periostitis

Periostitis is inflammation of the periosteum, the vascular fibrous layer that covers bone except at joint surfaces. The periosteum supplies nerves and blood vessels to the outer cortex and serves as an attachment for tendons and ligaments. Periostitis can arise from infection, inflammation, trauma, or systemic disease, and may occur in isolation or as a reaction to broader bone pathology.

Common causes include infectious processes that involve the periosteum or adjacent bone (such as osteomyelitis), traumatic injury, and repetitive mechanical stress (as in athletes with shin splints or other stress-related injuries). Noninfectious etiologies include inflammatory conditions, hypertrophic osteoarthropathy, scurvy, and paraneoplastic phenomena; malignant processes such as Ewing sarcoma or osteosarcoma may provoke a periosteal reaction. The characteristic pathology is subperiosteal new bone formation and edema of the periosteum, which can be detected radiographically.

Clinically, periostitis presents with localized bone pain and tenderness, sometimes with swelling, warmth, or erythema. Fever or systemic symptoms may accompany infectious causes. Diagnosis relies on clinical assessment and imaging, with X-rays often showing subperiosteal new bone; MRI or CT can delineate extent. Laboratory tests (inflammatory markers, blood cultures) aid in distinguishing infection from inflammatory or malignant etiologies. Biopsy may be required for uncertain or persistent lesions.

Treatment targets the underlying cause: rest and activity modification for stress-related periostitis, antibiotics for infection, and disease-specific therapies for inflammatory or neoplastic processes. Prognosis varies with cause and response to treatment.