LL Orthotics Flashcards
Orthoses
Orthoses are devices that are applied to the external surface of the body to achieve one or more of the following; relieve pain, immobilize musculoskeletal segments, reduce axial load, prevent or correct deformity and improve function.
Purposes
- Orthoses provide a direct support component to the braced limb segment and limit the range of motion of a joint. This mechanism largely gives rise to reduction of axial loads and thus perhaps aids in joint pain relief.
- It may also be used to partially or fully immobilize the joint, and in this manner produce deformity prevention or correction and also improve function.
- In conjunction with the above two mechanisms, a more difficult mechanism to visualize is the fact that orthoses modify the total static and dynamic force/ moment distributions in the braced and more distal segments (“in” joints or about a joint center) and provide a substitute power source for weak muscles while maintaining level surface walking safety and efficiency.
Corrective devices
Corrective devices are meant to improve the position of the limb segment, either by stretching a contracture or correcting the alignment of skeletal structures
Accommodative devices
Accommodative devices are meant to provide additional support to an already deformed tissue, to prevent further deformity, and ultimately to improve function.
Terminology
Orthotic devices are named by the joints they encompass in correct sequence followed by the word orthosis.
- For example, an orthosis that crosses the ankle and the foot is named an ankle-foot orthosis (AFO). One that crosses the knee, ankle, and foot is called a knee-ankle-foot orthosis (KAFO).
- The intended biomechanical function or material may complement the terminology (i.e., dorsiflexion assistance plastic AFO).
Wedges
Indications for a flare include
A) posttraumatic subtalar instability
B) hind foot contractures and tone disorders that increase the tendency to roll the ankle.
A wedge is used to help accommodate
C) a rigid deformity or
D) correct flexible deformities of the hind foot.
Elevations
Elevations are applied either under the heel only or under the whole foot. They can be applied internally or added to the outer sole of the shoe. A heel-only elevation is appropriate for accommodating a fixed equinus position or reducing the strain on the Achilles tendon. A buildup less than ½ in. (1.2 cm) can be easily added inside the shoe.
Rocker Sole
The basic function of a rocker sole is to rock the foot from heel strike to toe off without metatarsal bending. Rocker soles can effectively be used to reduce pressure under the metatarsal heads and can assist gait by easing and increasing forward propulsion in mid to terminal stance. It can reduce enough motion at the first metatarsophalangeal joint, mitigating the pain associated with hallux rigidus.
Cushion Heel
Cushion heel, which consists of a wedge of shock-absorbing foam that is sandwiched between the heel and the sole of a shoe. The purpose of a cushion heel is to increase shock absorption and reduce the knee flexion forces occurring at heel strike resulting in a stable stance phase.
- A cushion heel may be indicated for patients after
A) ankle fusion
B) calcaneal fracture.
C) quadriceps weakness or patients with other forms of early stance phase knee instability.
FO
When prescribing a FO, knowledge of the disease process in question, functional anatomy, biomechanics, materials, and finally, recognition of the anticipated functional outcomes are essential for proper prescription.
Non-articulated AFO
A molded footplate and a solid non-articulated ankle design immobilize the foot and ankle in slight equinus, which produces a knee extension force during stance phase.
Genu recurvatum
Potential genu recurvatum is controlled by the ligamentous structures of the knee joint or a supracondylar anterior shell and a counteracting posteriorly placed popliteal shell. Blocking plantarflexion of the foot can limit recurvatum as well.
Equinovarus deformity
Equinovarus deformity is the most common pathologic lower limb posture observed in the population after central nervous system injuries.
- This abnormal posture results in an unstable base of support during stance phase.
- The contact with the ground occurs with the fore foot first, and weight is borne primarily on the lateral border of the foot; this position is maintained during the stance phase.
- Heel contact may be limited or missing.
- Limitation in ankle dorsiflexion prevents forward progression of the tibia over the stationary foot in stance phase, causing knee hyperextension and interference with terminal stance and preswing where lack of a propulsive phase is evident.
- During the swing phase, there is a sustained plantar-flexed and inverted posture of the foot, possibly resulting in a limb clearance problem.
- The lack of adequate base of support results in instability of the whole body.
- For this reason, the correction of the abnormal ankle-foot posture by orthotic means is essential.
Equinovarus deformity
Equinovarus deformity is the most common pathologic lower limb posture observed in the population after central nervous system injuries.
- This abnormal posture results in an unstable base of support during stance phase.
- The contact with the ground occurs with the fore foot first, and weight is borne primarily on the lateral border of the foot; this position is maintained during the stance phase.
- Heel contact may be limited or missing.
- Limitation in ankle dorsiflexion prevents forward progression of the tibia over the stationary foot in stance phase, causing knee hyperextension and interference with terminal stance and pre-swing where lack of a propulsive phase is evident.
- During the swing phase, there is a sustained plantar-flexed and inverted posture of the foot, possibly resulting in a limb clearance problem.
- The lack of adequate base of support results in instability of the whole body.
- For this reason, the correction of the abnormal ankle-foot posture by orthotic means is essential.
AFO for Equinovarus deformity
The use of an AFO to control the abnormal posture of the ankle during stance and swing phases should be attempted.
- The orthosis should be attached preferentially to an orthopedic shoe
- An ankle inversion strap or pad should be used to assist in controlling the ankle inversion attitude.
- The orthotic ankle should include a plantar flexion stop to control ankle plantar flexion during swing and stance
- If ankle clonus is triggered during the stance phase, a dorsiflexion stop will need to be used as well to prevent the stretch response triggering this phenomenon. The stop should be set just before the clonus appears.
- A molded foot plate with a padded long plastic foot-plate,
- A toe strap and an extra-depth shoe with high toe box, can be used as an option to accommodate abnormal flexed toe posture
