Toxic efects on skeleton system

TOXIC EFECTS ON SKELETON SYSTEMTOXIC EFECTS ON SKELETON SYSTEM

Toxic effects ofHypervitaminosis A Lead poisoningBismuth intoxicationVinyl chloride poisoningFluorosisOchronosis

too much vitamin A in the body.

Causes• Acute -- caused by taking too much vitamin A over a short

period of time• Chronic -- occurs when too much of the vitamin is present

over a longer period

• One recognized cause is administration from 13-cis retenoic acid for treatment of cancers such as neuroblastoma

1.Hypervitaminosis A

Imaging findings• diffuse symmetric periostitis• may cause premature fusion of ossification centres• separation of cranial sutures• Tendenous/ligmentous calcification

Increased cortical density more marked in ulna

• Main source of lead intoxication is from lead containing paint and lead containing pipes

• Absorption is greater in children than adults

Pathology• Lead concentrates in metaphyses of growing

bonesDistal femurBoth ends of tibiaDistal radius

2.Lead poisoning

Clinical findingsMusculoskeletal• Muscle and joint painSoft tissue• Blue-black line in gum margins• Laboratory findings • Serum Lead Level >1.2 umol/L• Urine lead level elevated

IMAGING FINDINGSBands of increased density at metaphyses of

tubular bones (growing bone) Bone in bone appearanceAbnormalities in bone modelling

Erlenmeyer flask appearance to distal femur

Frontal radiograph of both knees of a child with lead poisoning show dense metaphyseal bandsinvolving not only distal femurs and proximal tibias but proximal fibulas as well

A large amount of lead paint chips in the abd & pelvis of a two year old boy

Differential Diagnosisanaemia - chronic (eg, sickle cell

disease; thalassemia)

chemotherapy - e.g. Methotrexate

growth acceleration lines

treated leukemia

Normal variant Healing rickets Trauma: non accidental injury ; stress fracture

3.BISMUTH INTOXICATIONFollowing treatment for syphilis in the past

A similar appearance to that of lead poisoning

Dense metaphyseal lines

4.Vinyl chloride poisoningFound in workers in PVC manufactureCauses Raynaud’s phenomenon and a

characteristic acro-osteolysisSacroiliitisHeamangiosarcoma of liver

Resorption of central portion of terminal phalanges

5.FLUOROSIS Chronic metabolic bone disease

Caused by ingestion of large amounts of fluoride through either water or food in geographic areas where high levels offluoride occur naturally.

Radiographic features Involvement of the axial skeleton is

characteristic, and changes are most marked in the

• Spine,Pelvis,Ribs Plan filmincreased bone density - osteosclerosisosteopaenia / osteoporosis trabecular blurring or hazinesscompact bone thickening

periosteal bone formationossification of the attachments of tendons,

ligaments, and musclesinterosseous membrane calcification ossification of the posterior longitudinal ligament

Early fluorosis bone deposition and thickening at the junctions

of trabeculae. sandlike, granular, or particle like bone structure

on radiographs.

Advanced fluorosis trabeculae are more generally thickened because

of new bone formation on the trabecular surface. If the trabeculae are fused, focal round densities

are seen in the medullary bone.Osteopenia (less common) also may occur in

fluorosis - especially in younger patients at an earlier stage

Calcification of the sacrotuberous ligament is considered a characteristic feature.

increased bone density Loss of cortico medullary diff

Increased bone density of the visualized bones

Differential DiagnosisHaematological causesmyelofibrosissickle cell diseaseMetabolic bone disordershyperthyroidismhypoparathyroidism

Congenitalsclerosing bony dysplasias, e.g.:

osteopetrosisPyknodysostosis

Malignancyleukaemia

6.OchronosisAutosomal recessive metabolic disorder.Caused by lack of homogentisic acid

oxalate,which accumulates in the connective tissue.

Clinical presentation Pigmentation of auricular cartilages and scleraDark urine  

Radiographic FeaturesPlain filmVertebral:• multi level disc space narrowing•  intervertebral disc calcification• Kyphoscoliosis 

Jointssymmetrical or assymetrical joint space losssub-chondral sclerosischondrocalcinosis

Interverteberal disc calcification and scoliosis

Gross joint space narrowing of sacroiliac joint and intervertebral disc space narrowing and calcification

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