knobblyknob‧bly /ˈnɒbli $ ˈnɑːbli/ (also knob‧by /ˈnɒbi $ ˈnɑːbi/ American English) adjective 
with hard parts that stick out from under the surface of something: 
knobbly knees
with hard parts that stick out from under the surface of something: knobbly knees