The bone region of the epiphysis that provides underlying mechanical and physiological support for the cartilage of joint articular surfaces. [ http://www.informatics.jax.org/accession/csmith http://www.ncbi.nlm.nih.gov/pubmed/24084727 http://www.ncbi.nlm.nih.gov/pubmed/20392241 https://github.com/obophenotype/uberon/issues/1195 ]