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Bone InfectionEdit

Bone infection, medically known as osteomyelitis, is an infection of bone tissue that can involve the cortex, cancellous bone, marrow, and adjacent soft tissues. It can arise from bacteria traveling through the bloodstream (hematogenous osteomyelitis), from an infection in surrounding tissues (contiguous osteomyelitis), or after trauma or orthopedic surgery that introduces organisms or disrupts blood supply (postoperative or implant-associated osteomyelitis). If not promptly diagnosed and treated, it can progress to chronic infection, bone necrosis, structural damage, and systemic illness such as sepsis. osteomyelitis bone

In epidemiologic terms, osteomyelitis can affect people of all ages, but risk profiles vary by route. Hematogenous osteomyelitis is more common in children, whereas adults often develop contiguous or postoperative infection related to fractures, debridement, or indwelling hardware. Conditions that impair blood flow or immunity—such as diabetes mellitus, peripheral arterial disease, immunosuppressive therapy, and trauma—raise the likelihood of bone infection and complicate treatment. The impact of osteomyelitis on health care systems is amplified by the need for prolonged therapy, potential surgical intervention, and the risk of relapse. diabetes mellitus peripheral arterial disease immunosuppression bone biopsy osteomyelitis prosthetic joint infection

Pathophysiology and anatomy

Bone has limited capacity to clear infection, particularly when blood supply is compromised. In acute hematogenous infection, bacteria seed a site in the metaphysis or around the physis, triggering inflammation that can spread to the marrow and cortex. In contiguous osteomyelitis, infection reaches bone from adjacent soft-tissue infections or ulcers, a scenario common with diabetic foot infections and pressure ulcers. Surgical implants or fractures can introduce bacteria and disrupt local circulation, fostering biofilm formation on hardware. Over time, infected bone may become necrotic, producing sequestra (dead bone) surrounded by reactive new bone called involucrum. These changes complicate eradication and often require combined medical and surgical management. sequestrum involucrum biofilm osteomyelitis diabetes mellitus bone

Etiology and routes of infection

  • Hematogenous osteomyelitis: spread through the bloodstream from distant sites, more frequent in children and in certain infections such as S. aureus. Typical locations include the long bones of the pediatric skeleton and the spine in adults. hematogenous spread osteomyelitis Staphylococcus aureus
  • Contiguous infection: arises from adjacent soft-tissue infections, ulcers, or wounds with poor vascular supply. Common in the foot and ankle, pelvis, and skull depending on the portal of entry. contiguous infection osteomyelitis
  • Postoperative or implant-associated osteomyelitis: follows orthopedic procedures or the presence of hardware, including joint replacements and fracture fixation devices. Biofilm formation on implants makes eradication harder and sometimes necessitates hardware removal. implant-associated infection prosthetic joint infection biofilm osteomyelitis

Microorganisms vary by age, setting, and anatomy, but Staphylococcus aureus remains the leading pathogen in many cases. Other important agents include Streptococcus species, Pseudomonas aeruginosa (notably in puncture wounds through footwear), and Gram-negative enteric bacteria in adults with comorbidities or wounds. In sickle cell disease, Salmonella species are a recognized cause in some patients. In chronic or culture-negative cases, anaerobes and less common organisms may be implicated. Culture from blood and bone biopsy helps tailor therapy. Staphylococcus aureus Streptococcus Pseudomonas aeruginosa Salmonella bone biopsy blood culture osteomyelitis

Clinical presentation

Acute osteomyelitis often presents with localized bone pain, warmth, swelling, and limited joint movement near the involved site, sometimes with fever and malaise. In children, symptoms can be nonspecific, with irritability and limp rather than overt pain. Contiguous infections may present with surrounding soft-tissue signs such as ulcers or cellulitis, while implant-associated infections may manifest with pain at the hardware site, drainage, or fever. Chronic osteomyelitis may show persistent bone pain, drainage through a sinus tract, recurrent inflammation, and radiographic evidence of necrotic bone despite therapy. bone osteomyelitis diabetes mellitus

Diagnosis

Diagnosis combines clinical assessment with laboratory testing, imaging, and microbiology. Key elements include:

  • Blood tests: elevated inflammatory markers such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR); white blood cell count may be normal or elevated in acute cases. CRP ESR white blood cell
  • Microbiology: blood cultures and cultures from site samples, including bone biopsy, help identify the causative organism and guide antibiotic selection. blood culture bone biopsy
  • Imaging: early X-rays may be unrevealing; MRI is highly sensitive for detecting marrow edema and soft-tissue involvement, while CT can delineate cortical bone and sequestra. Nuclear medicine bone scans may be used when MRI is contraindicated or inconclusive. MRI X-ray computed tomography bone scan
  • Local examination: assessment of surrounding tissues, presence of ulcers, and assessment for hardware-related infection. ulcer implant-associated infection

Management

Management requires a combination of antibiotics and, when indicated, surgical intervention. The goals are to eradicate infection, preserve as much native bone as possible, restore function, and prevent relapse.

  • Antibiotic therapy: begin empiric broad-spectrum coverage after cultures are obtained, then narrow to targeted therapy once pathogens are identified. Duration is typically several weeks and may extend longer in chronic cases or when hardware is retained. Routes may include intravenous (IV) administration followed by oral therapy, depending on clinical response and organism. Common choices target Staphylococcus aureus and Gram-negative bacteria, with adjustments for MRSA or resistant organisms as needed. antibiotic MRSA vancomycin linezolid daptomycin oral antibiotics
  • Surgical management: debridement of necrotic bone and infected tissue is often necessary. Removal or exchange of infected hardware may be required. In some cases, bone grafts or bone substitutes support reconstruction after debridement. Local antibiotic delivery methods, such as antibiotic-impregnated beads, can supplement systemic therapy. Hyperbaric oxygen therapy is used in select cases but remains a topic of debate. debridement hardware bone graft bone substitute antibiotic bead hyperbaric oxygen therapy
  • Adjunctive care: optimization of perfusion and wound care, diabetes control, and management of vascular disease improve outcomes. Multidisciplinary teams including surgeons, infectious disease specialists, and rehabilitation professionals are often essential. diabetes mellitus vascular disease rehabilitation

Controversies and debates

  • Duration of antibiotic therapy: opinions differ on how long IV and oral therapy should be continued, especially for chronic osteomyelitis or cases with implants. Prolonged courses reduce relapse risk but increase antibiotic exposure and resistance risk; many guidelines emphasize tailoring duration to clinical response and culture results. antibiotic
  • Role of surgery: some patients achieve infection control with antibiotics alone, particularly in select hematogenous cases, while others require aggressive surgical debridement and hardware management. The decision is individualized, balancing limb function, infection severity, and patient comorbidity. debridement implant-associated infection
  • Use of hyperbaric oxygen therapy: hyperbaric oxygen is considered in certain chronic or difficult cases, but high-quality, consistent evidence supporting its routine use is limited. Its role remains a point of discussion among clinicians. hyperbaric oxygen therapy
  • Access to care and disparities: outcomes can vary based on access to specialized orthopedic and infectious disease services, imaging modalities, and timely surgical intervention. Studies sometimes show differences in outcomes across populations, including variations by race and socioeconomic status, highlighting broader questions about health care delivery and equity. health care racial disparities
  • Local antibiotic delivery vs systemic therapy: antibiotic beads and local delivery can augment systemic antibiotics, but their indications and effectiveness continue to be refined, particularly in hardware-associated infections. antibiotic bead implant-associated infection

Prognosis and outcomes

With timely diagnosis and appropriate management, many patients recover functional limb use and infection control. Prognosis worsens with delayed treatment, extensive bone necrosis, comorbid conditions (such as diabetes and vascular disease), or infection involving prosthetic material. Recurrent infection remains a risk, especially when hardware cannot be removed or when soft-tissue coverage is poor. Long-term follow-up is often needed to monitor for relapse and to optimize rehabilitation. osteomyelitis diabetes mellitus prosthetic joint infection

See also