tuberculosis of the hip

TUBERCULOSIS OF THE HIP

DR.ABHINAV KESARKAR

THE BACILLI• Causative organism: mycobacterium tuberculi• Slow growing aerobic organism with a growth doubling

time of 20 hrs in favourable condition. In unfavourable condition the organism will grow only intermittently or will remain dormant for period of time till the host immunity is defecient.

• M. tuberculosis has an unusual, waxy coating on its cell surface (primarily due to the presence of mycolic acid), which makes the cells impervious to Gram staining. The Ziehl-Neelsen stain, or acid-fast stain, is used instead. The physiology of M. tuberculosis is highly aerobic and requires high levels of oxygen.

Buff colored , rough colonies

• Ideally , diagnosis of tuberculosis is confirmed on demonstration of the bacilli in skeletal tuberculosis lesion. However , this is not possible in numerous case series because , skeletal tuberculosis is supposed to be a paucibacillary condition.

• Bacilli load in osteoarticular TB is less than 105

THE TUBERCLE• The initial response is in the

reticuloendothelial depots of the skeletal tissue.

• PMNs Macrophages & Monocytes• The tubercle bacilli are phagocytosed and

broken down and their lipid is dispersed throughout the cytoplasm of mononuclear cells transforming them into epitheloid cells.

• The epitheloid cells fuse together to form the langhans giant cells when caesation occurs.

• Lympphocytes form a ring around the langhans cells with caesation necrosis.

• This mass formed by the reticuloendothelial cells together with caseous material is known as the tubercle.

• Tubercle with caesation called ‘soft tubercle’• Tubercle without caesation called ‘hard

tubercle’.

TUBERCULAR SEQUESTRA

• Osseous destruction occurs by lysis of bone,which softens and yields under gravity & muscle action leading to compression , collapse or deformation of bone.

• Necrosis occurs due to thromboembolic phenomenon , endarteritis and periarteritis.

• As a result of ischaemic changes , sequestra occurs and appears as ‘coarse sand’ pattern which is radiologically difficult to see.

• Sometimes , the adjacent articular cartilage or disc gets involved and becomes part of the sequestra.

• ‘ Feathery Sequestra’ occurs when caseous material becomes calcified.

‘TB HIP’

EPIDEMOLOGY

• Bones and joints and affected in ~5% of pts with TB

• Commonest is spinal TB in ~50% of cases

• Hip – 15% of all osteoarticular TB

• Can occur in any age group but is more common in children.

• Next common after spinal TB

PATHOLOGY• M.TB entry – inhalation, ingestion, skin innoculation• Primary complex, secondary spread and tertiary lesion.

osseoarticular TB is haematogenus• Always starts in bone, rarely synovium –granulomatous reaction• The anatomical sites of the lesions:

1.The superior rim of the acetabulam 2. Epiphysis 3. Babcock's triangle 4. Greater trochanter. 5. Rarely, purely synovial in location.

• In hip joint head and neck are intracapsular so a bony lesion invades the joint early

BABCOCKS TRIANGLE

CLINICAL PICTURE

• h/o previous TB infection or contact

• Insidious onset, chronic course

• Most pts are children

• Prior constitutional symptoms

• First symptom stiffness of hip with a limp

• Pain may be absent in early stages

• Pain worse at night – “night cries”

EXAMINATION

• INSPECTION

- Antalgic / stiff / trendelenberg- Muscle wasting- Discharging sinus / cold abscess- Limb length discrepecency, FFD

• PALPATION- Local tempreature - Pelvic tilt- Tenderness• MOVEMENTS- Restricted movements

STAGES OF TB HIP

• STAGE -1 ( STAGE OF SYNOVITIS) - effusion in the joint that demands the hip in

position of maximun capacity i.e FLEXION , ABDUCTION & EXTERNAL ROTATION causing APPARENT LENGTHENING

• STAGE -2 (STAGE OF ARTHRITIS)- Articular cartilage is involved leading to spasm

of the strong muscles of the hip i.e. the flexors and the adductors.

- FLEXION ADDUCTION & INTERNAL ROTATION. Causing APPARENT SHORTENING.

• STAGE – 3 ( ADVANCED ARTHRITIS)- Further destruction of hip elements leading to

exaggeration of FADIR , restriction of movements, muscle wasting and limb shortenings.

• STAGE – 4 (ADVANCED ARTHRITIS WITH SUBLUXATION & DISLOCATION)- More destruction of hip leading to displacement

of the femoral head in acetabulum leaving its lower part empty and broken shentons arc.

- Generally , movements are restricted but gross destruction may cause collapse and certain radiological appearance may retain fairly good ROM.

The subluxated or dislocated hip

Occurs due to capsular laxity and synovial hypertrophy

‘Wandering’ Acetabuli

‘Mortar & Pestle’

PROTRUSIO ACETABULI

Shanmugasundaram’s classification

IMPORTANT OBSERVATIONS

A] Childhood TB hip (growing period) chronic hyperemia would lead to enlargement of femoral head epiphysis and metaphysis leading to COXA MAGNA.

B] Thromboembolic phenomena of selective terminal vasculature create Perthe’s like changes and reduced blood supply due to effusion (tamponad effect) causing decrease size of femoral head and neck – COXA BREVA.

C] Restricted growth of femoral capital epiphysis with normal growth of trochanteric growth plate lead to – COXA VARA.

D] Restricted growth of trochanteric physis with normal growth of femoral epiphysis lead to - COXA VALGA.

E] A triad of radiologic abnormalities (Phemister triad);– periarticular osteoporosis – peripherally located osseous erosion– gradual diminution of joint space suggests the dx

of TB

F] Occasionally, wedge-shaped areas of necrosis (kissing sequestra) in joint margin. These marginal erosions may simulate RA

TREATMENT

• Rest

• Chemotherapy

• Arthroplasty

• Arthrodesis

• Osteotomy

• Thomas urged that TB should be treated by rest – which had to be

‘prolonged, uninterrupted, rigid and enforced’.

HUGH OWEN THOMAS

TRACTION

–Provides rest to the joint–Relieves muscle spasm–Prevents and corrects deformity–Maintains joint space–Minimises chance of developing wandering

acetabulum

CHEMOTHERAPYTB disease category Intensive phase

(2 months)Continuation phase(4 months)

All forms of PTB and EPTB except TB meningitis and osteoarticular TB

2RHZE 4RH

TB meningitis, osteoarticular TB

2RHZE 10RH

Courtesy : 2009 TB guidelines by ministry of health

ARTHROPLASTY

THR• RESERVED FOR ADULT TB ISSUES

• Reactivation of disease• Duration of dz free interval before arthroplasty• Anti-TB use peri-arthroplasty

EXCISION ARTHROPLASTY

ARTHRODESISoptimal positioning for function and limited effect on adjacent joints200 – 350 FLEXION0 – 50 ADDUCTION50 – 100 EXTERNAL ROTATION

* avoid abduction as it creates pelvic obliquity and increased back pain

BRITTAINS ARTHRODESIS

In, TB hip , ischium is not reached in disease progress, thus , extra articular arthrodesis can be done. Used in children with fibrous ankylosis to achieve painless hip. Studies showed upto 88 % favourable results.