A 3mm polypropylene orthotic is rigid and it does not move or flex. This type is very useful for hallux rigidus / hallux limitus where movement of the big toe joint is very painful due to arthritis. It is made exactly to the shape of the foot and is a passive 3D orthotic.

How we make a 3D and 4D orthotic starts with the same principle. Visual analysis is made to determine the ideal foot and ankle position. Measuring angles, an accurate fitting of a corrective orthotic can be made. Sometimes, visual planning is not enough and the acquisition of a high-quality imaging process such as 3D CT scan may be required. The biomedical model, such as a plaster-cast taken from a shaped mould of the foot, is obtained to plan and print the 3D orthotic.

With 4D orthotics, another process is added. Determining the movement and forces to be applied on the orthotic requires patient planning. Restriction of movement in a weight lifter is often required. More flexibility is required in a runner. During 4D orthotic manufacture, the dynamics of the required movement is forecast, depending on the movement and activity level.

Video showing flat foot to normal arch foot corrected by using orthotic.

A passive orthotic is made from a mould of the foot and conforms to the existing shape. It holds and cradles the foot creating support. A passive orthotic is similar to a dental mouthguard made for the shape of the teeth to protect them and keep them in place.

An active orthotic changes the position of the existing foot posture. If the ankle leans-in 32° and the arch collapses as a result, then an active orthotic is made to align the foot into neutral again. It is similar to orthodontic braces for the teeth and a dental mouth guard of the teeth. If the teeth are crooked you do not want to use a dental mouth guard to try and straighten the teeth. If you want to align and straighten the teeth. A dental brace would be initiated. A dental brace which is compared to an active orthotic. If the ankle is pronated (leaning-in), a tilted orthotic to align the ankle and arch is required. There are restrictions with this process. Osteoarthritis may cause restriction on the movement of the joints and the position of the bones will not allow the foot to be manipulated into a certain position.

This can be checked using an x-ray and possibly a 3D CT scan of the foot. This enables the Podiatrist to see if it is possible to maneuver the foot into the desired position.

For example, if you are using the same orthotic to walk in, how will it respond to lifting 80 kg of weight at the gym? It should be able to move with your body in response to the 80 kg of weight that you’re lifting – that’s what makes this type of orthotic 4D.

Another type of 4D orthotic can shape the foot into a different position over time in response to the outside stimulus of the orthotic. If the ankle leans in 32° and flatten the arch by using an orthotic that corrects the 32° tilt change the position of the arch and makes the foot smaller as a result. This is a 4D orthotic in action.

على سبيل المثال، إذا كنت تستخدم نفس جهاز تقويم العظام أثناء المشي، فكيف سيستجيب لرفع ٨٠ كجم من الوزن في صالة الألعاب الرياضية؟ يجب أن يكون قادرًا على التحرك مع جسمك استجابةً لوزن ٨٠ كجم الذي ترفعه – وهذا ما يجعل هذا النوع من أجهزة تقويم العظام رباعية الأبعاد.

يمكن لنوع آخر من أجهزة تقويم العظام رباعية الأبعاد تشكيل القدم في وضع مختلف مع مرور الوقت استجابةً للتحفيز الخارجي لجهاز تقويم العظام. إذا كان الكاحل يميل بزاوية ٣٢ درجة ويسطح القوس باستخدام جهاز تقويمي يصحح الميل بمقدار 32 درجة، قم بتغيير موضع القوس ويجعل القدم أصغر نتيجة لذلك. هذا هو جهاز تقويم العظام رباعي الأبعاد أثناء العمل.