Lower limb orthoses

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.

Description

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 .

KEY TERMS

Donning and doffing —Putting on and taking off an orthosis or prosthesis.

Legg-Calve-Perthes disease —Flattening of the femoral head in children, related to avascular necrosis.

Myelomeningocele —A neural tube defect causing herniation of the spinal cord, its meninges and cerebrospinal fluid, often leading to paraplegia.

Plantar fasciitis —Inflammation of the layer of fascia surrounding the muscles of the soles of the feet.

Proprioceptive input —Sensations of body movement and position without the use of visual cues.

Thermoplastic —A material used in orthosis fabrication that is formable when heated and rigid when cooled.

Trimline —The border of the orthosis, the location of which is a factor in determining the level of support or flexibility available.

Hip orthoses

Postoperative total hip orthoses sometimes are used after a total hip replacement in order to prevent the motions of hip flexion, adduction and internal rotation that can cause dislocation. In infants with developmental dysplasia of the hip, which causes hip instability, a Pavlik harness or hip abduction orthosis is used to position the hips in flexion and abduction to encourage desired bone development and prevent dislocation. Hip abduction orthoses are also used to treat children with Legg-Calve-Perthes disease.

Operation

Donning and doffing an orthosis can be a challenge at first, especially for children or for individuals with upper extremity impairments. The orthotist provides specific instructions for donning and doffing with the least difficulty. In addition, he or she provides instructions regarding the need to monitor skin for possible breakdown.

Maintenance

Orthotic maintenance may include resetting joint angles, which is usually done by an orthotist or a physical therapist under the direction of an orthotist. Screws in joint mechanisms also may loosen occasionally, and tightening can usually be done by the patient or caregiver at home with directions from the orthotist. As with operation, maintenance may vary depending on the type of orthosis, and users should follow the instructions of their orthotists.

Health care team roles

The patient, family, physician, orthotist and physical therapist all play important roles in orthotic intervention. The patient and family provide information about their lifestyles, home environment, and support network that allow for a realistic assessment of the ability to don, doff, care for and use an orthosis. The physician often plays an important role in identifying the need for an orthosis and preliminarily educating the patient about goals of orthotic intervention. The physical therapist and orthotist often cooperate in performing the preorthotic assessment. The physical therapist usually has important information regarding the patient's impairments and functional abilities, and may have an idea about what type of orthosis may be appropriate. The orthotist assesses limb function, takes necessary measurements for fabrication, and has extensive, up-to-date knowledge about what types of orthoses and components may best fit the patient's needs.

Training

The orthotist educates the patient about donning, doffing, caring for and using the orthosis. A wearing schedule is often provided for the patient to gradually grow accustomed to the orthosis. Because the physical therapist usually sees the patient regularly, he or she monitors the patient's progress with all aspects of orthotic intervention.

Resources

BOOKS

Lusaradi, Michelle M., and Caroline C. Nielsen. Orthotics and Prosthetics in Rehabilitation. Boston: Butterworth-Heinemann, 2000.

Nawoczenski, Deborah A. and Marcia E. Epler. Orthotics in Functional Rehabilitation of the Lower Limb. Philadelphia: W. B. Saunders Company, 1997.

PERIODICALS

Andrews, Karen L., and Kimberly A. Bouvette. "Anatomy for Management and Fitting of Prosthetics and Orthotics." Physical Medicine and Rehabilitation: State of the Art Reviews 10 (October 1996): 502-507.