Classification of<unk>  by the presence or absence of bones within the lower limb. I) all bones of thigh and lower leg present II) fused fibula III) fibula absent IV) partially fused femur, fused fibula V) partially fused femur VI) fused femur, fused tibia VII) fused femur, tibia absentSirenomelia is classified by the skeletal structure of the lower limb, ranging from class I, where all bones are present and only the soft tissues are fused, to class VII where the only bone present is a fused femur. It has also been classified as an expanded part of the VACTERL association and as a form of caudal regression syndrome.
Sirenomelia
Rhizomelia
Mesomelia
Dolichostenomelia
Phocomelia
Meromelia
Loxoscelism
Adiposogenital dystrophy