Page 361 - Medicine and Surgery

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Chapter 8: Osteoarthritis 357

necrosis of the femoral head especially in young chil- therapy is dependent on the suspected organism.
dren. Erosion of the articular cartilage results from the In previously healthy children and adults, penicillin
release of proteolytic enzymes from neutrophils within (Streptococcus cover) and flucloxacillin (Staphylococ-
the inflammatory exudate. Prolonged exposure to these cus cover) are used. A third-generation cephalosporin
enzymes can result in chondrocyte and bone damage. is used if gonococcus is suspected and in the immuno-
Pusmay find its way out of the joint causing an abscess, compromised gentamicin is added to cover for anaer-
which may drain via a sinus. obic organisms. Antibiotic therapy is reviewed in the
light of culture and sensitivities.
Clinical features Splintage and resting of the joint is essential. If the hip
The classical features of septic arthritis are a red, hot, is infected it should be held abducted and 30 flexed.
◦
painful monoarthritis associated with fever. Overall the Drainage of pus and arthroscopic joint washout under
knee is the most commonly affected joint, but hips are anaesthesia can be performed.
often the site in children. There may be evidence of the Surgical drainage may be indicated if the infection
source of infection such as a urinary tract infection, skin does not resolve with appropriate antibiotics or if per-
orrespiratoryinfection.Onexaminationthejointisheld cutaneous drainage is not possible. Arthroscopic pro-
immobilised in the position that maximises the intra- cedures allow visualisation of the interior of the joint,
articular volume (e.g. a hip is usually held flexed, ab- drainage of pus and debridement.
ducted and externally rotated). Movement of the joint Surgerymayalsoberequiredfortheremovalofforeign
is very painful and often prevented by pain and muscle bodies or infected prosthetic material.
spasm (pseudoparesis). If there is no cartilage damage, gentle mobilisation
should begin once inflammation has settled.
Complications
Iftreatmentisdelayedthereisseverearticulardestruc-
Prognosis
tion, which may heal by fibrosis with permanent re- Outcome is related to immune status of the host, viru-
striction of movement, deformity or bony union. lence of the organism and the speed at which adequate
Atense joint effusion may result in dislocation.
antibiotic therapy is started. In Staphylococcal infections
In children extensive destruction of the epiphysis may
involvement of multiple joints carries a significant mor-
occur causing growth disturbance and deformity. tality (>90% if more than three joints involved).
Investigations
X-ray of the affected joint may show widening of joint Osteoarthritis

spaceandsofttissueswellingbutareoflittlediagnostic
value. Definition
Blood tests may reveal a leucocytosis, raised ESR and Previously thought of as a degenerative joint disorder

CRP. Blood cultures should be taken and may be pos- of ageing, osteoarthritis is now considered to be a joint
itive in a third of cases. disorder resulting from damage and repair to cartilage
Diagnosis is confirmed by aspiration of joint fluid for and reaction in the surrounding bone.

urgent microscopy, culture and sensitivities. The fluid
often appears purulent at time of aspiration. Depend- Prevalence
ing on the joint involved and available facilities, aspi- Radiological changes universal in old age, symptomatic
ration may be blind, ultrasound guided, CT guided or disease occurs in 20%.
surgical.
Age
Management Peak onset 45–60 years.
Patients require adequate analgesia.

Antibiotics should start immediately after synovial Sex

fluid and blood cultures have been taken. Initial F > M