A 6-year-old develops acute hematogenous osteomyelitis of the proximal femur. The physis is INTRACAPSULAR. This anatomical feature means that epiphyseal infection and secondary septic arthritis:

• A Cannot occur because the physis blocks spread
• B Only occurs after 2 years of age when vascular transphyseal communication ceases
• C Is prevented by the synovial fluid's bacteriostatic properties
• D Can occur because pus tracking through the cortex enters the joint ✓

Explanation

In joints where the physis is intracapsular (proximal femur, proximal humerus, proximal radius, distal fibula), subperiosteal pus from metaphyseal osteomyelitis can rupture into the joint space, causing simultaneous septic arthritis. This is a critical anatomical point because it explains why osteomyelitis of the proximal femur in children is particularly dangerous — hip joint destruction can ensue rapidly. After 18-24 months the transphyseal vessels disappear, so epiphyseal involvement is less common in older children, but the intracapsular metaphysis still allows direct pus extension into the joint.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.