Foot implant helps knee, back pain

Dr. Conway McLean

Advances in medicine and science have had a tremendous impact on our quality of life. These developments have occurred throughout history. Where would we be if we hadn’t learned about germ theory? How about the development of antibiotics, without which even a mild ingrown nail could be life-threatening? Before the discovery of local anesthetics, any surgical procedure required the patient be tied down, and necessarily entailed tremendous pain. Elective surgery basically didn’t exist.

New advances in medicine continue to be made regularly, and some are tremendously exciting to those of us “in the field”. Many people have heard about new developments in regenerative medicine in which we can help the body heal an injury without the use of drugs or artificial materials.

We are researching biological super-glue, which should allow us to reattach damaged structures without the use of sutures or screws. Because of the tremendous advances in genetics and gene manipulation, we can look forward to the day that regenerating body parts will not be the stuff of science fiction, but of medical fact.

Another topic common to the movies involves the use of nanotechnology. It seems clear this will someday be a therapy available to treat a variety of medical conditions.

Another recent advance allows us to improve the mechanical functioning of the human body. Sounds like a fairly significant discovery, doesn’t it? I am referring to a special type of implant placed into the foot, specifically the joint just below the ankle joint (which is called the sub-talar joint). This particular joint allows the foot to move side to side, whereas the ankle allows the foot to move up and down.

When the joint is able to move too far out of the position, the lower leg is forced to rotate inward. This has the effect of changing the distribution of forces across the knee’s, hips and back. Consequently, a variety of slowly developing, over-use injuries can develop, resulting in chronic, recurrent pain, as well as the development of degenerative changes.

It is unlikely you think much about foot alignment, or, what I like to call foot architecture. This refers to the position and contour of the foot, which is critical to how well the foot works. Problems with foot function can lead to a variety of conditions, from arch pain, right on up the “kinetic chain.”

This term refers to the inter-connectedness of the musculo-skeletal system. How much the arch lowers when standing and walking affects how much, and how well, the spine bends. Nothing operates independently in the human body, especially mechanically. When someone has a problem with body mechanics, they may experience all manner of disparate and seemingly unrelated maladies. Unfortunately, this connection between musculoskeletal pain in some body part, and the body’s foundation, the feet, is often not made.

The positioning of all the joints of the foot and leg does change, moment to moment, step by step. This is directly related to how well the foot works to support your body, as well as transporting you from place to place. These are not trivial issues, but significant quality of life issues.

Physical fitness has a tremendous effect on health. How many cardiac rehabilitation programs for patients with heart disease don’t involve a walking program? How healthy can your heart be if you can’t walk for exercise? Quality of life is severely affected when you have chronic knee pain, which can be a consequence of a falling arch.

The latest version of this particular joint implant does not require any bone work for its placement, for it to function properly. Implantation is a simple process, requiring only a small incision. The same holds true for its removal, although removal is rarely needed. The individual can bear weight immediately after the implant is placed, and typically minimal pain is experienced since very little trauma is entailed with its placement.

Many treatments exist for this problem of instability of this joint (aka talo-tarsal displacement). Some are more effective than others. A multitude of arch supports are on the market, although these are helpful only when the displacement is extremely mild. Custom foot supports, known as foot orthotics, when properly prescribed, can help to reduce this dislocation of the sub-talar joint. If more severe, a foot-ankle brace can be very powerful at reducing this unwanted motion. As may be predictable, these can be bulky, noticeably affecting shoe fit.

What are the downsides of this implant, often referred to as a stent? As mentioned, removal is a simple process, so on the off-chance it does not work, no “bridges were burned,” meaning no lasting damage was caused by its placement. The most obvious obstacle is financial.

Even though numerous studies have been performed demonstrating its effectiveness, and thousands have been implanted, the insurance industry continues to call it ‘experimental’! How long does something have to be used before it is no longer experimental? Apparently, no one in the industry wants to answer that question. An obvious interpretation is that simply don’t want to pay for it.

I don’t want to get on my soapbox to rail against health insurance as it currently exists, but….it’s hard not to! What justification can there be for denying a therapy with a proven track record, and a long, successful history of use? If insurers were a bit more farsighted, they might recognize the savings in health care dollars. Preventing chronic stress to the joints and structures using the feet as their foundation can have long term benefits. These can include fewer knee replacements, less work time lost due to chronic back pain, along with arthritic pain of this specific joint.

No one is recommending this as a treatment for anyone with this problem. For some, a change in the type of shoes worn, and the appropriate exercises and stretches, can lead to sufficient improvement in alignment. Symptoms may be of an acute onset, perhaps resulting from a day of excessive activity with the wrong shoe gear. When that is the case, many simple treatments for inflammation exist. Surely you’ve heard of the benefits of icing? Oral anti-inflammatories or a steroid injection can work wonders. One of the more difficult prescriptions I write for is rest. That is a tough one: we live at a hectic pace, and few have the time to rest the painful part.

The joint stent is especially beneficial for children since they have not yet suffered the arthritic changes that poor joint mechanics can lead to. But kids don’t verbalize pain like adults, so the condition often goes untreated. Since foot function is largely inherited, long-suffering parents are more likely to recognize the similar situation that they have dealt with in their offspring.

Although this particular technique does not have the notoriety of, say, growing a new limb, it does have the potential to end the suffering of many. If you have arches or heels that frequently cause you pain, perhaps you are a candidate? More importantly, don’t neglect poor foot mechanics.

The ability to walk, to stand, to get places, is critical to health and well-being. You may not need a sub-talar joint stent, but you definitely need to be able to get around. It’s about quality of life!

Editor’s note: Dr. Conway McLean is a podiatric physician now practicing foot and ankle medicine in the Upper Peninsula, having assumed the practice of Dr. Ken Tabor. McLean has lectured internationally on surgery and wound care, and is board certified in both, with a sub-specialty in foot orthotic therapy. Dr. McLean welcomes questions, comments and suggestions at