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 salmonellapathogenesis
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 sequestrumpathology
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 modifiedinvestigation
X-RAY : It is normal during the first 10 days apart from soft tissue swelling . At the end of the 2nd 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 sensitiveBlood 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 indicatedI.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 weekscomplication
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 osteomyelitisMetaphyseal osteolytic lesion surrounded by area of sclerosis called (brodies absces) . The patient usually has long standing pain , swelling , local tenderness , but no fever