BONE INFECTION

micro-organism may reach the bone and joint either directly through a break in the skin e.g.. Wound, pinprick, open fracture. Or indirectly through blood stream from distant site any source of infection in the body. According to the type of micro-organism, site of infection and host response the result may be pyogenic osteomyelitis,arthritis, chronic granulomatus reaction e.g. T.B, fungal infection or parasitic infestation.e.g.hydatid.

INFECTION :is a condition in which pathogenic M.O. multiply and spread within the body tissue, this will give rise to acute or chronic inflammatory reaction which is the body way of defense to kill the M.O. the sign of inflammation are redness, swelling, heat, pain and loss of function

ACUTE HAEMATOGENOUS OSTEOMYELITIS It is almost a disease of children ; if it affect adult it may be due to low resistance for any cause. Trauma may predispose to this disease by heamatoma or fluid collection in the bone. The causal M.O. is usually staph. Aureus, less often strepto coccal pyogen or pnemonae. In children under 4 years haemophilous inflauanzae is common. E.Coli, proteus, pseudomonas seen in heroin addict. Patients with sickle cell disease are prone to infection by salmonella

pathogenesis The M.O. is blood born, it come from any source of infection any where in the body,inter the bone via the nutrient artery and reach the metaphysis where infection start, lead to pus formation which escape outside the cortex to become under the periosteum lead to periosteial reaction and new bone formation(envolicurum), then the pus escape through the clawaka to open to the skin as a discharging sinus. The dead bone called sequestrum

pathology Five steps 1- inflammation. 2- suppuration. 3- necrosis. 4- reactive bone formation. 5- resolution.

clinically The pt. is usually a child presented with sever pain, malaise, loss of function of the limb and fever. In neglected cases the child is dehydrated toxic and in advanced neglected cases the child may presented with septicemia (septic shock)

On examination The pt. look acutely ill feverish, dehydrated, pulse rate above 100 b/min. Local ex. : acute tenderness near one of the large joint, even gentle manipulation is painful, joint movements is restricted. Later on redness, swelling, hotness will be present and these signify that pus is escape from the bone to the soft tissue. If antibiotic is given, these signs will be modified

investigation investigation X-RAY : It is normal during the first 10 days apart from soft tissue swelling. At the end of the 2 nd week there will be periosteal reaction ; later on the periosteal reaction become more thick (new bone). Areas of cortical destruction shown as osteolytic lesion ( black lesions) mainly in the metaphysis it is called moth eaten lesions. Late sign is patches of rarefaction(area of decrease density) and patches of increase density.

Invest. Cont. ULTRASOUND : it may detect subperiosteal collection of fluid in the early stage of the disease. RADIO SCINTIGRAPHY(BONE SCAN) : Tc99, Ga67, In 111 show increase perfusion phase and bone phase in early stage of the disease. MRI : it is extremely sensitive

Blood investigations : C.B.P and ESR :show increase ESR, increase wbc count (mainly polymorph). C – reactive protein increase. Blood culture is positive in 50% of the cases. Anti staphylococcal anti body titer may be increased. Aspiration by needle (most certain)

Differential diagnosis 1- cellulitis. 2- acute suppurative arthritis. 3- acute rheumatism. 4- sickle cell crises.

treatment In osteomyelitis fluid(pus)and blood are taken from the patient for culture and sensitivity before any drug is administered and then the treatment is started immediately. Four important aspect of the treatment : A- supportive treatment for pain and dehydration. B- splintage of the affected limb. C- antibiotic. D- surgical drainage.

antibiotics Immediately started after aspiration of blood and fluid for culture and sensitivity. For staph. Aureus : flucloxaciliine and fucidic acid are used. In children before 4 years old when heamophilous inflauanzae is suspected, cephalosporine is indicated. Pt. with sickle cell disease when salmonilla is suspected, chloramphinicol, cotrimoxazol, amoxil with clavulonic acid (amoxyclave) is indicated

I.V. antibiotic should be continued until c- reactive protein return to normal level (usually take 1-2 weeks), and then change to oral antibiotic for 3-6 weeks. Surgical drainage : if after 36 hours of conservative treatment there is no improvement and there is sign of pus collection, then it should be drained.

rehabilitation Once the infection is subside, movement is encouraged and the child is allowed to walk with aid of crutches. Full weight bearing is allowed after 3-4 weeks

complication 1- metastasis of infection locally and systemically. 2- altered bone growth (due to damage to the growth plate of the bone) e.g. varus deformity of the knee (genu varum) 3- chronic osteomyelitis.

Genu varum deformity late complication of acute osteomyelitis

Sub acute osteomyelitis Metaphyseal osteolytic lesion surrounded by area of sclerosis called (brodies absces). The patient usually has long standing pain, swelling, local tenderness, but no fever

Sclerosing osteomyelitis of Garrie’s Non suppurative sclerosing osteomyelitis affecting young adult. Patient has chronic pain. X-ray show increase bone density. Treatment : by excision of the sclerosed bone