Osteomyelitis — Cierny–Mader Staging

Osteomyelitis refers to infection of bone and bone marrow caused by bacterial or occasionally fungal organisms. The infection may involve cortical bone, medullary cavity, periosteum and surrounding soft tissues. Osteomyelitis can occur through hematogenous spread, direct inoculation following trauma or surgery, or by contiguous spread from adjacent soft tissue infection.

The condition represents a significant clinical challenge in orthopaedic practice due to difficulty in eradicating infection from bone tissue. The presence of necrotic bone, impaired blood supply and biofilm formation on implants can make treatment complex and prolonged.

The Cierny–Mader classification system is widely used to classify chronic osteomyelitis. It combines anatomical involvement of the bone with the physiological status of the host. This classification assists clinicians in determining the appropriate surgical and medical management strategies.

Osteomyelitis may develop through several mechanisms depending on the source of infection and patient factors. The most common causative organism is Staphylococcus aureus, although other organisms may also be involved.

• Hematogenous spread from distant infection
• Direct inoculation following open fractures
• Postoperative infection after orthopaedic surgery
• Contiguous spread from soft tissue infection
• Infection associated with prosthetic implants

Once bacteria reach the bone, they trigger an inflammatory response. This results in increased intraosseous pressure and vascular compromise. Reduced blood supply leads to bone necrosis and formation of sequestrum, which acts as a nidus for persistent infection.

Osteomyelitis is commonly classified based on the route of infection and duration of disease.

Chronic osteomyelitis is characterized by several pathological changes that result from persistent infection and impaired blood supply.

• Sequestrum which is necrotic bone separated from viable bone
• Involucrum which is new bone formed around infected bone
• Cloaca which is an opening in the involucrum allowing drainage
• Sinus tract communicating with the skin surface

These pathological features are hallmarks of chronic osteomyelitis and are often identified on imaging studies.

The Cierny–Mader classification categorizes osteomyelitis according to the anatomical involvement of bone.

In addition to anatomical classification, Cierny and Mader also classified patients according to their physiological status.

Clinical presentation varies depending on whether the infection is acute or chronic.

• Pain and tenderness over affected bone
• Fever and systemic symptoms in acute infection
• Swelling and redness
• Sinus tract formation in chronic cases
• Reduced limb function

• Elevated ESR and CRP levels
• Blood cultures
• Plain radiographs showing bone destruction
• MRI for early detection and soft tissue evaluation
• Bone biopsy for definitive diagnosis

MRI is considered the most sensitive imaging modality for early osteomyelitis.

Management of osteomyelitis requires a combination of surgical and medical treatment.

• Removal of necrotic bone through surgical debridement
• Culture directed intravenous antibiotics
• Dead space management
• Stabilization of bone if required
• Soft tissue coverage procedures

Treatment strategy often depends on the Cierny–Mader stage and host physiological status.