An AFO, or ankle-foot orthosis, is a brace that wraps around your lower leg, ankle, and foot to support walking and standing. It’s one of the most commonly prescribed orthotic devices, used by people with conditions ranging from stroke and cerebral palsy to nerve injuries and arthritis. AFOs work by controlling ankle movement, keeping the foot properly positioned, and providing stability that weakened muscles can’t deliver on their own.
How an AFO Works
When certain muscles in the lower leg are weak or paralyzed, the foot can drag or drop during walking. This is called foot drop, and it’s the single most common reason people wear an AFO. The brace holds the foot at a functional angle so it clears the ground during each step, rather than catching on the floor and causing a trip or fall.
Beyond foot drop, AFOs serve several biomechanical purposes. They can limit excessive ankle motion in people with spasticity (involuntary muscle tightness), stabilize the ankle against sideways wobble, redistribute pressure away from wounds or fractures, and support the knee indirectly by controlling how force travels through the leg. In children with cerebral palsy, AFOs are often prescribed early to keep the feet in a neutral position and prevent deformities from developing over time. Research on these children found that the soleus muscle (a deep calf muscle) needs to be stretched at least six hours a day to prevent permanent tightening, and wearing an AFO throughout the day helps achieve that.
Conditions That Lead to an AFO
The list of diagnoses that can call for an AFO is long, but they share a common thread: something has disrupted normal ankle or foot function.
- Stroke: Weakness or spasticity on one side of the body frequently affects the ankle, making an AFO essential for safe walking during recovery and beyond.
- Cerebral palsy: Children at all functional levels use AFOs, whether to improve walking or simply to maintain foot position for comfortable sitting and standing.
- Multiple sclerosis and Guillain-Barré syndrome: Progressive or fluctuating nerve damage can weaken the muscles that lift the foot.
- Peripheral nerve injury: Damage to the peroneal nerve (which runs near the knee) is a classic cause of foot drop.
- Spinal cord injury: Depending on the level of injury, ankle control may be partially or fully lost.
- Charcot-Marie-Tooth disease: This inherited nerve condition gradually weakens the feet and lower legs.
- Arthritis, fractures, and ligament injuries: AFOs can immobilize or offload the ankle during healing.
- Diabetic foot complications: Specialized AFOs reduce pressure on ulcers and protect joints damaged by neuropathy.
Main Types of AFOs
Solid AFO
A solid AFO is a rigid shell, usually made of molded polypropylene plastic, that completely prevents ankle movement. It’s the go-to choice when the ankle needs maximum control: severe foot drop, significant weakness in both directions (up and down), ligament injuries, or mild knee instability. Because it locks the ankle in place, it provides excellent stability but sacrifices the natural push-off motion at the end of each step.
Hinged AFO
A hinged AFO adds a mechanical joint at the ankle, allowing some controlled movement. It lets the foot bend upward (toward the shin) during standing and walking while still blocking the downward drop during the swing phase of each step. This design preserves a more natural walking pattern and is widely used in children with cerebral palsy and adults recovering from stroke. Hinged AFOs aren’t a good fit for people with significant sideways ankle instability, since the hinge primarily works in one plane of motion.
Posterior Leaf Spring AFO
This is a thinner, more flexible design with a narrow strip of plastic running behind the ankle. It acts like a spring: when you step forward and your shin moves over your foot, the plastic flexes slightly, then snaps back to help lift the foot during the swing phase. It’s the lightest and least bulky option, ideal for people with mild foot drop who have decent ankle stability. The tradeoff is that it offers very little side-to-side support.
Carbon Fiber AFO
Carbon fiber AFOs are lighter and designed to store energy during the stance phase, then release it to assist push-off. In stroke patients, both carbon fiber and traditional plastic AFOs reduced the energy cost of walking by about 15% compared to walking without a brace, with no significant difference between the two materials. Carbon fiber tends to feel more responsive and less bulky, but both types get the job done.
What an AFO Does for Walking
Studies comparing walking with and without AFOs consistently show measurable improvements. In children with cerebral palsy after lower limb surgery, wearing an AFO reduced ankle drop by about 5 degrees and knee bending by nearly 5 degrees at the moment the foot hits the ground. Walking speed increased, step length got longer, and the foot was better positioned for each stride. The main effect is correcting residual foot drop and improving the way the foot meets the ground.
There is a trade-off. Because the brace restricts ankle motion, it also limits the power your calf muscles can generate during push-off. For most people, the stability and safety gains far outweigh this reduction, but it’s one reason orthotists try to prescribe the least restrictive AFO that still meets your needs.
Choosing the Right Shoes
An AFO takes up space inside your shoe, so your regular footwear probably won’t work. Plan on buying shoes at least a half size to a full size larger than usual, with extra depth in the toe box and heel. Wide or extra-wide widths help accommodate the added bulk without creating pressure points.
A few features make a big difference. Removable insoles free up interior space. A firm heel counter keeps the brace aligned. Adjustable closures like velcro straps or laces that extend toward the toe let you fine-tune the fit around both foot and brace. High-top styles can prevent the brace from sliding. Look for a firm, non-skid sole, and consider a slight rocker bottom, which helps create a more natural rolling motion through each step. High heels are generally not compatible with AFOs.
Skin Care and Daily Maintenance
Pressure sores are the most common complication of wearing an AFO, and they’re largely preventable with consistent skin checks. During the first week with a new brace, remove it every two to three hours and inspect the skin, including the bottom of the foot. Some redness is normal, but it should fade within an hour. Blisters or skin breakdown that doesn’t resolve means the brace needs adjustment.
Always wear a clean, knee-high sock underneath the AFO. The sock protects the skin, wicks moisture, and reduces friction. Change socks at least daily, and wash feet and legs every day. Clean the inside of the brace regularly with mild soap and water or rubbing alcohol, and let it dry completely before putting it back on. Moisture trapped between skin and plastic is the fastest route to irritation.
Insurance Coverage
Medicare covers AFOs when they meet medical necessity criteria tied to specific diagnoses. Covered conditions include ankle contractures, plantar fascia disorders, Charcot joint (a complication of diabetes and other neuropathies), and diabetic neuropathic arthropathy. Private insurance plans vary, but most require a prescription from a physician and documentation that the AFO is medically necessary rather than purely for comfort. Custom-molded AFOs cost significantly more than prefabricated ones, so confirming your coverage details before ordering is worth the phone call.
AFOs for Children
In a study of over 2,200 children with cerebral palsy, AFOs were used across all functional levels, not just in children who could walk. For non-walkers, the brace maintained foot position to improve sitting stability, reduce pressure sore risk, and prevent painful deformities. For walkers, 41% of children used AFOs specifically to maintain or improve ankle flexibility.
Children’s AFOs need to be replaced more frequently than adults’ because of growth. Parents and caregivers should watch for signs the brace no longer fits: new red marks, the child’s toes extending past the footplate, or difficulty closing the straps. A poorly fitting AFO can do more harm than good, creating pressure injuries or failing to provide the intended support.