Osteitis: general term for inflammation of the boneOsteomyelitis: infection of the bone marrow

Etiology:- Hematogenous osteomyelitis- Exogenous osteomyelitis: usually due to multiple pathogens→ Posttraumatic: infection following deep injury (penetrating injury, open fractures, severe soft tissue injury)→ Contiguous: spread of infection from adjacent tissue (foot ulcer, postoperative infection of a prosthetic joint implant)

Pathogens:- Staphylococcus aureus: Children and adults- Staphylococcus epidermidis: Diabetic patients with foot ulcers and pressure ulcers, patients with prosthetics- Pseudomonas aeruginosa: IV drug users, plantar puncture wounds - Salmonella: Sickle cell anemia patients- Klebsiella: Patients with UTIs or a history of UT instrumentation

Clinical features:- Onset: usually gradual, over several days- Chief complaint: pain at the site of infection, possibly related to movement- Possible localized findings: point tenderness, swelling, redness, warmth- Possible systemic findings: malaise, fever, chills- Common localization of hematogenous osteomyelitis:→ Infants: long bone metaphysis, joints→ Children: long bone metaphysis, joint infection very rare→ Adults: vertebral involvement is most common

Diagnostics:- Initial work-up includes blood cultures, inflammatory markers, and x-ray imaging.- MRI: the most sensitive diagnostic study- Bone biopsy: confirmatory test