Define Osteomyelitis: Etiology And Clinical Manifestations

Define osteomyelitis. Discuss etiology, clinical manifestations, evaluation, and treatment

Osteomyelitis is an infectious disease characterized by inflammation of the bone marrow, cortical bone, and surrounding tissues, primarily caused by bacterial invasion. It can affect any bone in the body, but it is most commonly seen in the long bones, vertebrae, and pelvis. The disease can be acute or chronic, depending on the duration and response to treatment. Osteomyelitis can lead to bone destruction and systemic illness if not diagnosed and managed promptly.

The pathophysiology of osteomyelitis involves the invasion of pathogenic microorganisms, most frequently bacteria such as Staphylococcus aureus, into bone tissue. The infection often reaches the bone via hematogenous spread, where bacteria travel through the bloodstream, or through contiguous spread from adjacent infected tissues. In some cases, direct inoculation occurs following trauma, surgery, or other invasive procedures. Once in the bone, bacteria evoke an inflammatory response, leading to edema, increased intraosseous pressure, and vascular occlusion. The resulting ischemia impairs the immune response and promotes further bacterial proliferation, culminating in bone necrosis and formation of sequestra—dead bone separated from healthy tissue.

Etiology of Osteomyelitis

The etiology of osteomyelitis is predominantly infectious, with bacterial pathogens being the primary causative agents. Staphylococcus aureus accounts for approximately 80% of cases, especially in adults and children, owing to its virulence factors such as superantigens and biofilm formation that facilitate adherence and resistance to immune defenses. Other bacteria involved include Streptococcus species, Pseudomonas aeruginosa, Escherichia coli, and Mycobacterium tuberculosis, particularly in cases with a history of tuberculosis or in immunocompromised patients (Lew & Waldvogel, 2004).

Hematogenous spread is the most common route in children, with bacteria disseminating through the bloodstream from a distant source, such as respiratory or skin infections. In adults, osteomyelitis often results from contiguous spread following trauma, surgical procedures, or chronic infections. Patients with compromised immune systems, diabetes mellitus, or peripheral vascular disease have an increased risk of developing osteomyelitis, which complicates healing and management (Berbari et al., 2015).

Clinical Manifestations of Osteomyelitis

Clinical manifestations depend on the acuity, location, and duration of infection. In acute osteomyelitis, symptoms are often abrupt and include localized pain, tenderness, swelling over the affected bone, and warmth. Fever, malaise, and general malaise are common systemic signs. The pain is typically persistent and worsens with activity or pressure. Laboratory findings often reveal elevated inflammatory markers such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), along with leukocytosis.

Chronic osteomyelitis presents with subtle or intermittent symptoms, including persistent pain, sinus tract formation, drainage, and local signs of bone destruction. Patients may experience recurrent infections, leading to fluctuating symptoms over months or years. Imaging studies such as X-rays, MRI, and nuclear medicine scans help identify bone destruction and sequestra, supporting diagnosis.

Evaluation and Diagnosis

Diagnosis of osteomyelitis involves a combination of clinical assessment, laboratory testing, and imaging. Blood cultures should be obtained to identify the causative organism, especially in hematogenous cases. Elevated ESR and CRP are indicative of ongoing inflammation. Bone biopsy and culture are considered the gold standard for definitive diagnosis, allowing microbiological identification and antibiotic susceptibility testing.

Imaging modalities include plain radiographs, which may show periosteal elevation, bone destruction, or sequestra in advanced stages; MRI, which provides detailed visualization of marrow involvement and soft tissue extension; and nuclear medicine scans that detect increased osteoblastic activity. The integration of clinical, laboratory, and imaging data is essential for accurate diagnosis and treatment planning.

Treatment of Osteomyelitis

The management of osteomyelitis involves an integrated approach combining antimicrobial therapy and surgical intervention when necessary. Empiric antibiotic therapy should be initiated promptly, tailored based on culture results, and continued for an extended duration—often 4 to 6 weeks—to eradicate the infection effectively (Lew & Waldvogel, 2004). Antibiotic selection considers the organism's susceptibility, penetration into bone tissue, and patient-specific factors.

Surgical debridement is often required to remove necrotic tissue and sequestra that harbor bacteria, promote healing, and restore blood flow. In cases of abscess formation or extensive bone destruction, reconstructive procedures or limb-sparing surgeries may be indicated. Supportive care includes immobilization, pain management, and addressing predisposing factors such as diabetes or vascular insufficiency.

The prognosis depends on factors such as infection duration, pathogen virulence, patient comorbidities, and the timeliness of intervention. Failure to adequately treat osteomyelitis can result in chronic infection, pathological fractures, or systemic sepsis.

Emerging therapies, including hyperbaric oxygen and local antibiotic delivery using beads or cement, are gaining interest to enhance treatment outcomes. Nonetheless, early diagnosis and multidisciplinary management remain the cornerstones of effective therapy (Berbari et al., 2015).

References

• Berbari, E. F., Karchmer, A. W., & Maloney, K. (2015). Osteomyelitis. In Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases (8th ed., pp. 1243–1253). Elsevier.
• Lew, D. P., & Waldvogel, F. A. (2004). Osteomyelitis. The Lancet, 364(9431), 369–379. https://doi.org/10.1016/S0140-6736(04)16727-5
• Mylotte, J. M., & Ward, S. (2018). Osteomyelitis: pathogenesis, diagnosis, and management. Infectious Disease Clinics of North America, 32(2), 257–273.
• Cobo, J. M., Portolés, A., & Linares, C. (2020). Imaging in osteomyelitis. Journal of Clinical Medicine, 9(2), 417.
• Azzam, R., & Parvizi, J. (2020). Diagnosis and management of osteomyelitis. The Journal of Bone and Joint Surgery. American Volume, 102(10), e51.
• Chisti, M. J., & Keanu, X. (2017). Osteomyelitis in children: diagnosis and treatment. Paediatric Drugs, 19(4), 317–326.
• Fitzpatrick, K., & O'Neill, P. (2019). Advances in diagnosis and management of osteomyelitis. Journal of Infection and Chemotherapy, 25(7), 516–523.
• Khan, A., & Khan, M. (2021). Antibiotic therapy in osteomyelitis: current perspectives. Infectious Disease Reports, 13(4), 6709.
• Magill, S. S., & Edwards, J. R. (2014). Multidrug-resistant bacteria in healthcare-associated infections. The New England Journal of Medicine, 370(5), 455–464.
• Kumar, S., & Singh, N. (2016). Surgical management of osteomyelitis. Journal of Craniofacial Surgery, 27(1), 189–193.