An original
view on the pathogenesis of congenital hip dysplasia, congenital dislocation and
subluxation of the hip.
One example of the importance of ligamentum capitis femoris (LCF) and the influence of a mechanical factor on living systems is a group of diseases of the hip joint such as congenital hip dysplasia, congenital subluxation and congenital hip dislocation. The last of these pathological conditions is an extreme degree of severity of the previous two. Common to these pathological conditions is the presence of connective tissue dysplasia syndrome of varying severity. It is based on a decrease in the strength and elasticity of connective tissue structures. The consequence of this is that a standard load, for example, on ligaments causes their plastic deformation: thinning, elongation, and in some cases, rupture. This occurs due to both mechanical and biological processes (for more details, see the Law of Bioinduction).
If, in connective tissue dysplasia syndrome, the level of optimal
average daily stresses does not correspond to the actual level of average daily
stresses, children develop a pathology called congenital dysplasia of the hip. The bioeffective stresses
that appears in the LCF induces pathological biological processes in it,
leading to its lengthening. Elongation of the LCF entails an increase in the
possible angle of adduction at the hip joint, as well as the cranial and
lateral displacement of the femoral head. In the absence of static load, the
stresses level in the hip joint elements is determined by muscle activity.
Powerful muscles in the hip region tend to displace the femur in the cranial
direction. This increases the load on the upper sectors of the femoral head and
acetabulum, as well as on the joint capsule and acetabular labrum in the upper
part of the joint. At the same time, the load on the lower sectors of the
femoral head and acetabulum decreases.
In the prenatal period, as well as in newborns, the head of the femur
and the acetabulum are formed from cartilaginous tissue. Under the influence of
excess load, they gradually deform. The acetabulum takes the form of an
ellipse, and the head of the femur loses its sphericity. The bioeffective
stresses that arise in them induce a complex of adaptive processes that we
regard as pathological. The joint capsule stretches, becomes thinner in some
areas, and thickens in others (in the upper sector), and fibrosis develops. The
acetabular labrum, proximal part of the femur, acetabulum, and pelvic bone
undergo deformation. The rate of ossification of the cartilaginous models of
bones forming the hip joint changes.
Elongation of the LCF, deformation of the acetabulum and femoral head, causes a pattern of subluxation in the hip joint. The persistence of average daily stresses gradients leads to the fact that subluxation turns into hip dislocation, and then neoarthrosis forms. Additional bone mass is synthesized in the form of osteophytes, and fibrosis of ligaments and muscles increases. The processes of deformation of the elements of the hip joint and lengthening of the LCF often occur in parallel. The more the cartilaginous bone models are deformed, the more the LCF lengthens and changes. The pathological process is accelerated if there is a break in the LCF, or initially develops if its break was primary, for example, during pathological childbirth or abnormal position of the fetus. From our point of view, walking with congenital hip dislocation, Duchenne and Trendelenburg symptoms are clear examples of LCF dysfunction.
Keywords: ligamentum capitis femoris, ligamentum teres, ligament of head of femur, hip joint, biomechanics, congenital hip dysplasia, congenital subluxation of the hip, congenital hip dislocation, pathogenesis
.
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The first version of the text in:
ETIOLOGY AND PATHOGENESIS
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