This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Orthopaedics
A most common cause of tarsal tunnel syndrome - 
Select and explain. 
A. Osteoarthritis, B. Ankylosing spondylitis, C. Psoriatic arthritis, D. Rheumatoid arthritis
D: Rheumatoid arthritis
Answer: D: Rheumatoid arthritis 
Explanation: Amongst the given options, RA is the most common cause of tarsal tunnel syndrome.

Facts about etiology of tarsal tunnel syndrome

Most common origin of tarsal tunnel syndrome is idiopathic (21-36%).
When the cause is known, trauma is the most common cause.
Two most common systemic causes of tarsal tunnel syndrome are diabetes (m.c.) and RA (2nd m.c.)