Lotus position - Padmasana

is a cross-legged sitting meditation pose in which each foot is placed on the opposite thigh.

Lotus is one of the yoga poses that most commonly causes injury. Attempts to force the legs into lotus pose can injure the knees by squeezing and damaging the medial meniscus cartilage; this is painful and takes a long time to heal. The hip joints must rotate outwards approximately 115 degrees to permit full lotus. Students who cannot achieve this much hip rotation may try to compensate by bending the knee joint sideways, risking injury. To avoid injury try easier variations such as:  

Half lotus position - Ardha Padmasana 

or Easy pose - Sukhasana