Least common site to be involved in osteoahritis amongst the following is:
Hip joint
Knee joint
Carpometacarpal joint of thumb
Metacarpophalangeal joint
Answer is D (Metacarphalangeal joints) Wrists and Metacarpophalangeal joints are generally not involved in Osteoahritis - Harrison 16th/2040 Sparing of wrist and metacarpophalangeal joint with involvement of base of thumb (i.e. carpometacarpal joint) is very characteristic of 'osteoahritis'.