The Aging Foot
by John K. Hyland, DC, DACBR, DABCO, CSCS
As society ages, the average age of our patients is also increasing. That fact is often overlooked, since we’re getting older at the same time! If you take a moment to review your current practice, I’ll bet that you’re seeing more chronic, age-related conditions than you were 10 or even just five years ago. This should also mean that your use of orthotics has been increasing. If it hasn’t, then you’re missing some critical factors in treatment, and your patients aren’t benefiting from your Chiropractic care as they should.
With aging, a number of important conditions begin to affect the feet. Some of these are not immediately symptomatic, and often the patients are unaware of the deterioration until they develop a loss of functional capacity and independence. Once we begin to pay attention, we will discover a variety of problems in the feet of our aging patients—some biomechanical, others systemic. Many of them can be helped with comprehensive Chiropractic care, along with custom-made functional orthotics.
Overweight and obese
Depending on the specific population studied and the exact definitions used, most researchers have found that somewhat more than half of all adult North Americans are overweight, and from 20% to 30% of our society is defined as obese. As we age, we tend to put on more weight. Since the additional weight load places more stress on the supportive skeletal structures, it’s not surprising that being overweight results in a greater frequency of musculoskeletal and arthritic problems, especially in the knees and feet.
Lower extremity biomechanics are very different in the overweight patient, and many gait changes and abnormalities are commonly seen. During walking, obese individuals take shorter steps, have an increased step width, and walk more slowly. They have increased Q-angles at the knee, more hip abduction, significantly more abducted foot angles, and increased out-toeing (foot flare). Hyperpronation is greatly increased, with a greater touchdown angle, more eversion of the foot, a more flat-footed weight acceptance period in early stance, and a faster maximum eversion velocity being measured. There is also greater ankle dorsiflexion, but less plantar flexion.
Joint degeneration becomes much more prevalent as we age. In the feet, the small joints are exposed to high forces over many years. While the causes of joint degeneration and osteoarthritis are still debated, several studies have clearly demonstrated that repetitive impact loading from a variety of sources results in the development of osteoarthritis.1,2
When a joint is exposed to cyclic impact forces, the appearance of degenerative changes is only a question of time.3 These repetitive forces cause a “fatigue-failure” in the joint tissues, a well-known phenomenon that includes alterations in both the articular cartilage and the cancellous subchondral bone. When this type of intermittent dynamic loading is combined with biomechanical faults, previous injury to a joint, or a rigid, non-yielding walking surface, degenerative changes progress rapidly and symptoms frequently develop.
Plastic deformation and breakdown
Over a period of years and decades, the repetitive stresses and normal forces result in a slow breakdown of support for the bones and joints of the feet. It is the connective tissues (collagen and proteoglycans) that are exposed to these long-term lengthening forces, resulting in a decrease in elasticity and a sagging of the foot’s arch. This breakdown then allows transmission of abnormal strains into the legs, the pelvis, and ultimately the spine. Since it is usually the spinal symptoms that have brought the patient into the Chiropractor’s office, the doctor must be able to identify the underlying foot dysfunction.
The tissues that must withstand this strain for years are the connective tissues (ligaments, tendons, and fascia), which are composed primarily of woven collagen fibers. This arrangement allows for the combination of flexibility and strength that keeps our joints within close alignment, while still allowing for a wide range of movement. The woven collagen fibers demonstrate a very important physical property—viscoelastic behavior. Viscoelasticity is the time-dependent response of tissues to a load.4 The longer a load is imposed on the tissues, the more likely is that there will be enough stretch to result in a permanent lengthening.
The result in many aging patients is a loss of the elastic support for the arches of the foot, and less shock absorption from the heel pads. Providing support for the aging foot’s arches can help prevent problems such as plantar fasciitis and heel spurs, which often develop as the foot ages. An additional recommendation for aging patients with loss of heel pad compliance is the use of a heel cup, which improves heel pad function by preventing lateral and medial bulging, thereby maintaining pad thickness.5
The aging of our population provides us with new challenges. Many of the chronic conditions reported by older patients will respond best when their chiropractic care is augmented by flexible, custom-made orthotics. With new materials and innovative construction techniques, orthotics are now being designed to meet the needs of this growing segment of our communities. When your “more mature” patients get relief from their chronic, degenerative conditions under your care, they’ll help build your practice with referrals. The use of orthotics will often complement and improve the chiropractic adjustment, while assisting the body to return to an improved state of function and health.
About the Author
Dr. Hyland is a 1980 graduate (cum laude) of Logan College of Chiropractic. He is a Diplomate of both the American Board of Chiropractic Orthopedists (DABCO) and the American Chiropractic Board of Radiology (DACBR). A popular speaker, Dr. Hyland is a postgraduate lecturer for several chiropractic colleges and a frequent contributor to Chiropractic publications.
1 Paul JL. Musculoskeletal shock absorption: relative contribution of bone and soft tissues at various frequencies. J Biomech 1978; 11:237-242.
2 Radin EL. Effect of repetitive impulsive loading on the knee joints of rabbits. Clin Orthop 1978; 131:288-291.
3 Radin EL. Effect of prolonged walking on concrete on the knees of sheep. J Biomech 1982; 15:487-494.
4 White AA, Panjabi MM. Clinical Biomechanics of the Spine, 2nd ed. Philadelphia: Lippincott, 1990. 692.
5 Jahss MH. Investigations into the fat pads of the foot: heel pressure studies. Foot & Ankle 1992; 13:227-232.