yogabook / pathologie / blount’s disease

Blount’s disease

Definition of

First described in 1922 by Erlacher in Graz, progressive development of a tibia vara before completion of the growth phase due to a growth disorder in the posteromedial parts of the proximal epiphysis and metaphysis of the tibia, usually in early childhood (infantile form, usually occurring in the 1st to 3rd year of life), more rarely later (adolescent, juvenile or late form). Recent studies show that this is not a primary ossification and growth disorder, but rather a delayed growth of the medial tibial epiphysis due to incorrect loading of the medial tibiofemoral compartment. The 50% bilateral infantile form usually develops in the first few years of life, but is not always recognized promptly, so that it can take until primary school years for the diagnosis to be made.
Bilateral involvement does not mean that both sides are deformed in exactly the same way. The usually unilateral late form occurs in the 8th – 15th year of life and tends to premature closure of the growth plate and damage to the neighboring epiphysis. In the late form, the juvenile form (4th-10th year) can still be distinguished from the adolescent form (from 10th year), but these cannot be distinguished clinically, radiologically or histologically. The causes include rickets, but also trauma. The infantile form is bilateral in 50% of cases and affects girls more frequently; the adolescent form is bilateral in only about 10% of cases, affects boys more frequently and mainly affects obese boys.
The infantile form of the disease occurs mainly in Africa and the Caribbean, in the rest of the world it is rare. The adolescent form is less geographically attributable and is more due to the consequences of obesity. Pathogenetically relevant is a mechanical misload of the medial compartment with delayed growth of the medial tibial epiphysis. Obesity and vitamin D deficiency predispose and accelerate the disease. It is not uncommon for the varus position to be accompanied by internal rotation of the tibia and sometimes (30% of untreated cases) by valgus of the femur and adaptive valgus of the ankle. An altered gait pattern and consecutive disorders of other parts of the locomotor system do not only occur in unilateral cases, although the leg length discrepancy and its consequences are then aggravating factors.
The infantile form of the disease is classified according to Langeskjöld is divided into stages:

1. Varus deformity with irregularity of the growth plate and medial hook formation
2. Medial lowering of the tibial metaphysis with slight inclination
3. marked varus of the tibia, pronounced medial hook, possible fragmentation of the medial metaphysis
4. Narrowing of the growth plate, clear inclination
5. Additional deformation and division of the epiphysis
6. Bridging between epiphysis and metaphysis, also with partial fusion of the fragmented epiphysis to the medial metaphysis

While the infantile form is self-limiting and spontaneous corrections can occur, neither is the case with the adolescent form, which is progressive. Diabetes mellitus (rare in the adolescent form), reduced zinc and increased AP in the serum are more frequently observed together with Blount’s disease. Epiphysiolysis capitis femoris is a frequently observed comorbidity, especially in the infantile form.

Fibrous tissue or bony bridge formations between the epiphysis and the metaphysis can be seen in the affected epiphyseal groove.

Causes

1. unclear, presumably growth disturbance due to inadequate pressure conditions

Predisposing

1. in the infantile form: early onset of walking, tall stature, overweight
2. in the adolescent form: Overweight

Diagnosis

1. In 1-3 year olds, the cover-up test shows whether the child has a physiological genu varum or an infantile Blount’s disease

Symptoms

1. Usually no signs such as: localized tenderness, joint swelling or effusion, no movement restrictions

Complications

1. Psychological changes
2. depending on the severity and time of diagnosis

Therapy

1. Conversative with orthosis in the infantile form. A nocturnal orthosis can lead to poorer night sleep resulting in irritability. If surgery is necessary, recurrence is likely.
2. There are various surgical techniques for the late form, recurrences after surgery are rare here.
3. PT
4. Movement therapy