Pressure Distribution of Diabetic Patients after Sensory-Motor Training with Unstable Shoe Construction

Fragestellung: In 2000 Abboud et al. showed an earlier initial contact time for all five metatarsal heads and a later occurrence of the maximum pressure in diabetic patients indicating an increased pressure contact time of the forefoot in diabetic patients. In addition they found a delay of eccentric contraction of the tibialis anterior muscle (TA) wich supports the view that TA-dysfunction leads to forefoot slap which in turn leads to higher pressure values and longer contact duration under the metatarsal heads in diabetic patients when compared to normal subjects.

Recently changes of gait pattern when walking with unstable shoe construction (USC) have been found (Romkes 2006, Nigg 2006). Romke found an increase of TA activity, while Nigg found a trend in a reduction.

In an earlier test, we found a decrease of maximum pressure in the forefoot and a slight increase of maximum pressure in the midfoot using USC.

So the question was, if a sensory-motor training can possibly change the muscular activity during gait and in turn lead to a change of pressure distribution which is favourable for diabetic patients.

Methodik: 3 groups of subjects gave their informed consent for the study. Group 1 included 23 non-diabtic normal subjects (9 male, 14 female; aged 36 +/– 11,8 y) and served as a reference group.

Group 2 included 24 subjects suffering from type 2 diabetes (13 male and 11 female; aged 59,6 +/– 12,1 y) and served as the intervention group.

Group 3 included 21 subjects also suffering from type 2 diabetes (11 male and 10 female; aged 62,95 +/– 6,82 y) and served as the non-intervention group.

Pressure distribution (mask of 7 areas) was measured with Pedar insoles (Novel) and muscular activity of the TA, peronaeus muscle group, gastrocnemius medialis and glutaeus medius with surface electromyography (Noraxon). Pedar insoles served as trigger signal for EMG analysis over at least 15 steps in normal shoes and in USC.

The initial measurements were repeated after 6 weeks. During this time group 1 and 2 had to wear an USC (Masai Barefoot Technology, MBT) for at least 4 hours per day. All subjects were instructed and trained by an external physiotherapist.

Ergebnis: For Group 1 results show significantly lower peak pressure values for the heel, the metatarsal head (MT) 1 and 2/3 and higher peak pressure values for the midfoot when walking in USC when compared to normal shoes. Time of peak activity of TA was earlier.

In Groups 2 and 3 the same significant differences could be seen with the exception that midfoot peak pressure was not significantly different. The values for the MT 4/5 area are also significantly lower.

After 6 weeks training each shoe was compared with the same condition. The differences between the two shoe conditions did not change. In both conditions peak pressure in MT 1, 2/3, and big toe was lower and peak pressure was higher for MT 4/5 in group 1. Group 2 showed a reduction in peak pressure in MT 1 and an increase in midfoot. No changes could be found for EMG timing. Group 3 did not show any significant changes in peak pressure but a later time of peak activity for TA.

Diskussion: A 6-week sensory-motor training with USC can change pressure distribution not only in healthy but also in diabetic patients. Areas where high pressure occurs showed a decrease and areas with low pressure showed an increase. This effect could be seen not only as an immediate effect when wearing USC, but also as a training effect. Wearing USC can therefore affect walking with normal shoes as well.

As we did not find any great changes in the timing of the muscles that we examined, one can suggest, that a verticalisation of the whole body posture when wearing USC (Vernon, 2004) is responsible for the changes in pressure distribution. In any case a reduction of forefoot pressure is welcome in diabetic patients and this can be done through sensory-motor training using USC devices.

Literatur: Abboud RJ, et al.: Lower limb muscle dysfunction may contribute to foot ulceration in diabetic patients. Clin Biomech; 15; 37–45, 2000.

Nigg BM., et al.: Effect of an Unstable Shoe Construction on Lower Extremity Gait Characteristics. Clinical Biomechanics; 21; 82–88, 2006.

Romkes J, et al.: Changes in gait and EMG when walking with the Masai Barefoot Technique. Clinical Biomechanics; 21; 75–81, 2006.

Vernon T, et al.: Changes in gait characteristics of a normal, healthy population due to an unstable shoe construction. University of Sheffield, 2004.