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
Triple deformity of knee is classically seen in -a) Fracture patellab) Tuberculosisc) Rheumatic arthritisd) Rheumatoid arthritis 
Select and explain. 
A. c, B. d, C. ab, D. bd
D: bd
Answer: D: bd 
Explanation: Triple deformity of knee refers to : -


Flexion of knee
External rotation of tibia
Posterior subluxation of tibia


Triple deformity is seen in RA, TB of knee and Polio.