Inner length of the footwear should be 1–2 cm longer than the foot length as measured from heel to the longest toe when a person is standing. Adequate length needs to be confirmed when people are weight-bearing while wearing the footwear.
Depth should accommodate the toes to move freely without causing pressure at either the medial, lateral or the dorsal side.
Width should equal the width of all parts of the foot. Width is good when the upper can be slightly bunched. The relation between forefoot and hindfoot is important, as accommodating a wide forefoot may result in the heel being too wide.
Footwear height can be low, ankle-high, or high. High footwear provides more firmness, stability and reduces joint motion. The shaft of high footwear also contributes to forefoot pressure reduction. See further Table 3 for specific height requirements for people with a foot deformity.
The removable moulded insole can be pre-fabricated, adjusted or custom-made. The primary function of the insole is pressure redistribution. This is achieved via the principle of increasing the contact area between the foot and the insole, and the addition of corrective elements in the insole. Shock-absorbing, soft but sufficiently resilient and non-slippery materials should be used. See further Table 4 for the offloading effects of specific insole modifications.
Rubber, plastic, and leather can all be used in construction of footwear outsoles, but rubber outsoles are thought to be superior.
Outsoles can be supple, toughened or stiff. The shoe should not be more supple than the foot, or friction between foot and shoe will develop during push-off. See further Table 3 for specific outsole requirements for people with a foot deformity and Table 4 for the offloading effects of specific modifications.
Rocker profiles have proven effectiveness in reducing plantar pressures, especially the forefoot. The rocker profile chosen depends on the affected joints and is determined by the apex position (pivot point) and the angle from the pivot point to the tip of the toe. For plantar pressure reduction of the metatarsophalangeal joints, the pivot point needs to be proximal to these joints.
The rocker profile also impacts balance; the more proximally placed, the greater the balance disturbance. A person’s balance should therefore always be taken into account when deciding on the rocker profile.
An adequately fitting and enclosed heel is recommended, as open backed footwear or a heel enclosure that is too wide can result in injury and usually requires a person to claw their toes in order to keep them on. The heel counter needs to be free of edges protruding into the footwear.
The heel lift (or heel-forefoot difference, or pitch) should be generally 1.5–2 cm, and should not exceed 3 cm.
Adequate closure (or fixation) is needed to keep the foot from sliding forward. Closure should allow secure longer-term fastening and individual adjustment. Laces have long been considered the optimal choice; however, alternatives that are easier to use while still meeting these criteria are available as well, and innovative closures continue to be developed.
The uppers consist of the ‘quarter’(hind- and midfoot) and ‘vamp’ (forefoot and toes). Uppers should be made from leather or a combination of materials (similar to sports shoes), with smooth inner lining made from a material that does not harden over time, with limited seams and preferably no seams in the vamp area as they reduce the ability of the leather to give.
Uppers should be breathable and durable and have the ability to mould to deformities of the foot without resulting in pressure areas. Uppers can be supple, toughened or stiff. The vamp area should generally remain supple to accommodate the toes. See further Table 3 for specific requirements for the uppers (quarter) for people with a foot deformity.
The part of the shoe that covers and protects the toes. This should be supple (unless specific requirements (e.g. for building professionals) require otherwise), and should accommodate the shape of the toes, to avoid any rubbing on the toes.