Abstract: A flexible support structure of a seat cushion, such as a wheelchair cushion, has an upper surface with a support contour having relief areas for establishing relatively less pressure on skin adjacent to bony prominences of a user's pelvis and having a support area for establishing relatively more pressure on skin covering a tissue mass spaced from the bony prominences. A slit is formed in the rear corner of the support structure and an insertion member is inserted into the slit to change a position of the support area to thereby adjust the support contour for better support of the pelvic area. A cover encases the support structure to resist outward deformation of the support structure. The cover has an extension portion that expands the cover at the rear corner to increase a dimension of the cover to encase an increase dimension of the corner caused by the insertion of the insertion member.

Abstract: A negative impression of an anatomical portion of a person is captured by forcing the anatomical portion into impression foam to collapse the impression foam into the negative impression. The impression foam has a crush characteristic of approximately constant resistance force over a relatively wide predetermined range of collapse distances. The negative impression is obtained by collapsing the impression foam within the range of constant-force collapse distances, thereby creating the negative impression under conditions which reflect an equally-loaded anatomical portion. A cushion support contour created from the equally-loaded negative impression is beneficial in more appropriately supporting the anatomical portion. The present invention is particularly useful in fabricating wheelchair seat cushions.

Abstract: Clearance between a support contour of a seat cushion and an adjacent pelvic and proximal thigh anatomical portion of a person is evaluated with a clearance measurement device that deforms in response to force applied thereto. The clearance measurement device is located on the support contour at a predetermined location where the clearance is to be evaluated. A person sits on the cushion with the clearance measurement device. The clearance is related to the extent of deformation. Impression foam, a malleable putty-like substance, or a fluid cushion are examples of clearance measurement devices.

Abstract: A support contour of a cushion, such as a wheelchair cushion, defines relief areas at locations adjacent to skin covering the ischial tuberosities, the greater trochanters and the coccyx and sacrum of a person sitting on the support contour. Support areas of the support contour transfer force into the pelvic area adjacent to skin covering tissue masses on opposite lateral sides of the posterior buttocks and beneath the proximal thighs of the person. Greater clearance is also provided in the perineal area. Risks of pressure ulcers from pressure and shear forces on bony prominences is reduced while providing support at the broader areas without bony prominences in such a manner to encourage postural alignment. The risks of skin breakdown perineal are diminished.

Abstract: A modular seat cushion includes a human interface portion and a base portion which are combined and interlocked or interconnected together. The human interface portion has an upper support contour for supporting the user, and the base portion has a contact configuration for contacting a variety of different types of seat support structures. By selecting among human interface portions that have different sizes and shapes of support contours and by selecting among base portions that have a contact configuration appropriate for the seat support structure, a seat cushion is obtained which accommodates both the user and the type of seat support structure with which it is used. The ability to combine the human interface and base portions is particularly useful for wheelchairs.