From 27 to 29 September in the province of Trento was held the VI National Congress SISAV (the Italian Society for the Study of Vascular Abnormalities). Special guest of the 2018 kermesse was Prof. Nicola Portinaro, Head of the Paediatric Orthopaedics Unit, who gave a ‘lectio magistralis’ on the subject of correction of lower limb dysmetries in vascular malformations.
“The formation of long bones begins between the second and fourth week of intrauterine life and ends when the bone reaches adult size,” explained Portinaro, and “it is precisely during this phase of growth that some conditions may occur that result in a dysmetria of the lower limbs.
Limb dysmetria: what it is and in whom it manifests itself
Dysmetria is a difference in the length of the lower limbs. The causes of dysmetria of the lower limbs are numerous and can be distinguished in congenital, such as hemihypertrophy, hypoplastic limbs, skeletal dysplasia, vascular diseases, or in acquired, therefore due to traumatic, infectious, inflammatory or neurological events.
“Dysmetria of the lower limbs” explained Portinaro “has a prevalence in paediatric patients between 21 and 32% and occurs in both congenital and acquired forms”. Having a reliable and fast diagnosis of the disease is very important to be able to predict any final dysmetria, once you reach skeletal maturity. Moreover, this pathology can have different consequences on patients, who tend to compensate for the difference in length of the limbs in different ways: “if the dysmetria is more than 3% of the stature, the main types of compensation are, for example, the ‘pelvic inclination, flexion of the knee in case of hypermetric limb or the plantar flexion of the ankle in case of hypometric limb,” explained the professor. “If, on the other hand, the dysmetria is greater than 5.5% of the height, there is an imbalance in the centre of mass (COM) and greater mechanical work in an upright position”, explained Portinaro.
In particular, in the case of vascular dysmetries, the asymmetric growth of bones can be caused by a hyperinflow of blood that causes an alteration of the growth area and a consequent increased growth of the bone and the length of the columns.
During the physical examination, the surgeon must evaluate various factors such as trophism, muscle strength and muscle mass. The articulation of all segments and the spine should then be studied. Among the diagnostic tests recommended at this stage, Humanitas tends to favour EOS over teleradiography. The EOS is in fact a new concept of radiological equipment that allows the study of the spine and lower limbs in an upright position (in load). The advantages of this technique are that it is possible to obtain digital images that are completely similar to those of a normal radiological device, but with a clearly reduced dose of exposure, and with the possibility of obtaining three-dimensional reconstructions.
“The objective of the examination and of the diagnostic examinations is therefore to establish the best timing for the treatment”, says Portinaro, “and it is important to consider the fact that in “vascular” patients the speed of correction is greater, so it is not always possible to apply to these patients the different scales of prediction of the difference in length”. In the second phase of his speech, the professor presented the different types of treatment (acute shortening or lengthening, or gradual lengthening) depending on the degree of dysmetria and bone maturity.
The indication to the treatment is traditionally confirmed if the degree of dysmetria is higher than 25 mm (assumed at the end of growth). But the first priority is the correction of axial deformities, if present (varus-valgo foot). Only in a second phase are longitudinal deformities, such as dysmetries, treated.
In general, in fact, if the dysmetria is less than 2 cm, no treatment is carried out. If the dysmetria is greater than 2 cm, a treatment with orthosis is preferred with equine foot and flexed knee. When, on the other hand, the dysmetria (expected at the end of growth) is greater than 2 cm, Professor Portinaro illustrated the temporary epiphysiodetic technique with 8 cm plates used by him in Humanitas.
The objective of this surgery is to cause a temporary stop in the growth of the longer limb or limb with axial deviations / asymmetry.
The professor also presented the results of several clinical cases he successfully treated with this technique, which has the advantage of being minimally invasive and very adaptable.
In conclusion, he stressed that the importance of timing is fundamental in these cases, both in the pre-operative phase, to predict potential growth peaks, and in the follow up with close clinical and radiographic controls.)