Rhizomelia refers to either a disproportion of the length of the proximal limb, such as the shortened limbs of achondroplasia, or some other disorder of the hip or shoulder.
According to Stedman's medical dictionary "Rhizomelic" means "relating to hip or shoulder joints", while "Micromelic" means "having disproportionately short or small limbs".[1]
References
Rhizomelia Wikipedia(Text) CC BY-SA