Which joint is rarely affected by ankylosing spondylitis -

Ans. is 'a' i.e., Ankle Joints involved in ankylosing spondylitis* Ankylosing spondylitis primarily affects axial skeleton.* The disease usually begins in the sacro-iliac joints and usually extends upwards to involve the lumbar, thoracic, and often cervical spine.* In the worst cases the hips or shoulders are also affected. Hip joint is the most commonly affected peripheral joint.* Rarely knee and ankle are also involved