Year : 2017 | Volume : 5 | Issue : 2 | Page : 74 - 76  

Case Reports
Tuberculous Synovitis of the knee with a discharging sinus

Syed Shafeequr Rahman1, V P Raman2, Indu Kapur3

1Professor Microbiology, 2Professor Orthopedics, 3Prof & HOD Microbiology, Malla Reddy Institute of Medical Sciences, Hyderabad

Corresponding author:

Dr. Syed Shafeequr Rahman



Extra pulmonary manifestations of tuberculosis are reported in less than one in five cases with the knee affected in 8% after the spine and hip. We report a case of tuberculous synovitis of the knee joint with a discharging sinus in a 40 year old female. The diagnosis was made by Ziehl – Neelson stain of the caseating discharge from the sinus, positive Mantoux test and radiological findings. The X-ray chest was normal. The patient responded well to anti-tuberculous treatment.

Key words: tuberculosis, knee joint, discharging sinus


Osteoarticular tuberculosis is an uncommon infection caused by Mycobacterium tuberculosis and constitutes 1-3% of all forms of TB. 30% of skeletal TB involves the joints, the knee being the third most commonly affected site after the spine and hip. The incidence of skeletal TB is increasing due to the emergence of multidrug resistant mycobacteria, increase in the number of immune-compromised patients and the AIDS pandemic.


We report a case of a 40 year old woman who presented with a 1 year history of pain and gradual swelling of the left knee. There was a history of fall 1 year back with injury to the left knee, the patient was able to get up immediately after the fall but had difficulty in walking. Intensity of the pain in the left knee increased gradually over a period of time. Her symptoms had gradually worsened and on admission she found it difficult to bear weight and had limited range of movement of the affected knee joint. There was no history of contact with tuberculous individuals. Her appetite was normal; there was no loss of weight. She was admitted in the Orthopedics Dept of Malla Reddy Hospital on 27/Aug/2015 with a provisional diagnosis of “Septic Arthritis”

Physical examination showed a swollen & erythmatous left knee with reduced flexion ability. A sinus discharging thick purulent material ?caseous was observed at the postero-lateral aspect of the left knee. The other joints were normal. Respiratory system examination revealed normal air entry in both the lung fields and the rest of the systemic examination was unremarkable except for mild anemia.

Laboratory examination revealed hemoglobin of 9 gm/dl. The ESR was 75 mm/1st hour, CRP 2.4 mg/dl, Mantoux positive with induration of 15mm. HIV serology was Non Reactive. Liver and Renal function tests were within normal limits except for a mild rise in AST and ALP. The patient was non-diabetic, non hypertensive; there was no history of any steroid intake. X-ray findings of the knee were unremarkable except for a subtle soft tissue swelling. X-ray chest and spine were normal. MRI left knee was suggestive of “Infective Arthritis ?TB” The sinus discharge was examined microscopically – it showed the presence of AFB. Culture for pyogenic organisms was Sterile, Culture by Radiometric method showed “No Growth of Mycobacterial species after 8 weeks of incubation.

Based on the AFB smear report, the patient was started on the following anti-tuberculous drugs – INH, Ethambutol, Rifampicin and Pyrizinamide. The patient responded well with gradual reduction of the knee swelling and drying of the sinus. The patient was discharged after 3 weeks of hospitalization and was advised for follow up in the OPD after 1 month.


Tuberculosis is an ancient disease. Mummified remains of ancient Egyptians show evidence of tuberculous disease. The earliest documented case of tuberculous spondylitis was written in Sanskrit dating back to 1500 BC1

Tuberculosis is no longer confined to underdeveloped or developing nations. An increase in incidence of patient with TB has been observed even in the developed countries due to the pandemic of HIV infection, immigration from endemic areas, alcoholism, chronic kidney diseases, immunosuppressive therapy, drug addiction, intra-articular steroid injections and systemic illness2. Although no age is exempt, TB usually affects elderly and debilitated patients.

Mycobacterium tuberculosis is a non motile, strictly aerobic slow growing bacilli (generation time – 20 hrs). Virulence of the organism is due to its ability to enter cells, to grow intracellularly & to interfere with the effects of toxic oxygen intermediates. Transmission is mainly airborne by droplet spread.

Skeletal tuberculosis is more common in children than in adults, probably owing to the greater amount of bone marrow present in immature bone. Clinical patterns of skeletal TB include spondylitis, osteomyelitis, and synovitis. In adults, TB shows a preponderance to the spine (40%), then the hip (25%), and the knee (8%). 3, 4 While extra pulmonary manifestations of TB are common, accounting for around 15-20% of cases in immuno competent patients5, the first presentation of the disease as a joint infection is rare. Primary bone infection with TB is less likely than hematogenous spread from a primary focus elsewhere. However, our patient showed no systemic symptoms of TB and a chest radiograph at the time of diagnosis was unremarkable. Pulmonary TB has been found to be present in only half of those found to have bone and joint disease. Tubercular arthritis is usually mono-articular. The large joints such as the hip and knee are most commonly involved. Lower extremity joints tend to be more frequently involved. Tubercular arthritis presents usually as chronic pain, swelling, local tenderness, warmth & progressive loss of function. Cold abscesses, sinuses and constitutional symptoms are also common features. 6, 7, 8

TB arthritis usually occurs as a result of metaphyseal TB osteomylitis crossing the epiphysial plate into the joint. This transphyseal spread is characteristic of TB and is not seen in pyogenic arthritis. After lodging in the joint synovium of the metaphysis there is marked joint effusion and thickening of the synovial membrane. The ensuing granulation tissue expands inwards from the joint periphery causing erosions at the bare area of the bone as well as the free surface of the articular cartilage. If left untreated, further erosions can occur and later progress to destruction of the articular surfaces. As the cartilage and bone destruction ensue, sequestrum formation occurs which involves both sides of the joint and hence is called a kissing sequestrum. 8, 9 Further extension to the para articular soft tissue may occur with formation of cold abscesses and sinuses

Because of the subtle nature of the symptoms, diagnostic evaluations are often not undertaken, until the disease has progressed. The possibility of tuberculous synovitis is often overlooked during clinical examination, therefore; it is necessary to increase clinical awareness to ensure early diagnosis and treatment.

Diagnosis of tubercular infection of bone and joints depends largely on suspicion of diagnosis, and in an age where the prevalence of the disease is rising, all clinicians should be aware of the potential of the infection. Joint TB may be suspected in a chronic case of joint pain, usually mono-articular. Although pulmonary TB may be absent at the time of presentation, patients may demonstrate systemic symptoms of fatigue, lethargy and weight loss. Pyrexia of unknown origin also may be a presenting feature. Radiographs demonstrate changes only after three to four weeks of infection, and initially soft tissue swelling maybe the predominant feature. Later, a classic triad of radiological findings, known as the Phemister triad 10 are seen, which include juxta-articular osteopenia, joint space narrowing, and erosions. Early changes are better demonstrated on MRI which has now become the mainstay of imaging in musculoskeletal tuberculosis. Joint effusion is hyper intense on T2 – weighted images7,8, but internal debris, septations, loose bodies and hemosiderin deposits due to bleeding may be hypo intense on both T1 and T2 sequences. Synovial thickening shows low to intermediate signal intensity on T2-weighted images and is hyper intense on T1- weighted images due to caseous material, which is atypical of other bony infections. This finding could be an important clue8.

Laboratory investigations may yield the classical, although non-specific findings of raised ESR, leucocytosis and high C-reactive protein11. Histological patterns in tissue specimens will show a central necrotic area surrounded by histiocytes and occasional giant cells with nuclei positioned at the margin of the cell12. Tuberculous synovitis is diagnosed by microscopy, culture of the synovial fluid and histopathological examination. According to western reports M. bovis is responsible for 80% of cases, while almost all cases in India are due to human strains- M. tuberculosis13. In the present case we could demonstrate AFB on primary smear of the synovial fluid which is observed in approximately 16% of cases only2. Culture positivity varies from 30.4% - 87%13 of cases. As the AFB was detected in the primary smear no histopathological examination was done.

Other differential diagnoses to be considered would be pyogenic arthritis, pigmented villonodular synovitis (PVNS) and juvenile rheumatoid arthritis (JRA). Pyogenic arthritis with a short course of illness can be differentiated on clinical grounds. PVNS shows intra-articular hypo intense hemosiderin deposits on T2 weighting, and absence of significant extra-articular soft tissue changes. JRA demonstrates earlier loss of articular space and is poly-articular in distribution.

Options for treatment once the diagnosis is confirmed must involve anti-tuberculous chemotherapy. Surgery may be indicated to improve symptoms and quality of life in some patients affected by joint infection. First line of treatment for joint TB revolves around four drugs: Isoniazid, Rifampicin, Pyrizinamide, and Ethambutol. Second- line treatments are also available to combat the increasingly common variant of multi-drug resistant TB (MDR-TB). Unlike for pulmonary TB, the treatment for bone and joint disease is a lengthier process, often requiring 12-18 months of chemotherapy14. Surgical management is occasionally indicated where there has been an unsatisfactory response to drug treatment, extensive bone involvement, or cold abscess formation, when synovectomy, drainage or debridement may be required. In later stages, where there is residual deformity, instability or subluxation, splinting, osteotomy or arthroplasty may be indicated. Partial synovectomy and more complex surgical procedures are restricted to joints that demonstrate severe cartilage destruction, joint deformity, abscess formation, multi-drug resistance or atypical mycobacteria11.

This case highlights the uncommon but increasingly recognized presentation of tuberculous arthritis of a joint. What may initially present as an uncomplicated arthritis, at a time when TB is increasing in prevalence must be considered as potential evidence of tuberculous arthritis, more in patients with a gradually worsening mono-articular arthritis and where risk factors for TB are present. Respiratory symptoms may be evident in only half of patients with skeletal involvement, and a multidisciplinary approach is required to offer patients an optimal outcome. It remains a controversial topic whether one can ever truly describe a case of primary tuberculosis of a joint; however, there remain isolated cases, such as that presented here, which seem to manifest only as extra pulmonary TB. These patients most likely represent a subset in whom TB is reactivated in some way many years after the primary infection and in whom the extra pulmonary symptoms predominate. It is these patients who often prove to be the most challenging to diagnose and treat.


  1. Watts HG, Lifeso RM. Tuberculosis of bones and joints. J Bone Joint Surg (Am) 1996;78: 288-98.
  2. Wanjari K, Baradkar VP, Mathur M et al. Tuberculous synovitis in a HIV positive patient- A Case Report. Indian J Med Microbiol 2009;27:72-75.
  3. Mittal R, Trikha V, Rastogi S. Tuberculosis of patella. The knee 2006;13:54-56.
  4. Adler AC. Tuberculosis: Old World treatment for New World disease. Clin Imaging 2009; 33:136.
  5. Sharma SK, Mohan A. Extra-pulmonary tuberculosis. Indian J Med Res 2004;120:316-53.
  6. Spiegel DA, Singh GK, Banskota AK et al. Tuberculosis of the musculoskeletal system. Tech Orthoped 2005;20(2):167-8.
  7. De Vuyst D, Vanhoenacker F, Gielen J et al. Imaging features of musculoskeletal tuberculosis. Eur J Radiol 2003;13:1809-19.
  8. Esteban PL, Soriano A, Tomas X et al. Tuberculous osteomylitis of the knee: A Case report. Arch Orthoped Trauma Surg 2004;124(10):708-10.
  9. Parmar H, Shah J, Patkar D et al. Tuberculous arthritis of the appendicular skeleton: MR Imaging appearances. Eur J Radiol 2004;52:300-9.
  10. Phemister DB. The effect of pressure on articular surfaces in pyogenic and tuberculous arthritis and its bearing on treatment. Ann Surg. 1924;4:481-500.
  11. Alberquerque – Jonathan G. Atypical tuberculosis of the knee joint. SA J Radiology 2006;10:28.
  12. Adler CP. Bone diseases: macroscopic, histological and radiological diagnosis of structural changes in the skeleton. Illustrated ed. Springer. 2000.
  13. Lakhanpal VP, Tuli SM, Singh H et al. The value of histology, culture and guinea pig examination in osteoarticular tuberculosis. Acta Orthop Scand 1974;45:36-42.
  14. Vaughan KD. Extra spinal osteoarticular tuberculosis: A forgotten entity? West Indian Med J 2005;54:202-6.


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