| Abstract|| |
Background: The accurate estimation of femoral neck anteversion in living subjects has always been difficult with lots of inter- and intra-method variations. The present study was undertaken to define the range of normal femoral neck anteversion in our adult population and to draw the relationship between the peroperative, biplane X-rays and clinical methods.
Methods: Femoral neck anteversion was evaluated by the peroperative, biplane X-rays and clinical methods on 31 otherwise healthy and normal adults who underwent closed reduction / open reduction and internal fixation for post traumatic fresh intracapsular fracture of the neck of femur.
Results: The mean value obtained by peroperative, biplane Xrays and clinical methods were 10.6° (n=31 hips), 11.7° (n=62 hips) and 13.0° (n=62 hips) respectively. No statistically significant difference was found between the sides and the sexes. The clinical method correlated better with the peroperative method than the X-rays method.
Conclusion: The average femoral neck anteversion in our subjects was estimated to be 10.6° (SD 2.2°) by the per-operative method, with 83.6% subjects having anteversion between 8.612.6°. This is less than most of the western data. Statistical relations have also been drawn between the peroperative, X-ray and the clinical methods.
Keywords: Femoral neck anteversion, Peroperative, Clinical, Radiological measurement
|How to cite this article:|
Maheshwari A V, Jain A K, Singh M P, Bhargava S K. Estimation of femoral neck anteversion in adults - A comparison between peroperative, clinical and biplane X-rays methods. Indian J Orthop 2004;38:151-7
|How to cite this URL:|
Maheshwari A V, Jain A K, Singh M P, Bhargava S K. Estimation of femoral neck anteversion in adults - A comparison between peroperative, clinical and biplane X-rays methods. Indian J Orthop [serial online] 2004 [cited 2019 Dec 10];38:151-7. Available from: http://www.ijoonline.com/text.asp?2004/38/3/151/37269
| Introduction|| |
The angle of anteversion of the neck of femur in humans exhibits a wide range (-25° to +50°) with the mean angle varying from 8 to 25 degrees,,,,,,. Racial variations are expected to exist in femoral neck anteversion and may have an important implication. Since our population is more apt to floor level activities with increased external rotation of the hip, our hips would be evolutionally different from the Western counterparts.
The accurate estimation of femoral neck anteversion in living subjects has always been difficult with lots of interand intra-method variations. Estimation of anteversion on dry bone is considered the most accurate method. But their greatest drawback is that involvement of femora from some of the skeletons with pathologic conditions can not be ruled out which may influence the statistical analysis. The measurement on dry bones may not be relevant for clinical practice since clinicoradiological measurements of the angle of anteversion may be different from those obtained on dry femora. The present study is undertaken to define the range of normal femoral neck anteversion in our adult population and to draw the relationship between the peroperative, biplane X-rays and clinical methods.
| Materials and Methods|| |
Thirty one consecutive patients, who underwent close reduction / open reduction and internal fixation for posttraumatic fresh intracapsular fractures of neck of the femur or undisplaced intertrochanteric fractures of the femur in our department constituted the clinical material for this study. These patients were otherwise medically fit adults, more than 18 years of age. Old hip pathology was ruled out by thorough clinical and radiological assessment. Osteopenic states like osteomalacia and malignancy were ruled out. Informed consent was taken in each case. Surgery was done within three to four days of trauma. These patients were evaluated for the estimation of the angle of anteversion by:
- Peroperative method (on affected side)
- Biplane X-rays method (bilateral hips)
- Clinical method (bilateral hips)
Evaluation of angle of anteversion by clinical and radiological methods were done three to six months after surgery, when there was evidence of radiological union with adequate range of motion.
The patients were placed supine on the fracture table. A standard lateral approach was used to expose the proximal part of the femur. A guide wire was put in the approximate center of the femoral neck after reduction in both the anteroposterior and lateral projections as confirmed by the C-arm image intensifier. The neck was fixed with 6.5 mm cannulated cancellous screws. The limb was then realigned on the spica table till the patella points skywards to get a horizontal condylar plane. The angle between the guide wire and the horizontal axis was, by definition, the true angle of anteversion (a). Since defining of horizontal axis was difficult on table, we defined the vertical axis by dropping a plumb line onto the guide wire from above. The angle formed between the guide wire and the plumb line was designated as 'b' and was measured by a variable angle guide, 90° minus 'b' was the angle of anteversion - 'a' (since the plumb line represented the true vertical i.e. 90° to the horizontal condylar axwas). Three different readings were taken for each case and the average of the three was taken as final for that femur [Figure - 1]a,b
X-rays method (Ogata et al, 1979)
The patient was kept supine on the X-rays table. The knee was flexed to 90° on the edge of the table with the legs perpendicular to the ground. An anteroposterior roentgenogram of the hip was taken with the tube centered over the femoral neck and the beam perpendicular to the table. This position brings the transcondylar axis of the distal end of the femur into the horizontal plane. The true lateral roentgenogram of the femoral neck was made with the patient lying supine on the table with the hip and knee flexed to 90° and the entire lateral aspect of the leg contacting the table top. This positioning rotates the femur 90° on its long axis compared with the anteroposterior roentgenogram, so that the transcondylar plane was perpendicular to the table. AP and lateral views for both the sides were obtained on each patient. The location of the axes on the roentgenograms was done by the technique described by Hubbard and Staheli, where the central axis of the neck was located on each film by a line connecting the center of the neck at its proximal and distal ends. To locate the axis of femoral shaft, two sites were marked – one, just inferior to the lesser trochanter, and the second, 10 cms distal to the lesser trochanter. The line joining the center of the shaft at these two sites represents the axis of the femoral shaft. The 10 cms mark was chosen as most of the X-rays of this region contained these points. The angle between the shaft axis and the neck axis was measured on each film and the angle of anteversion was then determined by trigonometric calculations or by available normograms.
Clinical Method (Ruwe et al)
The anteversion was measured clinically by the trochanteric prominence angle test. The patients were placed prone on a hard surface with knee flexed to 90° and legs vertically up. To measure the right hip the examiner stands on the left side of the patient. The left hand was used to palpate the greater trochanter while the right hand externally rotates the leg. At the point of maximum trochanteric prominence, representing the most lateral position of the trochanter, the neck of the femur was parallel to the ground. The angle subtended between the tibia and true vertical was measured with a goniometer, and this represents the angle of anteversion of femoral neck. Three such readings were taken for each limb and the average of those were considered as final reading.
| Results|| |
Thirty one patients (21 males and 10 females), involving the right hip in 15 cases and left hip in 16 cases were analysed. The right side was affected in 10 males and 5 females and the left side was affected in 11 males and 5 females. The mean of the peroperative observed angle of femoral neck anteversion was 10.6° with a standard deviation (SD) of 2.2°. The median was 10°, the mode was 9.3° and the range (mean±2SD) was from 6.0° to 15.1°. The mean of males was 10.8° (SD 2.6°) and the mean of females was 10.1° (SD 1.2°). The mean of right side was 10.7° (SD 1.6°) and the mean of left side was 10.5° (SD 2.8°). The mean of right sided males was 10.7° (SD 1.7°) and of left sided males was 10.8° (SD 3.3°). The mean of right sided females was 10.5° (SD 1.4°) and of left sided females was 9.9° (SD 1.2°). Twenty six (83.87%) of observations were within ±2° (8.6° to 12.6°) of the mean and 90% (28) were within ±3° of the mean [Table 1],[Table 2].
Since bilateral hips were evaluated, total hips in this group were 62, with 42 males and 20 females. Both the right and the left sides were evaluated in 21 males and 10 females (31 right sided and 31 left sided hips). The mean of the observed angle of anteversion of femoral neck was 11.7° (SD 4.6°). The median was 11.4° and mode was 13.2° with a range (mean±2SD) from 2.4° to 21.1°. The mean of males was 11.5° (SD 5.0°) and the mean of females was 12.2° (SD 3.8°). The mean of right side was 11.0° (SD 4.9°) and the mean of left side was 12.5° (SD 4.3°). The mean of right sided males was 10.6° (SD 5.6°) and of left sided males was 12.6° (SD 4.7°). The mean of right sided females was 11.9° (SD 4.7°) and of left sided females was 12.2° (SD 3.3°). Fourty three (69.3%) of observations were within ±5° of the mean (6.7° to 16.7°) [Table 3],[Table 4].
Same sets of patients as evaluated by X-rays method were clinically examined to measure the angle of anteversion. The mean of the observed angle of anteversion in this group was 13.0° (SD 2.7°). The median was 13.0°, the mode was 10.5° and the range (mean±2SD) was from 7.6° to 18.4°. The mean of males was 12.7° (SD 2.7°) and the mean of females was 13.5° (SD 2.4°). The mean of right side was 12.7° (SD 2.8°) and the mean of left side was 13.3° (SD 2.5°). The mean of right sided males was 12.5° (SD 3.1°) and of left sided males was 12.9° (SD 2.3°). The mean of right sided females was 13.0° (SD 2.2°) and of left sided females was 14.0° (SD 2.8°). Fourty nine (79.03%) of cases were within ±3° of the mean (10.0° to 16.0°) [table 5],[Table 6]
Test of Significance
The paired and unpaired't' tests of significance according to sexes and sides on all the methods showed no statistically significant difference between them (p=0.46, 0.56 & 0.28 for difference between the sexes by peroperative, X-rays and clinical methods respectively; p=0.84, 0.28 & 0.26 for difference between the sides by peroperative, X-rays and clinical methods respectively).
The comparison of the operated and non-operated side by X-rays and clinical methods using unpaired 't' test showed no statistically significant difference between the two groups (p=0.54 & 0.17 for X-rays and clinical methods respectively).
Comparison of methods
The readings obtained by all these three methods were then compared to each other.
Peroperative versus clinical methods: On the right side the mean difference was 2.4° (SD 2.2°) with a range from 2.0° to -6.5°. On the left side the mean difference was 3.2° (SD 2.9°) with a range from 2.5° to -9.1°. The correlation coefficient was 0.58 for the right and 0.43 for the left side.
Peroperative versus X-rays methods: On the right side the mean difference was 1.3° (SD 4.4°) with a range from 7.5° to -10.1°. On the left side the mean difference was 1.7° (SD 4.4°) with a range from 7.1° to -10.6°. The correlation coefficient was 0.42 for the right and 0.22 for the left side.
X-rays versus clinical methods: On the right side the mean difference was 1.6° (SD 2.9°) with a range from 7.6° to - 4.2°. On the left side the mean difference was 0.8° (SD 3.4°) with a range from 7.7° to -6.1°. The correlation coefficient was 0.83 for the right and 0.59 for the left side.
Degree wise distribution of observations by different methods is tabulated in [Table 7].
| Discussion|| |
The patients of fresh fractures of the neck of femur/ undisplaced intertrochanteric region, who did not have any other hip pathology and their hips were normal before the trauma, were chosen in our study as our aim was to measure the normal angle of anteversion in our population and to define the relationship between the peroperative, X-rays and clinical methods. There is no other clinical situation where peroperative estimation of data for normal angle of anteversion is possible.
The procedure described for peroperative measurement involves flexion of the knee followed by internal rotation of the limb. The angle is measured by the indirect measurement of the arc of the tibia with the vertical, when a guide wire/AO chisel is placed in the absolute center of the femoral neck under fluoroscopic guidance when the chisel and the neck come in a straight line. These studies were done in non-traumatic conditions like CDH, cerebral palsy and poliomyelitis where derotation osteotomy was planned for the patient. Since we have measured the angle of anteversion in cases of traumatic hips, it was unjustified and impossible to remove the traction and measure the angle between the tibia and the vertical axis. The measurement of tibia with an imaginary vertical axis adds lot of subjectivity to the measurement. We modified this method. We only needed to align the patella vertically upwards which involved rotation of the whole limb. The anteversion angle is measured between two sharp well defined lines i.e. the suspended thread of the plumb line and a solid guide wire. In our series, seven of the postoperative patients later on underwent CT scan for hip unrelated pathologies. Retrospectically, femoral neck anteversion was evaluated by the CT method and it has shown good correlation to our peroperative method (0.92).
The method of Ogata et al8 for the Roentgenographic measurements of the angle of anteversion has several advantages over other radiographic techniques in use. It requires no special X-rays equipment or positioning apparatus and can be done quickly and easily. This method has been found to be accurate and reproducible in clinical practice. The true femoral neck-shaft angle as well as the degree of femoral anteversion can be determined simultaneously.
Clinical measurements were performed by the trochanteric prominence test. Since this method is supposed to be influenced by various extrinsic and intrinsic variables like tension of the hip capsule, inclination of the acetabulum, muscle and fat mass over the trochanter and patients' cooperation, it has often not been used for investigative purposes. This method has not been used before to estimate the profile of anteversion angle in a normal population. But we have also used this method to obtain a correlation of clinical and other methods due to its simplicity.
Ruwe et al compared the peroperative method to the clinical, X-rays and CT methods in pathological hips like CDH, cerebral palsy and poliomyelitis, where there was already increased angle of anteversion. No study has been ever undertaken to estimate the normal angle of anteversion in a population by the peroperative method. Standardization of peroperative method and its relation with clinical and X-rays method is of utmost importance so that correct estimation can be made and correction of rotatory deformities can be undertaken. The position of the patient for a lateral X-rays was difficult in a postoperative case. The palpation of the greater trochanter also poses problem due to the postoperative scar and fibrosis. These factors could affect the calculation of normal anteversion of operated side. Since, no statistically significant difference was found between the operated and non-operated side by all the methods, these values thus obtained were combined to get the normal anteversion angle for the sample of patient.
Variable range of normal femoral neck anteversion has been reported by various authors and also by various methods. The combined study on 806 dry femora showed the mean average to be 14.09°. Kingsley and Olmsted6 in their study on 630 adult dry femora found the average to be 8.021°, with males averaging 7.97° and females 8.11°. Dunlap et al3 used X-rays method on 100 normal adults and found the average anteversion to be 8.7° with no mention of the range. This was stated to be 8° to 15 ° by Budin and Chandler, 18° by Gibson and 28° by Herrlin et al in normal adults. Ruby et al compared the radiological methods of Ryder and Crane (biplanar x-rays), Dunn (axial x-rays) and Rogers (fluoroscopy) and found them to be comparable in clinical practice. Terjeson et al compared the ultrasound method to plain X-rays and found discrepancy of less than 10° in more than 90% of the cases (47 girls and 10 boys). Braten et al found the average anteversion to be 18° (SD 7.4°) in normal females and 14° (SD 7.8°) in normal males using ultrasound. Using the Murphy (1987) method of CT scan, Reikeras et al found the anteversion angle to be 18° (SD 6°) in females and 16° (SD 5°) in males. Miller et al compared the various methods on 24 dry femora and the found the average as 16.4° (SD 5.9°) by Kingsley and Olmsted method, 11.4° (SD 6.7°) by CT method of Weiner, 16.8° (SD 4.1°) by flat goniometer method, 21.1° (SD 4.9) by ultrasound HN Tangent method and 21.3° (SD 4.5°) by ultrasound flat surface method. He stated that CT results were lowest that all other methods and the average difference between the CT and the ultrasound method was 10°. Thus the actual peroperative anteversion value in our patient is less than most of the western studies.
The average angle of anteversion by peroperative method in our series was 10.6° (SD 2.2°) which was less than those obtained by the X-rays method [11.7° (SD 4.6°)] and the clinical method [13.0° (SD 2.7°)]. More than 83.87% (26 hips) of our cases were within ±2° (8.6° to 12.6°) of the mean in peroperative method. Only 2 values were just lower than this (7.3° and 8.1°) and 3 values were higher than this (12.8°, 14.5° and 19.6°). 48.39% of cases have less than 10° of anteversion and 80.64% of cases had less than 12° of anteversion. About 70% of the cases were between 6.7° and 16.7° and 95% of the cases between 2.4° to 21.1° by the xrays method. 79% of the cases were between 10.0° to 16.0° and 95% cases between 7.6° to 18.4° by the clinical method. Since values at extremes of data influence the mean, we have defined our true range as mean±2SD and extended our statistical analysis to find out the range which covers about 3/4th of the population. No statistically significant difference was observed between the sides and the sexes.
In our series, all the three methods showed different readings in the same patient. Thus, there is a method specific variation in the angle of anteversion with a wide range of mean difference between various methods. The correlation between the clinical and peroperative method was however superior to the peroperative and X-rays method. Also the range of mean difference between the peroperative and clinical method is narrower than between the peroperative and the X-rays method. Thus the clinical method is better than the X-rays method for measurement of angle of anteversion. Though better modalities like CT scan method are desirable if any surgical procedure is being contemplated (e.g. restoration osteotomies), its use can be precluded by its cost factor and non-availability at all centres, radiation fear and its less reliability in cases of excessive coxa valga or excessive anteversion. Thus the peroperative value still remains the true available angle of anteversion in living subjects.
| Conclusions|| |
The average angle of anteversion by peroperative method was found to be 10.6° (SD 2.2°) with a range (mean±SD) from 6.0° to 15.1°. By the x-rays method this was 11.7° (SD 4.6°) with a range (mean±2SD) from 2.4° to 21.1°. About 70% of the cases were between 6.7° to 16.7°. By the clinical method this was 13.0° (SD 2.7°) with a range (mean±SD) from 7.6° to 18.4°. About 79% of the cases were between 10.0° to 16.0°. Peroperative value on an average was found to be 1.1° less than the x-rays and 2.4° less than the clinical method. It seems to be the value which is more near to the true angle of anteversion. Hence 83.8% of population has an anteversion between 8.6° and 12.6°, which is less than most of the western studies. No statistically significant difference was found between the sides and the sexes. The clinical method was found to correlate better to the peroperative method than the X-rays method.
| References|| |
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A K Jain
Department of Orthopaedics, University College of Medical Sciences and Guru Teg Bahadur Hospital, Delhi - 110095
Source of Support: None, Conflict of Interest: None
[Figure - 1]
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5], [Table - 6], [Table - 7]