Tuberculosis



DR. Alaa Abdul Hussein Al-algawy Lecture (8)

Bones and Joints Tuberculosis.( T.B.)

It is a granulomatous reaction associated with tissue necrosis and caseation, caused by Mycobacterium tuberculosis.

Aetiology: Mycobacterium tuberculosis is of two types (Human & Bovine) either through the inhalation (droplet infection) or through the Gut by swallowing of the infected milk, and rarely through the skin.

Pathology:

A- Primary complex: -

Initial lesion in the lung, pharynx or gut is small one with spread to the regional lymph nodes. This combination called (Primary complex). Which is either stay silent with out clinical signs or symptoms or it will fulminate with enlargement of the L.nodes in the neck or abdomen.

B-Secondary spread:-

If the resistance to the original infection is low, widespread dissemination via blood stream occur, giving rise to miliary T.B, T.B meningitis, some times the body can recovers from this miliary T.B but the one or more foci of extra pulmonary lesions still containing some living bacilli and it becomes active after few months or years causing destruction of that organ and called tertiary lesion.

C-Tertiary lesion:-

Affect bones and joints in about 5% of patients with T.B. There is predilection to the vertebrae, and large synovial joints.

The characteristic pathology is the T.B granuloma, ((which is a collection of epithelioid and multinucleated giant cells surrounding an area of necrosis with round cells (mainly lymphocytes).

In the affected area a small patch of caseous necrosis occurs and coalesce into a larger yellowish Mass., the centre will break down to form abscess containing pus and fragments of necrotic bone.

Either it affect the epiphyseal cartilage , or affect the synovium and make it thick & oedematous plus marked effusion, the destruction extend to the articular cartilage, and causing severe damage of the joint , if not treated at this stage it will extend to the surrounding soft tissue and cause a cold abscess.

The damaged joint if not treated early, will end with fibrous ankylosis.

Clinical features:

Usually there is a H/O previous infection or a recent contact with T.B.

The patient is a child or young adult, C/O pain and (in superficial joint) a swelling,

In advanced cases there may be a fever or lassitude and loss of weight. , locally there is muscles wasting, synovial thickening, and limitation of movements at that joint.

If the spine is affected, the pain is deceptively slight, so the patient may not present until there is visible abscess (usually in the groin or lumbar area lateral to the midline) or until collapse of the vertebrae occurs and causes kyphosis. Or the patient may present too late with neurological deficit (motor or sensory) due to spinal cord compression. (Pott’s paraplegia).

X-Ray findings:

Early :- soft tissues swelling , periarticular osteoporosis , are characteristic.

The bones ends are looking (washed out) and the articular space is narrowed.

Later: - erosion of the subarticular bone on the both sides of the joint (indicating that the inflammation started in the synovium), cystic lesions may appear in the adjacent bone ends but (there is a little or no periosteal reaction)

In the spine:- earliest sign is local osteoporosis of the adjacent tow vertebrae, and narrowing of the intervertebral disc, later more obvious sign of destruction and collapse of the adjacent vertebral bodies into each other, causing an angular deformity of the spine. ,the soft tissues may define a Para vertebral abscess .

Investigation :-

Blood test:-ESR is high , relative lymphocytosis.

skin test :-is positive ( Mantoux test, or Heaf test). The are sensitive but not specific i.e. ( negative test is excluding the disease but positive test may indicate TB infection now or in the past time).

Synovial fluid aspirate:- cloudy , protein is high, WBC count is elevated. Acid Fast Bacilli can be identified in Synovial fluid in about 10-20 % of cases, culture in specific media is positive in about 50% of cases.

Synovial biopsy :-is more reliable in showing characteristic histological picture.

Diagnosis :-

Important points in the diagnosis are :-

* long history of the complaint.

* involvement of only one joint.

* marked Synovial thickening .

* marked muscles wasting.

* periarticular osteoporosis .

* positive Mantoux test.

Synovial Biopsy for histological examination and culture is often necessary.

Differential Diagnosis :-

1-Transient synovitis :- common in children , as low grade inflammatory disease affecting the joint , most of the investigations are normal , usually needs only bed rest .

2-Mono articular Rheumatoid arthritis:- only differentiated by Synovial biopsy.

3- Sub acute Arthritis :- the history and clinical picture and other investigations are easy to differentiate between them.

4-Haemoarthrosis :- the history and clinical picture and other investigations are easy to differentiate between them.

5-Septic arthritis :- acute case is easy to differentiate but an old septic arthritis may be difficult to differentiate it.

Treatment :-

Joint rest : at first keep the joint in complete rest until the symptoms subsided , then allow an restricted activities until the joint changes resolved( usually 6-12 months) .full active movements must be encouraged as soon as possible ,and try to avoid occurrence of ankylosis in bad position .

Chemotherapy:- at first put on ( Rifampicin , Isoniazid, and Ethambutol (or pyrazinamide) for 8 weeks , then ( Rifampicin ,and Isoniazid ) for a further 6-12 months.

Operation:- early in the disease Joint drainage may be necessary , cold abscess may also needs drainage. And later if the joint was significantly damaged it may needs replacement arthroplasty or a corrective osteotomies.

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