Abstract: Retainer bar assemblies are provided for use is an adjustable base of a support cushion. The retainer bar assemblies include a retainer bar having a horizontal rod and two legs connected to the horizontal rod with an end portion that extends from each leg in a direction substantially parallel to the horizontal rod. The retainer bar assemblies further include a pair of brackets where each bracket defines at least one channel for receiving the end portion of the two legs. Each channel has a vertical segment and an angled segment such that each channel is configured to allow the horizontal rod to be moved upward and rotated away from each bracket. Adjustable support cushions or bed assemblies that include the retainer bar assemblies are also provided.