Glenn Pfeffer, MD, is the Director of the Foot and Ankle Center at Cedars-Sinai Medical Center in Los Angeles.

Foot drop: how it happens and what can help

Motor weakness is the hallmark of CMT. The ankle dorsiflexors, the muscles that lift the foot and ankle upward, are frequently involved. When the Tibialis Anterior muscle weakens, the foot begins to drop. This is usually a gradual process that unfolds over months to years.

It is very important to keep the Achilles tendon stretched. As the Tibialis Anterior weakens and the foot drops, the Achilles tendon contracts because it is no longer being stretched during walking. The more severe the contracture, the harder it becomes for the weakened muscle to lift the ankle. Keeping the Achilles limber can preserve normal walking for a long time. Stretch it for 60 seconds, three times each day. A simple method is to place the front of the foot on a step and let the heel hang over the edge, holding the railing for balance.

In more advanced cases, a brace may be required. These are generically called Ankle Foot Orthoses (AFOs). The brace should be lightweight and flexible enough to allow the ankle to move up and down during walking. An orthotist or certified pedorthist can fabricate these braces. The most common mistake is making them too heavy and rigid. A cushioned insert can be incorporated into the sole of the brace to reduce stress on the foot and unload painful areas.

Ankle stability and fall prevention

Three main problems contribute to ankle sprains in people with CMT:

  • Muscle weakness. The Peroneus Brevis is the major dynamic stabilizer of the ankle and is often the first muscle affected by CMT. In the early phases, it is important to keep this muscle and the other lateral muscles as strong as possible. A few sessions with a physical therapist focused on peroneal strengthening can be very helpful, especially early on. An elastic brace (similar to those used for ankle sprains) may also help.
  • Varus heel position. An in-turned heel means the center of gravity is not over the central axis, increasing sprain risk. This occurs alongside a very high arch, which is a common feature of CMT. An orthotic or heel insert with a 1/8-inch lateral heel wedge can help. A wide heel on the shoe also increases stability. Be sure not to let the outer heel wear down.
  • Plantar-flexed first ray. A downward inclination on the inside of the foot means the medial aspect of the sole contacts the ground first, causing the foot to turn inward. A custom orthotic (shoe insert) will often solve this by allowing the sole of the foot to lie flat in the shoe.

Proprioception exercises (training your sense of body position and balance) are helpful from the time of diagnosis. If you are able, stand on one foot for 30 to 60 seconds, three times per day. Once you have mastered that, try it with your eyes closed. If you use a brace or have advanced weakness or deformity, this exercise may not be possible, but for those with mild to moderate CMT it can improve strength and balance and reduce ankle instability.

Other CMT-related foot problems

Toe deformity is common in people with CMT. Muscle imbalance causes the toes to deform in a pattern called “clawing,” where each toe develops a fixed bent position at multiple joints. Contracted toes lack room in shoes and create increased pressure on the ball of the foot, leading to pain and calluses.

While the underlying muscle imbalance cannot be prevented, contractures can be delayed. Twice a day, morning and evening, stretch each toe joint: flex the joint at the base of the toe (the metatarsophalangeal joint) down as far as possible while bringing the middle joint (the proximal interphalangeal joint) to a straight position. Hold for thirty seconds, then move to the next toe.

Once a contracture develops, wear shoes with a wide toe box to reduce pressure on the toes. A shoe repair shop can stretch existing shoes, or wide toe-box shoes can be purchased. Look for cushioned soles and soft, stretchable uppers. A custom orthotic can also help relieve pressure on the ball of the foot.

Surgical options

When conservative measures are no longer sufficient, surgery can restore function and significantly improve quality of life. The goal is to achieve the most benefit with the least intervention, while preserving as much motion in the foot as possible.

The field has advanced considerably over recent decades. In the past, a patient with CMT might undergo a triple arthrodesis, a fusion of the three major joints at the rear of the foot. Today, orthopedic CMT specialists realign the heel and hindfoot joints without fusing them. Tendon transfers are performed earlier in the disease process to preserve a better-balanced foot and prevent further injury.

I will always remember my first CMT patient, in 1989. She was 17 and could just get by wearing sneakers. She did not want to go out with friends, could not walk more than a few blocks, and had never let anyone other than her parents see her feet. After surgery, in her words, she “was able to wear cute shoes and went out on her first date.” Surgery for CMT, when necessary, can restore a quality of life that is worth the effort.