Background
Pott disease, also know as tuberculous (TB) spondylitis, is a form of spinal infection typically caused by tuberculosis; it originates in a vertebral body and spreads to adjacent vertebrae, leading to narrowing of the disk space and potential vertebrae collapse. [1] Untreated, this can result in compression of the spinal cord, causing neurological deficits such as paraplegia. Patients with Pott disease may present with chronic, localized back pain and monoarticular arthritis, alongside potential paravertebral swelling indicating abscess formation. This condition is a classic presentation of extrapulmonary tuberculosis and is associated with significant morbidity and functional impairment.
The diagnostic challenge lies in the nonspecificity of early symptoms and delayed suspicion levels, necessitating a thorough clinical assessment. [1] Diagnosis typically is based on a combination of clinical presentation, imaging findings, and obtaining samples for bacteriological, pathological, or molecular confirmation. [2] Treatment protocol involves a prolonged course of medical therapy in line with current recommendations, with surgical intervention considered on a case-by-case basis. Early recognition and appropriate management of Pott disease are crucial to prevent severe complications and long-term disability in affected individuals.
Pott disease is one of the oldest demonstrated diseases of humankind, having been documented in spinal remains from the Iron Age in Europe and in ancient mummies from Egypt and the Pacific coast of South America. [3, 4, 5] In 1779, Percivall Pott, for whom the disease is named, presented the classic description of spinal tuberculosis. (See the image below.) [6]
MRI of a 31-year-old man with tuberculosis of the spine. Images show the thoracic spine before and after an infusion of intravenous gadolinium contrast. The abscess and subsequent destruction of the T11-T12 disc interspace is marked with arrowheads. Vertebral body alignment is normal. Courtesy of Mark C. Diamond, MD, and J. Antonio Bouffard, MD, Detroit, Mich.
Since the advent of antituberculous drugs and improved public health measures, spinal tuberculosis has become rare in industrialized countries, although it is still a significant cause of disease in developing nations. Tuberculous involvement of the spine has the potential to cause serious morbidity, including permanent neurologic deficits and severe deformities. Medical treatment or combined medical and surgical strategies can control the disease in most patients. [7, 8]
Pathophysiology
Pott disease usually results from an extraspinal source of infection and hematogenous dissemination. [1] Pott disease manifests as a combination of osteomyelitis and arthritis that usually involves more than one vertebra. The anterior aspect of the vertebral body adjacent to the subchondral plate is usually affected. Tuberculosis may spread from that area to adjacent intervertebral disks. In adults, disk disease is secondary to the spread of infection from the vertebral body. In children, the disk, because it is vascularized, can be the primary site. [9]
Progressive bone destruction leads to vertebral collapse and kyphosis. The spinal canal can be narrowed by abscesses, granulation tissue, or direct dural invasion, leading to spinal cord compression and neurologic deficits.
The kyphotic deformity is caused by collapse in the anterior spine. Lesions in the thoracic spine are more likely to lead to kyphosis than those in the lumbar spine. A cold abscess can occur if the infection extends to adjacent ligaments and soft tissues. Abscesses in the lumbar region may descend down the sheath of the psoas muscle to the femoral trigone region and eventually erode into the skin.
Epidemiology
Globally, extrapulmonary tuberculosis (TB) represented 14% of the 6.4 million TB cases reported in 2017, ranging from 8% in the WHO Western Pacific Region to 24% in the WHO Eastern Mediterranean Region. [10] Relative frequencies of different extrapulmonary forms of TB are not reported. More recent yearly global WHO reports do not include figures for extrapulmonary TB. After the decreased reporting numbers in the COVID-19 pandemic years, the total number of diagnoses was 7.5 million cases in 2022. [11] In the United States, the proportion of extrapulmonary cases in 2017 was 20.8% (1,887 cases). Of these, bone and joint involvement was the third most common (9.8% of cases), after lymphatic and pleural disease. [12]
Occurrence in the United States
Between 2002 and 2011, a total of 75,858 cases of TB were reported in the United States. Of these, 2,789 cases (3.7%) involved the spine. The median age among affected individuals was 51 years; 61% of cases involved males, and 11% had diabetes mellitus. Twenty percent required surgery, most commonly of the thoracic-lumbar segments. [13]
Although the incidence of tuberculosis increased in the late 1980s to early 1990s, the total number of cases has decreased. The frequency of extrapulmonary tuberculosis has remained stable. Bone and soft-tissue tuberculosis accounts for approximately 10-15% of extrapulmonary tuberculosis cases and between 1% and 2% of total cases. Tuberculous spondylitis is the most common manifestation of musculoskeletal tuberculosis, accounting for approximately 40-50% of cases. These figures are roughly similar for North American and international series. [14, 15]
International occurrence
Approximately 1-2% of total tuberculosis cases are attributable to Pott disease. In the Netherlands, between 1993 and 2001, tuberculosis of the bone and joints accounted for 3.5% of all tuberculosis cases (0.2-1.1% in patients of European origin, and 2.3-6.3% in patients of non-European origin). [16]
Race-, sex-, and age-related demographics
Data from Los Angeles and New York show that musculoskeletal tuberculosis affects primarily African Americans, Hispanic Americans, Asian Americans, and foreign-born individuals.
As with other forms of tuberculosis, the frequency of Pott disease is related to socioeconomic factors and historical exposure to the infection.
Although some series have found that Pott disease does not have a sexual predilection, the disease is more common in males (male-to-female ratio of 1.5-2:1).
In the United States and other developed countries, Pott disease occurs primarily in adults. In countries with higher rates of Pott disease, involvement in young adults and older children predominates. [17, 18]
Prognosis
Current treatment modalities are highly effective against Pott disease if the disorder is not complicated by severe deformity or established neurologic deficit.
Deformity and motor deficit are the most serious consequences of Pott disease and continue to be a serious problem when diagnosis is delayed or presentation of the patient is in advanced stages of the disease. [19]
Therapy compliance and drug resistance are additional factors that significantly affect individual outcomes.
Paraplegia resulting from cord compression caused by the active disease usually responds well to chemotherapy. However, paraplegia can manifest or persist during healing because of permanent spinal cord damage.
Operative decompression can greatly increase the recovery rate, offering a means of treatment when medical therapy does not bring rapid improvement.
Careful long-term follow up is also recommended, since late-onset complications can still occur (disease reactivation, late instability or deformity). [20]
Morbidity
Pott disease is the most dangerous form of musculoskeletal tuberculosis because it can cause bone destruction, deformity, and paraplegia.
Pott disease most commonly involves the thoracic and lumbosacral spine. However, published series have shown some variation. [21, 22, 23, 24] The lower thoracic vertebrae make up the most common area of involvement (40-50%), followed closely by the lumbar spine (35-45%). In other series, proportions are similar but favor lumbar spine involvement. [25] Approximately 10% of Pott disease cases involve the cervical spine.
Patient Education
Patients with Pott disease should be instructed on the importance of therapy compliance.
Please see Tuberculosis for more detail.
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MRI of a 31-year-old man with tuberculosis of the spine. Images show the thoracic spine before and after an infusion of intravenous gadolinium contrast. The abscess and subsequent destruction of the T11-T12 disc interspace is marked with arrowheads. Vertebral body alignment is normal. Courtesy of Mark C. Diamond, MD, and J. Antonio Bouffard, MD, Detroit, Mich.
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MRI of the T11 in a 31-year-old man with tuberculosis of the spine. Extensive bone destruction consistent with tuberculous osteomyelitis is evident. The spinal cord has normal caliber and signal. No evidence of spinal cord compression or significant spinal stenosis is distinguishable. Courtesy of Mark C. Diamond, MD, and J. Antonio Bouffard, MD, Detroit, Mich.
