Page 360 - Medicine and Surgery

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356 Chapter 8: Musculoskeletal system

obliteration, provision of soft tissue coverage of the bone Investigations
and stabilisation of bone. X-ray shows soft tissue swelling and decreased den-
sity (rarefaction) of the bone. In early stages the joint
space is preserved, but later there is narrowing and ir-
Tuberculous bone infection regularity with bone erosion and calcification within
adjacent soft tissue.
Definition
The ESR is usually raised and the Mantoux test is pos-
Spread of an infection by Mycobacterium tuberculosis to
itive in 90% of immunocompetent patients.
the bone and joints.
Synovial biopsy for histological examination and cul-
ture is often necessary.
Incidence
Patients with tuberculosis have a 5% lifetime risk of Management
developing bone disease. Chemotherapy with combination anti-tuberculous
agents for 12–18 months (see page 105). Rest and trac-
tion may be useful; if the articular surfaces are damaged,
Age
arthrodesis or joint replacement may be required.
Usually children or young adults.
Septic arthritis
Geography
Major illness in developing countries, with increasing Definition
incidence in the developed world. Inflamed painful joint caused by infection with a pyo-
genic organism.
Aetiology
Tuberculous osteomyelitis is usually due to haematoge- Aetiology
nous spread from a primary focus in the lungs or gas- Joint infection arises most commonly from haematoge-
trointestinal tract (see pages 105 and 154). HIV has in- nous spread. Other mechanisms include local trauma or
creased the incidence of tuberculosis and tuberculous an adjacent infective focus such as osteomyelitis. It can
bone infections. also occur as a complication of joint surgery, although
this is minimised by the use of laminar flow theatres and
sterile techniques. The commonest causative organism
Pathophysiology
is Staph. aureus.
Thediseasestartsintheintra-articularbone.Thelumbar Toddlers and children: Staph. aureus, Streptococci,
and lower thoracic spine is commonly involved (Pott’s
Haemophilus (rare since vaccination).
disease).Achronicinflammatoryreactionoccursleading Adults: Staph. aureus, Streptococci, Neisseria gonor-
to caseation and later abscess formation (cold abscess).
rhoea.
Abscesses may cause a mass effect on local structures. Immunosuppressed: Gram-negative bacteria, my-
Weakened vertebrae are prone to collapse.
cobacterium, fungi.
Patients with sickle cell anaemia are particularly prone

to infections with Salmonella.
Clinical features
The onset of symptoms is insidious and often missed.
The patient complains of pain and later swelling due to Pathophysiology
pus collection. Muscle spasm and wasting occur with Bacteriaareinitiallyfoundinthesynovialmembranebut
limitation of movement and rigidity. In spinal tubercu- quickly spread to the synovial fluid. Cytokine-mediated
losis, pain may be mild and presentation delayed until inflammationandariseinintra-articularpressurefollow
thereisavisibleabscessorvertebralcollapsecausingpain the spread of bacteria. The pressure may cause compres-
and deformity. sion of the blood vessels leading in the hip to avascular