Tuberculosis and Other Unusual Infections

Chapter 23 Tuberculosis and Other Unusual Infections





Tuberculosis


Tuberculosis is transmitted primarily through inhalation or ingestion of Mycobacterium tuberculosis or Mycobacterium bovis. After exposure, the infection may be cleared by the host, lead to a primary infection, or can later be reactivated from a latent infection. Thereafter, lymphogenous, hematogenous, or contiguous extension to other tissues and organ systems may occur. The clinical presentation depends on the presence of isolated musculoskeletal involvement or miliary disease. Miliary disease has a rapid course, and constitutional symptoms include fever, chills, and cough, with accompanying pleuritic pain, weight loss, and fatigue. The patient may have acute or chronic symptoms.


Current estimates of the worldwide rate of tuberculosis infection are as high as one third of the world’s population. Tuberculosis remains one of the most frequent causes of death worldwide; the World Health Organization reported 1.3 million deaths in 2008. The highest rate of new cases is in Southeast Asia, but the highest rates of infection and mortality are in sub-Saharan Africa.




Musculoskeletal Involvement


Tuberculosis commonly affects the pulmonary system but can affect virtually any organ system of the body. Extrapulmonary involvement is noted in approximately 14% of patients, with 1% to 8% having osseous disease. Approximately 50% of patients with osseous tuberculosis have pulmonary involvement, and 30% to 50% of patients with osseous disease have vertebral involvement, most often in the lower thoracic spine. Frequently, a primary extraosseous lesion is not well delineated. Less frequently observed appendicular involvement usually affects major weight-bearing joints of the lower extremity, most commonly the hip and knee, followed in frequency by the foot, elbow, and hand. Virtually any other bone or joint can be involved. Soft tissue abscesses with sinus tracks have been described, as has tenosynovitis.


The spine is the most common (30% to 50%) site of osseous involvement, especially in elderly individuals; however, spinal involvement also is common in children and in young adults from developing countries. A primary accompanying lesion may be discovered from the pulmonary or urogenital system or from an unknown source. Lymphogenous and hematogenous spread have been implicated in thoracolumbar lesions but less often in cervical or sacral lesions. Usually, active spinal lesions involve a particular segment: two vertebral bodies and the corresponding disc. Some authors have speculated that these areas are affected most often because of the generous arterial and venous supply and the high oxygen pressure requirement of the tuberculosis bacilli. A peridiscal presentation occurs in approximately 80% of patients, with the anterior vertebral body affected and contiguous progression through subligamentous burrowing (anterior longitudinal ligament) and eventual extension to the adjacent vertebrae. Less frequently, lesions occur centrally in the vertebral body. These lesions are more difficult to diagnose and may mimic a tumor or contribute to significant spinal deformities. Patients may have intramedullary granulomas, arachnoiditis, segmental collapse with anterior wedging, and gibbus formation (Pott disease). The posterior elements of the spine are rarely the only sites affected. Perispinal abscesses with sinus extension to the skin also may arise and extend through tissue planes to reach intraperitoneal structures. They have been reported to occur as far distally as the popliteal fossa. Patients present with pain, weakness, and, in the late stages, paralysis.


Appendicular joint involvement typically affects the major weight-bearing joints of the lower extremities. Lesions involve the articular cartilage, which eventually is separated by granulomatous tissue. The trabecular zones of the bone are affected, with subchondral involvement affecting the weight-bearing capability of the joint, which may progress to significant accelerated joint surface degeneration. Pathological assessment reveals a central caseating lesion within necrotic tissue and multinucleated giant cells.


Other, less frequently involved joints include the ankle, foot, and upper extremity joints. Patients may present with a limp and a joint that is warm and swollen and has a decreased range of motion. Tuberculosis in a joint markedly decreases its functional use; even when adequately treated, the disease may reactivate in isolated regions. Peripheral joint involvement from tuberculosis can be confused with other rheumatological conditions (e.g., gout and rheumatoid arthritis).





Nonoperative Treatment of Appendicular Tuberculous Infections


The primary treatment objectives for tuberculosis of bone include halting the infection, limiting deformity, maintaining mobility, and reducing discomfort. A multidisciplinary approach with the assistance of infectious disease and pain management specialists is ideal. Other affiliated team members should include nurses, physical therapists, occupational therapists, and orthotists. Approximately 90% of patients can be treated conservatively with chemotherapy, relative rest, and guided remobilization. Adjunctive splinting (passive, dynamic, functional) and casting techniques are useful for marked or painful and progressive joint involvement. At times, destructive changes are markedly progressive and eventually may lead to fusion of the joint (e.g., elbow), so it is crucial to place the extremity in a position of function (elbow flexion 70 to 90 degrees) to obtain an optimal range for future functional use.


A judicious, well-guided chemotherapeutic approach to tuberculosis along with the assistance of an infectious disease specialist yields optimal results. The pharmacological agents and duration of treatment depend on the patient’s age, dissemination of disease, and accompanying medical conditions (e.g., AIDS, chronic renal failure). Several agents interact with medications typically used for immunosuppressed individuals, especially patients infected with human immunodeficiency virus (HIV). In these patients it may be necessary to adjust dosages and modify treatment regimens. Various combinations of medications are available, including isoniazid, rifamycin, ethambutol, pyrazinamide, and streptomycin. The typical approach consists of the use of a wide variety of combinations with an intensive initial treatment regimen and a gradual phasing out of pharmacological agents. Treatment duration can last 6 to 12 months. Because treatment for tuberculosis frequently is modified, readily available guidelines from the Centers for Disease Control and Prevention should be consulted. Although primary and secondary resistance to multiple medications has been reported, especially in countries outside the United States, most are isolated cases. Generally, only a small percentage of patients (<3%) are resistant to multiple chemotherapeutic agents.


Treatment should not be limited to the patient, but chemoprophylaxis should be considered in family members and other close contacts who have a positive tuberculosis skin test. Chemoprophylaxis is particularly important in individuals who are younger than age 50 to 55 years. Older individuals may not tolerate some of the medications typically used for prophylaxis. Treatment for chemoprophylaxis may last 3 to 12 months, depending on the conversion of the tuberculosis skin test.


Patients may require analgesics for pain. In severe cases, a pain management specialist should be consulted. Although the use of systemic corticosteroids to reduce symptoms in severe cases has been described, their use may mask a septic joint, and intraarticular corticosteroid injections can accelerate the destructive articular changes.



Operative Treatment


Operations applicable to bone and joint tuberculosis include (1) arthrotomy, including biopsy, synovectomy, and curettage with bone grafting of articular erosions; (2) curettage and bone grafting of extraarticular skeletal lesions; (3) resection of joints; (4) resection of bones; (5) evacuation or excision of soft tissue abscesses; (6) arthrodesis; and (7) amputation. There have been reports of arthroscopic treatment of joint tuberculosis, but these series have been small. The best success has occurred in the knee with the use of arthroscopic débridement.


Most authorities agree that effective antibiotic therapy should be started before surgery for tuberculosis. Miliary dissemination of the disease has been reported when surgery was done without adequate chemotherapeutic coverage.



Foot


In tuberculosis of the foot (Fig. 23-1), many bones may become involved, and a delay in diagnosis increases the risk of joint involvement. Operative indications include juxtaarticular focus or joint destruction. Bones with cystic changes typically respond better than rheumatological-appearing joints. When present, isolated lesions usually involve the calcaneus or talus. When several bones are involved, especially in adults, amputation is the procedure of choice. Curettage is indicated for isolated lesions even when sinuses are present.




Curettage for Tuberculous Lesions in the Foot




When lesions involve the subtalar or midtarsal joints, a triple arthrodesis is indicated (see Chapter 34). When the subtalar and the ankle joints are affected, posterior arthrodesis (see Chapter 11) of these joints can be done.








Jun 5, 2016 | Posted by in ORTHOPEDIC | Comments Off on Tuberculosis and Other Unusual Infections
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