The development of hips (DDC) dysplasia is a condition that can develop in the period prenatal or after the birth. It is determined largely by mechanical factors acting on the hip and its apparatus of BRA, which can be normal or present increased laxity, which can lead to instability articulate and eventually permanent, passing through all the intermediate ranks dislocation. In this way, the morphological changes of the femoral head and the acetabulum would be secondary and would be developed over the course of time. The evidence point toward this etiology. Some authors have suggested that the primary factor of the DDC would be signs of canine hip dysplasia, but it has been shown that this is rather a consequence and not a causal factor of this pathology.
Barlow described the frequent finding of unstable hips at physical birth and arriving at a near two-week period to stabilize. This is probably due to the presence of circulating hormones that are transferred by the mother and whose effect is to relax the muscles, such as relaxin and others, which produce a physiological instability.
The term DDC has been almost universally accepted and has been replaced by terms such as congenital Dysplasia of the hips, dislocation of the hips, Dysplasia of hips, etc. luxante, and includes unstable hips or luxables, hip dislocation and acetabular dysplasia.
The risk factors for the development of DDC includes a narrow or constricted fetal environment as in the oligohidroamnios. Similarly, an anomalous position in the womb causing the extension of the hips and the action of the adductor muscles is also predisposing DDC, as it happens in breech presentation. There is also a higher prevalence in direct descent, especially in what refers to parents and siblings, in such a way that a family history of DDC is another factor to consider.
Other elements that have been associated with DDC include orthopedic anomalies of limbs, especially foot bot.Congenital muscular torticollis also partnered to DDC.
Considering that the DDC is an evolutionary disease at the time, which may develop in the first months of postnatal life, a normal test both the intrauterine period in the period of immediate born does not rule out the presence of this disease. However, most occurs in the neonatal period and only occasionally manifests itself in late. You must also be considered that examination may be ambiguity in DDC detection, even in experienced hands.
It is also clear that the DDC depends mainly of the precocity of diagnosis and treatment.
Is it necessary to carry out screening with methods of images?
This is an issue on which there is a unanimous opinion. In some countries, like the United States, we advise you to usual clinical screening and only study with some method of images to those children in whom a DDC, is suspected based on the concept that a careful clinical examination can detect a DDC in all cases.
Others argue that all children should be subjected to screening mass with a method of images, either with (Rx) x-ray of pelvis or ultrasonography (US) of hips, based on the fact that clinical examination can be negative in cases of DDC, especially considering that in countries such as ours the clinical screening often is carried out by medical or paramedical personnel not experienced and also by a cost-benefit ratio, since it would be cheaper to do mass screening with images and precociously detect those abnormal hips to undergo treatment in a timely manner and, therefore, shorter duration and much better prognosis, with significant reduction in the amount of sequels. Not making radiological screening would lead to late detection of some of the cases of DDC, that would require a more prolonged treatment, much higher cost and with a greater number of sequels.
Based on our experience, we dare to recommend that in our midst all children undergo screening with the most appropriate method of images, as the case may be.
Rx of pelvis
The radiological examination allows us to study bone structures and alterations that occur on them. As it is a morphologic and static test does not determine the first changes, which are dynamic alterations and initially only affecting the cartilaginous and ligamentous structures. The first changes on bone structures occur after four to six weeks of manifested laxity articulate. This is his best performance is achieved when it is obtained after 2 months of age.
It has the great advantage of being a test of simple, easy to obtain in most hospitals or health centers in our country, does not require sophisticated equipment and is virtually harmless, since the doses of radiation used is negligible. It is also cheap and can be interpreted by any physician trained or experienced. Unfortunately, there is tendency among medical radiologists and orthopedic surgeons to over-diagnosis and therefore to the overtreatment by mistake in the interpretation of the x-ray study. On the other hand, at least in our country, this radiological screening allows detecting and treating early cases of DDC and thus most cases of late submission are very uncommon.
It must also be taken into account that a radiological examination technically deficient can lead to errors of interpretation with misdiagnosis, especially in Rx rotated or basculadas in the axial plane.
ULTRASONOGRAPHY OF HIPS
The US is very appropriate in the first months of life and is superior to the Rx of pelvis, enabling you to visualize the cartilaginous femoral head and the acetabulum, also allows us to study dynamically hips and his sensitivity in the detection of DDC skirt 100%. There are two aspects that stability must be considered joint and acetabular morphology,
In 1980, Graf introduced technique and proposed a method which assesses only the morphology of the hip in a single cut crowns and drew up a classification with therapeutic implications according to the measurement of angles of descent of the bony acetabulum and the angle of the fibrocartilaginous labrum (static method).Subsequent studies have shown that using only this test methodology leads in many cases to an overdiagnosis, and therefore to an overtreatment. On the other hand, being this a static technique, not allows to detect the anatomically normal and unstable hips.
Subsequently, Harcke (1984) introduced the technical dynamic that virtually reproduces the physical examination during the procedure, introducing cuts at levels crowns and cross and the use of stress maneuvers.
In our experience, which coincides with other authors, a combined technique, using simultaneously static and dynamic methods, is most appropriate and most comprehensive method to evaluate the hip of (RN and the infant.)
Probably the US constitutes the ideal method of study in the DDC detection. Unfortunately, requires equipment that is not available in all centres of health in our environment, and is also a method strongly operador-dependiente, that requires an experienced observer. It is because of this that use this technique as part of a massive screening implies greater efficiency in the detection of DDC, but at the same time cost wholesale and retail availability with respect to the Rx of pelvis.
The US carried out in the immediate neonatal period detected in a significant number of children, a physiological instability of hips, meaningless pathological in the vast majority of cases, as it was already mentioned, which can lead to undergo these babies to unnecessary treatment.
When you apply for study by images? X-ray of pelvis or hips US?
According to the earlier referred, and based on the national, international and personal experience, we consider that in our half of the recommendations should be as follows, depending on the clinical situation:
Newborn with some of the predisposing factors of DDC mentioned above, but with negative physical examination: US’s hips between two and three weeks of life.
Newborn with or without predisposing factors and altered physical examination: hips birth US.
Newborn without predisposing factors and with negative physical exam, both in the neonatal period and in the subsequent clinical tests: Rx of pelvis at 3 months.
A relative indication of US of hips is the presence of a Rx of pelvis doubtful or technically deficient before a patient with a negative physical, on who you want to know the real relationship of femoral head cartilage with the acetabulum.
The scalability of the DDC, must take into account at all times so that a negative US during the first month of life does not absolutely rule out the possibility that this disease occurs later. For this reason, in patients with predisposing factors or altered physical examination and normal US during this period, it is advisable to check with Rx of pelvis at 3 months of age.
In general, the screening Imaging is a good complement to the physical examination. But it will be the clinical follow-up, with a meticulous examination of the hips during routine well-child visits, in the first year of life, which will allow an adequate control of the development of hips.
1. radiology, clinical Santa Maria and Dávila, José Joaquín Aguirre Hospital service.
2 Department of Radiology, Hospital Clínico Pontificia Universidad Católica de Chile.