LOWER LIMB ORTHOSES

Orthosis- device attached or applied to the external surface of the body to improve function, restrict or enforce motion or support a body segment
Lower Limb Orthoses- indicated to assist gait, reduce pain, decrease weight bearing, control movement and minimize worsening of a deformity.
Ambulation Aids- may be used with and without lower limb orthoses/prostheses to help patient ambulate more safely; represent extension of the upper limb and are technically upper limb orthoses

PRINCIPLES OF LOWER LIMB ORTHOSES

Use only as indicated and for as long as necessary.
Allow joint movement wherever possible and appropriate.
Orthoses should be functional throughout all phases of gait
Orthotic ankle joint should be centered over tip of medial malleolus.
Orthotic knee joint should be centered over prominence of medial femoral condyle.
Orthotic hip joint should be in a position that allows patient to sit upright at 90 degrees
Patient compliance will be enhanced if orthosis is comfortable, cosmetic and functional.

TERMINOLOGY

Lower Extremity- specifically refers to the foot
Leg- portion of the lower limb between the knee and the ankle joints
Lower Limb- refers to the thigh, leg and foot
Ankle Deformities- equinovarus and valgus
Knee Deformities- genu valgum and varum
Hip Deformities- coxa vara and valga
Lower Limb Orthotic Nomenclature

FO- foot orthosis
AFO- ankle-foot orthosis
KO- knee orthosis
KAFO- knee-ankle-foot orthosis
HKAFO- hip-knee-ankle-foot orthosis

MATERIALS FOR LOWER LIMB ORTHOSES

Plastic

Thermosetting- designed to be set after heating; not meant to be reheated for further molding
Thermoplastic- (e.g. polypropylene) softens when heated for molding purposes; can be remolded when necessary by warming

Combination Plastic/Metal- reduced weight + strength of metal components where necessary (e.g. joints)
Metal- aluminum alloy most commonly used; stainless steel may be needed for very heavy individuals and for joint components
Carbon Graphite- strength + low weight; very narrow temperature window at which it can be shaped without compromising strength; costly; frequently incorporated into plastic AFO at the ankle to increase rigidity

SHOES

Shoe Parts

Lower Parts

Sole
Shank- narrowest portion of the sole between the heel and the ball.
Ball- widest part of the sole in the region of the metatarsal heads.
Toe Spring- space between the outer sole and the floor; helps to produce a rocker effect during toe-off.
Heel- helps to prevent shoe from "wearing out"; shifts weight to the forefoot.

Upper Parts

Quarter- posterior portion of the upper; high quarter: "high tops", provide greater sensory feedback, does not offer significant M-L stability.
Heel Counter- provides posterior stability to shoe, reinforces quarters of shoe, supports calcaneus
Vamp- anterior portion of the upper
Throat- entrance of the shoe
Toe Box- reinforcement of the vamp; helps to protect toes from trauma
Tongue

Types of Dress Shoes:

Blucher- tongue is part of vamp with the quarters overlapping the vamp. Recommended for patients who require an orthosis.
Bal- quarters meet at the throat with vamp stitched over them--> decreases ability of shoe to open and accommodate orthosis.

FOOT ORTHOSES- range from arch supports to customized orthoses; affect the ground reactive forces acting on the lower limb; also affect rotational component of gait

COMMON FOOT CONDITIONS

Pes Planus ("Flatfoot")- results from excess pronation of the foot ("inrolling") due to excess internal rotation of the tibia or malalignment of the calcaneus

Treatment: custom FO (UCBL) molded on foot with subtalar joint in neutral position to prevent excessive rotational deformities, with anteromedial calcaneus elevated to prevent inrolling; orthosis extends beyond metatarsal heads to provide better leverage for control of deformity.

Pes Cavus ("High-Arched" Foot)- causes excess pressure along the heel and metatarsal head area leading to pain

Treatment: distribute weight by making height of longitudinal support high enough to fill in the space between the shank of the shoe and the arch of the foot, extending to metatarsal head areas. If there is excessive supination, cast the FO with the subtalar joint in neutral position.

Forefoot Pain (Metatarsalgia)

Treatment: distribute weight-bearing forces proximal to metatarsal heads with metatarsal pad (internally) or metatarsal bar (externally).

Heel Pain

Treatment: rubber heel pad inside shoe for minor discomfort; calcaneal bar for very sensitive foot placed distal to painful area to prevent calcaneus from assuming full weight-bearing status. For plantar fasciitis elevated arch support or heel well may help distribute pressure along the medial

Toe Pain- can be secondary to hallux rigidus, gout and arthritis

Treatment: extend steel shank forward and/or attach metatarsal bar to immobilize distal joints.

Leg Length Discrepancy- true leg length measured from distal tip of ASIS to distal tip of medial malleolus; apparent leg length measured from a midline point such as pubic symphysis or umbilicus to distal tip of malleolus- apparent leg length discrepancy may occur even with equal bilateral true leg lengths in which pelvic obliquity is present such as scoliosis, pelvic fracture or muscle imbalance.

Treatment: if less than 1/2 inch, no need to correct. Total discrepancy is not corrected-at most 75% of discrepancy is corrected with 1^st 1/2 inch discrepancy managed with heel pad and additional correction will require building up heel externally. The sole should be built up proportionally when heel is built up externally, to provide comfortable stable gait. A taller sole should have rocker bottom to help normalize gait pattern at toe-off.

Osteoarthritis of the Knee- mild pain secondary to medial compartment narrowing or obliteration

Treatment: lateral heel wedges 1/4 inch thick along the lateral border and tapers medially.

Pediatric Shoes- should have simple design, without heels to facilitate gait, should have soft sole to permit natural development of feet.
Flat feet- usual in infants, common in children and occur occasionally in adults. Improve over time (Intensive treatment with corrective shoes or inserts did not alter natural history of flat feet in 129 children age 1 to 6).

ANKLE FOOT ORTHOSES- most commonly prescribed; formerly known as short leg braces; control ankle DF and PF, provide M-L stability by controlling subtalar joint, and can also stabilize knee during gait

Metal AFO
Consist of proximal calf band, two metal uprights, ankle joints and attachment to the shoe to anchor AFO.
The posterior metal portion of the calf band should be 1 1/2 to 3 inches to distribute pressure.
The calf band should be 1 inch below the fibular neck to prevent common peroneal nerve palsy.
Ankle joint motion controlled with insertion of pins or springs into channels.
Solid stirrup is a U-shaped metal piece attached to shoe with its two ends bent upward to articulate with medial and lateral ankle joints. The sole plate may be extended beyond MT head area for better control of plantar flexion (such as plantar spasticity)
Split stirrup has two flat channels for insertion of uprights (now called calipers) which can open and close distally to allow donning and doffing of AFO. Split stirrup allows removal of the upright from the shoe so that AFO can be worn with other shoes.
Ankle Stops and Assists

Plantar Stops (Posterior Stop)- commonly set at 90 degrees with insertion of pin in posterior channel of the ankle joint; used to control plantar spasticity and to help incrementally stretch plantar contractures. A plantar stop at 90 degrees produce a knee flexion moment during heel strike while the proximal posterior portion of the AFO exert a forward push on the proximal leg to increase knee flexion moment after heel strike. At toe-off an extension moment is created at the knee. The greater the plantar flexion resistance greater flexion moment at knee at heel strike greater need for active hip extensors to prevent body from collapsing forward on buckling knee. Remedy: SACH heel (Solid ankle cushion heel) can reduce flexion moment at knee by serving as shock absorber at heel strike and by moving the ground reactive forces anterior to knee. OR Set posterior stop at minimal amount of plantar flexion to reduce to reduce bending moment at knee after heel strike.
Dorsiflexion Stop (Anterior Stop)- substitutes for gastroc-soleus complex and is set at 5 degrees of dorsiflexion; assist in push-off and assist the knee joint into extension. An earlier dorsiflexion stop would be useful in the added presence of quad weakness causes greater extension moment at knee. However, too great, too long extension moment at knee may result in genu recurvatum.
Dorsiflexion Assist (Klenzac ankle joint)- substitutes for concentric contraction of dorsiflexors to prevent flaccid footdrop after toe-off; also substitutes inadequately for eccentric activation of the dorsiflexors after heel-strike.
Metal AFO Varus/Valgus Control- achieved with attachment of T strap along the side of shoe distal to subtalar joint to help minimize varus (T strap applied to lateral side of shoe) or valgus (T strap applied to medial side of shoe) deformities

Table 1. Clinical Indications for Various Metal Ankle Joint Components

Channel	Rod or Spring	Function	Clinical Indications
Posterior	Rod	Limits plantar flexion	Plantar spasticity, toe drag, pain with ankle motion
Posterior	Spring	Assist dorsiflexion	Flaccid footdrop, knee hyperextension
Anterior	Rod	Limits dorsiflexion	Weak plantar flexors, weak knee extensors, pain with ankle motion
Anterior	Spring	Assist plantar flexion	None

Plastic AFO- most commonly used because of their cost, cosmetic acceptability, light weight, ability to be interchangeable with shoes, ability to control varus/valgus deformities, better foot support with the customized foot portion, and ability to accomplish what is offered by metal AFO.
Plastic AFO Components

Footplate should extend beyond metatarsal head and can be extended beyond toes to reduce spasticity aggravated by toe flexion.
To stabilize ankle and subtalar joint- extend trim line anteriorly at ankle level OR use thicker plastic material OR place carbon inserts along medial and lateral aspects of ankle joint OR make corrugations along posterior leaf of AFO.
To allow full/partial ankle motion, plastic AFO can be hinged at ankle.
Leg component should encompass 3/4 of leg and padded internally. Proximal extent ends 1 inch below fibular neck to prevent common peroneal nerve palsy.
Solid Plastic AFO- no ankle joint.
Plastic AFO Varus/Valgus Control- done by "building up" selected portions of AFO. Equinovarus deformity is controlled by applying force medially to metatarsal head area and calcaneus and proximally at lateral aspect of fibula.
Patellar Tendon Bearing AFO- uses patellar tendon and tibial condyles to partially relieve weight bearing stress on skeletal structures distally. PTB AFO is a misnomer because most of weight bearing is distributed throughout soft tissue of leg that is compressed by appropriately fitting orthosis.

Checkout- follow-up after fitting and use of orthosis- check ability to don and doff AFO, check skin for breakdown, evaluate AFO in dynamic setting, etc.

KNEE ANKLE FOOT ORTHOSES- formerly referred to as long-leg braces. Components are similar to AFO but also include knee joint, thigh uprights and proximal thigh band. Sensation and proprioception of lower limbs, good trunk control and upper body strength are needed to ambulate with KAFOs

Knee Joints

Straight set- provides rotation about a single axis and allows free flexion but prevents hyperextension.
Polycentric- uses double-axis system to simulate flexion/extension movements of femur and tibia ant knee joint; not proven to be advantageous over straight set knee joint
Posterior offset- prescribed for patients with weak knee extensors and good hip extensor strength; helps keep ground reaction forces anterior to knee joint in stance.

Knee Locks- used to provide complete stability to knee in cases in which quad strength is severely decreased or absent.

drop lock
bail lock
dial lock

Thigh Compartment AFO- should be wide enough to distribute pressure of ground reactive force transmitted through the knee axis.
Scott Craig Orthosis- designed to provide paraplegic patient with complete neurologic level at L1 or higher with more functional and comfortable gait; designed to keep knee in extension

KNEE ORTHOSES

Swedish Knee Cage- used to treat mild to moderate genu recurvatum.
Sport Knee Orthoses

Prophylactic- attempts to prevent or reduce severity of knee injuries; has actually increased number of athletes with knee injuries.
Rehabilitative- allow protected motion within defined limits; useful for postoperative and conservative management of knee injuries.
Functional- designed to assist or provide stability to unstable knee; shown to be effective only at loads much lower than those placed on knee during athletic participation.

PEDIATRIC ORTHOSES

Caster Cart- initial mobility aid in children with developmental delay in ambulatory skills who have enough upper body strength and trunk balance to propel themselves.
Standing Frame- used initially after successful use of caster cart (age range for initial use: 8-15 months).
Parapodium- referred to in past as swivel orthosis and allows crutchless gait. Prescribed after adequate use of standing frame in children with desire to ambulate but who are unlikely to become functional walkers due to severity of impairment; complements wheelchair use; commonly prescribed at 2 1/2 to 6 years of age.
Reciprocating Gait Orthosis- formerly called hip-guided orthoses; also referred to as Bilateral HKAFO; provides contralateral hip extension ipsilateral hip flexion. Successful use of RGO requires good upper limb strength, trunk balance and active hip flexion
Twister- commonly prescribed for patients with excessive internal rotation of lower limb to prevent tripping over the feet.

AMBULATION AIDS- purpose is to increase area of support for patients who have difficulty maintaining center of gravity over their own support area. ; also redistributes and extends weightbearing are, reduce lower limb pain, provide small propulsive forces and provide sensory feedback. Body weight transmission for unilateral cane opposite affected side is 20% to 25%, with the use of forearm or arm cane 40% to 50%, and with bilateral crutches up to 80%.

Canes- prescribed length = tip of cane to level of greater trochanter with the patient in upright position (elbow flexed approx. 20 degrees). Cane is usually held in patient's unaffected side to lessen force exerted on a hip (decrease work gluteus medius-minimus complex) with pathological condition- upper limb exerts force on the cane to help minimize pelvic drop on side opposite the weightbearing limb. For stairs - " up with good and down with the bad".
Walker- proper height with walker 12 inch in front of patient is determined with patient standing upright with shoulders relaxed and elbows flexed 20 degrees. Walkers are useful for patients with hemiplegia and ataxia, Wheels can be added if patient also has lack of coordination of upper limbs.
Visual Impairment Cane- length = distance of hand to floor with shoulder flexed and upper limb parallel to floor.

4. Crutches- length = distance form anterior axillary fold to a point 6 inches lateral to 5^th toe while the patient stands with shoulder relaxed. Handpiece height is measured with elbow flexed 30 degrees, wrist in maximal extension, and fingers forming a fist with crutch tip 3 inches lateral to foot.

FOREARM ORTHOSES

Lofstrand Forearm Orthosis- provides less support than crutches; often used bilaterally.
Wooden Forearm Orthosis (Kenny Stick)- has leather band around proximal portion of forearm; prescribed for patients with satisfactory proximal but weak distal upper limb musculature.
Platform Forearm Orthosis- useful for patients with painful wrists or hand conditions as well as those with elbow contractures
Triceps Weakness Orthosis (Arm Orthosis)- has cuff at midarm to prevent flexion (buckling) of elbow during gait.

CRUTCH GAITS

Four point- left crutch right foot right crutch left foot repeat. Stable: three points always at contact with ground but more difficult to learn and slow form of ambulation.
Three point- both crutches and weaker lower limb "good" lower limb repeat. Eliminates all weight bearing on affected limb; also known as non-weightbearing gait.
Two point- left crutch and right foot right crutch and left foot repeat. Useful for ataxic patients with decreased weightbearing capabilities.
Swing-through- both crutches advance both lower limbs past crutches. Very energy consuming and requires functional abdominal muscles; fastest gait.
Swing-to- both crutches advancement of both lower limbs almost to the crutch level.
Drag-to- alternate or simultaneous crutch advancement drag to crutch level

Sources:

Rehabilitation Medicine: Principles and Practice. DeLisa (ed.)

Physical Medicine and Rehabilitation. Braddom (ed.)