|Year : 2020 | Volume
| Issue : 4 | Page : 280-282
Tubercular arthritis of knee: Navigating the diagnostic dilemma
Nitin P Ghonge, Raju Vaishya
Departments of Radiology and Orthopedics, Indraprastha Apollo Hospital, New Delhi, India
|Date of Submission||26-Jul-2020|
|Date of Acceptance||05-Oct-2020|
|Date of Web Publication||24-Nov-2020|
Dr. Nitin P Ghonge
Indraprastha Apollo Hospital, New Delhi - 110 076
Source of Support: None, Conflict of Interest: None
The illustrated case of 48 years male highlights the challenges in clinical diagnosis of tubercular arthritis. Multi-modality imaging of knee joint and confirmation with synovial fluid aspiration and biopsy allowed prompt and accurate diagnosis.
Keywords: Tubercular, Arthritis, Knee, Multi-modality Imaging.
|How to cite this article:|
Ghonge NP, Vaishya R. Tubercular arthritis of knee: Navigating the diagnostic dilemma. Apollo Med 2020;17:280-2
| Introduction|| |
Mono-articular involvement of the knee joint is often caused by an infectious disease process but may be due to noninfectious etiology, mainly rheumatoid arthritis. The infections include pyogenic or tuberculous causes, while the noninfectious causes mainly include rheumatoid arthritis, synovial osteochondromatosis, pigmented villonodular synovitis, gout, or hemophilic arthropathy. In clinical practice, the differentiation of tuberculosis from rheumatoid disease in patients with knee arthritis is an important diagnostic dilemma. Accurate early diagnosis allows prompt treatment, which may ensure good prognosis and preservation of joint function. Diagnosis is often based on the imaging studies followed by culture of the synovial fluid or synovial biopsy. Image interpretation is the key for prompt imaging-based diagnosis in these patients.
| Case Report|| |
A 48-year-old male presented with gradual-onset painless swelling of 6 months duration in the left knee joint [Figure 1], arrow]. The overlying skin does not show any area of redness. Clinical examination showed restriction in the movement. There was no clinical history of any major illness or surgery in the past. Clinical diagnosis of infective or inflammatory arthritis was suspected. Laboratory investigations showed mild elevation of erythrocyte sedimentation rate (ESR) (35 mm/h) and C-reactive protein (4 mg/L) values.
|Figure 1: Clinical photograph showing a painless swelling of 6 months' duration in the left knee joint|
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Frontal and lateral radiographs [Figure 2] of the left knee joint showed peri-articular soft tissue swelling (arrow) with preserved joint spaces. There was a suggestion of articular surface erosions, mainly along the tibial condyle and intercondylar regions (thin arrows). Magnetic resonance image (MRI) study of the left knee joint [Figure 3] with T1 postcontrast coronal image (left upper panel) and STIR coronal image (left lower panel) showed joint effusion with diffuse synovial thickening and hyperenhancement (white arrows) and areas of large articular surface erosion in the tibia (thin white arrows). Sagittal proton-density MRI (right panel) showed enlarged popliteal lymph node with preserved hilum (black arrow). The constellation of findings suggested the diagnosis of tubercular arthritis. Arthroscopy of the left knee joint [Figure 4] was performed, which correlated with the imaging findings. Synovial biopsy confirmed the tubercular etiology of the disease process. Antituberculosis treatment was initiated, and the patient showed clinical response to the treatment at 6 months of follow-up.
|Figure 2: Frontal and lateral radiographs of the left knee joint showing peri-articular soft tissue swelling (arrow) with preserved joint spaces. There is a suggestion of articular surface erosions, mainly along the tibial condyle and intercondylar regions (thin arrows)|
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|Figure 3: Magnetic resonance image study of the left knee joint with T1 postcontrast coronal image (left upper panel) and STIR coronal image (left lower panel) showing joint effusion with diffuse synovial thickening and hyperenhancement (white arrows) and areas of large articular surface erosion in the tibia (thin white arrows). Sagittal proton-density magnetic resonance image (right panel) showing enlarged popliteal lymph node with preserved hilum (black arrow)|
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|Figure 4: Arthroscopy of the left knee joint correlated with the imaging findings. Synovial biopsy confirmed the tubercular etiology of the disease process|
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| Discussion|| |
Tubercular and rheumatoid arthritis may present with similar clinical presentation and may be difficult to differentiate. Laboratory investigations, including ESR, are often nonconclusive. Pulmonary involvement was reported in only one-third of the patients with tubercular arthritis. Appropriate imaging workup is the key for early diagnosis, which should mainly include plain radiographs and MRI. Uniform synovial thickening, large size of bone erosions, rim enhancement at the site of bone erosion, and extra-articular cystic lesions were reported to be more commonly associated with tubercular arthritis. Nonuniform synovial thickening with greater degree of synovial thickening is more likely with rheumatoid arthritis. Presence of enlarged popliteal nodes and relative preservation of the joint spaces are also more frequent in tubercular arthritis, which was the most important clue in our patient in favor of tubercular etiology. Synovial proliferation in patients with tuberculous arthritis is typically hypointense on T2-weighted images, which helps in the differentiation of tubercular arthritis from other causes of synovial arthropathies. Intra-articular rice bodies are shiny white structures of variable sizes, which may be seen on the radiograph, MRI, or arthroscopy. They are secondary to nonspecific response to chronic synovial inflammation in long-standing inflammatory arthritis but may also be seen in tubercular arthritis. Few small-sized lymph nodes may be seen in the popliteal fossa although they are usually not seen on MRI due to their small sizes and fatty changes. Contrast-enhanced MRI, however, allows detection and differentiation of the popliteal lymph nodes, which may be more common with tubercular arthritis.
As illustrated in this case, appropriate imaging workup, including plain radiographs and MRI study in patients with knee arthritis, may facilitate early and reliable differentiation of tubercular arthritis from rheumatoid arthritis for prompt treatment, which can be further confirmed with synovial fluid culture/biopsy.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]