Orthotics

Orthotics, also known as orthology, is a medical specialty that focuses on the design and application of orthoses, sometimes known as braces, calipers, or splints. An is "an externally applied device used to influence the structural and functional characteristics of the neuromuscular and skeletal systems." Orthotists are medical professionals who specialize in designing orthotic devices such as braces or foot orthoses.

Classification

Orthotic devices are classified into four areas of the body according to the international classification system : orthotics of the lower extremities, orthotics of the upper extremities, orthotics for the trunk, and orthotics for the head. Orthoses are also classified by function: paralysis orthoses and relief orthoses.
Under the International Standard terminology, orthoses are classified by an acronym describing the anatomical joints they support. Some examples include KAFO, or knee-ankle-foot orthoses, which span the knee, ankle, and foot; TLSO, or thoracic-lumbar-sacral orthoses, supporting the thoracic, lumbar and sacral regions of the spine. The use of the International Standard is promoted to reduce the widespread variation in the description of orthoses, which is often a barrier to interpreting research studies.
The transition from an orthosis to a prosthesis can be fluid. An example is compensating for a leg length discrepancy, equivalent to replacing a missing part of a limb. Another example is the replacement of the forefoot after a forefoot amputation. This treatment is often made from a combination of a prosthesis to replace the forefoot and an orthosis to replace the lost muscular function.

Orthotist

An orthotist is a specialist responsible for the customising, manufacture, and repair of orthotic devices. The manufacture of modern orthoses requires both artistic skills in modeling body shapes and manual skills in processing traditional and innovative materials— CAD/CAM, CNC machines and 3D printing are involved in orthotic manufacture. Orthotics also combines knowledge of anatomy and physiology, pathophysiology, biomechanics and engineering.
In the United States, while orthotists require a prescription from a licensed healthcare provider, physical therapists are not legally authorized to prescribe orthoses. In the U.K., orthotists will often accept referrals from doctors or other healthcare professionals for orthotic assessment without requiring a prescription.

Prescription and manufacturing

Orthoses are offered as:

Custom-fabricated products – they are in the foreground of an optimal supply and are individually manufactured. If the physical examination of a patient is carried out precisely, the clinical picture often shows a combination of several functional deviations. Each functional deviation can be slight or severe. The combination of the functional deviation and its characteristics leads to a detailed indication. A major advantage of custom-made products is that the various necessary orthotic functions when doing the configuration of the orthotics can be optimally matched to the determined functional deviations. Another advantage of custom-made products is that each orthosis is made to fit the individual body shape of the patient. Custom-fabricated products were traditionally made by following a trace of the extremity with measurements to assist in creating a well-fitted device. Subsequently, the advent of plastics and later even more modern materials such as carbon fiber composites and aramid fibers as materials of choice for construction necessitated the idea of creating a plaster of Paris mold of the body part in question. This method is still extensively used throughout the industry. By introducing composite materials made of carbon fiber materials and aramid fibers embedded in an epoxy resin matrix, the weight of modern orthoses is extremely reduced. With this technique, modern orthoses can achieve perfect stiffness in the areas where this is necessary and flexibility in the areas where flexibility is required.
Semi-finished products – they are used for fast supply in the case of diseases that occur frequently. They are manufactured industrially and in some cases can be adapted to the anatomical body conditions. Semi-finished products are also referred to as prefabricated products and custom fitted products, but in these cases it is not custom-fabricated.
Finished products – these include short-term orthoses or bandages for a limited duration of therapy and are manufactured industrially. Finished products are also referred to as off-the-shelf products.

Both custom-fabricated products and semi-finished products are used in long-term care and are manufactured or adapted by the orthotist or by trained orthopedic technicians according to the prescription. In many countries the physician or clinician defines the functional deviations in his prescription, e.g. paralysis of the calf muscles and derives the indication from this, e.g. orthotic to restore safety when standing and walking after a stroke. The orthotist creates another detailed physical examination and compares it with the prescription from the physician. The orthotist describes the configuration of the orthosis, which shows which orthotic functions are required to compensate for the functional deviation of the neuromuscular or skeletal system and which functional elements must be integrated into the orthosis for this. Ideally, the necessary orthotic functions and the functional elements to be integrated are discussed in an interdisciplinary team between physician, physical therapist, orthotist and patient.

Lower limb orthoses

All orthoses that affect the foot, the ankle joint, the lower leg, the knee joint, the thigh or the hip joint belong to the category of orthoses for the lower extremities.

Paralysis orthoses

orthoses are used for partial or complete paralysis, as well as complete functional failure of muscles or muscle groups, or incomplete paralysis. They are intended to correct or improve functional limitations or to replace functions that have been lost as a result of the paralysis. Functional leg length differences caused by paralysis can be compensated for by using orthosis.
For the quality and function of a paralysis orthosis, it is important that the orthotic shell is in total-contact with the patient's leg to create an optimal fit, which is why a custom-made orthotic is often preferred. As reducing the weight of an orthosis significantly lessens the energy needed to walk with it, the use of light weight and highly resilient materials such as carbon fiber, titanium and aluminum is indispensable for the manufacture of a custom-made orthosis.
The production of a custom-made orthotic also allows the integration of orthotic joints, which means the dynamics of the orthotic can be matched exactly with the pivot points of the patient's anatomical joints. As a result, the dynamics of the orthosis take place exactly where dictated by the patient's anatomy. Since the dynamics of the orthosis are executed via the orthotic joints, it is possible to manufacture the orthotic shells as stable and torsion-resistant, which is necessary for the quality and function of the orthosis. The orthosis thus offers the necessary stability to regain the security that has been lost due to paralysis when standing and walking.
In addition, an orthosis can be individually configured through the use of orthosis joints. In this way, the combination of the orthotic joints and the adjustability of the functional elements can be adjusted to compensate for any existing functional deviations that have resulted from the muscle weakness. The goal of a high-quality orthotic fitting is to adjust the functional elements so precisely that the orthosis provides the necessary support while restricting the dynamics of the lower extremities as little as possible to preserve the remaining functionality of the muscles.

Determination of strength levels for physical examination

In the case of paralysis due to disease or injury to the spinal/peripheral nervous system, a physical examination is needed to determine the strength levels of the affected leg's six major muscle groups and the orthosis's necessary functions.

The dorsiflexors move the foot through concentric muscle work around the axis of the ankle in the direction of dorsiflexion and control the plantar flexion through eccentric muscle work.
The plantar flexors contribute significantly to being able to stand upright by actuating the forefoot lever and thereby increasing the standing area when standing. This group of muscles moves the foot in the direction of plantar flexion.
The knee extensors extend the knee in the direction of the knee extension.
The knee flexors bend the knee in the direction of the knee flexion.
The hip flexors bend the hip joint toward the hip flexion.
The hip extensors stretch the hip joint in the direction of the hip extension and, at the same time, extend the knee in the direction of the knee extension.

According to Vladimir Janda, a muscle function test is carried out to determine strength levels. The degree of paralysis is given for each muscle group on a scale from 0 to 5, with the value 0 indicating complete paralysis and the value 5 indicating normal strength. The values between 0 and 5 indicate a percentage reduction in muscle function. All strength levels below five are called muscle weakness.
The combination of strength levels of the muscle groups determines the type of orthosis and the functional elements necessary to compensate for restrictions caused by the reduced muscular strength levels.

Physical examination for paralysis due to diseases or injuries to the spinal cord and/or the peripheral nervous system

Paralysis may be caused by injury to the spinal or peripheral nervous system after spinal cord injury, or by diseases such as spina bifida, poliomyelitis and Charcot-Marie-Tooth disease. In these patients, knowledge of the strength levels of the large muscle groups is necessary to configure the orthotic for the necessary functions.