Intoeing gait is a deformity seen during walks or runs. The causes of intoeing gait have been defined in the literature as metatarsus adductus, internal tibial torsion (ITT), and increased femoral anteversion angle (FAA) in healthy children(1). Metatarsus adductus is a condition where the anterior part of the foot faces inward. ITT is a condition where the tibia is rotated inwards. ITT is the most common cause of this deformity. Increased femoral anteversion is detected by an increase in the femoral anteversion angle. These causes often regress spontaneously in healthy children over time and rarely require surgical intervention(1). Increased FAA refers to the orientation of the femoral neck relative to the femoral condyles. Increased FAA leads to gait disorders, and can also cause hip dislocation and subluxation(2, 3, 4) . The FAA decreases from 30–40° in newborns to 10–15° around the age of 8 years(5).
SWE applies vibrations to the tissues with focused ultrasound waves. Shear wave velocities can be measured from Doppler frequency modulation of simultaneously transmitted ultrasound waves. Young’s modulus of elasticity is then measured as a function of shear wave velocity (SWV). As the tissue stiffness rises, the shear wave velocity passing through the tissue also increases(6). Studies in the literature have shown that SWE and shear modulus measurement values are highly correlated with the strength of a muscle to withstand changes in length when compressed(7).
The aim of this study was to evaluate the correlation between the FAA and elasticity of the hip muscles in children with intoeing gait due to increased FAA, using SWE.
This prospective study was approved by the institutional review board at our hospital. Written informed consent was obtained from the parents.
In this study, a total of 17 children with intoeing gait due to bilateral increased FAA diagnosed by CT were evaluated prospectively. All the children had normal activity of daily living scores. They were normal in growth. They did not have any other abnormalities in gait. The inclusion criteria were as follows: the diagnosis of intoeing gait with increased FAA confirmed by an orthopedist at physical examination and femoral anteversion CT within one month before enrolling in this study. The exclusion criteria were as follows: 1) cerebral palsy; 2) femoral pineal shift; 3) hip dysplasia; 4) hormonal and metabolic diseases (vitamin D-resistant rickets, etc.); 5) history of trauma or lower extremity operation; 6) clinical signs of metatarsus adductus, ITT; 7) injection of botulinum toxin or neurolytic agents; 8) cases receiving physical therapy; 9) polio; 10) neurological disorders (cerebral palsy, agenesis of the corpus callosum, etc.); 11) congenital hip dislocation; 12) syndromes; 13) structural abnormalities (congenital vertebral anomalies, etc.); 14) family history.
All CT were obtained from the picture archiving and communication system (PACS) of our institution. The age range of the patients was 5–8 years (mean of age: 5.41 ± 1.25 years), with the group comprising seven boys and 10 girls.
The CT examinations were performed on a 16-slice scanner (Alexion, Toshiba Medical Systems, Japan). CT was done when the patient was in the supine position with feet first and legs flat on the table. The legs were closed together as much as possible. Two small slabs acquired covered both:
1) hips (from the femoral heads to the lesser trochanters) and 2) knees (from the femoral distal physes to the proximal tibias). The scan parameters were as follows: 5.0 mm section thickness, 5.0 mm intervals, 120-kV voltage, 200- to 300-mA current, and 256 × 256 matrix. Two radiologists (with six and eight years of experience) examined the CT images for the FAA using a bone algorithm in the axial plane.
First, the axial view of the femoral neck, where the angle of the femoral neck can be measured best, was selected, and the measurement was performed. The condylar angle was measured from the back of the femoral condyles. These two angles were summed or subtracted depending on the direction, and the FAA was obtained (Fig. 1)(8).
Definition of femoral anteversion angle measurement on axial CT.
Two radiologists examined all the patients by US elastography. They were blinded to each other’s results. The US elastography evaluations were performed using a US system (Acuson S3000; Siemens Medical Solutions, Mountain View, CA, USA) with a linear transducer that enabled scanning with a frequency ranging from 4 to 9 MHz.
US elastography was performed when the patient was in the supine position with feet first and legs flat on the table. The legs were closed together as much as possible for the adductor magnus (adductor) and the iliopsoas (flexor) muscles. The elasticity of the gluteus medius (abductor) and the gluteus maximus (extensor) muscles was measured in the prone position with feet first and legs flat on the table. The legs were closed together as much as possible. The transducer was held in the longitudinal plane to the muscles. Quantitative muscle elasticity was measured by the Virtual Touch tissue quantification software (Siemens Medical Solutions) without pressure to the transducer. The examination was repeated until high-quality data was collected with color-coded quality maps. The high-quality data was frozen and saved. The region of interest (ROI) of the system was set to include the muscle. A rectangular electronic box-shaped region of interest measuring 5 × 5 mm was used for SWE measurements. Additionally, an SWE scale of 0–10 m/s was chosen. All the scans were repeated at least three times in all the muscles (Fig. 2). The mean value of the elastic modulus inside the rectangular was obtained automatically. The mean SWV values were used for the analysis.
SWE of a 5-year-old boy with femoral anteversion showing elasticity measurements of the adductor magnus (
Statistical analysis was performed with the SPSS software (version 21.0; IBM Corporation, Armonk, NY, USA). Descriptive statistical data were presented as a mean and standard deviation. According to the Kolmogorov– Smirnov test, all data showed normal distribution. The inter-observer compliance values were expressed using the kappa statistics which were evaluated as follows: κ ≥0.91 excellent, 0.90 ≥ κ ≥0.71 good, 0.70 ≥ κ ≥0.51 moderate correlation.
The relationship between the elasticity values obtained in the elastography examination of the muscles and the femoral anteversion angle, as well as the congruence between the observers were analyzed by Pearson’s correlation test. The correlation coefficients were evaluated as follows:
There was an excellent congruence between the femoral anteversion angle measurements performed by the two observers and a good consistency between the muscle elastography evaluations. Iliopsoas, adductor magnus, gluteus maximus, gluteus medius muscles elasticity values and femoral anteversion values are summarized in Tab. 1 for each observer.
Bilateral iliopsoas, adductor magnus, gluteus maximus, gluteus medius muscles elasticity, and femoral anteversion values for both observers
Patient number | Iliopsoas elasticity | Adductor magnus elasticity | Gluteus maximus elasticity | Gluteus medius elasticity | Femoral anteversion angle | |||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Right | Left | Right | Left | Right | Left | Right | Left | Right | Left | |||||||||||
O1 | O2 | O1 | O2 | O1 | O2 | O1 | O2 | O1 | O2 | O1 | O2 | O1 | O2 | O1 | O2 | O1 | O2 | O1 | O2 | |
1 | 2.04 | 1.9 | 2.75 | 2.6 | 2.13 | 2.13 | 2.79 | 2.79 | 2.14 | 2.2 | 2.14 | 2.2 | 2.13 | 2.3 | 2.03 | 2.2 | 25 | 24 | 28 | 28 |
2 | 3.55 | 3.4 | 2.48 | 2.2 | 2.76 | 2.76 | 2.15 | 2.15 | 1.66 | 1.7 | 1.86 | 1.8 | 2.05 | 2.2 | 2.27 | 2.1 | 28 | 29 | 25 | 26 |
3 | 2.9 | 3.2 | 2.37 | 2 | 2.99 | 2.99 | 2.76 | 2.76 | 1.56 | 1.6 | 1.51 | 1.5 | 2.29 | 2.1 | 1.75 | 1.5 | 26 | 26 | 24 | 22 |
4 | 1.7 | 2 | 2.45 | 2.2 | 2.02 | 2.02 | 2.81 | 2.81 | 1.52 | 1.6 | 1.53 | 1.5 | 2.31 | 2.5 | 1.48 | 1.5 | 21 | 21 | 29 | 28 |
5 | 2.08 | 2.6 | 3.84 | 3.6 | 2.23 | 2.23 | 3.71 | 3.71 | 1.38 | 1.4 | 1.45 | 1.4 | 1.93 | 1.8 | 1.67 | 1.8 | 20 | 21 | 44 | 41 |
6 | 1.78 | 2 | 3.36 | 3.7 | 3.23 | 3.23 | 4.63 | 4.63 | 1.92 | 2 | 1.72 | 1.7 | 1.72 | 2 | 2.3 | 2.5 | 30 | 32 | 44 | 42 |
7 | 1.96 | 1.7 | 3.86 | 4.1 | 2.02 | 2.02 | 3.32 | 3.92 | 1.36 | 1.3 | 1.52 | 1.6 | 1.47 | 1.6 | 1.38 | 1.5 | 31 | 33 | 36 | 38 |
8 | 3.46 | 3.2 | 3.06 | 3.6 | 4.09 | 4.76 | 2.55 | 2.03 | 1.47 | 2 | 1.46 | 1.4 | 1.38 | 1.4 | 1.83 | 1.5 | 21 | 22 | 16 | 15 |
9 | 2.5 | 2.9 | 2.48 | 2.1 | 2.77 | 2.14 | 2.73 | 2.21 | 1.4 | 1.6 | 1.4 | 1.4 | 1.84 | 1.7 | 1.59 | 1.7 | 37 | 38 | 36 | 37 |
10 | 2.66 | 2.2 | 3.19 | 3.9 | 1.65 | 1.21 | 2.23 | 2.98 | 1.16 | 2 | 1.49 | 1.5 | 1.34 | 1.5 | 1.36 | 1.6 | 26 | 25 | 30 | 32 |
11 | 1.88 | 2.3 | 3.6 | 4 | 2.02 | 2.97 | 2.93 | 2.03 | 1.41 | 1.4 | 1.43 | 1.4 | 1.25 | 1.4 | 2.08 | 2.3 | 33 | 32 | 36 | 38 |
12 | 3.61 | 3.4 | 3.4 | 3.9 | 3.28 | 3.88 | 3.07 | 3.97 | 2.18 | 2.2 | 2.37 | 2.4 | 2.54 | 2.6 | 2.47 | 2.6 | 31 | 33 | 30 | 32 |
13 | 2.19 | 2.5 | 2.04 | 2.6 | 2.58 | 2.08 | 2.4 | 2.98 | 1.5 | 1.5 | 1.75 | 1.8 | 2.54 | 2.4 | 2.38 | 2.6 | 29 | 27 | 27 | 28 |
14 | 3.38 | 3.7 | 3.35 | 3.1 | 3.13 | 3.97 | 2.57 | 2.07 | 1.22 | 1.2 | 1.81 | 1.8 | 2.03 | 2.3 | 1.27 | 1.4 | 38 | 36 | 37 | 35 |
15 | 2.66 | 2.5 | 4.44 | 4 | 2.08 | 2.98 | 4.78 | 4.08 | 1.63 | 1.6 | 1.49 | 2.2 | 1.35 | 1.5 | 1.21 | 1.4 | 30 | 31 | 54 | 51 |
16 | 2.39 | 3 | 3.72 | 3.3 | 1.22 | 1.92 | 2.82 | 2.02 | 1.63 | 1.6 | 1.86 | 1.8 | 1.58 | 1.7 | 1.61 | 1.8 | 30 | 32 | 39 | 37 |
17 | 2.35 | 2 | 1.32 | 1.8 | 2.8 | 2.08 | 2.35 | 2.95 | 1.98 | 1.9 | 2.2 | 2.3 | 1.67 | 2 | 1.98 | 1.4 | 31 | 32 | 26 | 26 |
O1 – Observer 1; O2 – Observer 2 |
The congruence between the measurements performed by the two observers is shown in Tab. 2.
Correlation of elasticity values and femoral anteversion angle measurements obtained by muscle elastography inter-observers with kappa statistics
Evaluated measurement | Inter-observer compliance values (κ) |
---|---|
Femoral anteversion angle | 0.913 |
Iliopsoas muscle elastographic elasticity value | 0.724 |
Adductor magnus muscle elastographic elasticity value | 0.711 |
Gluteus maximus muscle elastographic elasticity value | 0.674 |
Gluteus medius muscle elastographic elasticity value | 0.681 |
Pearson’s correlation analysis performed between the femoral anteversion angle measurements and muscle elastography measurements made by Observer 1 and Observer 2 is shown in Tab. 3. As can be seen, while there was a moderate significant correlation between the FAA measurements and the elasticity values of the iliopsoas and adductor magnus muscles for both observers, there was no similar correlation with other muscle elasticity measurements.
Correlation between elasticity values in muscle elastography examination and femoral anteversion angle measurements for each observer
Observer 1 | Observer 2 | |||
---|---|---|---|---|
Correlation between FAA and iliopsoas muscle elasticity value | ||||
Correlation between FAA and adductor magnus muscle elasticity value | ||||
Correlation between FAA and gluteus maximus muscle elasticity value | ||||
Correlation between FAA and gluteus medius muscle elasticity value |
The study aimed to evaluate the hip muscles by elastography in patients with intoeing gait due to femoral anteversion.
Femoral anteversion can result from stiff hip muscles due to the position of the fetus in the uterus. It also tends to occur in patient families(9).
Kong
Both in vitro and in vivo studies have demonstrated that the measurement of elastic shear modulus is strongly associated with localized passive muscle tension during stretching(11).
Dubois
Berrigan
In their study, Umehara
Gluteal muscle contracture has been linked to a decrease in the hip flexion passive adduction angle and a rise in the mean shear wave velocity in contracture strips in three individuals, as revealed in a study by Guo
Analan
Previous studies have investigated biomechanical changes during gait in children with genu varum. However, there was no study evaluating biomechanical changes in the hip muscles in the context of increased femoral anteversion angle with intoeing gait in children. In a study by Jafarnezhadgero
An important limitation of the study was the small number of participants. As a result, elastography changes throughout patient follow-up could not be examined.
In conclusion, iliopsoas muscle and adductor magnus muscle elasticity values were found to be correlated with the FAA. It might be beneficial to conduct further studies with more extensive patient series in the future. Based on their findings, physical therapy methods effective on the iliopsoas muscle and adductor magnus muscle elasticity can be developed.