Introduction

Tuberculous arthritis of the knee is the third most common site of skeletal tuberculosis in children, accounting for 10-20% of cases. The condition typically affects the synovium initially, with subsequent spread to articular surfaces.

Key Clinical Features

• Early Symptoms:
  • Vague knee pain
  • Morning stiffness
  • Gradual onset of swelling
  • Decreased range of motion
  • Limp while walking
• Late Symptoms:
  • Significant joint swelling
  • Muscle wasting (quadriceps)
  • Flexion deformity
  • Cold abscess formation
  • Sinus tract formation

Pathoanatomy and Classification

Stages of Disease (Kerri and Martini Classification)

1. Stage I (Synovial Stage):
   • Early synovitis
   • Minimal joint effusion
   • No bony changes
   • Preserved joint space
2. Stage II (Early Arthritis):
   • Granulation tissue formation
   • Early cartilage destruction
   • Marginal erosions
   • Joint space narrowing
3. Stage III (Advanced Arthritis):
   • Severe cartilage destruction
   • Bone destruction
   • Joint space obliteration
   • Early deformity
4. Stage IV (Advanced Destruction):
   • Fibrous ankylosis
   • Severe deformity
   • Subluxation
   • Bony ankylosis

Diagnostic Evaluation

Clinical Examination Findings

• Boggy synovial swelling
• Quadriceps wasting
• Popliteal swelling
• Restricted range of motion
• Fixed flexion deformity
• Knee instability in late stages

Imaging Studies

• X-ray Findings:
  • Phemister's triad
  • Joint space narrowing
  • Subchondral erosions
  • Periarticular osteoporosis
  • Ice cream scoop appearance
• MRI Features:
  • Synovial hypertrophy
  • Rice bodies
  • Bone marrow edema
  • Articular cartilage involvement
  • Subchondral bone changes
  • Para-articular collections

Laboratory Investigations

• Essential Tests:
  • ESR and CRP levels
  • Complete blood count
  • Mantoux test
  • IGRA (Interferon-Gamma Release Assay)
  • Chest X-ray
• Confirmatory Tests:
  • Synovial fluid analysis
  • PCR for MTB
  • Culture and sensitivity
  • Synovial biopsy (gold standard)

Treatment Protocol

Medical Management

• Anti-tubercular Therapy:
  • Initial Phase (2-3 months):
    • Isoniazid (H): 10 mg/kg
    • Rifampicin (R): 15 mg/kg
    • Pyrazinamide (Z): 35 mg/kg
    • Ethambutol (E): 20 mg/kg
  • Continuation Phase (7-9 months):
    • Isoniazid (H)
    • Rifampicin (R)

Surgical Management

• Early Disease:
  • Arthroscopic synovectomy
  • Debridement
  • Joint lavage
• Advanced Disease:
  • Open debridement
  • Synovectomy
  • Joint stabilization
  • Arthrodesis in severe cases

Conservative Management

• Rest during active phase
• Splinting in functional position
• Prevention of deformity
• Isometric exercises
• Gradual mobilization
• Weight-bearing as tolerated

Rehabilitation Program

• Phase I (Protection Phase):
  • Pain management
  • Gentle passive movements
  • Isometric exercises
• Phase II (Mobilization Phase):
  • Active assisted exercises
  • Range of motion exercises
  • Muscle strengthening
• Phase III (Functional Phase):
  • Full range exercises
  • Gait training
  • Functional activities

Complications

• Early Complications:
  • Joint effusion
  • Cold abscess
  • Sinus formation
• Late Complications:
  • Flexion deformity
  • Ankylosis
  • Growth disturbances
  • Secondary osteoarthritis
  • Genu valgum/varum

Monitoring and Follow-up

• Regular clinical assessment
• Monthly ESR and CRP monitoring
• Quarterly radiological evaluation
• Assessment of:
  • Range of motion
  • Deformity correction
  • Muscle strength
  • Functional improvement

Prognosis Factors

• Good Prognosis:
  • Early diagnosis
  • Compliance with treatment
  • Stage I/II disease
  • Good initial response
• Poor Prognosis:
  • Late presentation
  • Advanced disease
  • Multiple drug resistance
  • Poor compliance