Ultrasound measurement of femoral anteversion.
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Biomedical subjects
Publications and source records attributed to T Terjesen.
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Unilateral, midshaft tibial osteotomy was made in 16 rabbits. Reaming of the medullary canal was performed in half the animals, while the other half were operated on without reaming. Intramedullary fixation was accomplished with multiple Kirschner pins in both groups. Bone healing occurred with abundant peripheral callus in both groups. Mechanical testing after 6 weeks revealed higher strength of the osteotomized bones where reaming had not been performed compared with bones with reaming. We conclude that bone healing is delayed by medullary reaming, whereas the pattern of healing is similar in bones with and without reaming.
Fifty-two children with increased femoral anteversion had bilateral derotational subtrochanteric osteotomies at a mean age of 7 years. They were followed prospectively until at least 15 years of age; the mean observation time was 9 years. They were a subset of 95 children whose 2-year results were reported in 1989. The mean increase of femoral anteversion after the osteotomy was 6 degrees (0.7 degrees per year) and of the neck-shaft angle 5 degrees. The CE angle did not increase. Although we at present practice a more restrictive attitude towards operation of increased femoral anteversion, our study showed that a derotational osteotomy is effective in eliminating the intoeing gait and associated complaints, and the hip angles change only moderately during the remaining period of growth.
Femoral anteversion (AV) was determined by ultrasound in 40 adolescent and adult patients with rotational disorders of the femur, and the results were compared with AV measurements by biplanar roentgenography. With the patients supine, their knees flexed 90 degrees, and their lower legs strapped in the vertical position, one scan only of the proximal femur was needed to measure the anteversion by ultrasound. The transducer was tilted until the desired measuring line appeared horizontal on the monitor screen. The angle of tilt of the transducer, which represented the AV angle, was measured with an attached clinometer. The correlation between ultrasound and roentgenographic AV angles was high, indicating that reliable results were obtained by ultrasound. The preferred reference line was the head-trochanter tangent, which is recommended for clinical use. Consistently greater AV values were measured by ultrasound than by roentgenography. Thus, 10 degrees should be subtracted from the ultrasound values in order to obtain the real AV angles. One of the benefits of ultrasound is the elimination of radiation hazards to the patients. Ultrasound is recommended as a screening technique for patients with rotational disorders of the femur.
In a selected population, from four years old up to adult age, the function of 1522 hips of 761 apparently normal subjects of both genders were studied to define: (1) the lower and upper limits of normal hip rotation; and (2) the frequency of in-toeing gait related to age and gender. Internal and external rotation were measured with the subject lying prone with flexed knees. Presence of in-toeing gait was noted. A significant reduction of internal rotation with age was found in both females and males. In all age groups, females had significantly higher range of internal rotation than males. External rotation did not show the same age and gender dependency. Sixteen percent of all subjects had an in-toeing gait. The frequency decreased from 30% in the four-year-old group to 4% in adults. The subjects with in-toeing had a significantly increased internal rotation and decreased external rotation.
The hips of 1000 newborn babies were examined clinically and by ultrasonography. The ultrasound assessment was based on measurements of the coverage of the femoral head by the bony acetabular roof, and this parameter was called the Bony Rim Percentage (BRP). The mean BRP was 55.3% in girls and 57.2% in boys, a significant difference. Clinical instability occurred in 0.7% of the newborn babies, and all of the unstable hips had a BRP below the lower limit of normal. All infants with normal clinical findings and suspected abnormal hips based on ultrasound were followed up; in all but two the hips became normal spontaneously. We conclude that ultrasonography, using the measurements of femoral head coverage, is appropriate for screening the newborn, is reliable in differentiating between a true and a false positive Ortolani sign, and that hip dysplasia which is not clinically demonstrable at birth can be detected by ultrasound. Ultrasound should replace radiography as the routine method of following up high-risk infants and those with suspicious signs.
To study the spontaneous regression of femoral anteversion, 30 children referred to the outpatient clinic for intoeing were followed until at least 15 years of age. The mean observation time was 9 (7-12) years, and all the children were examined three times during the growth period. The mean radiographic angle at the first examination was 42 degrees, at the second examination 36 degrees, and at the last examination 28 degrees. The mean decrease of the AV angle per year was 1.5 degrees, with a considerable range (0.2-3.1 degrees). The mean internal rotation of the hip decreased from 74 degrees to 53 degrees during the observation period, and the external rotation increased from 19 degrees to 37 degrees. While all 30 children had an intoeing gait at the first examination, this disappeared in all but 5 children.
Totally, 95 children with increased femoral anteversion had derotational substrochanteric osteotomy with plate fixation. The mean anteversion angle was reduced from 48 degrees to 4 degrees, internal hip rotation from 81 degrees to 42 degrees, and external rotation increased from 9 degrees to 48 degrees. All the osteotomies healed, but serious complications occurred in 13 of the 95 patients. Because of the risk for complications and the trend towards spontaneous regression of femoral anteversion with age, we recommend a much more conservative attitude with regard to operative treatment.
Both hip joints in 156 children, aged 2 months to 2 years, were examined by ultrasonography (ultrasound) and radiography. Pathologic findings were based on an increased acetabular index, bony defects of the lateral acetabular rim, and lateral and/or proximal displacement of the proximal femur. Each hip was classified as normal, dysplasia, subluxation, or dislocation. The same diagnosis was reached by ultrasound and radiography in 303 of the 312 hips. The accordance was good in normal joints, in subluxation, and in dislocation. However in 7 of the 15 hips with radiographic dysplasia, ultrasound was normal. These patients were not treated, and spontaneous normalization or improvement occurred in all of them. One parameter only, the distance from the lateral margin of the ossification center of the femoral head to Perkins' line, was measured by both ultrasound and radiography; the correlation was high (r = 0.73). We recommend ultrasound as the primary imaging technique when congenital dislocation is suspected clinically.
In a selected population 4 years old to adult age, 1,522 hips in 761 healthy subjects of both sexes were studied. Arcs of passive motion of the hip were measured by the technique recommended by the American Academy of Orthopaedic Surgeons. The lower and upper limits of normal range of hip motion in all the planes were established for both sexes in the different age groups. We found that the amplitude of most hip motions decreased with age. Females had higher ranges of total hip motion, total rotation, internal rotation, and abduction compared with males.
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In order to throw some light on the controversial issue of the optimal stiffness in fracture fixation, the effects on bone healing of rabbit tibial osteotomies fixed by plates with four different degrees of stiffness were studied. The least stiff plate was made of glass fiber-reinforced epoxy; the other three were made of stainless steel. The median bending stiffness in vitro of tibial osteotomies fixed with the various plates were 13%, 17%, 61%, and 74%, related to the stiffness of intact tibiae. Transverse midshaft unilateral tibial osteotomies were fixed by the various plates, and the animals were killed after 6 weeks. The amount of periosteal callus was inversely related to the stiffness of the plates. A marked trend toward decreased strength and stiffness occurred in tibiae where the most rigid plate was used, compared with the values of those with the less rigid plates. This indicates that the stress-protecting effect of very stiff plates begins early in the healing period and is pronounced even at 6 weeks and that a steel plate of lower stiffness is more appropriate for bone healing. However, too flexible plates involve increased risk of redislocation and mechanical failure.
In tibial shaft fractures in the rabbit, the early stage of bone healing after metal-plate fixation was compared with that after treatment with a long or short plaster cast. The animals were killed after 6 weeks. The plate-fixed bones healed more rapidly, with less periosteal callus and less angulation of the fragments, than those treated with a cast. The results indicated that function of the muscles and joints of the injured limb, including weight bearing, promotes bony union, whereas the degree of fixation stiffness is relatively unimportant.
The femoral anteversion was measured by ultrasound and biplanar radiography in 57 children, most of whom had clinical signs of increased anteversion. A modification of previously reported ultrasound techniques was introduced, as the transducer was tilted instead of being kept horizontally. Four different modes of ultrasound examination were evaluated. The most appropriate technique involved only one ultrasound scan at the hip level. The correlation between the results of ultrasound and radiography was good with less than 10 degrees discrepancy in the majority. Ultrasound is suitable for screening children with rotational disorders of the femur. The main advantage of the method is that exposure to radiation is avoided.
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In rabbit tibial osteotomies, the effects on bone healing of three different degrees of stiffness of external fixation were investigated. Redislocation occurred in one third of the osteotomies with the least rigid fixation, and the amount of external callus was greater in this group. At 6 weeks there were no significant differences between the groups regarding bending strength and stiffness of the bones.
Unilateral midshaft tibial osteotomies in rabbits were fixed with 6-hole steel plates. In half the animals, no additional fixation was used, whereas in the other half, a plaster bandage from the toes to the midthigh was applied. At 6 weeks all the osteotomies had healed radiographically with little or no periosteal callus. The median strength of bones without plaster was 107 per cent of the normal value compared with 55 per cent in the plaster group. The results indicated a severely adverse effect of plaster immobilization on the healing of plate-fixed osteotomies.