From Big Medical Encyclopedia

OSTEOPOROSIS (osteoporosis; grech, a bone + poros is time for osteon + - osis; synonym rarefikation) — decrease in density of a bone as a result of reduction of amount of bone substance or its insufficient calcification.

The lake is expression osteodystrophies (see) also can be local or the general. Local O. is most often connected with disturbance of blood circulation, napr, venous outflow at an immobilization of an extremity, a long obezdvizhennost. In some cases O. of one of pair bones after removal another develops or at an overload of one extremity after dysfunction another, owing to disturbance of blood circulation patol, the center around, and also at a fracture of a bone, neuritis, a burn, freezing injury, phlegmon, etc. Local O. can be focal and uniform; focal O. can pass into uniform.

At damage of large nervous trunks, a leprosy, a Raynaud's disease, a scleroderma, an endarteritis, etc. O.'s process, as a rule, has widespread character.

At acute arthritises, an injury and nek-ry tumoral damages of bones a peculiar O. in the form of a tape-like strip of an enlightenment of spongy substance width in several centimeters crossing a bone on site of an epiphyseal cartilage — a so-called symptom of Shints meets.

The general O. can arise at toxicosis, alimentary and exchange disturbances, age involution, etc. Carry senile and climacteric O., and also O. at Itsenko's disease to it — Cushing, a hyperparathyreosis. Sharply expressed general O. is observed in some cases owing to prolonged use of corticosteroids.

Fig. 1. The microroentgenogram of a shlif of a diaphysis of a femur at osteoporosis: the spongization of a cortical layer with expansion of vascular channels (1), with formation of big cavities (2) in a cortical plate and sharp thinning of bone crossbeams in marrowy channel (3) is visible; x 10
Fig. 2. Microdrugs of spongy substance of a head of a femur are normal (and) and at osteoporosis: at osteoporosis bone crossbeams (1) are sharply thinned, atrofichna, with uneven contours; in expanded meshbalochny spaces (2) marrow is replaced with fibrous connecting fabric; coloring hematoxylin-eosine; x 75.

Development of deossification at O. is caused by decrease in an osteogenesis and strengthening of a resorption bones (see) that leads to expansion of channels of osteons (gaversovy channels). As a result of O. cortical substance of a bone loses a compact structure, spongizirutsya (fig. 1). Bone crossbeams of spongy substance become thinner, a part them resolves completely that leads to expansion of spaces (fig. 2) between them. Depression of spongy substance with reduction of total number of bone crossbeams and amounts of mineral substances in unit volume of a bone is quite often combined with a simultaneous thickening and coarsening of the remained bone crossbeams. Such reorganization especially often meets at an anchylosis of a joint.

As a result of O. durability of bones goes down that causes their deformation and emergence patol, changes. At sharply expressed O. there are fractures of bodies of vertebrae, edges, bones of extremities.

Fig. 3. The roentgenogram of the left foot at acute osteomyelitis of tibia: the centers of osteoporosis are specified by shooters.

O.'s development is usually estimated visually on density of the image of a bone on the roentgenogram. However it is so possible to notice only considerable (20 — 30%) loss of mass of bone substance, edges comes, e.g., at a fracture of a bone or acute inf. a disease on average later 2 — 3 weeks. For comparison on the same film do a picture and a symmetric part of other extremity. Focal O. on the roentgenogram has an appearance of a set of indistinctly delimited sites of depression of bone substance of a rounded oval or polygonal form (fig. 3) the size on average of 3 — 5 mm in dia. Between these centers the bone tissue has a usual structure, cortical substance is not changed or a little razvolokneno.

Fig. 4. The roentgenogram of a distal part of a shin at osteoporosis: uniform transparency of bones, reduction of number of bone crossbeams, thinning of a compact layer is noted.

At uniform O. the bone on the roentgenogram looks more transparent, than normal, bone crossbeams are thinned, the general drawing of spongy substance more gentle (fig. 4), and at sharply expressed O. disappears absolutely. Cortical substance of a bone becomes thinner, and a shadow its contrast, as if drawn.

For quantitative assessment of the changes happening in a bone at O. use a method X-ray densitometries (see), to-ry consists in assessment of density of a bone by comparison of optical density of its image on the roentgenogram with a standard, napr, with the roentgenogram of a wedge from aluminum. Determination of optical density of a bone is carried out by microphotometry, Edges it can be added with definition of so-called indexes O. with the help rentgenogrammetriya (see). Such index O., napr, for tubular bones, the relation of total thickness of cortical substance to diameter of a bone expressed in millimeters is. As auxiliary apply the ultrasound examination of a bone which is also allowing to establish change of its density. The method of a photon absorbtsiometriya based on assessment of weakening of the ionizing radiation which passed through the studied bone is developed for diagnosis and a research O.

At the fabric level apply a method to a research microx-ray analysis (see), to-ry allows to define degree of a mineral saturation of bone microstructures, and in combination with the standard gistol, methods also to differentiate conditions of deossification and osteomalacy (see).

Differential diagnosis For the lake it is not difficult. In some cases focal O. is differentiated with the limited multiple centers of destruction at inflammatory diseases of bones and a fibrous osteodystrophy. Widespread O. can have looking alike an osteoporoti-chesky form multiple myeloma (see). Nek-ry anatomic sites of bones normal have the increased transparency that on the roentgenogram can be mistakenly accepted for local O., napr, a big spit of a femur, a big hillock of a humeral bone, Ludloff's spot (see. Ludloffa spot ). The symptomatology and O.'s current are generally caused by a disease, against the background of to-rogo there is O.

Provoditsya treatment basic disease. E.g., at senile O. recommend good proteinaceous nutrition, the dosed physical. exercises, appoint drugs of calcium and phosphorus, redoxons and D, thyrocalcitonin, etc.

Bibliography: E. Ya. oak groves, Tarush-kin O. V. and Winter of JI. G. Ultrasonic diagnosis at damages and diseases of bones, Surgery, No. 4, page 61, 1972; Lagunova I. G. X-ray semiotics of diseases of a skeleton, M., 1966; The Multivolume guide to pathological anatomy, under the editorship of A. I. Strukova, t. 5, page 131, etc., M., 1959; Reynberg S.A. Radiodiagnosis of diseases of bones and joints, book 1, page 48, etc., M., 1964; X-ray methods of quantitative and quality standard of osteoporosis, Methodical instructions, sost. G. D. Rokhlin, JI., 1974; X-ray about densitometry of bones of extremities, Methodical recommendations, sost. JI.C. Rosen-shtraukh and B. M. Rassokhin, M., 1976; J about w-s e at J. Metabolic diseases of bone, p. 250 a. o., Philadelphia, 1977; P u 1 1 a n B. Roberts T. Bone mineral measurement using an EMI scanner and standard methods, Brit. J. Radiol., v. 51, p. 24, 1978; Sorenson J. A. a. Cameron J. R. A reliable in vivo measurement of bone-mineral content, J. Bone Jt Surg., v. 49-A, p. 481, 1967.

G. I. Lavrishcheva, A. H. Poles; V. V. Kitayev (rents.).