Lower Limb Orthoses Health Article

Definition

A lower limb orthosis is an external force system used to compensate or control for decreased or abnormal forces in the hip, knee, ankle, or foot.

Purpose

Orthoses may be used for any of the following reasons: to lend stability to a weak joint, correct or maintain alignment, control motion in the presence of abnormal tone, immobilize a body part, protect an inflamed joint, or provide proprioceptive feedback. Individuals who have upper or lower motor neuron dysfunction, inflammatory joint diseases, sports injuries, or skeletal deformities may use orthoses.

Foot orthoses

Foot orthoses are fabricated for individuals who have abnormal joint alignment in the foot, causing inappropriate motion during stance and gait. Abnormal mechanics may lead to pain and increased stress in the joints of the foot, leg and even back. Custom foot orthoses are made based upon a cast of the individual's foot, following a thorough biomechanical assessment of stance and gait. Based on the findings, rigid, semi-rigid, or soft inserts are fabricated to fit into the client's shoe to provide support where needed, for example, under the arch, the metatarsals, and/or the heel. The University of California Biomechanics Laboratory (UCBL) orthosis is a specific custom-molded orthosis that snugly holds the heel and midfoot in optimal alignment with regards to mediolateral stability.

Ankle-foot orthoses (AFOs)

In adults and children with neuromotor dysfunction, AFOs can be used to maintain appropriate alignment, provide mediolateral stability, and help with toe clearance or heel rise during the gait cycle. The supramalleolar orthosis (SMO) evolved from the UCBL orthosis to address not only mediolateral stability, but also anterior-posterior issues, including foot clearance. It extends to the area above the malleoli, and may be solid or include a mechanical ankle joint.

Ankle-foot orthoses that extend to the area just below the knee provide more stability than the SMO, and may be either static or dynamic. Static AFOs prohibit ankle motion; the most common is the solid AFO. The solid AFO prevents foot drop during gait and also can help to control knee extension or hyperextension, depending on how the ankle is set. Dynamic AFOs may allow for plantarflexion and/or dorsiflexion of the ankle through the use of either a mechanical joint or the location of trimlines. Various methods, such as pin stops and check straps, can be used to limit the amount of plan-tarflexion or dorsiflexion allowed as well. These options provide versatility in setting the range of ankle motion for individuals who have some control and/or expected return of function.

A variety of ankle supports are also available for individuals with musculoskeletal function. Air casts provide stability to those rehabilitating from ankle sprains, while Achilles straps may be used for tendonitis. Night splints and arch straps may help with positioning in those with plantar fasciitis.

Knee-ankle-foot-orthoses (KAFOs)

A KAFO is used when the knee needs to be stabilized and an AFO is insufficient. For example, KAFOs may be used in patients who have had a stroke, spinal cord injury or traumatic injury to the limbs. A conventional KAFO consists of double metal uprights connected to the shoe via a stirrup. A thermoplastic KAFO is custom-formed for total contact to the patient's thigh and calf. A variety of knee joints are available to allow for or restrict flexion and extension movement.

Knee orthoses

There are three categories of orthoses that address musculoskeletal impairments at the knee joint. Athletes use prophylactic orthoses in hopes of preventing knee injury. Rehabilitative orthoses are used post-operatively to allow protected motion to occur at the knee joint.

Functional orthoses are designed to provide stability and proprioceptive input to a patient returning to daily activities. Research is inconclusive on the effectiveness of prophylactic orthoses; however, studies do indicate that functional orthoses may be helpful in preventing further injuries in individuals who have already sustained an injury.

Hip-knee-ankle-foot orthoses (HKAFOs)

The hip guidance orthosis (HGO) and the reciprocating guidance orthosis (RGO) are two types of lumbosacral HKAFOs that can be used by adults or children to produce a reciprocal gait pattern. In both types, the user is braced from mid-trunk to the feet. These orthoses are most commonly used in children with myelomeningocele, but are also used by patients with traumatic spinal cord injury, muscular dystrophy, cerebral palsy, and multiple sclerosis.