Dr: Mahmood Abed AljumailyProfessor and Consultant in Orthopedic Surgery

BONE S AND JOINTS INFECTIONS

Osteomylitis is infection of bone by pyogenic organisms

Microorganism may reach bone and joint by:

1 - indirect spread via blood(haematogenous) from far focus of infection

2 - direct introduction. ( open wound, surgical infection, pinprick, injection----)

3 - direct spread from nearby infection.

Acute haematogenous osteomyelitis

it is acute pyogenic infection of bone and its marrow, the infecting microorganism reach bone via blood .

It is mainly disease of children 2-6 years but any age might be affected. When adult affected it is due to impaired immunity

Causative microoganism of Acute haematogenous osteomyelitis

Staphylococcus areus is usually the causative in 70%.

Sreptococcusis other cause Haemophilus influenzae may causative in children

between 1-4 years. G –ve microorganism( e-coli, psuedomonus, proteus

and bacteriod) in neonates Anaerobic (peptococcus) is rare cause. Salmonella in sickle cell anemia. Pseudomonus in adult drug addict.

Pathology of acute haematogenous osteomyelitis

In children Acute haematogenous osteomyelitis starts in metaphysis of long bone because of :

Blood vessels is terminal and sinusoidal and newly formed with relative stasis,

and low oxygen tension.

Local immunity is impaired,

weak structure predispose to hematoma

Eiphyseal plate in children and infants

Acute haematogenous osteomyelitis pathology show characteristic progression from

1- inflammation (congestion, exudation, cellular infiltration, increased intraosseous pressure and intravascular thrombosis).

2- suppuration: pus formation and spread of pus through Volkmann's canals to form subperiosteal abscesses.

3- bone necrosis by the effect of ischemia, pressure, toxic materials, periosteal stripping lead to necrosis of segment of bone (sequestrum).

4 –reactive new bone formation under elevated periostium, the layer of new bone enclosing sequestrum called involcrum

5- resolution and healing or chronicity.

If bone infection persist, sinus continue to discharge pus through perforation in bone called cloacae and tract extend from skin to bone

If acute haematogenous osteomyelitis treated early these changes will be controlled and progression can be prevented and changes limited to small area or even normality restored (resolution).

chronic osteomyelitis is common sequalae for delayed treatment.

acute haematogenous osteomyelitis in infants may complicated by septic arthritis.

Clinical features of acute haematogenous osteomyelitis

Clinical features in children: sever pain, malaise, ill, fever, inability to move and toxemia. Common side is proximal tibia, distal femur and proximal femur.

Child look ill ,feverish, tachycardia, there is acute tenderness near end of bone, movement restricted( pseudo paralysis) limb held still. Local redness, worm, local edema is late sign and indicate pus collection in soft tissue.

All these features might be attenuated by antibiotics.

In infants and especially neonates constitutional symptoms might be mild, irritable , drowsy, failure to thrive, metaphyseal tenderness and restricted movement (pseudo paralysis).

In adults the common site is thoracolumbar vertebrae following urological procedures. Fever and backache and local tenderness. Adult with osteomyelitis may be immune compromised.

Diagnostic imaging in acute haematogenous osteomyelitis.

1- plain X -ray: in first week no finding except soft tissue swelling, in second week periosteal reaction as a faint line over the bone become visible, patchy rarefaction in metaphysis. Area of decreased and increased bone density may be seen.

2- ultrasound can detect fluid collection.

3- radioactive isotope scanning is highly sensitive but has low specificity.

4- MRI is helpful in early diagnosis, it detect marrow inflammation, highly sensitive but has low specificity.

Laboratory investigation in acute haematogenous osteomyelitis.

1- The most certain way to confirm diagnosis is aspiration of pus or fluid from subperiosteal abscess. Aspirate examined for cells, gram

stain and culture sensitivity.

2- blood cultures is positive in less than half of patients.

3- ESR and C reactive protein CRP elevated.

4- CBP show leuckocytosis, neutrophilia and anemia.

Cardinal features of acute haematogenous

Pain

Fever

Tenderness

Refusal to bear weight.

Elevated WBCs.

Elevated ESR.

Elevated CRP.

Differential diagnosis of acute haematogenous osteomyelitis in children

1- pyogenic arthritis ( absolute stiffness of affected joint ).

2- cellulitis : redness and swelling early with lymphangitis.

3-acute rheumatism.

4- sickle cell crises and Gaucher’s disease.

5- primary bone tumors.

cellulitis

Treatment of acute haematogenous osteomyelitis

If osteomyelitis is suspected on clinical base,

blood and fluid samples should be taken for laboratory investigation,

and then treatment started immediately without waiting for final confirmation of diagnosis.

TREATMENT

1- supportive treatment for pain and dehydration; analgesia, rest, antipyretics, fluid therapy,

septicemia management.

2- splintage; skin traction, back slab or slings .

3- antibiotics: intravenous antibiotics started immediately on clinical bases and then changed on cultures and sensitivity. Antibiotics should cover expected microorganism especially staphylococcus.

Antibiotics selection on clinical bases

In children: flucloxacillin+ fusidic acid and or 3rd generation of cephalosporin.

Antibiotics continue intravenously until patient improved and CRP return to normal for about 2-4 weeks and continue orally for other 4- 6 weeks.

CRP, ESR , and WBCs values checked frequently and antibiotics stopped when be normal.

.

4- surgical drainage

If antibiotics start early in first 48 hours drainage may be unnecessary.

Surgical drainage indicated if:

1- condition not improved after 36 hours of treatment.

2- sign of pus collection present in delayed presentation ( swelling, edema, fluctuation).

3- if pus aspirated .

Drainage done by open operation under general anesthesia, window done in cortex , splintage applied post operatively.

Weight bearing delayed for one month or even more.

complications of acute haematogenous osteomyelitis

1- septicemia.

2- epiphyseal damage and altered bone growth.

3- Suppurative arthritis; infants or when metaphysis in side join like hip.

4- metastatic infection.

5- pathological fractures.

6- chronic osteomyelitis.