The joint commonly involved in sphffitic arthritis is-

Syphilic arthritis Syphilic arthritis may be seen in congenital or acquired syphilis. Congenital syphilis The joint may be affected early or late : - Early congenital syphilis : - Osteochondritis in juxta-epiphyseal region results in breakdown of the bone and cartilage. Late congenital syphilis : - Painless synovitis at puberty is called clutton's joint. Most common site is knee followed by elbow, and often is bilateral. Acquired syphilis Joint may be involved in the secondary or tertiary stage. Secondary stage : - Transient polyarthritis. Tertiary stage : - Gummatous polyarthritis, Chorcot's (neuropathic) joint.