Chronic hematogenous osteomyelitis

Causes of transition to the chronic form

As a rule, Osteomyelitis chronica naturally succeeds the acute period of the disease. Primary chronic forms are encountered in surgical practice as a rare exception. The morphological substrate of this transition is the final separation of sequestra (dead bone fragments) or the formation of a cavity at the site of osteolysis. Usually, these changes occur 2–3 months after the onset of infection.

Main causes of chronic inflammation:

• Late initiation of treatment.
• Antibiotic therapy errors: unjustifiably early discontinuation of the course or ignoring changes in microflora sensitivity.
• Insufficient drainage: the surgeon may fail to dissect the periosteum over the entire affected area or create burr holes that do not correspond to the actual extent of the pathological process.

Phases of the course and clinical picture

The disease proceeds cyclically. After the phlegmon opens (spontaneously or surgically), the exacerbation ends. At this point, the patient's local inflammation subsides, systemic intoxication decreases, and body temperature returns to subfebrile levels. Meanwhile, the purulent fistula may either close or continue to function. Thus, the remission phase begins, which can be replaced by a new relapse at any moment.

Unlike post-traumatic (including gunshot) osteomyelitis, in which inflammation and fistulae are limited to the fracture area, chronic hematogenous osteomyelitis has a number of features:

1. Scale of the lesion. The process covers a significant length of the bone, including the metaepiphysis and diaphysis.
2. Localization of fistulae. Fistulous tracts can open in various places and are often multiple.
3. Systemic manifestations. Patients suffer from pronounced chronic purulent intoxication. Blood tests reveal leukocytosis, elevated ESR, and dysproteinemia. Renal dysfunction frequently develops.

Instrumental and imaging diagnostics

To choose the tactics of surgical treatment, it is extremely important to accurately visualize the pathological focus. Classical radiography makes it possible to distinguish the chronic stage from the acute one: while acute osteomyelitis shows only periostitis and a subperiosteal abscess, chronic osteomyelitis clearly demonstrates a sequestrum and the surrounding involucrum (a capsule made of newly formed bone tissue).

In addition to X-rays, the following methods are used:

• Computed tomography (CT): of immense value for detecting subtle structural changes. CT allows for the detection of the tiniest sequestra, detailed examination of osteomyelitic foci, and assessment of the condition of surrounding soft tissues (e.g., in lesions of the pelvic bones or femur).
• Bone scintigraphy: a radioisotope method using gallium or technetium pyrophosphate. It helps in differential diagnosis with bone tumors. In addition, scintigraphy is indispensable for the early diagnosis of acute inflammation when X-rays are still uninformative.
• Fistulography: a radiopaque study of fistulous tracts. It is extremely important for planning the scope of surgery and choosing a safe surgical approach (often used for lesions of the ilium or femur).

Principles of surgical treatment and drainage

Radical treatment consists of sequestrectomy followed by the elimination of the bone cavity. One of the effective methods for eliminating dead space, especially in hematogenous osteomyelitis of the femur, is muscle-flap plasty.

The most critical stage of the operation is proper drainage of the postoperative cavity. Two main methods are used:

• Through-and-through irrigation drainage: provides continuous sanation (lavage). The antiseptic enters from a reservoir via the inflow tube, washes the bone cavity, and flows out along with the purulent exudate through the outflow tube into a collection container by gravity.
• Vacuum drainage: a sealed system where a negative pressure device (corrugated canister) is connected to the drainage tube. This ensures active aspiration of wound discharge and forces the cavity walls to collapse, reducing "dead space".

Class and exam questions

What else to study on this topic

• Pathogenesis of the formation of the sequestrum and involucrum.
• Differential diagnosis of chronic osteomyelitis and bone tumors on scintigraphy.
• Changes in microflora sensitivity during prolonged antibiotic therapy.
• Technique for performing muscle-flap plasty of a bone cavity in femoral lesions.
• Secondary renal damage against the background of prolonged purulent intoxication and dysproteinemia.

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

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.