Moon Boot and CAM Walker

What is it?

A CAM boot is a removable boot that works like a splint (a support that keeps an injured part steady). It has a firm sole and is held on with Velcro straps. Some boots have an inflatable liner, which you gently pump up so the boot fits snugly around your leg.

You may hear it called a Moon Boot, walker, walking cast, air-cast boot or fracture boot. These names are used for much the same kind of boot, so use the model and settings your clinician gives you.

The boot limits how much your ankle can move. It also shifts pressure on your foot from the front (the forefoot) towards the heel. That takes load off the front of the foot, but not off the heel. Your knee and hip also move a little differently when you walk in it.

What is it used for?

The boot is used when a foot or ankle needs protection but you can still walk on it, as your clinician allows. How much is known depends on the injury.

• Stable ankle fractures (breaks): this is where a boot is best supported. It is used for a stable Weber B fracture (a type of ankle fracture), and after surgery to fix an ankle fracture.
• Toddler's fractures: a boot can be used in young children.
• Some other foot fractures: a children's hospital protocol lists certain fractures that haven't moved out of place (the lower part of the outer ankle bone, the long bones in the middle of the foot, and the base of the bone on the outer edge of the foot). The best treatment for a type of foot fracture called a Jones fracture is still debated.
• Bone bruising in the ankle bone (talus bone marrow oedema): a boot and a plaster cast gave similar results.
• Taking load off the front of the foot: the boot does this well, and a short boot suits this purpose better than a tall one.

It isn't clear yet whether a boot helps an ankle sprain. Some leaflets list sprains, but some children's hospital advice says a boot isn't needed for them.

Is it right for me?

A boot may suit you if you have a stable ankle fracture that your clinician has checked, or if you have had an ankle fracture fixed with surgery and your surgeon plans for you to put weight on it. How stability is checked varies, so it is fair to ask whether your fracture has been assessed as stable, for example on x-rays taken while you stand.

A boot is not the right choice in some cases:

• A broken ankle, midfoot or heel bone that has moved out of place, or may have. These need emergency assessment, not a boot.
• A broken shin bone (including the inside ankle bone) or a broken toe. A stiff-soled shoe may be used for a broken toe.
• A foot ulcer under the foot in someone with diabetes. A removable boot is not the first choice for taking pressure off the ulcer. Guidelines recommend a total contact cast (a close-fitting cast) or a boot that can't be taken off. If you also have poor blood flow to your legs, you need to see a specialist foot team before any boot is chosen.
• Open wounds, a possible nerve or blood vessel injury, or a suspected torn tendon. These need urgent assessment first.

Tell your clinician before you get a boot if you have diabetes, numbness in your leg or foot, fragile skin, or have had blood clots or circulation problems before.

What happens?

Your clinician will usually fit the boot, choose the type (short or tall, with or without an air liner) and decide how much weight you can put on your foot and for how long. Follow their plan rather than a general schedule. Some people wear a boot for 6 to 8 weeks for a foot ulcer, or for up to 10 weeks after an Achilles tendon rupture (a torn tendon at the back of the ankle).

If you need to put the boot on yourself, these steps help:

• Sit down with your knee bent at a right angle.
• Slide your heel fully to the back of the boot, with your foot flat.
• Fasten the liner snugly.
• Fasten the straps from your toes upward until they feel firm but not tight. For the Air-step boot, the order is ankle, then foot, then calf.
• If your boot has air cells, pump them up, sore side first, until it feels comfortable and not too tight. Let the air out before you take the boot off.
• Stand up and check the fit. The top back edge should not press on the crease behind your knee. If a strap rubs, add the foam pads that came with the boot.

For a child, check that the toes don't stick out past the edge of the boot. They may poke a little over the soft liner.

Your clinic will tell you to take the boot off once a day or twice a day, to wash your leg and foot and check your skin. Check your heel especially.

How well does it work?

How well a boot works depends on the injury and on whether the bone was fixed with surgery. Results for one condition don't carry over to another.

For stable Weber B ankle fractures, people in a walking boot had better ankle function than people in a below-knee cast at 6 weeks and at 12 weeks. Even light supports, such as elastic supports or bandages, gave good results for these fractures, so a rigid boot isn't always needed.

After ankle fracture surgery, people who put weight on the foot straight away in a walking boot had better function at 6 weeks than people kept off their foot in a cast. They also returned to work earlier, saved money, and had a similar number of complications.

For toddler's fractures, a boot let children get back to daily activities and put weight on the leg sooner, and it did not affect healing. For bone bruising in the ankle bone and for some Jones fractures, results in a boot were similar to results in a cast.

Walking in a boot tends to be slower, and your ankle moves much less than usual.

Risks and side effects

Most people use a boot without serious problems, but there are things to watch for.

• Blood clots: being less mobile raises your risk of a clot in the leg (deep vein thrombosis). Keep as active as your clinician allows and drink plenty of fluids. The warning signs are listed at the end of this page.
• Skin damage and pressure sores: the heel is a common spot. Check your skin whenever the boot is off. Checks matter most if you have diabetes, fragile skin or less feeling in your leg. If you are at high risk and the boot greatly limits your movement, change the position of your leg every two hours.
• Pain in the knee, hip or lower back: this is commonly reported, on the same side as the boot at the knee and on the other side at the hip. A short boot limits the ankle less and may lower this risk. Tell your treating team if the pain is new or getting worse.
• Slower, uneven walking: your knee and hip do more of the work. Take extra care on wet or slippery surfaces.
• Knee strain: a poorly aligned boot can push your knee back too far. The boot's side bars should line up with your ankle bones and the middle of your lower leg.

Afterwards

Ask your clinician for a plan for coming out of the boot before you leave. In children, use may be tapered after 2 to 3 weeks, or as the clinician directs. After that, go back to supportive footwear and build up daily activities as you can manage them.

Ask which exercises are safe for the joints the boot doesn't cover, and when you can expect to go back to work or sport. Recovery time depends on your injury, so your clinician is the best guide.

Keep attending follow-up visits. If the boot isn't working for you, for example because of pain or rubbing, tell your clinician rather than stopping on your own.

When to see a podiatrist

Book an appointment if

your boot rubs or doesn't fit well and you aren't sure how to adjust it, you have new or worsening knee, hip or lower back pain, you aren't sure how much weight to put on your foot, or you have diabetes and have been given a removable boot for a foot ulcer and want to check it is the right device. Also book if you don't have a plan for coming out of the boot.

Seek prompt assessment if

you suddenly become short of breath, have chest pain, or cough up blood: call your local emergency number. Also call your local emergency number if your leg, foot or toes suddenly turn cold and pale or blue, with pain or numbness, if your toes turn blue or white in the boot (loosen the straps while you call), or if you suddenly can't move your leg or foot. After an injury, call your local emergency number or go to the nearest emergency department if a bone comes through the skin or your ankle or foot is at an odd angle. If your calf or thigh is painful or swollen, your leg swells more than before, or your leg looks red, see your GP or another doctor today. If your child has increasing pain, or is unsettled or distressed, take them to the clinic that fitted the boot or see your GP or another doctor today. If your GP can't see you today, go to an urgent care clinic or an after-hours GP. If your toes are painful or swollen, or you have numbness, pins and needles, or can't move your toes, loosen the straps and contact the clinic that fitted your boot straight away. If you can't reach them, see your GP or another doctor today. If you have pain or discomfort under the boot (especially at the edges or heel), sores, blisters or a red area that won't go away, contact the clinic that fitted your boot without delay and don't wait for your next appointment.

Frequently asked questions

Is a Moon Boot the same as a CAM walker?

For most purposes, yes. Moon Boot, CAM boot, walker and walking cast are names for much the same kind of removable boot. What matters more is the type you are given, such as short or tall, with or without an air liner, and the instructions that come with it.

Can I drive in a walking boot?

No. Don't drive while you are wearing a walking boot. Ask your clinician for advice on getting around, and on when you may be able to drive again once you are out of the boot.

Can I take the boot off to wash or sleep?

Some boots can be taken off for bathing and, if necessary, for sleeping. Only do this if your clinician has said it is okay for your injury. You will also need to take it off once or twice a day to wash and check your skin, as your clinic advises.

Further reading

• Walking Boot – Advice for Patients : University College London Hospitals NHS Foundation Trust NHS
• Display Patient Information Leaflets NHS
• Equaliser walker boot NHS
• Walker Boot Patient care leaflet NHS
• Walker boot - Leeds Teaching Hospitals NHS Trust NHS