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Haematogenous Osteomyelitis and Septic Arthritis 139
Clinical Presentation
Any child with fever and reluctance to move an extremity should be
considered to have osteomyelitis or septic arthritis until proven other-
wise. The history should include any factors that may make the child
more susceptible to the development of bacteraemia: recent systemic
illness (chicken pox), respiratory or urinary infections, otitis media,
indwelling intravenous catheters, immunosuppressive disorders, or
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sickle cell disease. There is often the history of a traumatic event
preceding the pain.
On examination, there is usually swelling and warmth over the joint,
pain with mobilisation of the joint, and restricted range of motion of the
joint. Tenderness over the metaphysis of a bone is more characteristic of
osteomyelitis, whereas tenderness directly over a joint or pain with slight
movement of a joint is characteristic of septic arthritis. The patient should
also be evaluated for pharyngitis, rash, heart murmur, hepatosplenomegaly,
and evidence of involvement of other bones or joints.
Diagnosis
Figure 22.7: Stage 3 chronic HO of the tibia: (A) extensive sequestrectomy Diagnosis must be made promptly to prevent damage to the articular
performed through a long cortical trough; (B) wound healing by secondary cartilage. Blood and joint fluid should be obtained for cultures, and
intention without antibiotics.
a gram stain and cell count should be performed on the joint fluid.
A WBC count of 50,000/cu mm or greater with a predominance of
out of the cortical trough. It is not painful for the children, and the polymorphonuclear cells is consistent with bacterial infection. Plain
wound can be managed solely by a parent without using the services radiographs may show joint space widening, effusion, soft tissue swell-
of hospital personnel. ing, or subluxation/dislocation of the joint. Radiographs are useful to
The proper procedure is controversial for management of chronic rule out fracture, malignancy, or osteomyelitis as the cause of pain.
osteomyelitis when the total bone from metaphysis to metaphysis has Ultrasound is useful in determining whether fluid is present in the joint
sequestered and there is not yet enough new involucrum to provide and is useful in guiding aspiration, but it cannot differentiate infected
stability to the bone. Some surgeons prefer to proceed with removal of the from noninfected fluid. The definitive diagnosis is made by either joint
giant sequestrum and splinting of the extremity to allow the involucrum aspiration or operative identification of a purulent effusion.
to grow in a clean environment without the infected sequestrum Treatment
interfering (Figure 22.5). Other practitioners believe that the best splint The three main therapeutic interventions are: (1) joint decompres-
for the affected extremity is the sequestrum itself and that it should be sion and debridement, (2) antibiotics and initial joint immobilisation
left in situ until the involucrum has coalesced. There are obviously no to decrease local irritation, followed by (3) mobilisation to decrease
prospective randomised studies to support either course of action.
the development of fibrous adhesions and improve cartilage nutrition.
Complications Intravenous antibiotics (choice depends on availability in a given locale)
Risk factors for development of complications of HO include delay in should be started after the arthrocentesis and continued for 1–2 weeks,
diagnosis, misdiagnosis, short duration of therapy, and a younger age at after which oral antibiotics are continued for another 2–6 weeks. Septic
the time of initial illness. Recurrent bone infection is the most common arthritis is a surgical emergency because prolonged elevated intracapsular
complication after treatment for osteomyelitis followed by disturbance pressure in the hip can tamponade blood flow to the femoral head and
in bone growth, limb-length discrepancies, axial displacement of the increase the possibility of developing avascular necrosis. A safe anatomi-
limb, pathologic fractures, and abnormal gait. cal approach to the joint should be conducted. 13,14 The joint is opened and
Septic Arthritis the pus drained. The joint is irrigated copiously with normal saline. After
the effluent is clear, the joint is digitally palpated to determine how much
Pathogenesis of the cartilage has already been destroyed. If it is a superficial joint
Although septic arthritis can be caused by joint trauma or extension of (knee), a drain is not necessary. For deeper joints (hip, shoulder), how-
osteomyelitis into a joint, the most common aetiology in African children ever, a Penrose or glove drain can be inserted to maintain the drainage
is haematogenous dissemination of Staphylococcus from an open skin tract between irrigations. The patient is placed at joint rest for at least 2
or mucosal wound. Other offending organisms include Streptococcus, weeks. The joint undergoes repeat irrigation daily under anaesthesia until
Haemophilus influenza (particularly in newborns), and Salmonella and there is no more purulent drainage. It is important, particularly in joints
Escherichia coli in sickle-cell children. Bacteria have an affinity for car- with extensive cartilage destruction, that the joint be placed in a func-
tilage and directly attach to the chondral surface. An acute inflammatory tional position because otherwise ankylosis may occur. If ankylosis does
response follows, resulting in migration of polymorphonuclear cells, pro- occur, reconstructive surgery will probably not be available in LWATs,
duction of proteolytic enzymes, and cytokine secretion by chondrocytes. and even if available, it will not be nearly as effective in providing func-
Degradation of articular cartilage begins within 8 hours of onset of infec- tion as would be a programme of splinting joints in a position of function
tion. The most commonly infected joints are the knee (41%), hip (20%), before ankylosis. After the period of posterior plaster immobilisation, the
ankle (14%), elbow (12%), wrist (4%), and shoulder (4%). joint is progressively mobilised to minimise ankylosis.