Orthotics, Prosthetics & Rehab

PORON medical, a microcellular polyurethane, is the industry-standard orthotic and prosthetic cushioning material. It gives controlled, soft force-deflection at low stress, so it cushions and conforms to the body, and it has low compression set, so it recovers over thousands of steps a day instead of flattening. That combination, cushioning plus recovery, is what makes it the default comfort layer in an orthotic top cover, a brace or socket liner, and a rehab cushion.

It is used as the comfort layer of a soft-to-firm stack, on the body side, with a firm crosslinked polyethylene behind it for structure. Where more energy return or a different firmness is wanted, a resilient or soft polyurethane foam (HyPUR-cel R or S) is the alternative, and for a heavier load a high-density polyurethane carries more before bottoming. Force-deflection and compression set are characterized per ASTM D3574; grade-specific values are per the maker TDS.

The grade is referenced to ISO 10993 and USP Class VI by designation.

Because comfort and structure are different jobs that want different firmnesses, and one foam in the middle compromises both. A soft foam cushions and redistributes pressure but, on its own, bottoms out under load and does not hold the part's shape; a firm foam holds shape and resists bottoming but does not cushion.

The reliable answer is a soft-to-firm stack: a soft microcellular polyurethane comfort layer on the body to cushion and offload the high points, and a firm crosslinked polyethylene behind it to hold the shape, carry the load, and stop the soft layer bottoming out, with an EVA or resilient polyurethane transition layer if needed.

The comfort layer feels right; the firm layer gives the structure. H-O laminates the stack and it as one part. Specifying a single firmness to do both jobs is the most common cushioning miss, producing a part that either bottoms out or does not cushion. State the layers, their firmness, and the order body outward.

Choose a cushioning grade with low compression set and size it for the wear. A cushion flattens because of compression set: a foam not chosen for low set gradually deforms permanently under the repeated load (thousands of steps a day in an insole, constant pressure in a brace), so it loses thickness, stops cushioning, and the pressure point it was meant to relieve returns.

A microcellular polyurethane such as PORON medical is selected for orthotic and bracing comfort precisely because it has low compression set and recovers over the wear; for a heavier or more repeated load, a resilient or high-density polyurethane lasts better. State the wear (steps per day, hours of wear, cycles of use) and the expected life so the grade recovers over it, and consider the soft-to-firm stack so the firm layer carries the structural load and the comfort layer only does the cushioning.

Compression set and fatigue are maker-TDS properties characterized per ASTM D3574; this page frames them qualitatively and defers grade-specific limits to the TDS on file.

Bottoming out means the foam is too soft or too thin for the load: under body weight it compresses to its limit, so it no longer deforms to spread the pressure and the user feels the hard surface through it. The fix is to match the firmness and the thickness to the load.

Step up to a firmer or denser foam, or build a soft-to-firm stack with a firm crosslinked polyethylene base behind the soft comfort layer so the part deforms to cushion without reaching its limit; for a heavier body weight or a load-bearing pad, a high-density polyurethane carries the load.

Increasing the thickness of the comfort layer helps only up to a point, the right answer is usually the stack, where the firm layer carries the structural load and the comfort layer does the cushioning. State the body weight and the load at the site so the firmness, density, and gauge are sized correctly. Force-deflection and density are characterized per ASTM D3574; grade values are per the TDS on file.

Yes, an over-firm cushion can concentrate pressure rather than relieve it, the opposite of its purpose. The job of a cushioning foam is to deform under load and spread the pressure across the contact area, so the bony high points carry less concentrated load. A foam that is too firm does not deform enough to conform to the body, so the high points still bear the concentrated load and the part can create a pressure point of its own.

The fix is to choose a comfort layer soft enough to deform and conform at the actual load, a microcellular polyurethane redistributes pressure at low stress, and reserve the firm foam for the structural layer behind it, not the contact surface. Size the comfort-layer firmness to the body weight and the site so it conforms without bottoming, which is the balance the soft-to-firm stack is designed to strike.

State the body weight and any bony prominence to offload so the comfort firmness is right. Force-deflection is a maker-TDS property per ASTM D3574. The clinical assessment of pressure and skin integrity belongs to the device maker and the clinician.

H-O references material grades by designation and assembles documentation aligned to your requirements. For a skin-contact comfort pad worn for prolonged periods, state that it is skin-contact, the wear duration, and the basis you need, ISO 10993 endpoints (especially -10 sensitization and -23 irritation, with -5 cytotoxicity as the baseline), a USP Class VI designation, or an FDA contact basis, and H-O sources a grade whose maker evaluates it against those frameworks and provides the material TDS, certificate of conformance, and lot traceability.

The structural foam behind the comfort layer has a lighter contact requirement. The important distinction is who owns what: the material maker evaluates the grade at the material level, and the device maker owns the finished-device biocompatibility and regulatory file. H-O is an ISO 9001:2015 certified converter; it does not independently certify materials and does not certify finished devices, and it does not claim an ISO 13485 certification, an FDA device registration, or a cleanroom certification.

Customer-specified compliance packages are assembled on request.

Yes. A flat pad is to its outline, but a footbed, an accommodative orthotic, or a socket liner often needs a varying thickness, thicker where more cushioning or offloading is wanted, thinner elsewhere, and H-O skives or profiles the foam to that contour. H-O also laminates the soft-to-firm stack and it as one piece, and adds a pressure-sensitive adhesive on one face, kiss-cut on a release liner, where the pad mounts to a shell or footbed.

State the outline, the thickness map or contour, the layers and their order, whether the part carries an adhesive and on which face, and how it ships. Where the comfort layer is skin-contact, name the contact basis so any adhesive near it is referenced too. Die-cut, skive, lamination, and kiss-cut-on-liner are the standard H-O converting operations that turn the cushioning foams into a finished, contoured orthotic or liner part to your drawing.

They sit at different firmnesses in the stack. A crosslinked polyethylene foam is firm, fine-celled, and durable, so it is the structural base layer: it holds the orthotic or brace shape, carries the load, and resists bottoming, but it is not the soft cushion. An EVA foam is softer and more resilient, so it is a midsole or transition cushion layer, sitting between the soft comfort top and the firm base, or a softer cushion surface; it is available across a firmness range by grade.

In a typical soft-to-firm orthotic, a microcellular polyurethane comfort top sits on the foot, an EVA transition layer cushions, and a crosslinked polyethylene base gives the structure. So crosslinked polyethylene is chosen for firmness and shape retention, EVA for a softer mid cushion. Both are closed-cell, durable foams characterized per ASTM D3574 and ASTM D1056. State the role each layer plays so the right firmness is chosen for each, and H-O die-cuts and skives them into the stack.

For a load-bearing rehab or seating cushion, the firmness and density have to carry the load without bottoming, while still cushioning. A high-density polyurethane foam (HyPUR-cel T) carries a higher load before bottoming, which suits a support cushion or a load-bearing pad; a resilient polyurethane foam (HyPUR-cel R) gives a lively cushion with energy return for a seat that should rebound; and a firm crosslinked polyethylene gives a structural base or positioning core under the cushion.

Often the answer is a stack: a resilient or comfort cushion on top for feel, and a high-density or firm base to carry the load. The deciding questions are the load and body weight, the durability the repeated use demands, and whether the surface is cleaned. State those, and H-O recommends the grade and the stack and the cushion to the equipment.

Force-deflection, density, and fatigue are maker-TDS properties characterized per ASTM D3574; grade values are per the TDS on file.

No. H-O Products is a precision converter: it makes the cushioning, pressure-redistribution, and liner foam parts to your drawing from cushioning material grades commonly used against the body, under an ISO 9001:2015 quality management system. H-O is an ISO 9001:2015 certified organization; that certification governs the converting process, not a device clearance. H-O does not make finished orthotics, prosthetics, braces, or rehab devices and does not claim an ISO 13485 certification, an FDA device registration or clearance, or a cleanroom certification.

Material grades are referenced by designation to ISO 10993 (especially -10 and -23 for skin-contact padding), USP Class VI, and FDA contact frameworks at the material level, where the material maker performs the evaluation. The finished-device biocompatibility, the clinical fit and pressure assessment, and the regulatory file belong to the device maker and the clinician. H-O supplies the converted foam parts, the material documentation, and lot traceability aligned to your requirements.

Send the orthotic, brace, or equipment drawing or a sample, the part you need, and the key facts: the body site and job (orthotic or insole, brace or support or socket, or rehab or therapy equipment), the load and body weight, the firmness and whether you want a soft-to-firm stack, the durability the wear demands (steps per day, hours, cycles), and the contact basis (whether the pad is skin-contact, the wear duration, and the ISO 10993 endpoints, USP Class VI designation, or FDA basis you need).

Add the outline and any contour or skive, the layers and their order, any adhesive side, and the prototype and annual volume. With that, engineering returns a material family and a soft-to-firm direction, a converted-part approach (including any lamination and contouring), prototype lead time, and the documentation that can be aligned to your requirements. The quote form below has fields for each of these.

Samples typically ship in 3 to 5 business days; standard production in about 2 weeks.

They overlap heavily, because the underlying job is the same: cushion the body and redistribute pressure. A microcellular polyurethane such as PORON medical is the comfort layer in both an orthotic insole top and a prosthetic socket or brace liner, chosen for low-set cushioning that offloads high-pressure points and recovers over the wear.

A soft conforming polyurethane (HyPUR-cel S) is favored for a socket or brace liner that has to wrap the limb and take up the gap to the rigid shell, while a firm crosslinked polyethylene is the structural base in an orthotic and a shell liner in a brace.

The differences are in the contour and the load: a prosthetic socket liner is contoured to the limb and may carry more concentrated load, an orthotic insole is contoured to the footbed and sees thousands of steps a day. So the families are shared, but the grade, the firmness, the contour, and the soft-to-firm stack are tuned to the site.

State the site, the contour, and the load, and H-O recommends and converts the right grade and stack. Foam properties are characterized per ASTM D3574.