bone health

Coxa Vara

Generality

The coxa vara is the deformity of the hip 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, the coxa vara can be a congenital deformity (ie present since birth) or acquired (that is, developed in 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: physical examination, medical history and a radiological examination related to the hip.

For the most serious cases, the treatment of coxa vara is exclusively surgical.

Short reference to varism

Varismo is the orthopedic term that indicates the deformities of the limbs, in which, due to an abnormal relationship between two adjacent bones or between two portions of the same bone, the most distal of these two presents a medial orientation, ie it tends to approach in atypical way to the sagittal plane.

The presence of varus can have different consequences on the articulation in which the deviated skeletal element participates; consequences that can be anatomical and, in the most serious cases, also of a functional nature. Furthermore, some painful symptoms may also depend on varus

Table . Meanings of proximal-distal, sagittal and medial-lateral plane
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 bones of the foot;
  • In the femur, the extremity bordering the trunk is the proximal end.

It means "further away from the center of the body" or "further away from the point of origin".

Examples:

  • The tibia is distal to the femur;

  • In the femur, the extremity bordering on the knee is the distal end.
Sagittal plane
Antero-posterior division of the human body, from which two equal and symmetrical halves are derived.
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 femoral head-neck complex and the femoral body measures less than 120 degrees, ie 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, because, due to the lower angle 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 that lower gradation of the aforementioned corner.

Coxa vara can be mono- or bilateral

Coxa vara can affect one or both hip joints; when it concerns only one hip, it is called unilateral coxa vara, whereas, 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 to the coxa valga . According to medical definitions, in fact, the coxa valga is the abnormality 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 maximum limit of normality is 135 degrees, measuring at least 140 degrees, ).

Before closing this brief parenthesis on the coxa valga, it is necessary to remember that this last is an example of valgism, the condition contrary to varism.

Causes

The coxa vara can be a congenital deformity, that is present since birth, or an acquired deformity, that is developed during the life due to a disease or a particular event.

Causes of congenital coxa vara

A congenital cause of coxa vara is an error during fetal development, which involves a malformation of the femur in the affected subject.

Congenital coxa vara can be observed already at birth or at a slightly later stage, to be precise during the period of the first steps.

Curiosity

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

Causes of coxa vara acquired

The causes of coxa vara acquired include:

  • The rickets;
  • Some bone diseases, such as Paget's disease, osteogenization imperfect osteoporosis;
  • Perthes' disease;
  • Osteomyelitis;
  • Hip trauma at a young age, such as to interfere with the correct growth process of the femur;
  • Fibrous dysplasia, bone cancer;
  • Some inflammatory conditions of infectious origin, such as tuberculosis.

Risk factors

Among the risk factors of the coxa varus are the traumas to the femur at a young age, the presence of Perthes' disease, bone diseases, osteomyelitis, fibrous dysplasia and skeletal abnormalities of the lower limbs due to incorrect fetal development.

Epidemiology

The only reliable epidemiological data, related to the coxa vara, concern the congenital form.

Congenital coxa vara is a very rare disease (it affects a newborn every 25, 000), it affects both sexes equally and has a bilateral character in one case every 3.

Symptoms and complications

In those suffering from 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 serious, it is generally responsible for a broad symptomatological picture, which includes:

  • Pain at the hip (or hip, if the deformity is bilateral);
  • Joint stiffness, felt on one or both sides, 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 can be guessed, in the unilateral coxa vara, the lower limb object of shortening is the one whose femur is deformed);
  • Unusual development of abductor muscles of the hip;
  • Development of the so-called knee valgus or knee to X. 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, due to the same cause of congenital coxa vara (ie an error during embryonic development), the carriers of the latter present other congenital anomalies, such as for example the fibular hemimelia or the cleidocranial dysostosis .

These anomalies are responsible for their own symptomatological framework, which is clearly added to that of the coxa vara.

  • Hemimelia fibulare → 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 the clavicles, failure or delayed closure of the so-called fontanelles, poor development of bones and joints, short stature, protruding forehead and anomalies in the teeth.

Complications

In the long run, a severe coxa vara has a high probability of causing coxarthrosis, or arthrosis of the hip . In the osteoarthritis of the hip, the joint undergoes a progressive degenerative process, which leads to a gradual thinning of the so-called articular cartilage, that is the "bearing" that protects the femoral head and the acetabulum from mutual frictions 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 the simplest motor activities, obliging the patient to depend on other people and, in psychologically more fragile individuals, to 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 a hip radiograph.

What may be in-depth examinations?

Sometimes, on hip radiography, doctors could add some other diagnostic imaging tests, such as nuclear magnetic resonance or CT.

To justify the use of these more in-depth instrumental tests is the lack of useful information relating to the causes of coxa vara, which emerged through the canonical exams.

What is the appearance of the femur in radiological images?

Radiological images of an individual's hip with coxa vara show the femoral head almost perpendicular to the body of the femur. This is due to the reduction, with respect to normality, of the angle between the two femoral portions considered.

Therapy

Reserved for the most serious cases (presence of symptoms incompatible with a normal life), the only treatment currently available for those suffering from coxa vara is a surgical procedure known as femoral osteotomy with valgating effect .

Femoral osteotomy with valgating effect

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

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

Is spontaneous healing possible?

A certain percentage of cases of congenital coxa vara (about 20%) heals spontaneously (so 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. A late treatment, when the hip joint is already the object of osteoarthritis, may have limited benefits;
  • The triggering cause (this applies, of course, for the acquired forms of coxa vara). There are clinically more serious causes of coxa vara than others.

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