when walking, which is why such a technical solution is not recommended due to newer technical alternatives.: 105 : 134 functional elements in paralysis of the plantar flexors – in order to compensate for a weakness of the plantar flexors, the orthosis has to transfer great forces that the strong muscle group of the plantar flexors would otherwise take over. the forces in the orthosis 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 should preferably be used in the ankle joint in order to secure the dorsiflexion. static functional elements would completely block the dorsiflexion. a completely blocked dorsiflexion would have to be compensated by compensatory movements in the upper body, which would result in an increasing of energy cost when walking. the resistance of the functional element to protect against unwanted dorsiflexion should be able to be adapted to the weakness of the plantar flexors. in the case of very weak plantar flexors, the resistance of the functional element to secure against undesired dorsiflexion must be very high in order to be able to compensate for the functional deviations of the plantar flexors. adjustable functional elements of an orthosis allow an exact adjustment of the resistance to the weakness of the muscle and scientific studies have come to the recommendation that the resistance of the orthosis should be adjustable 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 hip extensors, the orthosis must take over the stability and stance phase control when walking. depending on the weakness of these two muscle groups, different knee-securing functional elements are integrated into the orthosis. in order to compensate for functional deviations with slightly weakness of these muscle groups, free moving mechanical knee joints with a posterior shift of the mechanical pivot point behind the anatomical knee pivot point can be sufficient. in the case of significant weakness, the knee flexion effect when walking must be controlled by functional elements that mechanically secure the knee joint against unwanted knee flexion in the early stance phases between loading response and mid stance. stance phase control knee joints can be used here. these lock the knee joint in the early stance phases and release the knee joint for knee flexion during the swing phase. with stance phase control knee joints, a natural gait pattern can be achieved despite mechanical securing against unwanted knee flexion. in these cases, locked knee joints are often used, which have a good safety function, but do not allow knee flexion when walking during swing phase. the knee joint remains mechanically locked during the swing phase. patients with locked knee joints have to manage the swing phase with stiff leg. this only works if the patient develops compensatory mechanisms, e.g. 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 be mechanically "unlocked" so that the knee joint can be flexed to sit down. ankle–foot orthoses (afo) in the field of paralysis orthoses ankle-foot orthosis for the care of patients after stroke, cerebral palsy, multiple sclerosis and other paralyzes of the dorsiflexors and plantar flexors. (designation of the orthosis according to the body parts included in the orthosis fitting: ankle and foot, english abbreviation: afo for ankle-foot orthoses) afo is the abbreviation for ankle-foot orthoses; english name for an orthosis that spans the ankle and foot. in the treatment of paralyzed patients, an afo is mainly used when there is a weakness of the dorsiflexors or plantar flexors. through the use of modern materials such as carbon fibers and aramid fibers and the new knowledge about processing these materials in composite fiber materials, the weight of orthotics has been extremely reduced compared to previous techniques. taking into account the weight reduction, it were these materials and technologies that created the possibility of making special areas of an orthosis so rigid that the forces of the weakened muscles can actually be taken over by the afo, e.g. the connection from the ankle joint to the frontal contact surface on the shin. at the same time, the areas in which flexibility is required can be produced very flexibly, e.g. the flexible part of the forefoot. the new technologies with the possibility of producing lightweight orthotics with high rigidity values at the same time brought new demands on orthotics: despite the necessary rigidity, the orthoses should not block the mobility of the ankle. despite the necessary rigidity, the orthoses should not block the functionality of the muscles, but rather promote it. despite the necessary rigidity, contractures and spasticity should not be stimulated. since several years it has been possible to combine the required rigidity of the orthotic shells with simultaneous dynamics in the ankle. a custom-made afo can compensate for the functional deviations of the muscle groups mentioned. it should be configured according to the patient data through a function and load calculation so that it meets the functional requirements and the loads. when calculating or configuring, functional variants are optimally matched to individual requirements with regard to the functional elements in the area of the ankle joint, the stiffness of the foot shell and the shape of the lower leg shell. the size of the components used is selected by calculating their resilience to match 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. different functional elements to compensate for a weakness of the dorsiflexors or a weakness of the plantar flexors can be integrated into the ankle joint of the orthosis depending on the combination of the degree of paralysis of the two muscle groups. in case of weakness of both muscle groups, both functional elements should be integrated in one orthotic joint. the necessary dynamics and the resistance to movements in the ankle are specifically adapted via adjustable functional elements in the ankle joint of the orthosis. in this way, the orthosis can compensate for muscle weaknesses in order to provide safety when standing and walking and at the same time allow as much mobility as possible. for example, adjustable spring units with pre-compression can enable an exact adaptation of the static basic resistance and the dynamic movement 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. an afo 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. if other muscle groups, such as the plantar flexors, are weak, additional functional elements must be taken into account. an afo of the drop foot orthosis type is therefore not suitable for the care of patients with weakness in other muscle groups. ankle-foot orthosis (afo) manufactured using old technology from polypropylene in a variant that is also called "hinged afo". it can be used to support an isolated foot drop, but it will block plantar flexion. this afo cannot transmit the high forces required to counterbalance weak plantar flexors while standing and walking. before these new technologies were available, there was a standard that the international committee of the red cross published in its 2006 manufacturing guidelines for ankle-foot orthoses. at that time, the aim was already to offer people with disabilities worldwide standardized processes for the production of high-quality, modern, durable and economical devices. because the new technologies are still not widely used, afos are often still made from polypropylene-based plastic, mostly in the shape of an "l" with the upright part behind the calf and the lower part under the foot. the continuous "l" shape of these constructions, however, only offers the rigidity that can be produced with these materials. such constructions made of polypropylene are still called "dafo (dynamic ankle-foot orthosis)", "safo (solid ankle-foot orthosis)" or "hinged afo". either they are not stable enough to transfer the high forces required to balance the weak plantar flexors when standing and walking (dafo) or they block the mobility of the ankle joint (safo). a "hinged afo" at that time, only allow for the compensation of that kind of muscular weakness that could be achieved with the orthotic joints available at that time. in this technology, for example, it is still common to block plantar flexion, as the orthotic joints available at the time cannot simultaneously transmit the large forces that are required to compensate for muscle deviations and at the same time offer the necessary dynamics. while there was this multitude of afos in clinical practice, which differed in their design, studies have already established that there was a clear lack of details regarding the design and the materials used for manufacture. eddison and chockalingam have called for a new standardization of the terminology. with a focus on the care of children with cerebral palsy (cp), there was already a recommendation from clinical practice in the context of the manufacture of orthotics made of polypropylene and their multitude of possible designs that the potential for improving the gait pattern through specifically adapted orthotics through further studies to investigate. the integration of orthotic joints with modern functional elements in the old production technology with polypropylene, on the other hand, is unusual because the orthotic shells made of polypropylene could not transfer the high forces under the boundary condition of an acceptable weight or would be too soft. new studies now show the better possibilities for improving the gait pattern through the new technologies. unfortunately, today's terminologies were determined on the basis of the technologies available until then and therefore now require a particularly high level of explanation. the international committee of the red cross published its manufacturing guidelines for ankle–foot orthoses in 2006. its intent is to provide standardized procedures for the manufacture of high-quality modern, durable and economical devices to people with disabilities throughout the world. because of the studies already mentioned above which recognize the new technologies available, the main types mentioned are in need of revision today. afo known as: safo afo known as: dafo afo known as: hinged afo afo known as: posterior leaf spring afo known as: frafo afo with stiff carbon fiber frame and dynamic ankle joint for adjustable stiffness through separately adjustable spring resistance in plantar- and dorsiflexion designation of the orthosis according to one function: s for solid plus the body parts included in the orthosis fitting: ankle and foot, english abbreviation: afo for ankle-foot orthoses "safo" designation of the orthosis according to one function: d for dynamic plus the body parts included in the orthosis fitting: ankle and foot, english abbreviation: afo for ankle-foot orthoses "dafo" designation of the orthosis according to one function: hinged plus the body parts included in the orthosis fitting: ankle and foot, english abbreviation: afo for ankle-foot orthoses "hinged-afo" "hinged" simply means a flexible connection between the two parts of the orthosis. the joint itself does not offer any further functional elements. designation of the orthosis according to one function: "posterior leaf spring" spring made from flexible material behind (posterior) the ankle a dafo often also known as "posterior leaf spring" designation of the orthosis according to one function: fr for floor reaction plus the body parts included in the orthosis fitting: ankle and foot, english abbreviation: afo for ankle-foot orthoses "frafo" designation is misleading as other orthoses also have this function designation of the orthosis according to the body parts included in the orthosis fitting: ankle and foot, english abbreviation: afo for ankle-foot orthoses. plus further descriptions, such as: - ventral shell with torsionally rigid reinforcement to focus the dynamics on the ankle joint - dynamic ankle