We have two special types of chronic OM
(Brodie’s abscess): A localized osteolytic lesion at the end of the long bone surrounded by sclerosis .(Gary’s osteomyelitis ): Sclerosing osteomyelitis . Characterized by localized sclerosis in the shaft of long bone .DDX ostiod osteomaTuberculosis of the Bone:
- Spread from infected joint.- Any bone affected but the spine is the most common site with predilection to the dorso lumber area .Findings in the spine (Pott’s Disease ) : -Usually affect 2 adjacent vertebrae .-There is erosion of the superior and inferior end plates .-There is irregular narrowing of the joint space .If not treated end with wedging of the vertebra (anterior loss of vertebral height) End by angular kyphosis .-May be complicated with para –spinal cold abscess ,seen as a fusi form Para spinal soft tissue on AP or PA view of the chest .T.B of peripheral bone is not common and usually affect the small bones eg phalanx T.B Dactylitis or spina ventosa : - There will be destruction of the phalanx - - expansion with soft tissue shadow around it .
Multiple Focal Bone Lesions:
Types of metastasesOsteolytic (most common causes) : neuroblastoma (in children), breast (adult female), bronchus (adult male), thyroid, kidney, colon The vertebral pedicles are often involved. Osteoblastic : prostate, breast , carcinoid , TCC of bladder,, neuroblastoma. Mixed: breast, prostate, lymphoma. Solitary expansile bubbly metastases with soft tissue involvement: thyroid, kidney. Bone metastases with sun burst periosteal reactions: prostate, retinoblastoma and neuroblastoma .
Multiple Myeloma
Site: axial skeleton. Findings: -Well demarcated lytic lesion occasionally with expansion of the bone. -In the skull called (rain drop) appearance (pathognomonic ). - In the spine Generalized form can resemble osteoporosis. - Solitary type (plasmacytoma): Represent early stage of MM; precede it by 1-20 years. Negative IgG spike in the serum. It affects the thoracic, lumbar spine, pelvis, ribs, femora. It is seen as expansile lytic ill-defined lesion with soft tissue mass. - Myeloma resembles metastases in everything except : it's more well defined, cause bone expansion and spares vertebral pedicle.Rain drop appearance
Myeloma
Generalized decrease in Bone Density: Osteoporosis:Findings: - the changes are best seen in the spine - Overall reduction in bone density with clear penciled in cortex. - Collapse of the vertebral bodies that represent compression fracture resulting In wedged vertebra with widening of the disc space. Long bones appear with thin cortex and resorption of many trabeculae but those that remain stands out clearly. The diagnosis of osteoporosis need to be made after the exclusion of other possible causes of reduced bone density: Metastatic carcinoma. Multiple myeloma. Hyperparathyroidism. Osteomalacia. Bone mass assessed by quantitative CT or by dual energy X-ray( DEXA scan ) .
Postmenopausal osteoporosis.
Rickets and Osteomalacia:Pathophysiology: poor mineralization of osteoid. If occur before epiphyseal closure then it is rickets, after that called osteomalacia. Causes: -Dietary deficiency of vit. D, lack of exposure to sun light. - Malabsorption. - Renal disorders. Findings in rickets : the findings are maximum at areas of bone growth so best seen at the knee, wrist & ankles: -Deficient zone of provisional calcification , the metaphysis is wide , irrigularly mineralized (frayed) and cupped . -Increased distance between the growing epiphysis & metaphysis. -Generalized decrease in bone density. -Deformity of bones due to softening (bossing and bowing ). -Greenstick fractures are common. -Rackety rosary of the ribs .
Rickets. There is obvious 'fraying' of the visible metaphyseal
Rickets. There is splaying of all of the visible metaphyses, with widening of the epiphyseal plates.Rickety rosary. Widening of the anterior ribs is clearly demon- strated (arrows)..
Findings in osteomalacia: - Decrease bone density. - Thin cortex & trabeculae. - Looser's zones: these are thin short lucent lines with sclerotic margins running across the cortex at right angle, best seen in the scapula, medial aspect of the femoral neck & pubic rami. - Vertebral collapse resulting in biconcave vertebra with widened disc (codfish appearance ). Bowing of the femur. In severe cases the pelvic side walls bend inwards resulting in triradiate pelvis.
Osteomalacia
Looser's zone.Hyperparathyroidism:
Renal Osteodystrophy:Occurs in patients with chronic renal failure. Findings: Features of osteomalacia in adults & rickets in children. Features of hyperparathyroidism. Sclerosis: this is infrequent finding seen as bands of increased density in the spine named as rugger jersey spine & across the metaphysis of long bones.
Osteogenisis imperficta : Imperfect formation of the bone . Die within 2-3 years or still birth due to associated CHD. *generalized decrease in bone density *The medulla is very thin . *Multiple bone deformity (large, small and flat bones ) due to multiple fractures and bizarre healing . *widening of the sutures and (wormmian bone formation )
Osteogenesis imperfecta. The child is stillborn. Multiple fractures are demonstrated in the short and broad long bones, which are cystic in appearance. Numerous rib fractures are seen.
Generalized increase in Bone Density:
- Sclerotic metastases. - Osteopetrosis (Marble bone disease); * congenital condition, * the bone is brittle & easily fracture but heals normally. Myelosclerosis: - Replacement of the bone marrow by fibrous tissue & progress to lay down new bone. - Splenomegaly is invariably present.Alteration in the Trabecular Pattern: Hemolytic anemia
Thalasaemia and sickle cell anaemia result in bone hyperplasia. Sickle cell anaemia in addition causes infection & infarction. Bone marrow hyperplasia: Thinning of cortex. Increase thickness of bone with resorption of some trabeculae & increase, thickness of the remaining. Increase diploic space thickness with vertical striation resulting in hair on end appearance. Enlargement of ribs, widening of the phalanges. Infarction: Infarction of the bone ends results in sclerosis and flattening of the femoral & humeral heads Medullary infarction appears as lytic areas with or without periosteal reaction. Healing appears later as areas of irregular medullary calcification.Changes in Bone Shape:
Achondroplasia: Defective ossifications of bones formed in cartilages. Shortening of the shaft of the long bones with distal metaphyseal flaring . Deformity of the pelvis (contracted pelvis). Bullets like vertebrae due to anterior beaking . Diaphyseal achlasia : Multiple bony projections arise from the bone covered by cap that may calcify. In the long bones they arise near the metaphysis & grow away from the nearby joint. Transformation into chondro sarcoma suspected when there is rapid increase in size, pain, ill-defined edge, extensive calcification in the soft tissue.