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Foot drop makes walking dangerous

Conway McLean, DPM

Walking is a complex act. So many different structures are involved in putting one foot in front of the other. Muscles pulling, joints moving, ligaments tightening, as a person strolls casually down the street, nary a thought given to the complexity of the act.

It’s an unconscious process, performed almost carelessly. Unless a person has problems walking, in which case, this is an entirely different conversation.

Our ability to ambulate is one of the key components of quality of life measures. It helps define our independence, our sense of self. All manner of repercussions result when we can’t walk painlessly and safely. Most people suffering from heart disease have been told by their cardiologist to walk more.

After all, walking is the best form of exercise for most seniors. But what if ambulation itself is dangerous, with a high probability of injury simply by going for a walk. This is the experience of those with the diagnosis of a drop foot, a common complication of many medical conditions.

The term is a common one. And it sounds rather benign, doesn’t it? But any illness or injury which leads to impaired function of the muscle in the front of your shin region can result in a foot drop. It occurs when the tibialis anterior muscle does not function properly.

This muscle is essential in lifting your foot up in the swing phase of gait. This is the part of the gait cycle where the other foot is on the ground while the affected limb is swinging through the air prior to contacting the supporting surface.

A drop foot condition can be produced by weakness, irritation or damage to any of the nerves innervating the muscles in the front of the lower leg. Probably the most commonly injured is the peroneal nerve which passes over the outside of the lower part of the knee.

Any disease leading to weakness of muscles can also cause foot drop. Some disorders expected to produce this loss of function are any of the muscular dystrophies, Lou Gehrig’s disease (ALS, amyotrophic lateral sclerosis), or polio. Included in this category would be a traumatic injury which impacts the peroneal nerve. Some possible events leading to this damage are a sports injury, hip or knee surgery, a cast on the lower leg, even crossing your legs. Thus, paralysis of this muscle, the tibialis anterior, is usually a symptom of a greater problem, not a disease in itself.

A stroke can obviously result in paralysis of certain muscles. This is a condition where a blood clot lodges in some part of the brain, shutting off the blood supply. If cell death occurs in the area that controls this particular muscle, the muscle will not function. But the consequences of a stroke can vary greatly depending on where the clot lodges and the function of the nerve cells afflicted. Other neurologic conditions can lead to foot drop as well. Some possibilities include cerebral palsy, multiple sclerosis or Charcot-Marie-Tooth disease.

Although you probably aren’t thinking about it when you walk, this muscle is pulling the foot up towards the leg during this part of gait. Those experiencing foot drop are often unable to fully lift their leg or foot while taking a step forward. When this action does not occur, it is very easy to catch the toes or foot on the floor as you are walking. Many falls have occurred because of this condition and, in case you haven’t read about it, these can be devastating events in seniors.

The human body works in mysterious ways. Any problem altering gait will typically elicit some compensatory mechanism for this situation. Due to this weakness, the knee may compensate by bending deeper and lifting the leg higher.

This will lessen the chance of the foot dragging or hitting the supporting surface. This compensation creates what is referred to as a steppage gait, in which there is exaggerated bending of the hip and knee.

While this prevents the foot from dropping, and therefore tripping the individual, it also creates awkward and inefficient forces placed on the joints. A steppage gait also tends to produce a subsequent slapping of the foot on the ground, an unpleasant and noisy consequence. This gait pattern is easily recognizable in people with this condition.

Naturally, we should now turn our attention to treatment options. Essential to this discussion is the concept that nerves have limited healing abilities. And we have few options or therapies when nerve death has occurred. Although a palliative approach, many choices are available in the way of bracing.

Some of the newer braces are both lightweight, slim and effective. Generally, braces work by helping to pull your foot up during the appropriate phase of gait. Some of these go inside the shoe, while some recent additions go over the shoe, thus not altering shoe fit.

Physical therapy is routinely employed. Exercises that strengthen certain leg muscles can help to maintain range of motion in the knee and ankle, and can sometimes improve some of the gait problems associated with foot drop. Specific exercises can strengthen the muscles in the area, helping with the symptoms of foot drop. Stretching exercises are also considered beneficial.

A newer approach involves the use of a nerve stimulating device, an option only when there is a neurologic cause. With this technique, a brief electrical signal is sent to the nerve controlling the muscle. When it functions properly, it can result in a fairly normal gait pattern.

There are surgical procedures used in the management of drop foot, especially when the primary problem is the nerve that stimulates the muscle. Surgery to repair this nerve is possible in some cases, but only if the injury occurred recently, ideally less than a year. This may be accomplished by freeing up the nerve, called a decompression procedure. A more unreliable technique involves grafting another nerve in place of the damaged one. If insufficient improvement is obtained with this approach, transferring a tendon may be considered. If a foot drop is chronic and accompanied by a shortening of the Achilles tendon, a procedure to lengthen it may be necessary to achieve adequate motion at the ankle.

Difficulties with mobility are a common issue in our culture. This is to be expected with the dramatic increase in the aging population. But gait disorders lead to a loss of personal freedom. They can also result in injuries and falls. The latter can potentially be devastating. Foot drop can result in a marked reduction in quality of life but is always the result of some other problem.

Although a cure may not be achievable, this is a condition that should not go untreated. Although not everyone can or should have surgery, some simple therapies can make all the difference. Newer bracing designs can be comfortable and effective, and greatly reduce the possibility of suffering a fall. Just as important, they can go a long way to regaining one’s independence, and that is a wonderful goal.

Editor’s note: Dr. Conway McLean is a physician practicing foot and ankle medicine in the Upper Peninsula, with a move of his Marquette office to the downtown area. McLean has lectured internationally on wound care and surgery, being double board certified in surgery, and also in wound care. He has a sub-specialty in foot-ankle orthotics. Dr. McLean welcomes questions or comments atdrcmclean@outlook.com.