Extendable postural support cushion

An extendable cushion assembly for a seated user support apparatus, comprising:

• a cushion that is movable between an extended state and a retracted state;
• a base upon which the cushion is removably coupled, the base comprising a first part and a second part that are slidable longitudinally with respect to one another between the extended state and the retracted state,
• wherein the first part comprises a forward section and two opposing side walls, and
• wherein the second part comprises a bottom part and two opposing side walls;
• wherein the opposing side walls of the first part each comprise a channel and the opposing side walls of the second part each comprise a respective male member which is configured to slide within the respective channels;
• and
• a coupling portion removably coupled to the base and seated, at least in part, on top of the bottom part of the second part;
• a posterior support and a thigh support removably coupled between the cushion and the base,
• wherein the posterior support is coupled to a top surface of the coupling portion, and
• wherein the thigh support is coupled to a top surface of the forward section of the first part;
• wherein an upper surface of the coupling portion lies substantially flush with an upper surface of the forward section of the first part so as to define a substantially flush mounting surface across the first part and the second part of the base;
• wherein the posterior support and the thigh support are shaped and dimensioned to substantially conform, at least in part, to one or more body parts of a user which they are configured to support;
• wherein each of the posterior support and the thigh support comprises releasable coupling means on a lower side for attachment to the base or the coupling portion and on an upper side for attachment to the cushion;
• and
• wherein, when the cushion is coupled to the base and the base adopts the extended state or the retracted state, the cushion, the posterior support and the thigh support are configured to adopt corresponding extended or retracted positions, such that displacement of the first part relative to the second part varies a spacing between the posterior support and the thigh support in accordance with the user's dimensions.