Tuberculosis of the knee joint
The knee joint is the largest joint in the body having the largest intra-articular space.
Tuberculosis of the knee joint constitutes about 10% of all cases of osteoarticular tuberculosis and it is the third common site of osteoarticular tuberculosis.
The clinical feature is insidious and presents with swelling and pain over the knee joint.
On examination, there will synovial effusion with synovial hypertrophy, restriction of knee movement with muscle spasm.
Late cases will present with posterolateral subluxation of the knee joint.
Other usual constitutional symptoms like a low-grade fever, lassitude, anorexia, loss of weight, night sweats, tachycardia, and anemia will be present.
There are four stages of tuberculosis of the knee joint. Stage I is the stage of synovitis where there is a terminal restriction of movements (>75% of movement are present). Stage II is the stage of early arthritis where 50 to 75% of movements are preserved. Stage III is the stage of advanced arthritis with loss of movement > 75% in all directions. Stage IV is the stage of advanced arthritis with subluxation or dislocation of joints.
Blood investigation like complete blood count, erythrocyte sedimentation rate (ESR), CRP is the basic investigations.
Other investigations are the Mantoux test, synovial fluid analysis, and serological investigation.
The basic radiologic investigation includes knee joint anteroposterior and lateral view followed by higher investigations like ultrasonography, computed tomography, and magnetic resonance imaging.
Biopsy demonstrating the caseation necrosis with tubercle is the diagnostic of tuberculosis of the hip joint.
All patients during the active stage of the disease are treated with multi-drug therapy and traction to correct the deformity and to give rest to the part.
Traction is mandatory to relieve muscle spasm, to prevent or correct the deformity and subluxation, to maintain the joint space, and to minimize the chance of development of deformity.
Any palpable cold abscess or joint collections need surgical intervention.
The favourable response is seen in the early stage of disease with appropriate medical and surgical intervention.
In advanced cases, cases treated inappropriately or neglected cases result in unfavourable outcome with deformity and ankylosis of the knee joint.