Deep phlegmon of the extremities

Pathogenesis and routes of spread

Deep phlegmons represent severe purulent inflammation localized deep within the tissues of the extremities. Depending on their relationship to fascial structures, two main types are distinguished: subfascial phlegmons, developing directly beneath the deep fascia, and interfascial phlegmons, located between various fascial layers.

The pathological process is highly aggressive and never remains localized. It actively spreads along natural anatomical pathways — fascial spaces. The main pathways for pus migration are intermuscular clefts and perivascular (paravascular) tracts.

The development of phlegmon is a staged process that sequentially passes through three stages:

1. Serous edema is the initial tissue reaction to infection invasion.
2. Purulent infiltration is the impregnation of affected tissues with leukocytes and inflammatory exudate.
3. Purulent melting with necrosis is the irreversible death and destruction of involved structures. Muscles, fasciae, and adipose tissue undergo this process.

In some cases, the body's defense mechanisms are able to wall off the inflammation. When this happens, one or several local abscesses form at the site of the diffuse phlegmon.

Clinical presentation and diagnostics

The disease is always acute in nature and characterized by rapid development. The clinical picture consists of pronounced general and local symptoms.

General symptoms are caused by severe purulent intoxication. The patient experiences diffuse, intense pain in the affected extremity. Body temperature rises sharply up to 39–40 °C, accompanied by severe chills. General weakness, lethargy, and a complete loss of appetite are characteristic. In an extremely severe course, intoxication is so great that the patient may experience confusion.

Local manifestations depend on the depth of the pus location. First of all, pronounced edema and severe tissue tension, especially of the skin, draw attention. The volume of the affected extremity increases significantly, which is a direct consequence of impaired venous outflow. The lymphatic system is rapidly involved in the inflammatory process: enlarged and sharply painful regional lymph nodes are determined upon palpation.

Diagnostics largely depends on the topography of the abscess. If the phlegmon is located relatively superficially (for example, in the region of the femoral triangle), diagnostics is significantly facilitated. In such cases, swelling and pronounced skin hyperemia are visually determined, and a positive fluctuation sign is revealed upon palpation. With a deeper location, classical skin symptoms may be absent, and the topographic anatomy of fascial compartments and neurovascular bundles comes to the forefront.

Surgical approaches to the upper extremity

Treatment of deep phlegmons requires precise knowledge of the topography of cross-sections of the extremities, the location of fascial compartments, and neurovascular bundles. The opening of abscesses is performed using specialized surgical approaches that minimize the risk of damaging important structures.

The following surgical incisions are used for the upper extremity:

• Anterolateral approach is used for safe exposure of the humeral diaphysis.
• Approach for opening the phlegmon of the anterior fascial compartment.
• Incisions for phlegmon of the lateral fascial compartment.
• Approaches for palmar intermuscular and interosseous-muscular phlegmons.
• Specialized approach according to Voyno-Yasenetsky, which is used specifically for opening the palmar interosseous-muscular phlegmon.
• Incisions for adequate drainage of Pirogov's space.
• Incisions for purulent lesions of the ulnar bursa.

When performing approaches, the surgeon must strictly take into account the projections of main vessels: the brachial vascular bundle, as well as the radial and ulnar arteries.

Surgical approaches to the lower extremity

Topographically substantiated approaches have been developed for the lower extremity, allowing safe opening of deep fascial spaces and ensuring the outflow of pus:

• Anterolateral approach is used to access the femur.
• Approach to the anteromedial intermuscular phlegmon of the thigh.
• Approach to the anterior intermuscular phlegmon of the thigh.
• Approach directly to the vascular sheath.
• Approach to the phlegmon of the anterior fascial compartment of the leg.

As with the upper extremity, the safety of surgical intervention is ensured by precise knowledge of projection lines. On the lower extremity, it is critically important to orient oneself to the projection of the femoral vessels and the projection of the anterior tibial artery.

Class and exam questions

What else to study on this topic

• Topographic anatomy of the fascial compartments of the upper and lower extremities
• Projection lines of major neurovascular bundles
• Technique of performing the Voyno-Yasenetsky approach
• Features of drainage of Pirogov's space
• Differential diagnostics of phlegmon and local abscess

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.