record their results, and answer several questions about the techniques. Although greater precision was not evident when performed by diplomates, descriptive statistics and a significant difference among the student-derived variances of the four methods demonstrated that the symax-based measurements were most consistent.

Femoral anteversion: assessment based on function axes

This study describes a clinically oriented anatomical assessment of anteversion on 32 cadavers ranging from 61 to 89 years. The method used a three-dimensional reference system based on functional axes of the femur. Each soft tissue-free femur was mounted on an osteometric table and aligned to its functional axes. The long axes were defined as passing from the centre of the femoral head to the femoral attachment of the posterior cruciate ligament (PCL). A line that ran through the PCL attachment (equal distal origin of this system) and was parallel to a transepicondylar line served as transverse axis. Anteversion of the femur was defined as an angle formed to the transverse axis by a line running through the centre of the femoral head through the midpoint of the narrowest segment of the femoral neck. The measurement mean for anteversion among these specimens was 7.4 degrees with a range from -10.8 degrees (retroversion) to 22.1 degrees. There was no statistical difference in mean values (p less than 0.05) between sexes or between right and left sides of the group; however, there were large variations for anteversions when each side in the same individual was compared (although there was no dominant side). Retroversions were observed in four of 32 femurs (12.5%). No correlation was found between the anteversion in these femurs and rotational geometry at the knee. We compared our data with those obtained by conventional techniques, by which anteversion for each femur was measured after the bone had been placed on a flat surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Computerized tomography in the measurement of femoral anteversion in legg-calve perthes disease

This article reviews the method by which computerized axial tomography is utilized in the management of femoral anteversion, and the use of this method in Legg Perthes disease.