Yes, POLYDACTYLY is a Scrabble word!

Letter values in Scrabble US: P 3, O 1, L 1, Y 4, D 2, A 1, C 3, T 1, Y 4, L 1, Y 4.

Is it a valid word?

POLYDACTYLY is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

birth defect characterized by the presence of more than the normal number of fingers or toes

Not playable in Scrabble US: HYPERDACTYLY.