Effectiveness of insoles used for the prevention of ulceration in the neuropathic diabetic foot: a systematic review

[A comparative study of social representations of diabetes mellitus and diabetic foot]

The study aimed to investigate social representations of the terms "diabetes" and "diabetic foot" in different populations. Participants were divided into groups: diabetics (GD); non- diabetics (GN); and non-diabetic healthcare professionals (GP). Personal data were collected, and subjects answered two questions that were expected to evoke five words that came to mind when they thought of "diabetes" and then "diabetic foot". The evoked material was analyzed with the software Ensemble de Programmes Permettant l'Analyse dês Èvocations. A total of 161 subjects participated, including GD (n = 72) with a mean age of 56.12 ± 5.49 years; GN (n = 38) with a mean age of 54.29 ± 7.91 years; and GP (n = 51) with 34.95 ± 7.52 years. The term "diabetes" evoked 297 words in GD, 172 in GN, and 235 words in GP. The term "diabetic foot" evoked 180 words in GD, 90 in GN, and 236 in GP. The groups proved to be anxious for more information, thus confirming the need for awareness-raising and educational programs on diabetes, covering comprehensive issues concerning the disease.

Validation of plantar pressure measurements for a novel in-shoe plantar sensory replacement unit

BACKGROUND

Research concerning prevention of diabetic foot complications is critical. A novel in-shoe plantar sensory replacement unit (PSRU) has been developed that provides alert-based feedback derived from analyzing plantar pressure threshold measurements in real time. The purpose of this study was to compare the PSRU device to a gold standard pressure-sensing device (GS-PSD) to determine the correlation between concurrent measures of plantar pressure during walking.

METHODS

The PSRU had an array of eight sensors with a range of 10-75 mm Hg and collected data at 4 Hz, whereas the GS-PSD had 99 sensors with a range of 1-112 mm Hg and collected data at 100 Hz. Based on an a priori power analysis, data were collected from 10 participants (3 female, 7 male) while walking over ground in both devices. The primary variable of interest was the number of data points recorded that were greater than 32 mm Hg (capillary arterial pressure--the minimum pressure reported to cause pressure ulcers) for each of the eight PSRU sensors and corresponding average recordings from the GS-PSD sensor clusters. Intraclass correlation coefficient (2,1) was used to compare data between the two devices.

RESULTS

Compared with the GS-PSD, we found good-to-very-good correlations (r-value range 0.67-0.86; p-value range 0.01-0.05) for six of the PSRU's eight sensors and poor correlation for only two sensors (r = 0.41, p = .15; r = 0.38, p = .18) when measuring the number of data points recorded that were greater than 32 mm Hg.

CONCLUSIONS

Based on the results of the present study, we conclude the PSRU provides analogous data when compared with a GS-PSD.

Pressure-reduction and preservation in custom-made footwear of patients with diabetes and a history of plantar ulceration

AIMS

To assess the value of using in-shoe plantar pressure analysis to improve and preserve the offloading properties of custom-made footwear in patients with diabetes.

METHODS

Dynamic in-shoe plantar pressures were measured in new custom-made footwear of 117 patients with diabetes, neuropathy, and a healed plantar foot ulcer. In 85 of these patients, high peak pressure locations (peak pressure > 200 kPa) were targeted for pressure reduction (goal: > 25% relief or below an absolute level of 200 kPa) by modifying the footwear. After each of a maximum three rounds of modifications, pressures were measured. In a subgroup of 32 patients, pressures were measured and, if needed, footwear was modified at 3-monthly visits for 1 year. Pressures were compared with those measured in 32 control patients who had no footwear modifications based on pressure analysis.

RESULTS

At the previous ulcer location and the highest and second highest pressure locations, peak pressures were significantly reduced by 23%, 21% and 15%, respectively, after modification of footwear. These lowered pressures were maintained or further reduced over time and were significantly lower, by 24-28%, compared with pressures in the control group.

CONCLUSION

The offloading capacity of custom-made footwear for high-risk patients can be effectively improved and preserved using in-shoe plantar pressure analysis as guidance tool for footwear modification. This provides a useful approach to obtain better offloading footwear that may reduce the risk for pressure-related diabetic foot ulcers.

Effect of heating on the mechanical properties of insole materials

BACKGROUND

The most common method of customizing shoe insoles to the shape and surface of the foot is to heat and then mold the materials. The effect of heating on the mechanical properties of these materials is unknown.

METHODS

The properties of individual and common combinations of insole materials were tested before and after heating. Individual materials tested were soft Plastazote (SP), medium Plastazote (MP), Puff (F), and Nickelplast (N); combinations of materials that were tested were SP + F and MP + F, each with and without Poron (P). Three samples of each were tested five times. Materials were heated and then compressed with an MTS servohydraulic device. Load transmission and percent compression at maximal load were measured on single materials and their combinations. Stress-strain curves were measured.

RESULTS

Compared to unheated material, the heated material transmitted higher forces. After heating, the combinations transmitted maximal load at a lower percentage of compression (i.e., became stiffer). Heating also changed the stress-strain curves of the three-material combinations, causing them to transmit maximal pressure at a lower strain.

CONCLUSION

Heating insole materials changed their mechanical properties. The materials became stiffer and less effective in the attenuation of applied forces.

CLINICAL RELEVANCE

The common practice of heating insole materials to improve their contact with the foot reduced the pressure-reducing properties of the materials, which may decrease their clinical effectiveness.

Effect of insole material on lower limb kinematics and plantar pressures during treadmill walking

BACKGROUND

Currently there is a paucity of research providing recommendations on the type of orthotic or material used in its construction for different patient requirements.

OBJECTIVES

To gain a greater understanding of the characteristics of orthotic materials and how they affect gait so to enhance the clinical decision-making process.

STUDY DESIGN

Repeated measures.

METHODS

Plantar pressures and kinematics were evaluated for 10 participants while walking on a treadmill under various conditions which included, shoes only and shoes with four different flat insoles and custom devices created in each of two densities of two materials.

RESULTS

For the flat insoles, medium density ethyl vinyl acetate was found to produce greater peak pressures than at least one of the other material conditions and low and medium density polyurethane were most effective at increasing average contact area and at reducing pressure time integral. For the custom devices, while no significant differences were evident, when compared to the shoe only condition, medium density polyurethane increased average contact area by a greater percentage than the other materials.

CONCLUSIONS

Results for medium density polyurethane suggest a possible difference in loading characteristics, indicating a potential material suitability for patients with a compromised ability to deal with pressure.

Twelve steps per foot are recommended for valid and reliable in-shoe plantar pressure data in neuropathic diabetic patients wearing custom made footwear

BACKGROUND

Dynamic in-shoe plantar pressure assessment is used both in research and clinical practice to evaluate therapeutic footwear interventions in neuropathic diabetic patients. The aim was to determine the required number of footsteps for reliable and valid in-shoe plantar pressure data in these patients.

METHODS

In 30 neuropathic diabetic patients wearing custom-made therapeutic footwear, in-shoe plantar pressures were measured for a minimum of 20 midgait walking steps per foot. For each incremental number of steps and for each of six anatomical regions per foot, peak pressure, pressure-time integral, contact area, contact time, and force-time integral were calculated. Reliability was assessed by calculating intraclass correlation coefficients. Validity was assessed by calculating the coefficient of variation between each n-step protocol and the 20-step reference protocol based on Limits of Agreement analysis. Data was considered reliable with intraclass correlation coefficients >0.90 and valid with coefficients of variation <10%.

FINDINGS

Three steps per foot were required to obtain reliable data for each foot region and parameter. Depending on the parameter, between 7 and 17 steps per foot were required to obtain valid data. With the exception of deviant outcomes in three forefoot regions for force-time integral, overall 12 steps per foot were required for valid data.

INTERPRETATION

For neuropathic diabetic patients wearing custom-made therapeutic footwear, 12 midgait steps per foot are required to obtain valid and reliable in-shoe plantar pressure data. This provides directions for the use of in-shoe plantar pressure analysis in research and clinical practice in this patient group.

Forefoot plantar pressure reduction of off-the-shelf rocker bottom provisional footwear

BACKGROUND

Increased plantar pressures have been shown to be a risk factor in ulceration of the neuropathic foot. Prescriptive footwear is a common medical treatment, yet evidence regarding the efficacy of these prescriptions is underdeveloped. The purpose of this study is to determine the off-loading properties of four provisional shoes; a rocker sole compared to a flat sole shoe with and without the addition of a 1.25 cm plastizote insert.

METHODS

Fifteen subjects with peripheral neuropathy and a normal longitudinal arch were recruited to compare four types of provisional (post-operative) footwear. Plantar surface foot pressures were measured while wearing a rocker sole shoe or a flat stiff sole shoe. Both shoes were worn with and without a 1.25 cm plastizote insert. Peak plantar pressures were recorded for the hallux, metatarsal heads (1-5), midfoot, and heel.

FINDINGS

The rocker sole shoe with plastizote had the best off-loading properties. While wearing this footwear, mean peak plantar pressure was 2.8 kg/cm(2) (range: 1.7 to 4.5 kg/cm(2), 50% mean reduction from flat sole shoe without plastizote) and 1.9 kg/cm(2) (range: 0.7 to 3.6 kg/cm(2), 35% mean reduction) at the five metatarsal heads and hallux, respectively.

INTERPRETATION

For patients with a normal longitudinal arch and forefeet, either at risk of developing an ulcer or are healing a forefoot ulcer, a provisional shoe with a rocker sole and plastizote insole provides plantar pressure reduction of the forefoot. However, when results were analyzed for the subjects individually the amount of off-loading varied.