関連ワード:  at what age does the patella develop    at what age does the kneecap develop    at what age does the patella form    at what age does the kneecap form    at what age does your kneecap develop    what age do babies kneecaps develop    at what age do you develop knee caps    at what age do kids develop knee caps    at what age do humans develop knee caps    at what age does a baby develop knee caps