Lower Limb Orthotics/Therapeutic Footwear

Overview and Description

Terminology: Orthosis is the medical term for a brace while orthoses is the plural form. The term orthotics refers to the science and practice of patient assessment, fabrication, fit and adjustment of an orthosis. Orthotic device can be used interchangeably with the term orthosis. An orthosis or orthotic device is applied to the body to modify or control skeletal structure or function. A basic principle for limb orthoses is to use three points of pressure to perform at least one of the following functions: 1) stabilize or immobilize a body part; 2) improve alignment; 3) prevent deformities; 4) protect against injury; 5) assist with motion, 6) off load a joint or body part or 7) improve function. Orthoses are named for the joints/segments they manage according to the International Organization for Standardization (ISO) and are classified based on action (static vs. dynamic or accommodative vs. corrective).

 “Off the shelf” orthoses are prefabricated, mass-manufactured and are available in various designs, sizes, and materials. Custom molded orthoses refer to those made specifically for individual patients.

A static orthosis has no motion across the joint or segment involved. A dynamic orthosis indicates that there is motion across the joint. A static progressive orthosis is a type of adjustable orthosis that applies force to a joint and holds it at end range with a goal to improve passive joint range of motion.¹

Orthoses in acute injury tend to focus on maintaining range of motion, preventing contractures, managing pain, protecting damaged or weakened soft tissue, or providing immobilization. Chronic orthosis use aims to prevent or control unwanted motion, enhance desired motion, decrease abnormal tone, alleviate pain, or maximize function. These interventions apply to all phases of a rehabilitation plan and depend on the patient’s level of impairment.

Medical conditions which warrant the use of limb orthoses or therapeutic footwear may include trauma, stroke, brain injury, spinal cord injury, multiple sclerosis, cerebral palsy, peripheral nerve injury, peripheral neuropathy, arthritic conditions, burns, hypotonia, hypermobility, neuromuscular disorders, and contracture management in both pediatric and adult populations.

Common complications associated with orthotic management include pressure injuries, infection, and pain. Thus, it is essential that special attention made to examine the skin, neurological function, vascular status, and musculoskeletal system in patients who will be using an orthosis.

Relevance to Clinical Practice

Lower Limb Orthoses

Ankle foot orthoses (AFOs):

• AFOs are commonly prescribed for weakness of ankle dorsiflexors, plantar flexors, invertors, and evertors. AFOs improve gait deviations by taking advantage of ground reaction force, such as, controlling the progression of the tibia over the ankle and limiting knee flexion and/or extension during stance. An AFO can also assist pre-swing phase toe off and foot clearance during swing phase.
• Anterior ground reaction AFOs feature a strap or plate across anterior tibia to translate forces which provide maximal resistance to plantar flexion and promote knee extension. Of note, the AFO neutral angle and degree of dorsiflexion in stance will influence the position of the knee; ground reaction AFOs and solid ankle AFOs have been found to be equivalent for correcting crouch gait in children with cerebral palsy²
• Carbon fiber AFOs are effective for patients without abnormal tone and with neutral foot alignment and distal muscle weakness.³

Type of Orthosis	Mechanism	Indications
Double up right AFO	Metal AFO attached externally to the shoe that can control ankle movements with pins and springs (see below for details)	Fluctuating edema; Insensate feet at risk for pressure wounds
Semi-rigid plastic AFO	Pressure point at the anterior tibia can promote knee extension during the mid-stance phase	Ankle instability or foot drop; Extensor tone in pediatric patients
Posterior leaf spring AFO	Allows some medio-lateral ankle movements and provides foot clearance during the swing phase; provides dorsiflexion assist	Dorsiflexion weakness
Rigid plastic AFO	Limits ankle movements (including limiting medio-lateral control) and assists with ankle control during the swing phase	Severe tone/spasticity when immobilization is needed
Articulated/ hinged AFO	Can set to the desired range of ankle dorsiflexion or plantar flexion with pins and springs (see below)	Crouch gait: various patterns of weakness (see separate table)
Off the Shelf Carbon fiber AFO	Light weight, lower profile, can provide dynamic response	Assist with dorsiflexion weakness and give minimal plantarflexion assist

AFOs with metal upright(s) are less common than plastic AFOs. However, some patients (such as those with morbid obesity or edema) may benefit from a metal AFO.

The construction of a hinged AFO with ankle joints with channels allows for a greater control of gait. The following table explains the ankle joint motion control with pins (stop) or springs.

Permutations for articulated/hinged AFO

Anterior channel	Posterior channel	Mechanism	Indications
Pin/Stop	Free	Dorsiflexion stop. Assists with pre-swing and the knee extension. Anterior stop set at 5 degrees can mimic the function of gastrocnemius/ soleus	Weak ankle plantar flexors and/or weak knee extensors; Crouch gait
Free	Pin/Stop	A plantar flexion stop at 90 degrees or at neutral produces a knee flexion moment during heel strike.	Spasticity or plantar flexion contractures
Free	Spring	Dorsiflexion assist. Mimics concentric contraction of dorsiflexors. Minimizes plantar flexion at heel strike	Flaccid foot drop

Knee ankle foot orthoses (KAFOs):

• KAFOs extend the AFO to control the knee. Quadriceps weakness below antigravity strength or knee hyperextension not controlled by an AFO are indications for a KAFO.¹

Type of Knee Joint	Mechanism	Goals/ Indications
Straight knee joint	Allows free flexion but prevents knee hyperextension. Used with various knee locks for specific indications/functions	Prevents knee hyperextension and provides medial-lateral stability; With locking mechanism provides knee extensor/flexor stability
Polycentric knee joint	Double axis system, closer approximation of the normal knee kinematics that includes femoral rollback	Allows knee to flex in swing phase
Posterior offset knee joint	Allows free flexion and extension of the knee during the swing phase. The center of gravity is posterior to the knee joint axis at the heel strike helps creating knee flexion moment	For weak knee extensors and with some hip extensor strength. Use with an ankle joint that is limited in dorsiflexion.4

In order to stabilize the knee, one of four locks can be used at the knee – cam lock, bail lock, ratchet lock, and drop lock. The most common is the Ratchet lock with 12-degree increments built into the joint. A lever allows for the knee to be released for flexion and to allow sitting.⁴

Knee orthoses (KO):

• KO provide support or control of the knee joint. KO can limit motion in the sagittal, axial, or coronal planes. Generally, KOs are prescribed to prevent knee hyperextension and provide mediolateral stability.⁵Flexible KOs are made from elastic or rubber, and mostly provide comfort, proprioceptive feedback, mechanical support, and stabilization of patellar tracking.

Type of Orthosis	Mechanism	Goals/ Indications
Flexible KO	Made from flexible material; provides proprioceptive feedback, mechanical support and stabilize patellar tracking	Knee pain; Patellofemoral instability
Swedish knee cage	Controls knee hyperextension while permits full flexion	Osteoarthritis, genu varus, flexible genu valgum
Rigid KO	Provides a frontal plane thrust and unloads the affected compartment	Osteoarthritis

Hip orthoses (HOs):

• HO are indicated for isolated acetabular region problems and are commonly used for post-operative care, hip dislocation, dysplasia, and injury.¹ Fracture bypass orthoses also can be used post fracture.

Hip-knee-ankle-foot orthoses (HKAFOs):

• HKAFO are typically used in patients with spina bifida (myelomeningocele) or acquired spinal cord injury to stabilize the entire lower limb in order to stand and walk with assistive devices.
• Reciprocal gait orthoses (RGO) are a type of bilateral HKAFO with a set of cables or a rocker bar linking the legs together to couple hip flexion with opposite side hip extension in order to create a reciprocal gait pattern.¹
• Successful RGO use typically requires antigravity hip flexion strength, but can be challenging to use as they are heavy, bulky, and with high energy expenditure.⁶ RGO are often utilized in therapeutic setting for a dedicated period of weight bearing, or for household distance ambulation, but are less commonly used for community distances.

Other lower limb orthoses

• Stretching AFO, KO, and KAFO are dynamic orthoses that can be utilized to improve range of motion by applying a constant, low-load, passive stretch. Static progressive stretch orthoses are set just beyond the current range of motion to improve range of motion or prevent further contractures, but compliance can be difficult due to the need for prolonged wearing time.⁶
• An off the shelf ankle brace with an air cell is a semi-rigid shell ankle orthosis with air cells on both sides of the ankle. This device is worn inside the shoe to provided ankle support in the case of ankle instability after ankle sprains. It has shown to improve ankle joint function in ankle sprains.⁷

Foot Orthoses and Therapeutic Footwear

Foot orthoses (FOs)

• FOs are used as the foundation for other lower limb orthoses or can be used alone. FO align and support the foot and prevent, correct, or accommodate foot deformity, or improve the overall function of the foot. FOs are commonly used with therapeutic shoes which should be properly fitted and have adequate room for the foot to expand during weight bearing.¹
• Supramalleolar orthoses (SMO) are used primarily in pediatric patients with hypotonia and those with flexible foot pronation.^7,8
• Leg length discrepancies less than 2cm without symptoms typically do not require correction. The total leg length discrepancy is not corrected. At most, 75% of the discrepancy should be corrected. Up to 1cm lift can fit in a shoe. For shoe lifts that need more than 1cm, the patient would need a custom-built shoe with a shoe lift or have an external shoe lift added.⁹
• Carbon fiber foot plates have recently started to be incorporated into athletic shoes, with studies suggesting they redistribute power to the distal foot and decrease energetic demand on the ankle.¹⁰ These also offer a less restrictive bracing option for idiopathic toe walking with similar results in the brace and improved carryover after brace is removed.¹¹

Therapeutic Footwear

• Both internal and external shoe modifications can be added to the sole or body of the shoe. Heel and internal sole excavation can relieve pain or ulcers over bony prominences. Pad placement provides arch support or relieves pressure; heel and lateral wedges promote appropriate foot positioning or alignment. Bars on the soles of shoes can be added to assist with weakness, relieve pressure, transfer load, or promote dorsi or plantar flexion.
• Heel flares widen the base and support with different heel material providing cushioning, stability, positioning, and arch support.¹²
• High top shoes or boots can provide ankle stability in patients with mild ankle instability or mild foot drop, especially in young patients.

Cutting Edge/ Unique Concepts/ Emerging Issues

Human factors engineering is a technique that has been explored and applied in fabricating orthotics; where it combines artificial intelligence to design orthotics.¹⁴

Functional electric stimulation (FES) devices are available as an alternative to traditional orthoses. These devices generate an electrical current that stimulating a muscle causing muscle contraction in a predictable movement pattern to create physiological bracing. The most common FES device for the lower limb is the FES-AFO which stimulates the tibialis anterior muscle to produce ankle dorsiflexion and eversion.¹⁵ These devices have shown moderate gait improvements when compared to traditional AFO. Recent improvements in traditional lower limb orthoses include stance control orthotic knee joints to provide stance-phase stability, while allowing swing-phase flexion and permitting a more normal gait pattern by eliminating some of the motion restrictions of other orthoses.

Advances in materials including expanded use of carbon fiber, 3-D printing, and robotic exoskeletons are dramatically changing the durability, fabrication time, overall function, and level of assistance provided by orthotic devices.¹⁶

Gaps in Knowledge/ Evidence Base

The literature supports the use of AFO when stroke or cerebral palsy results in lower limb impairment by demonstrating improved gait, functional mobility, and energy efficiency.³

Despite controversies, orthoses that allow patients to use their paretic limb for functional tasks and a broader range of rehabilitative interventions, generally result in improved limb function and improved quality of life. Patients rely on orthotic intervention as a cost effective and less invasive means to manage common medical conditions such as a valgus knee braces for symptomatic knee osteoarthritis relief.

The cost of orthotic devices varies based on complexity, materials used and fabrication process. To optimize both patient care and utilization of health care resources, it is paramount to have an in-depth knowledge of the patient’s deficits, as well as an understanding of the environmental and personal factors that will influence a patient’s orthoses use. Typical barriers to device utilization include its appearance, weight, and ability to don and doff the orthoses.¹³ Incorrectly prescribed orthoses may lead to functional impairment and biomechanical derangement which cause medical complications. To limit these obstacles, a team including orthotists, therapists, and physicians must work in concert to maximize patient benefit.

Reference

1. Webster JB (Joseph B, Murphy D (Douglas P). Atlas of Orthoses and Assistive Devices. Accessed August 14, 2019. https://www.sciencedirect.com/book/9780323483230/atlas-of-orthoses-and-assistive-devices
2. Ries AJ, Schwartz MH. Ground reaction and solid ankle-foot orthoses are equivalent for the correction of crouch gait in children with cerebral palsy. Dev Med Child Neurol. 2019;61(2):219-225. doi:10.1111/dmcn.13999
3. Betancourt JP, Eleeh P, Stark S, Jain NB. Impact of Ankle-Foot Orthosis on Gait efficiency in Ambulatory Children with Cerebral Palsy. Am J Phys Med Rehabil. Published online March 26, 2019:1. doi:10.1097/PHM.0000000000001185
4. Frontera WR. DeLisa’s Physical Medicine and Rehabilitation: Principles and Practice: Fifth Edition.; 2012.
5. Khosravi M, Arazpour M, Sharafat Vaziri A. An evaluation of the use of a lateral wedged insole and a valgus knee brace in combination in subjects with medial compartment knee osteoarthritis (OA). Assistive Technology. Published online April 4, 2019:1-8. doi:10.1080/10400435.2019.1595788
6. Karimi MT, Fatoye F. Evaluation of the performance of paraplegic subjects during walking with a new design of reciprocal gait orthosis. Disabil Rehabil Assist Technol. 2016;11(1):72-79. doi:10.3109/17483107.2014.921247
7. Davids JR, Rowan F, Davis RB. Indications for orthoses to improve gait in children with cerebral palsy. Journal of the American Academy of Orthopaedic Surgeons. Published online 2007. doi:10.5435/00124635-200703000-00008
8. Martin K. Effects of supramalleolar orthoses on postural stability in children with Down syndrome. Dev Med Child Neurol. Published online 2004. doi:10.1017/S0012162204000659
9. Cifu DX. Braddom’s Physical Medicine & Rehabilitation. Fifth. Elsevier; 2016. https://www.clinicalkey.com/dura/browse/bookChapter/3-s2.0-C20130099252
10. Henderson A, Hulcher T, Koller C, Bruening D, Arch E. Deformable foot orthoses redistribute power from the ankle to the distal foot during walking. J Biomech. 2021;128:110728. doi:10.1016/j.jbiomech.2021.110728
11. Herrin K, Geil M. A comparison of orthoses in the treatment of idiopathic toe walking. Prosthet Orthot Int. 2016;40(2):262-269. doi:10.1177/0309364614564023
12. Buldt AK, Menz HB. Incorrectly fitted footwear, foot pain and foot disorders: a systematic search and narrative review of the literature. J Foot Ankle Res. 2018;11:43. doi:10.1186/s13047-018-0284-z
13. Boyce SH, Quigley MA, Campbell S. Management of ankle sprains: A randomised controlled trial of the treatment of inversion injuries using an elastic support bandage or an aircast ankle brace. Br J Sports Med. Published online 2005. doi:10.1136/bjsm.2003.009233
14. Yu Z. Study on Ergonomic Design of Artificial Intelligence Lower Limb Assist Brace for the Elderly. Comput Intell Neurosci. 2022;2022:3304513. doi:10.1155/2022/3304513
15. Prenton S, Hollands K, Kenney L, Onmanee P. Functional electrical stimulation and ankle foot orthoses provide equivalent therapeutic effects on foot drop: A meta-analysis providing direction for future research. J Rehabil Med. 2018;50(2):129-139. doi:10.2340/16501977-2289
16. Ford C, Grotz R, Kope Shamp J. The Neurophysiological Ankle-Foot Orthosis. Clinical Prosthesis and Orthotics. 1986;10:15-23.

Original Version of the Topic

Marlis Gonzalez-Fernandez, MD, PhD, David Taftian, MD, Mark Hopkins, PT, CPO. Upper and lower limb orthoses and therapeutic footwear. 9/20/2014

Previous Revision(s) of the Topic

Mi Ran Shin, MD, Olga Morozova, MD, Jeffery Rubin, DO. Upper and lower limb orthoses and therapeutic footwear. 2/26/2019

Author Disclosure

Mi Ran Shin, MD, MPH
Nothing to Disclose

Katherine DeGraaff, DO
Nothing to Disclose

Olga Morozova, MD
Nothing to Disclose