Osteomyelitis

Causes and mechanism of development (pathogenesis)

The disease is caused by various microorganisms. Most often, this is nonspecific flora (staphylococci, streptococci, pneumococci, enterobacteria) or microbial associations. Specific infections (tuberculosis, typhoid fever, syphilis) and fungal infections (actinomycosis) are significantly less common. The infection is introduced into the bone marrow via the bloodstream (hematogenously) from primary foci: boils, inflamed tonsils, carious teeth, or phlegmons.

The development of the disease is explained by two main concepts:

• Bobrov-Lexer embolic theory: links the settling of bacteria in the epiphyses and metaphyses with sluggish blood flow in their dense, looped capillary network, which is characteristic of childhood.
• S.M. Derizhanov allergic theory: states that bacteremia alone is not enough to initiate a purulent process. A mandatory condition is the sensitization of the body (altered reactivity) due to previous infections or exposure to decay products.

Inside the bone, pus spreads through the medullary canal and passes through osteons to the subperiosteal space, stripping the periosteum. Due to inflammation, increased pressure, and periosteal stripping, blood supply is impaired, leading to bone necrosis and the formation of sequestra (dead areas). Soon, the abscess ruptures into the soft tissues, forming a paraosseous phlegmon, and then opens externally with the formation of fistulae.

Forms of acute hematogenous osteomyelitis

The disease begins abruptly with sharp, bursting pain in the limb, which becomes unbearable with the slightest movement. Tachycardia, lethargy, pallor of the skin, and high fever occur. Depending on the severity, three forms are distinguished:

1. Toxic (fulminant): rare. Massive septic intoxication predominates. The process develops rapidly, local bone changes do not have time to form, and the patient may die within the first 24 hours.
2. Septicopyemic (severe): purulent-destructive foci appear simultaneously in several bones in a short time. The development of metastatic abscesses in internal organs (liver, lungs, kidneys) is characteristic.
3. Local: the most common. Intoxication is less pronounced, and local symptoms in the area of a single purulent focus come to the fore. Most often, this form transitions into a chronic stage.

Chronic osteomyelitis

The chronic form is characterized by a wave-like course: phases of remission are replaced by relapses against the background of hypothermia, trauma, or weakened immunity.

Main diagnostic markers of the chronic process:

• Presence of a bone sequestrum or osteomyelitic cavity;
• Functioning purulent fistula;
• Signs of osteosclerosis on radiography.

During a relapse, the patient's condition worsens. If the old fistula is closed, pus begins to accumulate inside: skin hyperemia appears, severe pain develops, tissues become indurated, and the fluctuation sign occurs until the abscess ruptures the skin again.

A special variant is fibrous osteomyelitis (panostitis). There is no destruction and sequestra in this condition: the bone marrow is replaced by connective tissue, which eventually becomes sclerotic and almost completely metaplasizes into bone.

Principles of Diagnosis and Treatment

The diagnosis is confirmed by radiography (the main method for visualizing sequestra and cavities), fistulography (study of the direction of fistulous tracts), and mandatory microbiological culture. Immunological tests are also performed, showing a decrease in complement titer and phagocytic activity.

Conservative therapy: includes potent antibiotic therapy with osteotropic drugs (lincomycin, gentamicin) intraosseously or regionally, immunotherapy (hyperimmune plasma, gamma globulin), detoxification, and strict immobilization.

Surgical treatment:

• In the acute stage: early decompressive drainage. Several burr holes are drilled in the bone, through which drains are installed for continuous lavage with antiseptics (chlorhexidine, sodium hypochlorite) for 7–10 days.
• In the chronic stage: radical surgery is indicated — necrectomy (sequestrectomy). All sequestra and granulations are removed, and fistulae are excised. Then, plasty of the resulting cavity is performed, most commonly using a full-fledged muscle flap on a proximal feeding pedicle. The wound is sutured, and long-term active flush drainage with suction is established.

Class and exam questions

What else to study on this topic

• Clinical presentation of acute purulent intoxication in adolescents
• Surgical technique for forming a pedicled muscle flap
• Biopolymer materials and chondroplasty in the treatment of osteomyelitis
• Features of the immunological status in the chronic form of the disease

Other topics from the section "CHAPTER 11. SURGICAL INFECTION (PURULENT-INFLAMMATORY DISEASES)"

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