Emphasizing Proactive Gait Assessment In Patients With Diabetes
Why A Widened Base Of Gait May Be A Warning Sign
Another parameter to consider in patients with diabetes is the base of gait. Brach and colleagues as well as Petrofsky and co-workers noted that patients with diabetes exhibit a wider base of stance in their gait in comparison to non-diabetic individuals.10,11 The base of gait is defined as the distance between the center of the left and right heel during gait, specifically at heel strike of the stance phase perpendicular to the line of progression. The exact increase in the base of gait for patients with diabetes varies with Brach and colleagues reporting an approximate 14 percent increase while Petrofsky and co-workers report a 13.49 percent increase.10,11
Although the exact pathophysiology as to why the base of gait widens in patients with diabetes is not definitively known, it is believed to increase stability and balance during ambulation.10,11 One may see an extension of a widened base of gait whereby the ambulating patient with diabetes begins to abduct both the arms and legs. Children beginning to walk also exhibit these same features, a widened base of gait and abducted arms, in an attempt to increase stability and balance. As their motor skills and nervous system mature and develop, these features typically disappear. The presence of these symptoms in the patient with diabetes should be a warning that his or her diabetic condition is progressing, and warrants increased attention not only from the podiatrist but other members of the multidisciplinary team.
A distinct finding of a widened base of gait is an increased lateral or frontal plane sway when walking. This may be referred to as weight shifting. This sway begins during toe off, occurs initially toward the support limb and then falls back to the swing limb as it becomes ready for heel strike. One may envision it as an excessive push off from the toes but it is a secondary effect of the widened base of gait. Clinicians may experience this phenomenon themselves just by walking with their feet exaggeratedly wide apart.
Why Are There More Diabetic Wounds In The Forefoot And Lesser MPJs? A Closer Look At Biomechanical Factors
So what are some key points that podiatrists should include as part of any screening exam? If one were to look at the percentage of where a majority of diabetic wounds develop, there is clearly an increased incidence of these wounds developing in the forefoot. Furthermore, the wounds also seem to have a predilection for the lesser metatarsophalangeal joints (MPJs).12-14
This is not by accident. The biomechanical changes that occur during the gait cycle convert the foot temporarily into a very efficient shock absorber. Unfortunately, persistent abnormal pronation of the foot leaves the forefoot susceptible to the reactive force of the ground and this can have serious implications for patients with diabetes. This particularly affects the integrity of the first and fifth rays, which are unable to resist the upward force that develops. As these two segments are loaded, the fifth ray is forced into a dorsiflexed, everted and abducted position, and the first ray, having its own axis, is forced into a dorsiflexed and inverted position. What is the result? The development of hyperkeratosis plantar to the second, third and fourth MPJs due to increased pressures.
Propulsive phase pronation in conjunction with feet that demonstrate a high degree of a congenital forefoot adductus often leads to transverse plane deformities of the first MPJ in the way of a hallux abducto valgus deformity. The relatively abducted malalignment of the digits to their respective metatarsals changes the vector of the muscles that collectively are responsible for lesser digit stability, resulting in hammertoe conditions and the like.