Footwear modifications

What are footwear modifications, and how do they work?

Footwear modification (also called shoe adaptation) means changing an existing shoe, usually on the outside, rather than making a new one¹. Common changes are a raise (for a shorter leg), a rocker sole (a curved sole that reduces pressure on the ball of the foot), a wedge or flare (to shift your weight line), and a socket for a calliper². The aims are to relieve pain, reduce pressure, protect the bottom of the foot, or improve comfort, stability and how you walk²³.

In healthy people, rocker soles change how the ankle and knee move⁴. Changes like this don't prove you will feel better, so it's worth asking whoever recommends a change what it's meant to achieve. Please don't modify shoes yourself.

What are they used for, and how well do they work?

The best-supported use is helping prevent a foot ulcer coming back in adults with diabetes who have had one. Therapeutic footwear (shoes made or chosen to protect the foot) can reduce repeat ulcers, but the certainty is low⁵, and one older trial found no significant benefit⁶. It works best when it's worn consistently⁷.

For knee osteoarthritis, a lateral wedge insole (an insole thicker on the outer edge) reduces load on the knee⁸ but doesn't ease pain more than a plain insole⁹. In adults with hallux rigidus (a stiff big toe joint), orthoses (shoe inserts) reduced pain¹⁰. Heel lifts may ease Achilles tendinopathy (a sore tendon above the heel) a little more than calf exercises, though the difference may be too small to notice¹¹.

It isn't clear yet how well modifications work for leg length differences or in children, so an individual assessment matters.

Is it right for me?

It's best studied in adults with diabetes who have had a foot ulcer or are at high risk of one¹². If that's you, the footwear should be matched to your ulcer risk and any foot deformity, and checked by a team of health professionals⁷.

Not every shoe can be adapted. Services prefer enclosed, well-fitting shoes with a firm sole and a low, broad heel³.

What happens when my shoes are modified?

Before. Bring comfortable shoes in good condition, with a secure fastening and no excess wear on the soles, and ask whether your pair can be adapted². New shoes can be adapted if you've tried them on and found them comfortable first².

During. The service adds the change, such as a raise, rocker sole, wedge or flare, to your shoe². For adults with diabetes, the clinician sets the pressure targets and prescription, so there's nothing for you to measure⁷. How many visits you need depends on the service, so ask how often your footwear will be reviewed.

After. Wear new or adapted shoes for short periods at first, then build up¹². If you've been given therapeutic footwear for diabetes, wear it whenever you're on your feet, at home too, instead of slippers¹².

What are the risks and side effects?

Good information on side effects is limited. New aches in the back, hips, knees, feet or ankles, or blisters, can happen with heel lifts¹¹. Rocker soles change how your joints move and how you walk¹⁰¹³. Steeper wedge insoles are often harder to tolerate⁹.

For people with diabetes, the main risk is skin damage from rubbing or pressure, and from not wearing the footwear enough. If new footwear causes rubbing, discolouration or new pain, contact the orthotic department or your podiatrist straight away¹². Check inside your shoes daily for stones or other small objects, check nothing sharp has pierced the sole, and don't take out insoles unless you've been advised to¹². If you have diabetes or reduced feeling, check the skin of your feet daily too.

How do they compare with other options?

To prevent repeat ulcers in adults with diabetes, custom in-shoe orthoses based on pressure measurements led to fewer ulcers than standard orthoses¹⁴. Therapeutic footwear with custom insoles is described as the most effective preventive step⁷. Careful foot care from health professionals may matter more than the footwear itself⁶.

For healing an open neuropathic ulcer under the forefoot or midfoot in diabetes, footwear isn't the first choice. Guidelines recommend a non-removable knee-high offloading device first, with fitted footwear and felted foam only a third choice¹⁵.

For knee osteoarthritis, don't expect a wedge insole on its own to relieve pain; ask about other options. It also helps to ask how footwear changes fit with orthoses, exercise and foot care.