Septic arthritis

Dr. Mehzabin Ahmed

The clinical features suggestive of inflammation

Symptoms • Fever• Pain• Swelling of the right hip joint• Refusal to walk/ bear weight

Signs• Restricted joint movement• Skin- hot tender & swollen over the affected joint

                           

The hugely swollen thigh of a child suggesting that pus may have burst out of the hip joint, or through the periosteum of the femur

Why the hip joint is flexed, abducted and externally rotated at rest

• When the hip joint is extended the anterior joint capsule is stretched producing pain.

• In the above position this stretching is avoided and the joint space is maximum so the fluid in the space is redistributed within the cavity and thus reduces the tension on the capsule.

Arthrotomy

• It is a Surgicalprocedure by which fluid collected in the joint space is drained

• It is done immediately to remove the inflammatory exudate to:

• 1) reduce the bacterial load• 2) relieve the pressure on the joint produced by the

accumulated fluid• 3) for diagnostic purposes- to identify the cause.

Synovial fluid findings

• Increased WBC count (150,000/ml)- the fluid is due to an inflammatory process

• Differential count- Neutrophilia (90%)- the inflammation is acute in nature and is due to a bacterial infection

• Decreased glucose concentration, though the blood glucose is normal- the bacteria use up the glucose to multiply and the neutrophils also use it up to provide energy for phagocytosis

• Culture- Staphyloccus aureus- the agent causing the infection.

Hematological findings

• Increased total leucocyte count (15,000 cells/ml)- indicates an acute infection due to a bacteria

• Increased ESR (45mm/1st hr)- indicates acute inflammation- the acute phase reactant proteins and CRP increase and coat the RBC which reduces the charge on it and the RBC pile up and settle quickly

Immobilization of the hip

• To prevent the movement to reduce the pain and also allow time for healing

Early passive range of movement

• To prevent contractures and joint stiffness

Etiopathogenesis

• infection spreads from other sites like boils, respiratory system, ear or from a local osteomyelitic focus etc.

• The organisms gain entry in to the blood stream and get seeded into the joint and cause arthritis.

Complications If left untreated the infection may become chronic

and the child may:• Limp forever: the growth plate may get affected and

may cause limb shortening• The tissues may undergo extensive necrosis and the

pus may then drain to the surface through a tract or sinus

• The sinus tract in a long standing case may develop squamous cell carcinoma

• Amyloidosis: the deposition of an abnormal protein at the site of a chronic inflammation may occur

                                        

Destruction of the joint in a long standing case of septic arthritis