Osteopetrosis is a rare hereditary disease in which there is a compaction of the bones of the skeleton and the closure of the bone marrow channels with dense bone tissue. Usually it first appears in childhood. It is accompanied by fatigue when walking and pain in the extremities. Pathological fractures are possible. Due to the closure of the bone marrow channels, anemia develops, combined with an increase in the liver and spleen. There may be skeletal deformities, delayed teething, visual disturbances due to compression of the optic nerve. The diagnosis is established on the basis of objective data, the results of radiography and other studies. Treatment is symptomatic, in most cases conservative.
ICD 10
Q78.2 Osteopetrosis
General information
Osteopetrosis (Alberts-Schoenberg disease, osteopetrosis, hyperostotic dysplasia, congenital osteosclerosis, congenital familial diffuse osteosclerosis) is a rare hereditary disease accompanied by compaction of the bones of the skeleton and a decrease in the bone marrow space. The disease was first described in 1904 by the German physician Alberts-Schoenberg. On average, it is detected in 1 child per 200-300 thousand newborns, but in some ethnogenetic groups the number of patients may increase. So, in Chuvashia, symptoms of the disease are found in 1 child out of 3.5 thousand, in Mari-El – in 1 child out of 14 thousand. Such a high incidence rate is due to the peculiarities of the ethnogenesis of the indigenous inhabitants of these republics. The treatment of osteopetrosis is carried out by traumatologists-orthopedists.
Causes
Osteopetrosis is transmitted by an autosomal recessive type. The reason for the change in the structure of bones are deep violations of phosphorus-calcium metabolism and an imbalance between the destruction of old bone tissue and the formation of a new one. As a result, the cortical layer of the bone thickens, the medullary space narrows until it completely disappears. Progressive osteosclerosis develops, the bones become very dense and, at the same time, fragile. Due to the closure of the bone marrow channels, hypoplastic anemia occurs, accompanied by a compensatory increase in lymph nodes, liver and spleen.
Pathanatomy
During pathoanatomic examination, the bones of a patient with osteopetrosis are heavy, poorly sawn, but easily split. The saw reveals a surface with a smooth structure, resembling polished marble in appearance. Osteosclerotic changes develop mainly due to endostasis. At the same time, there may be overgrowth of the periosteum, due to which areas of spongy bone substance are formed on the surface of the bones, not dense, as in the norm. The medullary canals of the tubular bones are narrowed or completely replaced by dense bone tissue. Pathological processes are more pronounced in the growth zones. Especially striking changes are detected in the upper third of the tibia and humerus, as well as in the lower third of the femur and radius – these sections “swell” and acquire a cone-shaped shape.
The spongy tissue of flat bones (vertebrae, collarbones, skull) is replaced by dense bone matter. Due to the proliferation of bone tissue, the skull can increase and deform. Narrowing of the openings for the exit of the cranial nerves causes progressive deterioration of vision and increasing hearing loss. Due to the uneven restructuring of the cortical layer and the formation of roughness on the inner surface of the skull, epidural, less often subdural hemorrhages may occur.
During the histological examination, an increase in mass and a violation of the architectonics of the bone substance are revealed. Bone cells are randomly piled up and form characteristic rounded layered structures that are unevenly located in the areas of enchondral growth. Due to the accumulation of such structures, the architectonics of the bone is disrupted, the bone of a patient with osteopetrosis becomes less durable, unable to withstand normal loads.
Symptoms
The disease can be detected in women and men of any age – from infancy to senility. However, more often the symptoms of osteopetrosis appear in childhood. In some cases, the process is asymptomatic, and bone compaction becomes an accidental finding during X-ray examination for another disease or injury.
The severity of clinical symptoms in osteopetrosis, as a rule, depends on the time of the appearance of the first signs. Early onset entails more severe changes on the part of various organs and systems. With the development of osteopetrosis in the first years of life, hydrocephalus is detected in children, resulting from the compaction and proliferation of the bones of the base of the skull. Patients lag behind in growth, start walking late, often suffer from hearing and vision disorders. It is also characterized by late teething and an increased tendency to caries development.
With the later development of osteopetrosis, the reason for contacting specialists in the field of traumatology and orthopedics becomes fatigue when walking and pain in the extremities. Sometimes osteopetrosis is diagnosed after a pathological fracture. Femoral bones suffer more often, fractures are usually transverse, occur with minor traumatic effects, fuse in the usual time (with the exception of fractures of the femoral neck, in which fusion does not occur). In some cases, osteomyelitis develops in the fracture area. With an odontogenic infection, osteomyelitis of the lower jaw may occur. During the examination, the physical development of the patient is usually normal. In some cases, deformities of the limbs are detected: varus curvature of the upper parts of the femurs, galifiform deformity of the shins, etc.
Diagnostics
To clarify the diagnosis, an X-ray examination of flat and tubular bones is prescribed: X-ray of the skull, X-ray of the spine, X-ray of the hips, etc. All images reveal a sharp compaction of bone tissue. The epiphyseal sections of the tubular bones are rounded and thickened, and bulbous thickenings are defined in the metaphysical region. All bones are opaque to X-rays, the cortical layer and the medullary canal are not visible. Sometimes there are areas of transverse enlightenment in metaphysical areas.
The reduction or closure of the bone marrow channels causes hematopoiesis insufficiency. Patients with osteopetrosis develop hypochromic anemia of varying severity. The skin is pale, there may be complaints of dizziness, weakness, fatigue. The examination reveals compensatory enlargement of lymph nodes, hepatomegaly and splenomegaly. Lymphocytosis is detected in the blood with the appearance of immature forms – normoblasts. Mutations in genetic material are established by molecular genetic testing.
If violations of the activity of various organs are suspected, patients with osteopetrosis are referred for appropriate studies. With changes in the hematopoietic system, a hematologist’s consultation, a general blood test and ultrasound of the abdominal cavity are prescribed, with vision deterioration – an ophthalmologist’s consultation, an overview radiography of the orbit in two projections, optical and electrophysiological studies, with hearing impairment – an otolaryngologist’s consultation, audiometry and a study of auditory evoked potentials.
Treatment
There is no pathogenetic therapy. Symptomatic treatment aimed at strengthening the nervous and musculoskeletal system is carried out. Patients are recommended to eat foods rich in vitamins (natural juices, cottage cheese, fresh fruits and vegetables), give directions for massage, physical therapy and spa treatment. With anemia, iron preparations are prescribed, supportive vitamin therapy is carried out, and in severe cases, transfusions of erythrocyte mass are performed.
In case of pathological fractures, standard therapeutic measures are carried out: reposition, application of plaster or skeletal traction, etc. In case of hip neck fractures, hip replacement is performed. With pronounced deformation of the bones of the lower legs, corrective osteotomy is performed. Treatment of osteomyelitis is carried out according to a standard scheme, including antibiotic therapy, immobilization, detoxification measures, stimulation of immunity, opening and drainage of ulcers.
Prognosis and prevention
With timely prevention and adequate treatment of complications, the prognosis for osteopetrosis is usually favorable, with the exception of malignant forms with early onset and damage to myelogenous tissue. Fatal outcome occurs as a result of increasing anemia or septicopyemia in osteomyelitis resulting from a pathological fracture or odontogenic infection. Prevention has not been developed.