A patient support apparatus is provided with selective stiffening features. The patient support apparatus may include a support substrate defining a patient support surface. The support substrate may include a magnetorheological material providing selective reinforcement support of at least a portion of the patient support surface to redistribute pressure about a surface of a patient. The magnetorheological material may include a distribution of ferromagnetic particles disposed within a polymeric material and exhibits a shape conforming, variable stiffness in response to exposure to a magnetic field. A controller may be provided and configured to create a correlation of patient specific data with an optimal stiffness or inflection force deflection (IFD) of the patient support surface, and generate a strength of the magnetic field based on the correlation.