Femoral Anteversion
The clinical significance of femoral anteversion is controversial. The contribution of excessive anteversion to childhood intoeing is accepted, whereas the relationship, if any, between anteversion and osteoarthritis of the hip and knee in adulthood remains uncertain.
Definition
Femoral anteversion is defined by the angle of the femoral neck in relation to the femoral shaft in the coronal plane ( Fig. 20-1 ). The degree of anteversion is greatest in infancy and gradually decreases as skeletal maturity is approached. In infants, the mean degree of anteversion is approximately 40 degrees, but decreases to 16 degrees by adulthood. When anteversion is increased or when it fails to decrease with age, the gait is altered and the person walks with the hip internally rotated. This rotation produces a gait in which the patella is medially rotated in stance phase and the foot is also internally rotated, resulting in intoeing. Some individuals have excessive internal rotation of the tibia, which increases the degree of intoeing; others have external rotation through the tibial segment, which reduces intoeing. The latter combination produces an awkward gait that is accentuated during running; the feet swing out to the side in swing phase.
Clinical Features
Children with excessive femoral anteversion come to medical attention because of an intoeing gait. This gait may be noted when the child first begins to walk or it may be noted later in childhood, when the intoeing fails to resolve. Parents also note that the child trips on the intoed feet and that the intoeing is more prominent with running. The condition is not painful.
Physical examination confirms the diagnosis ( Fig. 20-2 ). The knees are internally rotated in the stance phase of gait and the feet follow unless external tibial torsion is present. There is excessive internal rotation of the hips and decreased external rotation. This is best demonstrated in the prone position ( Fig. 20-3 ). The degree of tibial torsion, which is measured by the thigh-foot angle, is also noted in the prone position. In severe cases, there may be 90 degrees of internal rotation of the hip without any external rotation.
Differential Diagnosis
Intoeing may be caused by increased femoral anteversion, internal tibial torsion, or metatarsus adductus. A child with some residua of a clubfoot deformity will intoe because of internal rotation of the foot. Intoeing may be the presenting symptom of a child with mild cerebral palsy; the reflex examination, muscle tone evaluation, and a developmental assessment will suggest the correct diagnosis.
Prognosis and Natural History
Most children with excessive anteversion gradually outgrow the tendency to intoe. In most cases, this occurs through a gradual reduction in the degree of anteversion. In some children, the intoeing resolves as external tibial torsion increases. This is especially likely to occur in children with spastic cerebral palsy. In a small group of children, however, the intoeing fails to improve.
Shands and Steele have found that the reduction in anteversion continues throughout growth. Children between 3 and 12 months of age had an average of 39 degrees of anteversion, which decreased to 31 degrees by the end of the second year. Subsequently, the anteversion decreased by 1 or 2 degrees a year through age 10 years, to an average of 24 degrees. Between 14 and 16 years of age there was a further decrease, from 21 to 16 degrees (see Fig. 20-1 ). Fabry and co-workers have studied 1148 hips over 20 years and found that anteversion decreased from 40 degrees at birth to 16 degrees at 16 years of age. Jacquemier and colleagues have studied 1319 normal children; they found anteversion to be greater in females than males and tended to decrease with age. In 175 patients with intoeing, the average anteversion was 42.7 degrees, which they considered to be 18.5 degrees above normal. Over a 5-year period, they saw no reduction in anteversion and concluded that after 8 years of age there would be no spontaneous correction of anteversion. Half of the patients walked without intoeing at the second examination and this improvement was attributed to the development of external tibial torsion. Matovinović and co-workers have reported that children with normal gait and children who intoed experienced a gradual reduction in anteversion between ages 7 and 14 years. Anteversion in the children with normal gait decreased by 1 degree/yr and in the intoeing children by 1.6 degrees/yr. Children with outtoeing did not experience any change during the study period. Svenningsen and associates studied 30 children with intoeing and found that in all but 5, the intoeing resolved spontaneously over 9 years. The degree of internal rotation of the hip decreased from 74 to 53 degrees during the same period.
Several factors can retard the natural reduction of anteversion with growth. The most common factor is abnormal muscle tone. Children with spastic cerebral palsy often have increased tone in the adductor muscles and hamstrings and it is presumed that these excessively rotate the hip internally, causing anteversion to persist. One biomechanical study using a deformable femur model did not substantiate this hypothesis and suggested that other causes should be sought. Another such study, using a finite element model, found that the nature of loading of the upper femur in the patient with cerebral palsy favors increased anteversion. Other paralytic disorders may also be associated with excessive persistent anteversion. Obese children often have reduced anteversion, possibly as a result of excessive forces about the hip.
Association With Other Conditions
Excessive anteversion has been proposed to cause osteoarthritis of the hip ; however, a number of studies have been unable to demonstrate a significant relationship between anteversion and osteoarthritis of the hip. Hubbard and co-workers studied 44 hips with osteoarthritis and found no difference in anteversion compared with a control group. Wedge and colleagues studied 220 cadavers and also found no relationship between anteversion and arthritis.
A correlation between excessive femoral anteversion and arthritic problems of the knee has been proposed. One study has suggested that increased anteversion reduces the function of the vastus medialis and gluteus medius. The authors suggested that this leads to an increased knee injury rate among female athletes. This correlation has been debated, especially in the patient with a combination of femoral anteversion and external tibial torsion, the so-called torsional malalignment syndrome. Although some believe that this combination leads to patellar malalignment and chondromalacia, other studies have failed to confirm a causal relationship. In addition, the corrective procedure of bilateral osteotomies above and below the knee would have a high likelihood of complications and would seldom be justified. Eckhoff and associates have shown that patients with patellofemoral pain have a greater degree of anteversion than a control group. Reikerås was unable to show a correlation between the degree of femoral anteversion and radiographic indices of a patellofemoral disorder.
Increased anteversion has been noted in children with clubfoot, Blount disease, and flatfoot. Elite female soccer players have also been found, almost uniformly, to have excessive anteversion.
Measurement
Many methods of measuring femoral anteversion have been devised, ranging from the simple to the complex. I prefer to use the method I learned as a resident at Children’s Hospital, Boston. We examined the femoral neck under fluoroscopy and rotated the hip until the longest neck or a true anteroposterior (AP) projection of the femoral neck was obtained. The recorded position of rotation of the limb relative to the table was then the degree of anteversion. For example, if it took 90 degrees of rotation to see the longest neck, the patient had 90 degrees of anteversion.
Another simple method of determining the degree of anteversion is based on the clinical observation of the prominence of the greater trochanter. The examiner places the patient prone and rotates the hip internally until the maximum prominence of the greater trochanter is noted by palpation. The angle of the tibia to the table represents the degree of anteversion. In a controlled comparative study, Ruwe and co-workers have found this method to be superior to radiographic indices. Davids and colleagues have studied the use of this method, which he termed the trochanteric prominence angle test, and found that it was not accurate compared with computed tomography (CT) scan measurements.
The most popular current methods for measuring anteversion are CT, magnetic resonance imaging (MRI), and ultrasonography ( Fig. 20-4 ). On CT or MRI, the angle of the femoral neck is computed relative to the position of the femoral condyles. This may be done with relatively few sections (three or four) and in a reasonable amount of time. *
* References .
The ultrasonographic technique involves using the anterior tangent of the femoral head and greater trochanter as a reference line. When the transducer is tilted until this tangent is horizontal on the monitor, the degree of tilt represents the anteversion angle. Most studies have noted that ultrasonography overestimates anteversion by approximately10 degrees compared with the other methods.A number of radiographic techniques have been used over the years for anteversion measurement. Radler and associates have compared CT-measured anteversion with gait deviations by three-dimensional gait analysis and concluded that gait analysis was necessary when evaluating children for surgical correction of anteversion-related gait deviations.
Treatment
The first step in managing a child who intoes because of excessive femoral anteversion is careful education of the parents. They should understand that intoeing is a common problem, usually but not always self-correcting, and one that is not improved by exercises, braces, sitting posture, or parental instructions. I tell parents that I will be happy to reevaluate the child in several years if the child continues to have significant difficulty and stress, that there are no known serious consequences from having excessive anteversion, and that surgical treatment can be performed in those rare cases in which there is no improvement.
There is no evidence that nonoperative measures have any effect on excessive femoral anteversion, and some complications of so-called conservative methods have been reported. Fabry and colleagues have carefully measured femoral anteversion in a large group of children and found no benefit with the use of Denis Browne splints or twister cables. Thus, the treatment of excessive anteversion is limited to observation or surgical correction.
The indications for surgical treatment of femoral anteversion are controversial, with investigators failing to agree over whether excessive femoral anteversion is a significant pathologic entity, with negative health consequences, or a minor variation of normal that should be left alone. Blackmur and Murray have reviewed 202 patients referred for intoeing, noting that 86% required no follow-up and no significant pathology was identified. In my institution, quite a few children are referred for intoeing and found to have other diagnoses, including cerebral palsy, clubfoot, and even fibular hemimelia.
Staheli and associates have studied a number of indicators of athletic performance and found that excessive anteversion has no demonstrable negative effects. Staheli and co-workers have reviewed the cases of 78 patients who underwent bilateral derotational osteotomies and noted a 15% complication rate. They concluded that the operation was indicated only in a child with persistent severe disability from femoral torsion. In a later publication, Staheli listed the following five indications for surgical correction: (1) child older than 8 years; (2) deformity severe enough to create a significant cosmetic and functional disability; (3) measured anteversion exceeding 50 degrees; (4) medial hip rotation greater than 85 degrees and lateral rotation of less than 10 degrees; and (5) family aware of the risks of the procedure. Bruce and Stevens have reported 14 patients who had patellofemoral pain refractory to conservative treatment who underwent combined femoral and tibial osteotomies to correct femoral anteversion and external tibial torsion. Preoperative anteversion averaged 36 degrees and tibial external torsion averaged 36 degrees; 29 degrees of femoral and 17 degrees of tibial correction were obtained. They reported good results with four significant complications. I rarely perform corrective surgery for normal children with excessive anteversion. Most rotational femoral osteotomies in my institution are done in children with cerebral palsy and significant gait disturbances or for severe, persistent, and functionally disabling intoeing.
A femoral osteotomy to correct excessive femoral anteversion may be done at the intertrochanteric, subtrochanteric, or supracondylar level. Several authors have reported better results with the more proximal osteotomies. The intertrochanteric femoral osteotomy is usually fixed with a blade plate or a screw–side plate combination. Staheli has indicated a preference for crossed pin fixation. With stable internal fixation, older, reliable children may be managed without a cast, whereas spica cast immobilization is preferred for younger, less cooperative children. The prone position for surgery is preferred by several authors because the leg may be used to gauge more precisely the degree of anteversion and amount of correction. Svenningsen and colleagues have reviewed results in 95 children who underwent derotational subtrochanteric osteotomies for excessive femoral anteversion. Of these, 19 children had persistent intoeing after surgery. Two had deep infections, four had femoral fractures below the fixation plate, and one developed avascular necrosis of the femoral head. Six children had postoperative retroversion with “an ugly outtoeing gait and a long-lasting limp.” Because of the frequency of serious complications, the authors recommended surgical correction in otherwise healthy children rarely.
Moens and associates have reported using the Ilizarov frame for fixation after a corrective diaphyseal osteotomy. They also reported using the Ilizarov technique for osteotomies above and below the knee, with good outcomes.
Others have cited several advantages to performing supracondylar osteotomies. A tourniquet is used, resulting in minimal blood loss. Also, the correction is said to be more precise and healing is usually rapid. Disadvantages include the possibility of loss of fixation, with resulting angular deformity. Pin tract infections have also been problematic. Payne and DeLuca have compared intertrochanteric osteotomy with supracondylar osteotomy for severe anteversion. The results of the intertrochanteric osteotomy performed using blade plate fixation with the patient prone were good, with no major complications. The supracondylar osteotomies were fixed with crossed pins and had a 15% complication rate. The most frequent complication was loss of fixation, with rotatory or angular malalignment. I prefer proximal femoral osteotomies when correction is warranted.
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