Tuberculosis

Skeletal tuberculosis
Authors
Malcolm McDonald, PhD, FRACP, FRCPA
Daniel J Sexton, MD
Section Editors
Daniel J Sexton, MD
C Fordham von Reyn, MD
Deputy Editor
Elinor L Baron, MD, DTMH
Last literature review version 18.3: septiembre 2010 | This topic last updated: enero 21, 2010 (More)
INTRODUCTION — Tuberculosis (TB), including skeletal tuberculosis, is an ancient infection based uponevidence from remains.
* The typical features of spinal TB have been identified in Egyptian mummies dating back to almost 4000 BC [1].
* Analysis of 483 pre-Columbian skeletons from Chile showed lesions consistent with bony tuberculosis in 2 percent [2].
* DNA analysis revealed Mycobacterium tuberculosis in a vertebral lesion of a 12 year-old girl who lived about 1000 AD [2].
Themajor clinical issues related to skeletal TB will be reviewed here.
EPIDEMIOLOGY — Bone and joint infection may account for 10 to 35 percent of cases of extrapulmonary tuberculosis and, overall, for almost 2 percent of all cases of TB [3-7]. Musculoskeletal tuberculosis involves the spine in approximately one-half of patients. The next most common syndrome is tuberculous arthritis, followed infrequency by extraspinal tuberculous osteomyelitis [8].
* Spinal TB (Pott's disease) most often affects the lumbar and lower thoracic region; upper thoracic and cervical disease is less common but potentially more disabling [9,10]. Tuberculous abscess, a complication of spinal TB, is frequently bilateral.
* Tuberculous arthritis tends to occur in the weight-bearing joints, the hip and theknee, and is usually monoarticular. However, multifocal lesions are reported in 10 to 15 percent of cases in developing countries [11].
A retrospective multicenter review from France of all cases of musculoskeletal tuberculosis from 1980 through 1994 documented 206 cases of which 103 involved the spine; 68 percent of these patients were foreign-born, the majority from Africa [12]. None of thepatients in this series were HIV-positive.
PATHOGENESIS — The bacillemia associated with primary M. tuberculosis infection typically seeds organisms throughout the body; bone and synovium may be infected during this stage. Vertebral bodies are especially vulnerable to this seeding since blood flow remains high even in adulthood. In the majority of cases, small foci of disseminated infection areconfined by local immune processes and the extrapulmonary infection is clinically inapparent.
Following primary infection, there is evidence of ongoing containment of small, reactivating foci by the cellular immune response. In addition, CD4 and CD8 lymphocytes play critical roles, as does IFN-gamma [13]. (See "Role of cytokines in the immune system", section on 'T cell subsets'.)
Genetic determinantsmay also play a role in maintaining immunity. When local immune defenses fail, as with poor nutrition, advancing age, HIV infection, or renal failure, reactivation with progression to clinically apparent disease may occur [14].
Thus, active tuberculosis can develop immediately or after decades. In highly endemic regions, musculoskeletal TB usually manifests within about one year after primarylung infection and mainly occurs in the young. In industrialized countries, bony tuberculosis is more commonly associated with late reactivation of infection and mainly occurs in adults.
Rarely, bones and joints are involved in contiguous spread of TB from another site. Contiguous spread from an apical pulmonary focus of active TB, for example, can lead to atlantoaxial TB, involving the jointbetween the first and second cervical vertebrae [15].
Sites of musculoskeletal infection — In spinal TB, infection usually starts in the anteroinferior aspect of the cancellous vertebral body with inflammatory bone destruction and caseating necrosis. Once the process is established, active infection spreads down behind the anterior ligament to involve the adjacent vertebral body. Local destruction...