Pathogenesis and limits of conservative therapy
The development of tuberculous spondylitis is accompanied by the formation of necrotic and caseous masses. The body attempts to wall off the inflammation by building an avascular granulation capsule made of connective tissue around the focus, which subsequently undergoes sclerosis.
It is this avascular zone that becomes the primary barrier to antibacterial therapy—drugs physically cannot reach the pathogen in the necessary concentration. As a result:
- The infectious process transitions into a latent form.
- Chronic inflammation persists for many years, maintaining constant intoxication.
- The zone of destruction gradually expands, involving the bodies of adjacent vertebrae.
- Severe functional impairments and complications develop despite ongoing specific therapy.
Gold standard of treatment and preoperative preparation
Although conservative treatment is a mandatory component, it is often insufficient for the complete eradication of the focus. If specific therapy yields no results within 1.5–2 months, the issue of surgical intervention is raised. The combined therapeutic-surgical method is considered the most effective.
The success of reconstructive surgery depends on thorough preoperative preparation, which is carried out in two directions simultaneously:
- Antibacterial preparation. The patient is prescribed a combination of three tuberculostatic agents: streptomycin, isoniazid (or pyrazinamide), and rifampicin. The course lasts for 1–2 months until signs of decreased activity and containment of the process appear.
- Local preparation. Includes unloading the affected segment using traction on an inclined plane and physical therapy to maintain limb muscle tone.
Before starting preparation, a comprehensive clinical, radiological, functional, and neuro-orthopedic examination is performed to determine the scope of the upcoming surgery.
Indications for surgical treatment
Surgical intervention makes it possible to remove the source of infection, enhance the effect of medications, shorten treatment time, and correct spinal deformity.
Planned indications include:
- Localized foci filled with caseous masses.
- Marginal and other destructive forms with paravertebral or prevertebral abscesses in the stage of clinical compensation.
- Progression of destruction and development of paraspinal abscesses despite a full course of antibiotics (1.5–2 months).
Emergency indication is only one: the development of spinal cord compression accompanied by pronounced neurological deficit.
Essence of surgical intervention
The main task of the surgeon is to achieve the formation of a durable bone block between the bodies of the affected vertebrae. To achieve this, the following steps are performed:
- Opening and adequate drainage of abscesses.
- Removal of sequestra and radical excision of altered soft tissues.
- Resection of vertebral bodies strictly within healthy bone tissue. In cases of spinal cord compression, transcorporal decompression is indicated (subtotal resection up to the posterior longitudinal ligament).
- Bone-graft reconstruction of the resulting defect (interbody fusion) with simultaneous correction of kyphosis.
To prevent bone grafts from migrating, additional posterior fixation of the spine using metal structures or devices is permitted.
Extravertebral lesions: joint tuberculosis
Tuberculous infection can also affect large joints of the extremities, which is particularly characteristic of childhood. Unlike spondylitis, the mechanism of development here begins with general hematogenous dissemination. Mycobacteria enter the metaphyseal bone regions, forming a primary focus, from which the process spreads to the articular surfaces and destroys them. Primary tuberculous arthritis (direct involvement of the synovial membrane) is extremely rare.
The clinical picture is divided into two phases:
- Pre-arthritic phase. Bone osteitis develops. It proceeds covertly, with no symptoms of intoxication. Only vague periarticular pain, transient contractures, and moderate synovitis are noted.
- Arthritic phase. The infection breaks into the joint. In the early stage, pain becomes distinct, and muscles atrophy due to reduced load. Signs of general intoxication appear. Alexrov's sign is characteristic—a specific thickening of the skin fold over the affected elbow or knee joint. In the acute stage, intoxication increases significantly.
Briefly: answers to topical questions
What radiological features are characteristic of the initial stage of tuberculous spondylitis?
The initial (prespondylitic) stage of tuberculous spondylitis is characterized by signs of primary osteitis. Radiographs reveal:
- A limited cavity — forming directly within the body of the affected vertebra.
- Destruction of bone trabeculae — accompanied by rarefaction of bone tissue and destruction of trabeculae.
- Lytic lesions (lytic lesions) — have clear contours and proceed with weak regeneration of the surrounding bone and a poorly expressed periosteal reaction.
In acute infection, the radiological picture may remain within normal limits.
What stages are distinguished in the clinical course of tuberculous spondylitis according to Kornev?
Three phases are distinguished in the clinical course of tuberculous spondylitis:
- Prespondylitic phase — the onset and development of primary osteitis in the vertebral body; the disease is practically undiagnosed at this stage due to the absence of clinical manifestations.
- Spondylitic phase — destruction of the vertebral body, transition of the process to adjacent discs and vertebral bodies, and the appearance of specific symptoms.
- Post-spondylitic phase — outcome of the disease and stabilization of the process; orthopedic and neurological consequences may persist.
What specific complications develop with the progression of tuberculous spondylitis?
With the progression of tuberculous spondylitis, severe orthopedic and neurological complications develop. Specific consequences include:
- Cold abscesses (cold abscesses) — paraosseous accumulations of pus without pronounced signs of inflammation, capable of forming in distant areas (for example, in the iliac regions).
- Purulent fistulae (sinus formation) — form when abscesses spread into soft tissues with subsequent skin ulceration.
- Neurological disorders — compression of the spinal cord by displaced vertebrae causes paresis, limb paralysis, and pelvic organ dysfunction.
- Spinal deformities — formation of kyphosis, scoliosis, or sharp-angled gibbus (Gibbus deformity) as a result of compression fractures.
Which parts of the spine are most frequently affected in tuberculous spondylitis?
In tuberculous spondylitis, the thoracolumbar junction is most frequently affected. The incidence decreases in both directions from this level, but the process can occur in any part of the spine. Involvement of the posterior structures of the vertebra is rare but specific to patients of Asian descent.
The classical preoperative therapy regimen can be remembered by the abbreviation SIR: Streptomycin, Isoniazid, Rifampicin.
Class and exam questions
Why is medication alone insufficient in tuberculous spondylitis?
Due to the formation of an avascular (connective tissue) capsule around the focus. Antibacterial drugs cannot penetrate through it in sufficient concentration.
In what cases is emergency surgery indicated?
Emergency surgical intervention is indicated for destructive forms complicated by spinal cord compression with pronounced neurological symptoms.
What is Alexandrov's sign?
This is a clinical sign of tuberculous arthritis in the early stage, manifested by the thickening of a skin fold when pinching the skin over the affected elbow or knee joint with the fingers.
How long does conservative therapy last before deciding on surgery?
Specific antibacterial therapy is administered for 1.5–2 months. If there is no clinical and radiological improvement during this time, the patient is prepared for surgery.
What else to study on this topic
- Radiological signs of loss of activity and demarcation of the tuberculosis process
- Technique of interbody fusion for vertebral body defects
- Types of metal implants for posterior spinal fixation
- Differential diagnosis of transient contractures in the prearthritic phase
- Assessment of neurological status in spinal cord compression
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