Keywords
skeletal - tuberculosis - knee - arthritis - therapy
Introduction
Although tuberculosis (TB) is not a common disease in industrialized countries, it
remains a common and endemic illness in developing countries.[1] Every year, approximately 10.4 million infected people develop active disease, resulting
in almost 1.4 million deaths annually.[2]
Although the majority of newly diagnosed cases have pulmonary TB, a considerable number
of organs, bones, and joints can be affected too. In particular, skeletal TB accounts
for approximately 10 to 35% of extrapulmonary cases,[3] and the knee is the third most frequently affected site after spine and hip.[4] In Italy, TB incidence is 10 cases per 100,000 inhabitants.[5] According to this data, active pulmonary TB was simultaneously detected only in
one third of patients suffering from skeletal TB. Osteoarticular TB remained a diagnostic
challenge, because in the majority of cases, the disease is detected late when lesions
are paucibacillary and smears are in most cases not diriment.[6]
[7]
The aim of this review was to report a recent clinical case of TB of knee to highlight
that a high level of suspicion might be adopted to establish the correct diagnosis
of joint TB. Besides, an update on current concepts of clinical and surgery therapies
is given.
Case Presentation
A 29-year-old Philippine woman suffering from knee pain was referred to our Septic
Orthopaedic Care Unit in 2015. We obtained patient consent to publish her clinical
case data.
According to her history, she complained of continuous and progressive lateral knee
pain since 1 year that forced her to use two crutches to walk. No constitutional symptoms
were reported. She had visited her native country few months before symptoms appeared
and reported that one of her brothers and her father had just been treated for pulmonary
TB. At physical examination, her knee was swollen and loss of motion was observed
(range of movement 0–100 degrees). Pressure pain could be induced on lateral femoral
condyle (LFC). Liquid collected from knee arthrocentesis was clear. Blood investigations
revealed elevated C-reactive protein (CRP) of 5.4 mg/dL, erythrocyte sedimentation
rate (ESR) of 35 mm/h, and white blood cell count of 9.19 × 109/L. Chest X-ray showed obscured costodiaphragmatic recesses and signs of a previous
pleurisy. Knee X-ray showed a bone lesion in the LFC ([Fig. 1]). Magnetic resonance showed a 1.5 × 1.5 cm focal lesion with subcortical development,
hypointense in T1-weighted sequences, and with hypointense core plus hyperintense
surrounding in T2-weighted sequences ([Fig. 2]). Computed tomography (CT) scans confirmed the lesion, showing a cortical bone interruption
surrounded by an area of osteolysis in the LFC.
Fig. 1 X-ray of the knee showing a bone lesion (arrow) of lateral femoral condyle.
Fig. 2 T2-weighted MR scan with hypointense core plus hyperintense surrounding the lesion
(arrow). MR, magnetic resonance.
The patient underwent a surgical LFC curettage and synovectomy with synovial biopsy
that was found to be inflamed and hypertrophied with multiple “rice bodies” ([Fig. 3]). The histopathologic exam revealed granulomatous inflammation with caseous necrosis,
suggestive of TB. Polymerase chain reaction (PCR) test for Mycobacterium tuberculosis DNA was positive, resulting in an isoniazid monoresistance profile. The patient was
treated with a polytherapy consisting of rifampin, pyrazinamide, and ethambutol that
continued for 1 year. At 2-year follow-up, the patient reported relief from pain and
swelling with knee movements from 0 to 120 degrees.
Fig. 3 Rice bodies in the lesion of lateral femoral condyle.
Discussion
In low-incidence European countries, a substantial proportion of TB patients comes
from developing countries, where the disease is more common among young adults. In
our reported case, the patient was a 29-year-old Philippine woman.
Identification of M. tuberculosis is essential for definitive diagnosis of TB arthritis based on culture or histopathologic
examinations. Acid-fast stain test results positive in only 0 to 5% of cases, while
M. tuberculosis is isolated in approximately 60 to 90% of cases.[8]
Medical treatment of TB is necessarily based on a combination therapy, divided into
two phases: the initial phase (usually based on four drugs) lasts 2 months, and the
continuation phase (usually with two drugs administered) can last from 4 to 7 months
or more in specific cases.[9]
[10] The optimal duration of therapy in musculoskeletal TB is uncertain. For most patients,
6 to 9 months of treatment is enough,[11] but a longer duration (9–12 months) is warranted for patients with extensive or
advanced disease.[12] The approach to treatment of monoresistant TB depends on the drug to which the isolate
is resistant. Isoniazid monoresistance is the most common type as in our case report.
These patients are usually treated with rifampin, pyrazinamide, and ethambutol for
6 to 9 months, with no difference between initial and continuation phase.[13]
[14] Effective therapy for isoniazid monoresistant TB is associated with very high bacteriologic
and clinical response rates (> 95%) and low relapse rates (<5%).[13]
When knee TB is limited to bones, the most common treatment in adult patients is arthrotomy
and curettage of the lesion. Complete debridement is crucial for an effective treatment
of TB arthritis, which can eradicate infected tissues to lower risks of disease reactivation.
According to Vohra et al,[15] CT scan and MR are helpful in accurately localizing skeletal lesions resulting from
TB, while surgical resection of the pathological mass can completely eliminate the
symptoms.[16] The prognosis is better in articular disease, as there is less deformity as well
as less residual pain and disability.[17]
Old surgical options consisted of articular debridement and joint fusion as the best
treatment, but postoperative joint function was poor and had a serious impact on patients'
working and daily living activities. Moreover, a 1 to 9% of recurrence rate has been
reported. Unfortunately, sometimes joint fusion is the only viable treatment option.
Arthrodesis may be more appropriate for patients with minimal bone loss and broad
cancellous surface, which allows a good bone apposition and compression.
Patients with end-stage TB arthritis, severe damage to joints, and periarticular abscess
who undergo a single debridement may have a relatively higher recurrence rate.[18] Teo et al[19] reported on an isolated case of highly erosive knee TB in a 35-year-old fit Burmese
worker who had migrated to Malaysia. The patient was first treated with arthrotomy,
debridement, and full-length back slab immobilization, but the treatment was unsuccessful
and 5 months later, a knee arthrodesis was performed using an Ilizarov frame.[19] Open debridement and arthrodesis are the main treatment options for this condition
in adults. Several techniques have been described for knee fusion, including internal
fixation with single plate, double plate, antegrade locking nail, modular intramedullary
nails, and external fixation. Tang et al[20] reported on 26 patients who underwent open debridement and fusion with a unilateral external
fixator (EF) combined with crossed cannulated screws, intended to increase stiffness
while limiting the size of the EF, thereby minimizing the risk of TB dissemination.
Complete fusion was achieved within 8 months, with a mean postoperative alignment
of 5.4 degrees valgus and 12.5 degrees flexion, and a mean leg length discrepancy
of 2.8 cm.[20]
Total knee arthroplasty (TKA) can help patients to get relief from pain and restoration
of a good knee function. However, a stationary knee TB is required for this kind of
treatment. Attempt to eradicate TB should be made before implanting a TKA. Habaxi
et al[21] suggested prolonging anti-TB treatment until there was a downward trend in ESR levels,
possibly under 40 mm/h. Furthermore, surgeons should make sure to clean out the joint
capsule and synovial tissue necrosis, as well as to check for sinuses.
Habaxi et al[21] reported on 10 patients where no dislocations or aseptic loosening of TKA was reported
with an average HSS score of 86.7 ± 5.4 and ROM improvement to 95 ± 5 degrees at follow-up;
only one patient had recurrence and a two-stage revision operation was performed.
Some authors believe that cemented TKA should be preferred in knee TB to fill the
possible bone defects. Moreover, the production of heat during bone cement polymerization
can kill Mycobacterium and lower the recurrence rate.[21]
Klein and Jacquette[22] reported a case of TB arthritis of the knee in a 36-year-old Haitian woman treated
with TKA that failed due to a misinterpreted diagnosis. A static antibiotic-impregnated
cement spacer after removal of prosthetic components was used, and a new prosthesis
was implanted after 7 months of four-drug regimen, added with a daily oral moxifloxacin
and thrice weekly intravenous amikacin for sterilization of joint space.
TB arthritis after TKA is clinically indistinguishable from infections caused by most
pathogenic bacteria. Although it is a rare presentation, it should be easily detected,
especially in patients with predisposing conditions with a history of TB infection.
Indeed, late diagnosis of TB after TKA requires implant removal. However, when patients
are promptly treated, joint retention is possible and could have long viability.
In a suspected TB infection after TKA, empiric anti-TB treatment should be administered
based on clinical diagnosis, and since a viable pathogen is required for susceptibility
testing, alternative culture material might be used (wound drainage, joint aspiration,
lung or genitourinary tract samples).[22] The evolution of the treatment is often favorable. Lara-Oya et al[23] published a literature review on 17 cases reporting a disease onset between 2 months
and 15 years (45 months average) after TKA with only one failed case.
TB of the patellar bone is rare with an incidence of 0.09 to 0.15%.[24] MacLean et al[25] published a case of TB of the patella mimicking prepatellar bursitis. The first
diagnosis was based on clinical appearance and on a Staphylococcus aureus positive test of fluid collected from bursitis. Successively, X-ray showed a central
nidus of necrotic bone in the patella and MRI confirmed osteomyelitis. Treatment options
depend on the extent and spread of osteomyelitis. Curettage may be used to remove
the sequestrum and establish a tissue diagnosis. Prepatellar bursitis is frequent,
but in high-risk patients, further diagnostic tests and imaging studies are required
to facilitate diagnosis.[17]
[25]
[26]
Conclusion
The greatest challenge in diagnosing osteoarticular TB is to take diagnosis of the
disease into consideration, especially in nonendemic countries where TB is infrequent.
A high level of suspicion for TB should be recommended in every infection of knee
joint, especially after TKA.
