2. Normal skeletal system
Bone is a type of connective tissue
Inorganic component – calcuim hydroxyapatite
Organic component – cells & protein of matrix
3.
Bone forming cells – osteoprogenitor
cells, osteoblasts & osteocytes
Osteoblasts – uninucleate, along new bone
forming surfaces, synthesise bone matrix
Osteoblasts surrounded by matrix - osteocytes
4.
Osteocytes – numerous, osteoblasts which get
incorporated into bone matrix during
synthesis, found within lacunae
Osteoclasts – large multinucleate cells, bone
resorption
Osteiod matrix – 90-95% of type I collagen
9. INFECTIONS – OSTEOMYELITIS
Inflammation of bone & marrow
Manifests as primary solitary focus of disease
Systemic diseases spreading to bone –
typhoid, actinomycosis, syphilis, brucellosis, myc
etoma
* Pyogenic bacteria & mycobacteria
10. PYOGENIC OSTEOMYELITIS
Bacterial infection – hematogenous route
, contiguous site , direct implantation
Infants & young children – 5-15 yrs
Long bones / vertebral bodies
Common – staph aureus- express receptor to
bone matrix components & facilitates adherence
to bone tissue
12. Morphology –
Depends on stage – acute , subacute or chronic
& location of infection
Suppuration, ischaemic necrosis, healing by
fibrosis & bony repair
Acute inflammatory reaction -> cell death
Entrapped bone – necrosis
Bacteria & inflammation spreads
13.
Infection begins in metaphyseal end of marrow
cavity occupied by pus, microscopy shows
congestion, oedema, & exudate of neutrophils
Infection spreads along marrow cavity to
endosteum, haversial canal – Periosteitis
May reach subperiosteal space – subperiosteal
abscess
14.
May penetrate through cortex creating draining
sinus tracts
Combination of suppuration & impaired blood
supply to cortex results in erosion, thinning &
infarction necrosis of cortex – Sequestrum
Later there is formation of new bone beneath
periosteum present over infected bone. This
forms encasing sheath around necrosed bone Involucrum
15.
Continued neo-osteogenesis gives rise to dense
sclerotic pattern of osteomyelitis
Occasionally acute osteomyelitis may be
contained to a localised area & walled off by
fibrous tissue & granulation tissue – Brodie’s
abscess
16.
17. Clinical course –
Acute systemic illness with malaise , fever, chills
, leucocytosis & pain
X – ray – lytic focus of bone destruction
surrounded by zone of sclerosis
Blood culture , biopsy
20. TUBERCULOUS OSTEOMYELITIS
Adolescents or young adults
Morphology –
Blood borne , originate from focus of active
infection
Sites – spine , knees & hips
21.
Central caseous necrosis, granuloma
Involvement of joint space & interverebral disc
are frequent
Pott’s disease – TB of spine commences in
vertebral body, may be associated with
compression #, destruction of intervertebral
discs -> permanent damage & paraplegia
22.
Psoas abscess – extension of caseous material
alongwith pus from lumbar vertebrae to sheaths
of psoas muscle