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Orthotics () 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 muscle." Orthotists are medical professionals who specialize in designing orthotic devices such as braces or foot 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 vertebrae and sacrum regions of the Vertebral column. 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 (ortho prosthesis).
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.
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 (paresis) of the calf muscles (M. Triceps Surae) 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 therapy, orthotist and patient.
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 alloy and Aluminium alloy 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.
According to Vladimir Janda, a muscle function test is carried out to determine strength levels. (2025). 9783437464300, Urban und Fischer. ISBN 9783437464300 The degree of paralysis is given for each muscle group on a scale from 0 to 5, with the value 0 indicating complete paralysis (0%) and the value 5 indicating normal strength (100%). 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 (AFO or KAFO) and the functional elements necessary to compensate for restrictions caused by the reduced muscular strength levels.
One way of classifying gait is according to the "Amsterdam Gait Classification", which describes five gait types. To assess the gait pattern, the patient is viewed directly, or via a video recording, from the side of the leg being assessed. At the point when the leg is mid-stance the knee angle and the contact of the foot with the ground are assessed. The five gait types are:
Patients with paralysis due to cerebral palsy or traumatic brain injury are usually treated with an ankle-foot orthosis (AFO). Although in these patients the muscles are not paralyzed but being sent the wrong impulses from the brain, the functional elements used in the orthotics are the same for both groups. The compensatory gait is an unconscious reaction to the lack of security when standing or walking that usually worsens with increasing age; if the right functional elements are integrated into the orthosis to counter this, and maintain physiological mobility, the right motor impulses are sent to create new cerebral connections. (2025). 9783131513519, Georg Thieme Verlag. ISBN 9783131513519 The goal of an orthotic is the best possible approximation of the physiological gait pattern.
An important basic requirement for regaining the ability to walk is that the patient trains early on to stand on both legs safely and well balanced. An orthosis with functional elements to support balance and safety when standing and walking can be integrated into physical therapy from the first standing exercises, and this makes the work of mobilizing the patient at an early stage easier. With the right functional elements that maintain physiological mobility and provide security when standing and walking, the necessary motor impulses to create new cerebral connections can occur. Clinical studies confirm the importance of orthoses in stroke rehabilitation.
Patients with paralysis after a stroke are often treated with an ankle-foot orthosis (AFO), as after a stroke stumbling can occur if only the dorsiflexors are supplied with incorrect impulses from the central nervous system. This can lead to insufficient foot lifting during swing phase of walking, and in these cases, an orthosis that only has functional elements to support the dorsiflexors can be helpful. Such an orthosis is also called drop foot orthosis. When configuring a foot lifter orthosis, adjustable functional elements for setting the resistance can be included, which make it possible to adapt the passive lowering of the forefoot (plantar flexion) to the eccentric work of the dorsal flexors during loading response.
In cases where the muscle group of the plantar flexors is supplied with wrong impulses from the central nervous system, which leads to uncertainty when standing and walking, an unconscious compensatory gait can occur. When configuring an orthosis functional elements that can restore safety when standing and walking must be used in these cases; a foot lifter orthosis is not suitable as it only compensates for the functional deviations caused by weakness of the dorsiflexors.
Patients with paralysis after stroke who are able to walk have the option of analysing the gait pattern in order to determine the optimal function of an orthosis. One way of assessing is the classification according to the "N.A.P. Gait Classification", which is a physiotherapeutic treatment concept. (2025). 9783131468819, Renata Horst. ISBN 9783131468819 According to this classification, the gait pattern is assessed in the mid-stance phase and described as one of four possible gait types.
This assessment is a two step process; in the first step, the patient is viewed from the side of the leg to be assessed, either directly or via a video recording. In gait type 1 the knee angle is hyperextended, while in type 2, the knee angle is flexed. In the second step, the patient is viewed from the front to determine if the foot is inverted, if it is the letter "a" is added to the gait. This is associated with a varus deformity of the knee. If instead the patient stands on the inner edge of the foot (eversion), which is associated with a valgus deformity of the knee, the letter "b" is added to the gait type. Patients are thus classified as gait types 1a, 1b, 2a or 2b. The goal of orthotic fitting for patients who are able to walk is the best possible approximation of the physiological gait pattern.
This sequence of muscle function test and six-minute walk test is used to determine whether muscular fatigue can be induced. If the test reveals muscular fatigue, the strength levels and measured fatigue should be included in the planning of an orthosis, and when determining the functional elements.
Paralysis of the plantar flexors – If the plantar flexors are weak, the muscles of the forefoot lever are either inadequately activated or not activated at all. The patient has no balance when standing and has to support themself with aids such as crutches. The forefoot lever required for energy-saving walking in the gait phases from mid-stance to pre-swing cannot be activated by the plantar flexors. This leads to excessive dorsiflexion in the ankle joint in terminal stance and a loss of energy while walking. The center of gravity of the body lowers towards the end of the stance phase and the knee of the contralateral leg is flexed excessively. With each step, the center of gravity must be raised above the leg by straightening the excessively flexed knee. Since the plantar flexors originate above the knee joint, they also have a knee-extension effect in the stance phase.
Paralysis of the knee extensors – if the knee extensors are weak, there is an increased risk of falling when walking, as between loading response to the mid-stance the knee extensors control knee flexion inadequately, or not at all. To control the knee, the patient develops compensatory mechanisms that lead to an incorrect gait pattern, for example by exaggerated activation of the plantar flexors, leading into hyperextension of the knee, or when initial contact is with the forefoot and not the heel in order to prevent the knee-flexing effect of the heel rocker.
Paralysis of the knee flexors – if the knee flexors are weak, it is more difficult to flex the knee in pre-swing.
Paralysis of the hip flexors – if the hip flexors are weak, it is more difficult to flex the knee in pre-swing.
Paralysis of the hip extensors – the Gluteus maximus help control of the knee against unwanted flexion when walking between loading response and mid-stance.
Functional elements in paralysis of the dorsiflexors – if the dorsiflexors are weak, an orthosis should lift the forefoot during the swing phase in order to reduce the risk of the patient stumbling. An orthosis that has only one functional element for lifting the forefoot in order to compensate for a weakness in the dorsiflexors is also known as a drop foot orthosis. An AFO of the drop foot orthosis type is therefore not suitable for the care of patients with weakness in other muscle groups, as these patients require additional functional elements to be taken into account. Initial contact with the heel should be achieved by lifting the foot through the orthosis, and if the dorsiflexors are very weak, control of the rapid drop of the forefoot should be taken over by dynamic functional elements that allow for adjustable resistance of plantar flexion. Orthoses should be adapted to the functional deviation of the dorsiflexors in order to correct the shock absorption of the heel rocker lever during loading response, but should not block plantar flexion of the ankle joint as this leads to excessive flexion in the knee and hip and an increase in the energy needed for walking. This is why static functional elements are not recommended when there are newer technical alternatives.
Functional elements in paralysis of the plantar flexors – in order to compensate for a Muscle weakness of the plantar flexors, the orthosis has to transfer large forces that the strong muscle group would otherwise take over. These forces are transmitted in a similar way to a ski boot during downhill skiing via the functional elements of the foot part, ankle joint and lower leg shell. Dynamic functional elements are preferable for the ankle joint as static functional elements would completely block the dorsiflexion, which would have to be compensated for by the upper body, resulting in an increased energy cost when walking. The functional element's resistance to protect against unwanted dorsiflexion should be able to be adapted according to the weakness of the plantar flexors. In the case of very weak plantar flexors, the functional element's resistance against undesired dorsiflexion must be very high in order to compensate for the functional deviations this causes. Adjustable functional elements allow the resistance to be adjusted exactly to the weakness of the muscle, and scientific studies recommend adjustable resistance in patients with paralysis or weakness of the plantar flexors.
Functional elements in paralysis of knee extensors and hip extensors – in the case of weak knee extensors or Gluteus maximus, the orthosis must take over the stability and stance phase control when walking. Different knee-securing functional elements are needed depending on the weakness of these muscles. In order to compensate for functional deviations with slightly weakness of these muscle groups, a free moving mechanical knee joint with the mechanical pivot point behind the anatomical knee pivot point can be sufficient. In the case of significant weakness, knee flexion when walking must be controlled by functional elements that mechanically secure the knee joint during the early stance phases between loading response and mid stance. Stance phase control knee joints which lock the knee in the early stance phases and release it for knee flexion during the swing phase can be used here, with these joints, a natural gait pattern can be achieved despite mechanically securing against unwanted knee flexion. In these cases, locked knee joints are often used, and while they have a good safety function, the knee joint remains mechanically locked during the swing phase while walking. Patients with locked knee joints have to manage the swing phase with a stiff leg, which only works if the patient develops compensatory mechanisms, such as by raising the body's center of gravity in the swing phase (Duchenne limping) or by swinging the orthotic leg to the side (circumduction). Stance phase control knee joints and locked joints can both be mechanically "unlocked" so the knee can be flexed to sit down.
Through the use of modern materials, such as carbon fibers and aramid fibers, and new knowledge about processing these materials into composite materials, the weight of orthotics has been reduced significantly. In addition to the weight reduction, these materials and technologies have created the possibility of making some areas of an orthosis so rigid that it can take over the forces of the weakened muscles (e.g. the connection from the ankle joint to the frontal contact surface on the shin), while at the same time leaving areas requiring less support very flexible (e.g. the flexible part of the forefoot).
It is now possible to combine the required rigidity of the orthotic shells with the dynamics in the ankle, with this, other new technologies, and the possibility of producing lightweight but rigid orthoses, new demands have been made of orthotics:
A custom-made AFO can compensate for functional deviations of muscle groups, it should be configured according to the patient data through a function and load calculation so that it meets the functional and load requirements. In calculating or configuring an AFO, variants are optimally matched to individual requirements for the functional elements of the ankle joint, for the stiffness of the foot shell, and for the shape of the lower leg shell. The size of these components is selected by matching their resilience to the load data.
An ankle joint based on new technology is the connection between the foot shell and the lower leg shell and at the same time contains all the necessary adjustable functional elements of an AFO.
Depending on the combination of the degree of paralysis of the dorsiflexors or plantar flexors, different functional elements to compensate for their weakness can be integrated into the ankle joint; if both muscle groups are affected, the elements should be integrated into one orthotic joint. The necessary dynamics and resistance to movements in the ankle can be adapted via adjustable functional elements in the ankle joint of the orthosis, which allows it to compensate for muscle weaknesses, provide safety when standing and walking, and still allow as much mobility as possible. For example, adjustable spring units with pre-compression can enable an exact adaptation of both static and dynamic resistance to the measured degree of muscle weakness. Studies show the positive effects of these new technologies. It is of great advantage if the resistances for these two functional elements can be set separately.
An AFO with functional elements to compensate for a weakness of the plantar flexors can also be used for slight weakness of the knee-securing muscle groups, the knee extensors and the hip extensors.
A drop foot orthosis is an AFO that only has one functional element for lifting the forefoot in order to compensate for a weakness in the dorsiflexors. If other muscle groups, such as the plantar flexors, are weak, additional functional elements must be taken into account, making a drop foot orthosis unsuitable for patients with weakness in other muscle groups. In 2006, before these new technologies were available, the International Committee of the Red Cross published in its 2006 Manufacturing Guidelines for Ankle-Foot Orthoses, with the aim of providing people with disabilities worldwide standardized processes for the production of high-quality, modern, durable and economical devices.
Because new technologies are not widely used, AFOs are often made from polypropylene-based plastic, mostly in the shape of a continuous "L" shape, with the upright part behind the calf and the lower part under the foot, however, this only offers the rigidity of the material. AFOs made of polypropylene are still called "DAFO" (dynamic ankle-foot orthosis), "SAFO" (solid ankle-foot orthosis) or "Hinged AFO". DAFOs are not stable enough to transfer the high forces required to balance the weak plantar flexors when standing and walking, and SAFOs block the mobility of the ankle joint. A "Hinged AFO" only allowed for the compensation that could be achieved with the orthotic joints of the time, for example, they commonly block plantar flexion, as the joints cannot simultaneously transmit the large forces that are required to compensate for muscle deviations while also offering the necessary dynamics.
While there was a multitude of AFOs with differing designs in clinical practice, there was also a clear lack of details regarding the design and the materials used for manufacture, leading Eddison and Chockalingam to call for a new standardization of the terminology. With a focus on caring for children with cerebral palsy there is a recommendation to investigate the potential for gait pattern improvement via the design and manufacture of orthotics made of polypropylene. On the other hand, integrating orthotic joints with modern functional elements into the production of older technologies using polypropylene is unusual because the orthotic shells made of polypropylene either could not transfer the high forces or would be too soft.
New studies now show the better possibilities for improving the gait pattern through the new technologies.
The International Committee of the Red Cross published its manufacturing guidelines for ankle–foot orthoses in 2006, and, unfortunately, today's terminologies are still based those guidelines and therefore require a particularly high level of explanation. The intent was to provide standardized procedures for the manufacture of high-quality modern, durable and economical devices to people with disabilities throughout the world. However, with the new technologies available, the main types mentioned are in need of revision today.
KAFOs can be roughly divided into three variants, depending on whether the mechanical knee joint is: locked, unlocked or locked and unlocked.
KAFO with locked knee joint - The mechanical knee joint is locked both when standing and also when walking (in both the stance and swing phases) in order to achieve the necessary stability. To sit, the user can unlock the knee joint. When walking with a locked knee joint it is difficult for the user to swing the leg forward and, in order to not stumble, the leg must be swung forward and out in a circular arc (circumduction) or the hip must be raised unnaturally to swing the stiff leg. Each of these incorrect gait patterns can lead to secondary diseases in the bone and muscle system, and such compensatory movement patterns lead to increased energy consumption when walking. The film Forrest Gump impressively shows how the main character Forrest Gump is additionally hindered in his urge to move by such orthoses. For centuries, KAFOs were built with mechanical knee joints that stiffened the knee of the paralyzed leg, and even today, such orthotic fittings are still common. Typical designations for a KAFO with a locked knee joint include "KAFO with Swiss lock" or "KAFO with drop lock lock".
KAFO with unlocked knee joint - An unlocked knee joint can move freely both when standing and when walking, both in the stance phase and in the swing phase. In order for the leg to swing through without stumbling, knee flexion of approximately 60° is allowed; the user does not need to unlock the knee joint to sit. As a KAFO with an unlocked knee joint can provide only minor compensation for paralysis-related issues while standing and walking, an orthotic knee joint with a rearward displacement of the pivot point can be installed in order to increase safety. However, even with this, a KAFO with a non-locked knee joint should only be used in cases of minor paralysis of the knee and hip extensors. With more severe paralysis and low levels of strength in these muscle groups, there is a significant risk of falling. A typical designation for a KAFO with a unlocked knee joint is, among other things, "KAFO with knee joint for movement control".
KAFO with locked and unlocked knee joint - The mechanical knee joint of a KAFO with locked and unlocked knee joint is locked when walking in the stance phase, providing the necessary stability and security for the user. The knee joint is then automatically unlocked in the swing phase, allowing the leg to be swung through without stumbling. In order to be able to walk efficiently, without stumbling, and without compensating mechanisms, the joint should allow knee flexion of approximately 60° in the swing phase. The first promising developments of automatic knee joints, or stance phase locking knee joints, emerged in the 1990s. In the beginning there were automatic mechanical constructions that took over the locking and unlocking, now automatic electromechanical and automatic electrohydraulic systems are available that make standing and walking safer and more comfortable. Various terms are used for a KAFO with a locked and unlocked knee joint. Typical designations are "KAFO with automatic knee joint" or "KAFO with stance phase control knee joint". In scientific articles, the English term Stance Control Orthoses SCO is often used, but as this term differs from the ICS classification, one of the first two terms is preferable.
Different functional elements to compensate for weakness of the dorsiflexors or plantar flexors can be integrated into the ankle joint of the orthosis depending on the degree of paralysis of the two muscle groups. It is of great advantage if the resistances for these two functional elements can be set separately. The functional elements to compensate for paralysis of the knee-securing muscle groups of the knee and hip extensors are integrated into the knee joint of the orthosis via knee-securing functional elements. A KAFO can use a variety of combinations of different variants in the stiffness of the foot shell, the different variants of the functional elements of a dynamic ankle joint, the variants in the shape of the lower leg shell, and the functional elements of a knee joint to compensate for the user's limitations.
Relief orthosis may also be used to:
Functional braces are designed for use by people who have already experienced a knee injury and need support while recovering from it, or to help people who have pain associated with arthritis. They are intended to reduce the rotation of the knee, support stability, reduce the chance of hyperextension, and increase the agility and strength of the knee. The majority of these are made of elastic. They are the least expensive of all braces and are easily found in a variety of sizes.
Rehabilitation braces are used to limit the movement of the knee in both medial and lateral directions, these braces often have an adjustable range of motion, and can be used to limit flexion and extension following ACL reconstruction. They are primarily used after injury or surgery to immobilize the leg and are larger in size than other braces, due to their function.
Spinal orthoses may also be used in the treatment of spinal fractures. A Jewett brace, for instance, may be used to aid healing of an anterior wedge fracture involving the T10 to L3 vertebrae, and a body jacket may be used to stabilize more involved fractures of the spine. There are several types of orthoses for managing cervical spine pathology. The halo brace is the most restrictive cervical thoracic orthosis in use; it is used to immobilize the cervical spine, usually following fracture, and was developed by Vernon L. Nickel at Rancho Los Amigos National Rehabilitation Center in 1955.
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