Coxa Vara

Generality

The coxa vara is the hip deformity in which the angle existing between the head-neck complex of the femur and the body of the femur measures less than the minimum value considered normal, which is 120 degrees.



Image taken from en.wikipedia.org


An example of varus varus, coxa vara can be a congenital deformity (i.e. present from birth) or acquired (i.e. developed over the course of life, following some disease or other condition).
In people suffering from coxa vara, the presence of symptoms depends on the severity of the deformity: if the deformity is mild, the coxa vara is asymptomatic; on the contrary, if the deformity is severe, the coxa vara is responsible for various symptoms and signs, including pain, joint stiffness, lameness, valgus knee, abnormal development of the abductor muscles of the hip, etc.
The diagnosis of coxa vara is generally based on: the physical examination, the medical history and a radiological examination referred to the hip.
Reserved for the most serious cases, the treatment of coxa vara is exclusively surgical.

Brief reminder of varus

Varismus is the orthopedic term that indicates deformities of the limbs, in which, due to an anomalous relationship between two adjacent bones or between two portions of the same bone, the more distal of these two presents a medial orientation, i.e. it tends to approach in atypical way in the sagittal plane.
The presence of varus can have various consequences on the joint in which the deviated skeletal element participates; consequences that can be of an anatomical nature and, in the most serious cases, also of a functional nature. In addition, a certain painful symptomatology may also depend on the varus


Table. Meanings of proximal-distal, sagittal and medial-lateral planes Proximal Distal It means "closer to the center of the body" or "closer to the point of" origin. Examples:
  • The femur is proximal to the tibia, which is proximal to the foot bones;
  • In the femur, the end bordering the trunk is the proximal end.

It means "farther from the center of the body" or "farther from the point of" origin ".
Examples:

  • The tibia is distal to the femur;
  • In the femur, the end bordering the knee is the distal end.
Sagittal plane Anterior-posterior division of the human body, from which two equal and symmetrical halves derive. Medial Lateral It means "near" or "closer" to the sagittal plane.
Example:
  • The first toe (big toe) is medial to the other toes.
It means "far" or "farther" from the sagittal plane.
Example:
  • The second, third, fourth and fifth toes are all lateral to the big toe.

What is coxa vara?

Coxa vara is the name of the hip deformity, in which the characteristic angle existing between the head-neck complex of the femur and the femoral body measures less than 120 degrees, which is the minimum limit that establishes the normal range for the angle. in question (NB: the maximum limit is 135 degrees).

Why is it an example of varus?

The coxa vara is an example of varus varus, because, due to the smaller angle existing between the head-neck complex of the femur and the body of the femur, the latter tends to assume a more medial orientation than normal, to compensate for the lower gradation of the aforementioned angle.

Coxa vara can be mono- or bilateral

Coxa vara can affect one or both hip joints; when it affects only one hip, it is called unilateral coxa vara, while when it is present in both hips, it is called bilateral coxa vara.

Is it the opposite of coxa valga?

The coxa vara is the deformity of the hip opposite the coxa valga. According to medical definitions, in fact, the coxa valga is the anomaly of the hip in which the angle existing between the proximal end of the femur and the body of the femur is wider than normal by at least 5-15 degrees (so, if the upper limit of normal is 135 degrees, it measures at least 140 degrees,).
Before closing this brief parenthesis on the coxa valga, it should be remembered that the latter is an example of valgus, the condition contrary to varus varus.

Causes

Coxa vara can be a congenital deformity, that is present from birth, or an acquired deformity, that is, developed over the course of life due to a disease or a particular event.

Causes of congenital coxa vara

Congenital coxa vara is caused by an error during fetal development, which leads to a malformation of the femur in the affected person.
The coxa vara congenita can be observed already at birth or at a slightly later stage, to be exact during the period of the first steps.


Curiosity

According to some experts, the most correct name for congenital coxa vara observable during the period of the first steps is developmental coxa vara.

Causes of acquired coxa vara

Causes of coxa vara acquired include:

  • Rickets;
  • Some bone diseases, such as Paget's disease, osteogenesis imperfecta, osteoporosis;
  • Perthes' disease;
  • L "osteomyelitis;
  • Trauma to the hip at a young age, such as to interfere with the correct growth process of the femur;
  • Fibrous dysplasia, a bone tumor;
  • Some inflammatory conditions of infectious origin, such as tuberculosis.

Risk factors

The risk factors of coxa vara include trauma to the femur at a young age, the presence of Perthes disease, bone diseases, osteomyelitis, fibrous dysplasia and skeletal abnormalities in the lower limbs due to incorrect fetal development.

Epidemiology

The only reliable epidemiological data relating to coxa vara concern the congenital form.
Coxa vara congenita is a very rare disease (it affects one new born in every 25,000), affects both sexes equally and is bilateral in one out of 3 cases.

Symptoms and complications

In people with coxa vara, the presence of symptoms depends on the severity of the deformity.
In fact, if it is mild, coxa vara tends to be asymptomatic; on the contrary, if it is severe, it is generally responsible for a broad symptom picture, which includes:

  • Pain in the hip (or hips if the deformity is bilateral);
  • Joint stiffness, felt in one or both hips, depending on whether the deformity is mono- or bi-lateral;
  • Lameness
  • Shortening of one or both lower limbs, depending on whether the deformity is mono- or bilateral (as "it can be guessed, in the unilateral coxa vara, the lower limb subject to shortening is the one whose femur is deformed);
  • Unusual development of the abductor muscles of the hip;
  • Development of the so-called valgus knee or X-shaped knee. It is the particular anatomical deformity, in which one or both knees point inwards.
    In severe cases of coxa vara, the valgus knee is the result of the strong medial orientation of one or both femurs.

Diseases associated with congenital coxa vara

Very often, for the same cause of congenital coxa vara (ie an error during embryonic development), the carriers of the latter present other congenital anomalies, such as fibular hemimelia or cleidocranial dysostosis.
These anomalies are responsible for their own symptomatic picture, which, clearly, is in addition to that of the coxa vara.

  • Fibular hemimelia → characteristic signs: absence of the fibula, one of the two bones of the leg (the other is the tibia);
  • Cleidocranial dysostosis → characteristic signs: absence of collarbones, failure or delay in closing of the so-called fontanelles, poor bone and joint development, short stature, protruding forehead and tooth anomalies.

Complications

In the long run, severe coxa vara has a high probability of causing coxarthrosis, or "osteoarthritis of the hip". In "hip" osteoarthritis, the joint undergoes a progressive degenerative process, which leads to a gradual thinning of the so-called articular cartilage, that is the “cushion” that protects the head of the femur and the acetabulum from mutual friction and rubbing.
Coxarthrosis is an irreversible condition which, in its most advanced stages, can drastically affect the quality of life of patients; in fact, its presence can be an obstacle to simpler motor activities, force the patient to depend on other people and, in psychologically more fragile individuals, cause depression.

Diagnosis

Canonically, the diagnosis of coxa vara is based on: a thorough physical examination, a thorough medical history and a radiological examination such as radiography of the hip.

What can be any in-depth exams?

Sometimes doctors may add some other imaging tests to the hip x-ray, such as a nuclear magnetic resonance or CT scan.
To justify the use of these more in-depth instrumental tests is the paucity of useful information, relating to the causes of coxa vara, which emerged through canonical examinations.

What is the appearance of the femur on radiological images?

The radiological images of the hip of an individual with coxa vara show the head of the femur in a position almost perpendicular to the body of the femur. This is due to the reduction, compared to normal, of the angle existing between the two femoral portions considered.

Therapy

Reserved for the most severe cases (presence of symptoms incompatible with a normal life), the only treatment currently available for coxa vara sufferers is a surgical procedure known as femoral osteotomy with valgus effect.

Femoral osteotomy with valgising effect

A rather delicate operation, the "femoral osteotomy with valgizing effect involves the remodeling of the proximal portion of the femur, in order to reduce the varus present (NB: deriving from valgus, the opposite condition to varus, the term" valgising effect "refers precisely to the aforementioned purpose).


In the presence of severe coxa vara, the risk / benefit ratio of a delicate operation such as femoral osteotomy with valgus effect tends to favor the latter. In other words, when the coxa vara is severe, it is better to operate and take risks. of the planned therapy, rather than leaving free space for possible complications of the present deformity.

Is spontaneous healing possible?

A certain percentage of cases of congenital coxa vara (about 20%) heal spontaneously (therefore without any treatment), during the normal growth process.

Prognosis

In the case of coxa vara, the prognosis depends on several factors, including:

  • The degree of severity of the deformation. The more severe the deformation, the more difficult the treatment;
  • The timeliness of the treatment. Late treatment, when the hip joint is already the subject of arthrosis, can have limited benefits;
  • The triggering cause (this clearly applies to the forms of coxa vara acquired). There are more clinically serious causes of acquired coxa vara than others.

Under ideal conditions (treatable deformity, timely treatment, etc.), surgical interventions aimed at correcting the coxa vara can guarantee excellent results.


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