Blount’s disease is a disease in which the tibia is bent in the upper part, resulting in varus (O-shaped) deformation of the tibia. In some cases, there is a valgus (X-shaped) deformation. The cause of the disease is a lesion of the epiphyseal cartilage in the area of the condyles of the tibia. Usually the inner condyle suffers, less often the outer one. The disease develops either in 2-3 years, or at the age of over 6 years. It is manifested by visible deformation of the upper third of the lower leg. The diagnosis is made on the basis of clinical and radiological signs. Treatment in most cases is surgical.
Q68.4 Congenital curvature of the tibia and fibula
Blount’s disease (Erlacher-Blount-Biesin’s disease, Barber syndrome, deforming osteochondrosis of the tibia, deforming epiphysitis of the tibia) is a deformation of the upper third of the lower leg caused by damage to the epiphyseal cartilage of the tibia. Opinions on the prevalence of the disease vary. In most medical manuals, this pathology is considered to be rare, but some specialists in the field of traumatology and orthopedics believe that mild forms of the disease are often not diagnosed or are considered as rickets-like deformities. Girls suffer more often than boys.
The causes of Blount’s disease have not been definitively established. It is assumed that the violation of the development of epiphyseal cartilage is caused by local osteochondropathy or chondrodysplasia. The disease can be combined with other congenital anomalies of development, the family nature of inheritance is not excluded. Predisposing factors are considered to be overweight, early onset of walking and endocrine balance disorders. The starting point is the overload of the unprepared musculoskeletal system in combination with a certain anatomical variant of the structure of the lower limb.
The varus installation of the lower leg causes an overload of the inner or outer condyle of the tibia, as a result of which the epiphyseal zone expands, mows down, shifts inward and downward. Due to the uneven distribution of the load, not only bones, but also soft tissues are subjected to increased pressure, which leads to the occurrence of neurodystrophic disorders. As a result, the function of the limb is further impaired, pathological changes in the epiphysis are aggravated. The ossification process is disrupted, cartilage cells either turn into bone tissue more slowly than normal, or transform into defective bone, unable to withstand normal loads. The condyle grows at an angle, a beak-shaped protrusion appears in the metaphysis area, and a curvature is formed below. In the lower parts, the lower leg remains almost straight, the foot rotates inward.
There are two forms of Blount’s disease:
- Infantile. The first signs of the disease appear at the age of 2-3 years. A symmetrical lesion of both shins is characteristic.
- Teenage. Symptoms of the disease occur at the age of over 6 years. Usually one shin is affected.
Taking into account the type of deformation , there are:
- Varus curvature of the shins (O-shaped legs). Occurs in most cases.
- Hallux valgus of the shins (X-shaped legs). It is rarely detected.
Taking into account the degree of deformation, there are four variants of Blount’s disease:
- Potential. The angle of curvature does not exceed 15 degrees, marginal sclerosis is detected (usually from the inside, less often from the outside) in the upper part of the tibia.
- Moderately pronounced. The angle of curvature is 15-30 degrees, the destruction and fragmentation of the proximal epiphysis of the tibia are determined.
- Progressive. Extensive fragmentation and expansion of the proximal epiphysis in the middle part is revealed.
- Rapidly progressing. The germinal zone in the medial part closes, a bone bridge between the metaphysus and the epiphysis arises.
Signs of pathology usually appear at the age of 2-3 years. The first manifestation is the curvature of the shins associated with the beginning of walking. Subsequently, the deformity of the limbs gradually increases. The child gets tired quickly, lameness occurs. A clumsy “duck gait” is characteristic, due both directly to the curvature of the shins and the looseness of the ligaments of the knee joint. With a bilateral lesion, after a while, a disproportion in the length of the upper and lower limbs becomes noticeable – the legs are relatively shortened due to curvature, so the arms look unnaturally long. In some cases, the fingers of the hands can reach the knee joints.
Patients have a height below the age norm due to the relative shortening of the lower extremities. An external examination reveals a bayonet-shaped curvature of the lower legs in the upper part in combination with straight diaphyses. A beak-shaped protrusion is found in the upper parts of the tibia. The head of the fibula will stand. The lower legs are rotated inside, the degree of rotation can vary widely (from 20 to 85 degrees). Flat feet, atrophy and decreased muscle tone of the lower leg are also determined.
The diagnosis of Blount’s disease is made on the basis of a characteristic clinical and radiological picture. On the X-ray of the knee joints, the following changes are revealed:
- The tibia is curved in the upper part of the metaphysis or almost at the border of the metaphysis and epiphysis. The bone in the area of curvature protrudes in the form of a beak.
- The articular surface of the tibia has a uniformly concave shape and is beveled at an angle. The height of the internal epiphysis is 2-3 times less than normal. Signs of increased mineralization are often detected, sometimes marginal fragmentation is observed.
- The growth zone on the inside is expanded, the bone-closure plates have indistinct contours. In older children, premature closure of germinal zones may be detected.
- The cortical layer on the inner surface of the tibia is thickened.
- Due to the twisting of the tibia, the shadows of the fibula and tibia in the picture are layered on top of each other.
Differential diagnosis is usually not required. For a detailed study of the state of bone and cartilage tissue in the upper parts of the tibia, CT scan knee can be prescribed, and knee MRI can be used to assess the condition of soft tissue structures.
All patients with suspicion of this disease, even with minimal curvature of the lower leg, should be constantly monitored by a pediatric orthopedist. With minor deformities (potential degree), massage and a physical therapy complex are prescribed, including corrective exercises and training in corrective poses. The child is referred for HBO therapy, paraffin and mud applications. If necessary, muscle stimulation is carried out using special preparations. Patients with flat feet are recommended to wear orthopedic shoes and perform special exercises.
Moderate and pronounced deviation of the tibia in Blount’s disease can cause the development of deforming arthrosis, therefore, early prevention is carried out when such deformities are detected. At a younger age, staged plaster dressings and special orthopedic products are used in combination with general strengthening therapy and UV irradiation. If the deformity has not been eliminated after reaching the age of 5-6, the child is sent to the orthopedics department for surgical removal of the deformity.
The most effective technique is the application of the Ilizarov apparatus in combination with corrective high osteotomy of the tibia. In some cases, low fibular osteotomy is additionally performed. Sometimes bone allografts are placed between bone fragments after osteotomy. With pronounced instability of the knee joint, ligament plasty is performed simultaneously.
Prognosis and prevention
The prognosis for Blount’s disease depends on the severity of the deformation, the degree of lesion of the germ plate, the timely start of treatment and the timing of surgical interventions. Primary prevention is absent due to the uncertainty of the causes of the pathology. Secondary preventive measures provide for early access to a specialist when detecting signs of the disease in a child.
- Richards B.S., Katz D.E., Sims J.B. Effectiveness of brace treatment in early infantile Blount’s disease // J. Pediatr. Orthop. 1998. Vol. 18, No 3. P. 374-380. link
- Management of infantile Blount’s disease with molded orthoses: a new perspective / M.C. de Miranda Luzo, N.B. Montenegro, B.S. Massa, L.R. de Angeli, F.G. Cordeiro, R. Guarniero // Acta Ortop. Bras. 2016. Vol. 24, No 2. P. 85-89.
- Zionts L.E., Shean C.J. Brace treatment of early infantile tibia vara // J. Pediatr. Orthop. 1998. Vol. 18, No 1. P. 102-109. link
- Ferriter P., Shapiro F. Infantile tibia vara: factors affecting outcome following proximal tibial osteotomy // J. Pediatr. Orthop. 1987. Vol. 7, No 1. P. 1-7.
- McCarthy J.J., Ranade A., Davidson R.S. Pediatric deformity correction using a multiaxial correction fixator // Clin. Orthop. Relat. Res. 2008. Vol. 466, No 12. P. 3011-3017.
- Alsancak S., Guner S., Kinik H. Orthotic variations in the management of infantile tibia vara and the results of treatment // Prosthet. Orthot. Int. 2013. Vol. 37, No 5. P. 375-383. link
- Eamsobhana P., Kaewpornsawan K., Yusuwan K. Do we need to do overcorrection in Blount’s disease? // Int. Orthop. 2014. Vol. 38, No 8. P. 16611664.