Radiographic density of the bone depend on the amount of calcium present in the bone. decrease in bone calcium lead to decrease in bone density.
Main causes of generalized decrease in bone density; Osteoporosis. Osteomalacia. Hyperparathyroidism. Multiple myeloma.
osteoporosis Osteoporosis is the consequence of a deficiency of protein matrix(osteoid) & decrease amount of the normal bone (i.e. loss of bone mass) while remaining bone is normally mineralized (microstructure of the bone remain normal & histologically also normal)
Main Causes of osteoporosis 1-Idiopathic; according to the age, subdivided to; Juvenile Senile Postmenopausal; up to 50% of female over 60 years of age have osteoporosis. 2-Cushing’s disease & steroid therapy. 3-disuse
Radiological features Change in bone density usually unapparent until 30-50% of the bone mass has been lost. Decreased cortical thickness. Decreased no. of the trabeculae present in the bone.
Changes best seen in the spine. Resorption of the horizontal trabeculae. Empty box ; apparent increased end plate density due to Resorption of the spongy bone. VB compression fracture; wedged or biconcave types with apparent widening of the disc spaces
Generalized decrease in bone density Prminent vertical trabicuale Empty box VB compression fracture
Local decreased bone density caused by localized pain or immobilization of a fracture Disuse osteoporosis
Indistinctness of the cortex of the right femoral head and osteopenia of the entire femoral head
Rickets & osteomalacia There is poor mineralization of osteoid. If occur before epiphyseal closure, it known as rickets. If occur in adult ,it known as osteomalacia.
Radiological finding of rickets The changes are maximal where bone growth is occur, so they best seen in the knees, wrists & ankles Loss of provisional zone of calcification. Indistinct metaphyses& metaphyses become irregular and cupped. Wide growth plate. decreased bone density. Deformities of the bones occur because of bone softening. Greenstick fractures are common
This patient shows abnormal bone density, with coarsened abnormal trabeculae in a generalized pattern. Even more prominently, we see widened and irregular metaphyses Rickets
The anterior ends of the ribs are quite abnormal in this patient, with splaying at the costochondral junction (rachitic rosary)
Radiological findings; Decreased bone density. Looser’s zones; are short lucent band running through the cortex at the Rt angles & may have sclerotic margin, commonest site are scapula, medial aspect of femurs,& pubic rami & ribs Bone deformity due to bone softening e.g. biconcave vertebra bodies osteomalacia
This patient has generalized osteopenia. In addition, several of the right lower ribs demonstrate transverse fractures with a wide lucency at the fracture site (arrow). Your diagnosis? Osteomalacia with looser’s zone
Hyperparathyroidism Cause mobilization of the calcium from the bone, resulting in a decreased bone density. Hyperparathyroidism could be primary hyperparathyroidism (90 percent due to an adenoma) or secondary hyperparathyroidism due to renal dysfunction.
Many patients with primary hyperparathyroidism present with renal stone & minority present with radiologically detected bone changes.
Radiological features of hyperparathyroidism Generalized decrease in bone density. The hallmark of hyperparathyroidism is subperiosteal bone Resorption. Soft tissue calcification; vascular & chondrocalcification sometime occur. Brown tumor are occasionally present which are small lytic lesion which could be single or multiple
Extensive subperiostealresorption is seen on both the radial and ulnar side of the middle phalanges (white arrows, left hand). brown tumor in the left distal ulna as well as the left trapezoid (black arrows, left hand). as well as in the right head of the third metacarpal and the base of the proximal phalanx of the fifth digit (black arrows, right hand).
Features of both primary & secondary hyperparathyroidism are similar except that brown tumors are much rarer & vascular calcification is commoner in secondary hyperparathyroidism
vascular calcification is the predominant finding Hyperparathyroidism from renal osteodystrophy.
Generalized increase in bone density
Causes; Sclerotic metastases, commonest cause. Osteopetrosis (marble bone disease); congenital, bone sclerotic & brittle leading to multiple fractures. Myelosclerosis; there is replacement of the bone marrow by fibrous tissue & lay down of the bone which is usually appear as patchy areas of sclerosis
This child has extremely dense bones throughout the body. There is abnormal modeling at the metaphyses with flaring. Your diagnosis? Osteopetrosis
Alteration in trabecular pattern & changes in the shape1-Paget’s disease2-Hemolytic anemia3-Radiation induced bone diseases
Usually is the chance finding in elderly. One or more bones may be affected, the usual sites are pelvis, spine , skull & long bones 1-Paget’s disease
Cardinal features are ; thickening of the trabeculae & the cortex, causing increase in bone density & loss of corticomedullary differentiation. Enlargement of the affected bone.
Bone softening causes bowing & deformity of the bones & pathological fracture may occur
Radiological finding of Paget’s disaese;
this patient gives a classic appearance of advanced mixed lytic and sclerotic Paget's disease , bone expansion,loss of corticomedullary differentiation and anterior bowing of the tibia Paget’s disease
typical picture-frame appearance of VB due to the enlargement and mixed lytic sclerotic pattern. Paget's dsease
There are many types of hemolytic anemia , but radiological changes are seen in main two types; thalassaemia & sickle cell disease. Both causes bone marrow hyperplasia, but sickle cell disease also may show evidence of bone infarction & infection 2-Hemolytic anemia
dense striations in a very widened diploic space of the cranium (hair-on-end appearance). Additionally, note that the paranasal sinuses are obliterated Thalassemia
The metacarpals and phalanges are squared and show a very thinned endosteal cortex with abnormal density. Resorption of some trabeculae & remaining trabeculae become thick & prominent. Thalassemia
Radiological features of marrow hyperplasia Thinning of the cortex & bone expansion. Resorption of some trabeculae & remaining trabeculae become thick & prominent. In the skull; it cause widening of the deploe & perpendicular striation occur which is known as ‘ Hair-on-end’. The ribs may enlarged & phalanges may become rectangular.
3-Radiation induced bone diseases
Mixed lytic and sclerotic density is seen involving most of the right upper ribs, the right clavicle, scapula, and proximal humerus. Multiple healed rib fractures are seen in this area. Radiation osteonecrosis
Radiotherapy may cause local damage of the bone in the radiation field. Early change may be limited to osteoporosis. In severe case it may cause osteonecrosis; bone thinning & patchy increase in bone density with small lytic areas. Pathological feature may occur Occasionally radiation induce sarcomatous changes , usually osteosarcoma, which occur several years after the radiation therapy.
Changes in bone shapes
Is congenital disorder. There are multiple bony projections known as osteochondromas or exostoses. They have cartilaginous cup which may contain calcification. When exostoses occur in the long bone , they occur near metaphyses & are directed away form the joint Diaphyseal aclasia (multiple exostoses)
. Diaphyseal aclasia (multiple exostoses)
Radiological features of joint diseases
Imaging technique Plain film remains important for imaging the joint, but MRI is being increasingly used & specially useful for;
Meniscal & ligamentous tear in the knee.
Rotator cuff tear of the shoulder.
Avascular necrosis in the hip joint.
MR Arthrography; involve injection of the contrast media in to the joint space & then performing an MRI scan.MR arthrography has role in the shoulder & wrist joints.
Plain film signs indicating presence of arthritis
1-Joint space narrowing; It occur in all forms of joint diseases except avascular necrosis.
2-Soft tissue swelling; Periarticular soft tissue swelling is a feature of inflammatory & infective arthritis. Discrete asymmetrical periarticular soft tissue swelling can be seen in gout due to gouty tophi
3-Osteoporosis; Occur in many type of painful conditions & under use of the bones is an important cause.
Diagnosis of arthritis
To Dx arthritis, it is important to have the following information; 1-Is more than one joint involved? RA, typically involve several joint while infection & synovial tumors usually involve single joint.
2-Which joints are involved?
RA virtually involve the hand & feet, principally MCP, PIP, wrist joint &MTP.
Psoriatic arthritis usually affect the DIP.
Gout typically involve MTP of the big toe.
OA when seen in the hands ,it almost always involves DIP& often affect the CM joint of the thumb & in the large joints, it commonly involve hip& knee, but relatively rare in the ankle , shoulders & elbow joints unless there is some underlying causes.