An Instructive Guide To Different Types Of Tailor Made Calipers
The last blog was about orthotics and their components. This blog is about the orthotics of the upper and lower extremities in detail. the following are the orthotic devices for upper and lower respectively.
Other orthoses include shoulder, wrist, arm, and elbow regions of the upper extremities. The orthotic devices of the lower extremities are called calipers. The stability of the knee, hip, and muscle power grading of hip abductors, extensors, and knee extensors have to be checked for the design of the caliper. Alignment of the ankle over medial malleoli, medial femoral condyle, and 90 degree of the hip are also essential for caliper prescription.
It is a boot that covers the malleoli, consisting of wedges and supports made of leather/rubber to correct foot deformities. There are two components in foot orthosis namely, upper and lower.
Components of lower foot orthosis
- Sole- Point of contact with the ground, insole provides cushion for the feet
- Bars, straps, and wedges- attachments that leverage force
- Ball- Widest part present in the metatarsal region
- Shank- Narrowest region present in between ball and heel
- Toe spring- Space between sole and floor that provides rocker effect in toe-off phase of gait
- Heel- A thicker and resilient posterior part that shifts weight and prevents wearing
Components of upper foot orthosis
- Quarter- Posterior part, known as the high top used to increase sensory feedback and prevent retrocalcaneal pain in athletes
- Heel counter- Placed posterior to quarter to increase stability and support calcaneus.
- Vamp- Anterior portion reinforced with toe box, protect upper fore boot and provide extra orthotic intervention
- Toe box- Prevent trauma while kicking a ball and avoid shoe stubbing
- Throat- Opening of the shoe
- Tongue- Region where vamp extends down the throat
- Stirrup- placed outside shank to provide attachments for metal bars
The following table shows the disorder/injury and the orthotic modification done to avoid them.
|Hallux valgus||Soft vamp, high toe box, extra depth and metatarsal pad|
|Inversion injury||Outside heel float|
|Hammer toes||Metatarsal pads|
|Callus, corn, and spurs||Heel cushion with sponge|
|Pes cavus||High quarter, high toe box, metatarsal bar/pad, arch, inner mould sole|
|Pes equinus||heel lift, metatarsal bar/pad, high quarter, open throat, heel elevation|
|Pes equinovarus||lateral wedge- flexible deformity, medial wedge- fixed deformity|
|Pes plano-valgus||heel wedge, high quarter, and arch|
|Limb shortening||heel elevation|
Ankle foot orthosis (AFO)
It consists of a proximal calf band with leather straps, medial and lateral metal bars for control of dorsiflexion and plantar, and stirrups to anchor to the shoe. It is the foot orthosis in addition to the aforementioned components. Based on the type of deformity, there are five types of AFO.
- Fixed ankle joint- Protect and reduce weight bearing through weight relieving orthosis
- 90-degree foot drop stop- Allows 90-degree dorsiflexion and prevents plantar flexion, used when dorsiflexors are weak and plantar normal or plantar becomes spastic when dorsiflexors are normal.
- Reverse 90-degree ankle joint- allows 90-degree plantar and prevents dorsiflexion, used when plantar flexors are weak while dorsiflexors are normal.
- Free ankle- normal ankle power
- Limited ankle- Limited range of motion
Knee ankle foot orthosis (KAFO)
Comprises of uprights extended to the thigh, suspension bands, and are worn to the leg or thigh in order to provide stability from the knee to the foot. Used for muscle weakness due to polio, spine damage, upper motor lesions; loss of structural integrity due to injuries in ligaments, arthritis, and osteoarthritis. the KAFO can limit hyperextension, relieve weight and produce extensor synergy in the lower limbs.
The straight set knee joint consists of an upper segment rotating in a single transverse axis with a drop lock for stability. These are cheap and easy to repair. The polycentric knee joint comprises of double axis system for flexion/extension of the tibia and fibula. Polycentric offset knee joint keeps knee extended during less stance control, placed behind the knee joint to increase stability and generate enough momentum to walk.
Note- The ideal joint should have stability during weight bearing and flexion during the swing phase of gait when it is non-weight bearing and more energy efficient & decreases the exaggerated movements of the hip which is seen when the knee is locked.
Hip Knee Ankle Foot Orthosis (HKAFO)
A hip joint that allows flexion and extension of hip alone, suspension with the pelvic band (in between trochanter and iliac crest) to extend in lateral and posterior directions and provide stability from the hip to the foot. It is fastened with elastic/velcro strap fastener with a uniaxial hip joint and drop lock. The weight is transmitted to the ischial seat and metal uprights to the ground and hence helps in weight relief.
It provides balance during standing, improvised posture, and better control for forwarding leg swings when hip muscles are weak or the tendency of varus and valgus in the ankle. The problems associated are difficulty in wearing and removing limited step length, and lumbar movements in compensation to hip motion.
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