How can I make a Player's arm collidable?

This seems simple but I cant find an answer for this. Am trying to make a ragdoll script where the player is still alive. So I've made the script copy the limbs of the character and attached them to the torso with a socket constraint. unfortunately the arms hang through the ground. How do I make the arms collide with the ground?(setting the arms to CanCollide dos not work)

Heres the code I have for the ragdoll script if you are interested...

local character = script.Parent
local player = game.Players:GetPlayerFromCharacter(character)

player.PlayerGui.Health.Changed:connect(function()
	print("HURT")
	if player.PlayerGui.Health.Value > 0 then
		character.Humanoid.PlatformStand = false
	end
	if player.PlayerGui.Health.Value <= 0 then
		character.Humanoid.PlatformStand = true
		local FakeArm = game.Lighting.FakeArm:Clone()
		--find Left Arm
		local children = character:GetChildren()
		for i=1,#children do
			if children[i].Name == "Left Arm" then
				local clone = children[i]:Clone()
				FakeArm.RealArmAttachment.Parent = children[i]
				FakeArm.FakeArmAttachment.Parent = clone
				FakeArm.BallSocketConstraint.Parent = clone
				clone.BallSocketConstraint.Attachment1 = children[i].RealArmAttachment
				clone.BallSocketConstraint.Attachment0 = clone.FakeArmAttachment
				children[i].Transparency = 1
				clone.Parent = character
			end
		end
		FakeArm.Parent = character
	end
end)

I solved this by changing the humanoid parent to lighting then putting it back to the character model (after the fake arm is set to Can Collide)