This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Orthopaedics
The following Xray has a feature which is characteristic of 
Select and explain. 
A. Osteoahiritis, B. Rheumatoid ahiritis, C. Ankylosing spondylitis, D. Psoriatic ahiritis
A: Osteoahiritis
Answer: A: Osteoahiritis 
Explanation: Radiographic hallmarks of osteoahritis: Joint space narrowing, Osteophytes, Subchondral cysts, Bony sclerosis (eburnation) Kellgren & Lawrence staging: Grade 0 Normal Grade 1 Minimal osteophyte Normal joint space Grade 2 Definite osteophyte Possible joint space narrowing Grade 3 Definite osteophyte Definite joint space narrowing Grade 4 Large osteophytes, Marked joint-space narrowing, Sclerosis, Deformity OA is common in first CMC of thumb, DIP, PIP, knee, hip joint and spine. Osteophytes that form at DIP joints are known as Heberden nodes. At PIP joint, such osteophytes are known as Bouchard nodes. Ref: Maheshwari 6e pg 295.