Infecciones Osteoarticulares: Artrosis y Osteomielitis

Infecciones Osteoarticulares (Artrosis y Osteomielitis)

• Artritis Séptica: A severe bacterial infection in a joint, most commonly in the hip or knee, requiring urgent medical and surgical intervention.
• Importance: High risk of joint destruction, it's a medical emergency with a hospital mortality rate of 7-15%.
• Origin: Infection can be hematogenous (blood-borne) or direct inoculation from an open wound or procedure. A contiguous focus (adjacent infection) is also possible.
• Factors Predisposing to Artritis Séptica: recent joint surgery/procedures, rheumatoid arthritis, advanced age (>60), skin infections, diabetes mellitus, immunosuppression and trauma/injuries.
• Etiology: Primarily Gram-positive cocci (80-90% cases), with Staphylococcus Aureus being the most frequent pathogen. Gram-negative cocci (1-5%) like Gonorrhea are less common but important to consider. Other possible causes include Streptococcus species, Enterococci, and in immunocompromised patients, Gram-negative bacilli.
• Localization: Most common site is the knee, followed by the hip, ankle and foot. Typically monoarticular (affecting one joint) in 90% of cases, but can be polyarticular.
• Pathophysiology: Bacteria in the joint leads to inflammation, swelling, increased joint fluid, and pressure. This causes enzyme release and rapid cartilage destruction.
• Clinical Presentation: Severe joint pain, limited movement, redness, warmth, and fever.
• Diagnosis: Diagnosis is critical and needs prompt action, critical to detect early. Important diagnostic tools include joint aspiration (analysis of synovial fluid, microscopy, cell count, Gram stain, culture, and glucose levels), imaging studies (radiography, ultrasound, CT scan or MRI), and blood tests (full blood cell count, erythrocyte sedimentation rate [ESR] and C-reactive protein [CRP]).
• Treatment: Early and aggressive antibiotic therapy (empiric coverage) is essential following microbiological testing (Gram stain/culture of synovial fluid) with consideration for surgical drainage/debridement of the affected area.
• Prognosis: A timely intervention is key. Timely treatment leads to good outcomes in most cases. Untreated articular infections lead to significant joint damage in a few hours

Osteomyelitis

• Definition: A bone infection that usually arises in the bone marrow and cortical bone.
• Risk Factors: Trauma (open fractures), surgical procedures, prior infections, prosthetic implants, diabetes mellitus, vascular disease, and immunocompromised states.
• Classification: Osteomyelitis can be categorized by duration (acute, subacute, chronic) and the route of entry (hematogenous, contiguous spread). Categorization is important for effective treatment.
• Etiology: Commonly caused by Staphylococcus aureus and other bacteria.
• Pathophysiology: In acute cases, bacteria enter the bone through the bloodstream or from a nearby infected site. The organism causes an inflammatory response and bone destruction. Chronic cases frequently involve a sequestrum, which is dead bone.
• Clinical Presentation: Pain, erythema, swelling, and warmth over the affected area, often with systemic symptoms like fever and chills.
• Diagnosis: X-ray or MRI. Important diagnostic testing includes blood tests, blood cultures, and aspiration of any drainage.
• Treatment: Early and appropriate antibiotic therapy is essential to prevent the complication or progression to chronic cases. Surgical intervention may be required in some instances involving debridement and/or bone resection to treat necrosis, and facilitate antibiotic delivery.
• Prognosis: A timely diagnosis and treatment intervention may lead to good results, however failure to diagnose promptly may lead to chronic osteomyelitis and joint destruction, potentially requiring bone resection and long hospital stays.