The reproducibility of acquiring three dimensional gait and plantar pressure data using established protocols in participants with and without type 2 diabetes and foot ulcers

A Narrative Review on the Tests Used in Biomechanical Functional Assessment of the Foot and Leg: Diagnostic Tests of Deformities and Compensations

BACKGROUND

To date, scientific literature has not as yet come up with any review showing the diagnostic tests used for functional assessment of the foot and leg.

METHODS

A literature review was conducted of electronic databases (MEDLINE, PEDro, DOAJ, BioMed Central, PLOS, and Centre for Reviews and Dissemination at the University of York) up to December 8, 2018. The biomechanical tests, which have adequate supportive literature, were divided into qualitative tests that provide a dichotomy/trichotomy-type answer to clinical diagnostic questions; semiquantitative tests that provide numerical data to clinical diagnostic questions; and quantitative tests that record continuous numerical data (in analogue or digital form).

RESULTS

These tests produce a useful functional evaluation model of the foot and leg for different purposes: evaluation of lower limb deficits or abnormalities in healthy patients and in athletes (in sports or other physical activities); assessment of tissue stress syndromes caused by pathomechanics; evaluation of lower limb deficits or abnormalities in rheumatic disease and diabetic foot patients; and to determine the appropriate functional or semifunctional foot orthotic therapy and therapeutic path used in gait rehabilitation.

CONCLUSIONS

Many of these tests have adequate diagnostic reliability and reproducibility and therefore can be considered diagnostic. Few of these are validated, and some have initiated the validation process by determining their sensitivity and specificity. The widespread use of these tools in clinical practice (diagnosis of function) lacks scientific evidence and in-depth analysis of their limitations.

Predicting the risk of future diabetic foot ulcer occurrence: a prospective cohort study of patients with diabetes in Tanzania

OBJECTIVES

The aim of this study was to identify the parameters that predict the risk of future foot ulcer occurrence in patients with diabetes.

RESEARCH DESIGN AND METHODS

1810 (male (M)/female (F): 1012/798) patients, with no foot ulcer at baseline, participated in this study. Data from a set of 28 parameters were collected at baseline. During follow-up, 123 (M/F: 68/55) patients ulcerated. Survival analyses together with logistic regression were used to identify the parameters that could predict the risk of future diabetic foot ulcer occurrence.

RESULTS

A number of parameters (HR (95% CI)) including neuropathy (2.525 (1.680 to 3.795)); history of ulceration (2.796 (1.029 to 7.598)); smoking history (1.686 (1.097 to 2.592)); presence of callus (1.474 (0.999 to 2.174)); nail ingrowth (5.653 (2.078 to 15.379)); foot swelling (3.345 (1.799 to 6.218)); dry skin (1.926 (1.273 to 2.914)); limited ankle (1.662 (1.365 to 2.022)) and metatarsophalangeal (MTP) joint (2.745 (1.853 to 4.067)) ranges of motion; and decreased (3.141 (2.102 to 4.693)), highly decreased (5.263 (1.266 to 21.878)), and absent (9.671 (5.179 to 18.059)) sensation to touch; age (1.026 (1.010 to 1.042)); vibration perception threshold (1.079 (1.060 to 1.099)); duration of diabetes (1.000 (1.000 to 1.000)); and plantar pressure at the first metatarsal head (1.003 (1.001 to 1.005)), temperature sensation (1.019 (1.004 to 1.035)) and temperature tolerance (1.523 (1.337 to 1.734)) thresholds to hot stimuli and blood sugar level (1.027 (1.006 to 1.048)) were all significantly associated with increased risk of ulceration. However, plantar pressure underneath the fifth toe (0.990 (0.983 to 0.998)) and temperature sensation (0.755 (0.688 to 0.829)) and temperature tolerance (0.668 (0.592 to 0.0754)) thresholds to cold stimuli showed to significantly decrease the risk of future ulcer occurrence. Multivariate survival model indicated that nail ingrowth (4.42 (1.38 to 14.07)); vibration perception threshold (1.07 (1.04 to 1.09)); dry skin status (4.48 (1.80 to 11.14)); and temperature tolerance threshold to warm stimuli (1.001 (1.000 to 1.002)) were significant predictors of foot ulceration risk in the final model. The mean time to ulceration was significantly (p<0.05) shorter for patients with: dry skin (χ²=11.015), nail ingrowth (χ²=14.688), neuropathy (χ²=21.284), or foot swelling (χ²=16.428).

CONCLUSION

Nail ingrowth and dry skin were found to be strong indicators of vulnerability of patients to diabetic foot ulceration. Results highlight that assessments of neuropathy in relation to both small and larger fiber impairment need to be considered for predicting the risk of diabetic foot ulceration.

Gait in People With Nonhealing Diabetes-Related Plantar Ulcers

BACKGROUND

Abnormalities in gait have been associated with high plantar pressures and diabetes-related plantar foot ulcers. Whether these are a transient response to the ulcer or are representative of long-term lower limb biomechanical abnormalities is currently unknown.

OBJECTIVE

The aim of this study was to examine whether 12 gait parameters identified as being associated with nonhealing diabetes-related plantar foot ulcers at baseline remained associated during a 6-month follow-up period.

DESIGN

This was a longitudinal observational case-control study.

METHODS

Gait assessments were performed at entry and twice during follow-up over a 6-month period in 12 participants with nonhealing diabetes-related plantar foot ulcers (case participants) and 62 people with diabetes and no history of foot ulcers (control participants) using a standardized protocol. Linear mixed-effects random-intercept models were used to identify gait parameters that consistently differed between case participants and control participants at all assessments after adjustment for age, sex, body mass index, presence of peripheral neuropathy, and follow-up time. Standardized mean differences (SMD) were used to measure effect sizes.

RESULTS

Five of the 12 gait parameters were significantly different between case participants and control participants at all 3 time points. Case participants had a more abducted foot progression angle (SMD = 0.37), a higher pelvic obliquity at toe-off (SMD = -0.46), a greater minimum pelvic obliquity (SMD = -0.52), a lower walking speed (SMD = -0.46), and a smaller step length (SMD = -0.46) than control participants.

LIMITATIONS

The limitations included a small sample size, the observational nature of the study, and the inability to evaluate the impact of gait on wound healing.

CONCLUSIONS

This study identified abnormal gait parameters consistently associated with nonhealing diabetes-related plantar foot ulcers. Further research is needed to test the clinical importance of these gait characteristics.

Within- and Between-Body-Site Agreement of Skin Autofluorescence Measurements in People With and Without Diabetes-Related Foot Disease

BACKGROUND

Skin autofluorescence has been used to assess longer term glycemic control and risk of complications. There is however no agreed site at which autofluorescence should be measured. This study evaluated the within- and between-site agreement in measurement of skin autofluorescence using a noninvasive advanced glycation end product (AGE) reader.

METHODS

Overall, 132 participants were included: 16 with diabetes-related foot ulcers (DFU), 63 with diabetes but without foot ulcers (DMC), 53 without diabetes or foot ulcers (HC). Skin autofluorescence was measured using the AGE Reader (DiagnOptics technologies BV, the Netherlands). Three consecutive skin autofluorescence measurements were each performed at six different body sites: the volar surfaces of both forearms (arms), dorsal surfaces of both calves (legs), and plantar surfaces of both feet (feet). Within- and between-site agreements were analyzed with concordance correlation coefficients (CCC) and 95% confidence intervals (95% CI), absolute mean differences (±standard deviation), and Bland-Altman limits of agreement.

RESULTS

The agreement between repeat assessments at the same site was almost perfect (CCC [95% CI] ranging from 0.94 [0.91-0.96] for assessments in the right foot to 0.99 [0.99-0.99] for assessments in the left arm). The limits of agreement were narrow within ±0.5 arbitrary units for all sites. The between-site agreement in measurements was poor (CCC < 0.65) with large maximum absolute mean differences (±SD) in arbitrary units (DFU = 3.40 [±2.04]; DMC = 3.15 [±2.45]; HC = 2.72 [±1.83]) and wide limits of agreement.

CONCLUSIONS

Skin autofluorescence measurements can be repeated at the same site with adequate repeatability but measurements at different sites in the same patient have marked differences. The reason for this variation across sites and whether this has any role in diabetes-related complications needs further investigation.

A fitting problem: Standardising shoe fit standards to reduce related diabetic foot ulcers

AIMS

Incorrectly fitting shoes are implicated in callus formation and a significant proportion of diabetic foot ulcers, yet remain surprisingly prevalent. We review the current shoe fit guidelines for consistency and discuss ways in which technology may assist us in standardising methods of footwear assessment.

METHODS

Narrative review.

RESULTS

Incorrectly fitted shoes are implicated in the development of some diabetic foot ulcers yet surprisingly there's no consensus on shoe fit, despite substantial spending on prescription footwear. Suggested toe gaps vary from 6 to 20 mm and measurement methods also vary from Brannock Devices and callipers to manual measurement.

CONCLUSIONS

To prevent fit-related foot ulceration, we need to standardise our biomechanical definition of fit. Future research should (1) evaluate the potential use of 3D scanning technology to provide a standardised means of capturing foot morphology; (2) develop a working biomechanical definition of fit, including toe gap through the identification of key physiological markers that capture and predict dynamic foot shape changes during different physical activities and body weight loading conditions; and (3) determine whether changes in dynamic foot shape of those with diabetes differs from those without, impacting on their shoe fitting needs, potentially necessitating specialist footwear at an earlier stage to avoid ulceration.

Can a combination of lifestyle and clinical characteristics explain the presence of foot ulcer in patients with diabetes?

AIMS

The aim of this study was to identify the biomechanical, neurological and clinical parameters along with other demographics and lifestyle risk factors that could explain the presence of foot ulcer in patients with diabetes in Africa.

METHODS

A total of 1270 (M/F:696/574) patients; 77(M/F:53/24) with ulcerated vs 1193 (M/F: 643/550) with non-ulcerated feet; participated in this study. A set of 28 parameters were collected and compared between the participants with and without active foot ulcers. Multivariate logistic regression was utilised to develop an explanatory model for foot ulceration.

RESULTS

Foot swelling (χ2(1,n = 1270) = 265.9,P = 0.000,Phi = 0.464) and impaired sensation to monofilament (χ2(2,n = 1270) = 114.2,P = 0.000,Cramer'sV = 0.300) showed strong association with presence of ulceration. A lower Temperature sensitivity to cold stimuli and limited ankle joint mobility were observed to be significant (P < 0.05) contributors to ulceration. The logistic regression model can justify the presence of foot ulceration with 95.3% diagnostic accuracy, 99.1% specificity and 37.3% sensitivity.

CONCLUSION

Participants with ulcerated foot show distinct characteristics in few foot related parameters. Swollen foot, limited ankle mobility, and peripheral sensory neuropathy were significant characteristics of patients with diabetic foot ulcer. One out of three patients with ulcerated foot showed common characteristics that could be justified by the model.

Reliability of peak foot pressure in patients with previous diabetic foot ulceration

BACKGROUND

Previous reliability studies on peak plantar pressure measurements in patients with previous diabetic foot ulceration (DFU) did not stratify their analyses according to whether the foot had a previous ulcer.

RESEARCH QUESTION

Does test-retest reliability of peak foot pressure measurements from the various foot regions differ between the ulcerated and non-ulcerated feet?

METHODS

Data from 23 participants with peripheral neuropathy and healed plantar DFU were analysed in this test-retest reliability comparison study. Plantar pressure was evaluated on two sessions using Pedar^®-X in-shoe system, with a mean of 7.2 days (SD = 1.6) between sessions.

RESULTS

The intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated for 10 foot regions. Overall, test-retest reliability was excellent (ICCs, 0.82 to 0.95) for all peak pressure variables. CV ranged between 6.3% and 18.3%, and exceeded 15% over the hallux and medial forefoot regions in the ulcer foot (18.3% and 16.4%, respectively). Hallux peak pressure CV was significantly higher over the ulcer foot than over the non-ulcer foot (5.7%, 95% CI, 1.7%-10.2%). Peak pressure CV over the forefoot also tended to be higher over the ulcer foot (medial forefoot: 6.1%, 95% CI, -0.5%-14.5%; lateral forefoot: 4.1%, 95%CI, -0.7%-11.1%).

SIGNIFICANCE

Peak plantar foot pressure may be useful to distinguish between groups of patients with peripheral neuropathy and healed plantar DFU. However, clinical decisions based on ulcer foot hallux and forefoot peak pressure measurements should be interpreted with caution.

Soft-Material-Based Smart Insoles for a Gait Monitoring System

Spatiotemporal analysis of gait pattern is meaningful in diagnosing and prognosing foot and lower extremity musculoskeletal pathologies. Wearable smart sensors enable continuous real-time monitoring of gait, during daily life, without visiting clinics and the use of costly equipment. The purpose of this study was to develop a light-weight, durable, wireless, soft-material-based smart insole (SMSI) and examine its range of feasibility for real-time gait pattern analysis. A total of fifteen healthy adults (male: 10, female: 5, age 25.1 ± 2.64) were recruited for this study. Performance evaluation of the developed insole sensor was first executed by comparing the signal accuracy level between the SMSI and an F-scan. Gait data were simultaneously collected by two sensors for 3 min, on a treadmill, at a fixed speed. Each participant walked for four times, randomly, at the speed of 1.5 km/h (C1), 2.5 km/h (C2), 3.5 km/h (C3), and 4.5 km/h (C4). Step count from the two sensors resulted in 100% correlation in all four gait speed conditions (C1: 89 ± 7.4, C2: 113 ± 6.24, C3: 141 ± 9.74, and C4: 163 ± 7.38 steps). Stride-time was concurrently determined and R2 values showed a high correlation between the two sensors, in both feet (R² ≥ 0.90, p < 0.05). Bilateral gait coordination analysis using phase coordination index (PCI) was performed to test clinical feasibility. PCI values of the SMSI resulted in 1.75 ± 0.80% (C1), 1.72 ± 0.81% (C2), 1.72 ± 0.79% (C3), and 1.73 ± 0.80% (C4), and those of the F-scan resulted in 1.66 ± 0.66%, 1.70 ± 0.66%, 1.67 ± 0.62%, and 1.70 ± 0.62%, respectively, showing the presence of a high correlation (R² ≥ 0.94, p < 0.05). The insole developed in this study was found to have an equivalent performance to commercial sensors, and thus, can be used not only for future sensor-based monitoring device development studies but also in clinical setting for patient gait evaluations.

Plantar pressures are elevated in people with longstanding diabetes-related foot ulcers during follow-up

Objective

High plantar pressures are implicated in the development of diabetes-related foot ulcers. Whether plantar pressures remain high in patients with chronic diabetes-related foot ulcers over time is uncertain. The primary aim of this study was to compare plantar pressures at baseline and three and six months later in participants with chronic diabetes-related foot ulcers (cases) to participants without foot ulcers (controls).

Methods

Standardised protocols were used to measure mean peak plantar pressure and pressure-time integral at 10 plantar foot sites (the hallux, toes, metatarsals 1 to 5, mid-foot, medial heel and lateral heel) during barefoot walking. Measurements were performed at three study visits: baseline, three and six months. Linear mixed effects random-intercept models were utilised to assess whether plantar pressures differed between cases and controls after adjusting for age, sex, body mass index, neuropathy status and follow-up time. Standardised mean differences (Cohen’s d) were used to measure effect size.

Results

Twenty-one cases and 69 controls started the study and 16 cases and 63 controls completed the study. Cases had a higher mean peak plantar pressure at several foot sites including the toes (p = 0.005, Cohen’s d = 0.36) and mid-foot (p = 0.01, d = 0.36) and a higher pressure-time integral at the hallux (p<0.001, d = 0.42), metatarsal 1 (p = 0.02, d = 0.33) and mid-foot (p = 0.04, d = 0.64) compared to controls throughout follow-up. A reduction in pressure-time integral at multiple plantar sites over time was detected in all participants (p<0.05, respectively).

Conclusions

Plantar pressures assessed during gait are higher in diabetes patients with chronic foot ulcers than controls at several plantar sites throughout prolonged follow-up. Long term offloading is needed in diabetes patients with diabetes-related foot ulcers to facilitate ulcer healing.

Plantar pressures are higher in cases with diabetic foot ulcers compared to controls despite a longer stance phase duration

BACKGROUND

Current international guidelines advocate achieving at least a 30 % reduction in maximum plantar pressure to reduce the risk of foot ulcers in people with diabetes. However, whether plantar pressures differ in cases with foot ulcers to controls without ulcers is not clear. The aim of this study was to assess if plantar pressures were higher in patients with active plantar diabetic foot ulcers (cases) compared to patients with diabetes without a foot ulcer history (diabetes controls) and people without diabetes or a foot ulcer history (healthy controls).

METHODS

Twenty-one cases with diabetic foot ulcers, 69 diabetes controls and 56 healthy controls were recruited for this case-control study. Plantar pressures at ten sites on both feet and stance phase duration were measured using a pre-established protocol. Primary outcomes were mean peak plantar pressure, pressure-time integral and stance phase duration. Non-parametric analyses were used with Holm's correction to correct for multiple testing. Binary logistic regression models were used to adjust outcomes for age, sex and body mass index. Median differences with 95 % confidence intervals and Cohen's d values (standardised mean difference) were reported for all significant outcomes.

RESULTS

The majority of ulcers were located on the plantar surface of the hallux and toes. When adjusted for age, sex and body mass index, the mean peak plantar pressure and pressure-time integral of toes and the mid-foot were significantly higher in cases compared to diabetes and healthy controls (p < 0.05). The stance phase duration was also significantly higher in cases compared to both control groups (p < 0.05). The main limitations of the study were the small number of cases studied and the inability to adjust analyses for multiple factors.

CONCLUSIONS

This study shows that plantar pressures are higher in cases with active diabetic foot ulcers despite having a longer stance phase duration which would be expected to lower plantar pressure. Whether plantar pressure changes can predict ulcer healing should be the focus of future research. These results highlight the importance of offloading feet during active ulceration in addition to before ulceration.

Gait parameters of people with diabetes-related neuropathic plantar foot ulcers

BACKGROUND

Foot ulceration associated with diabetic peripheral neuropathy is a global concern. Biomechanical investigation allows the identification of gait abnormalities that may adversely affect ulcer healing. The objective of this case-control study was to compare the gait parameters of cases with diabetes-related foot ulcers to controls.

METHODS

Three-dimensional movement analyses were performed on 21 people with diabetes-related neuropathic plantar foot ulcers (cases), 69 people with diabetes without a foot ulcer history (diabetes controls) and 56 healthy controls. Outcome data were reported as mean differences, 95% confidence intervals and Cohen's d effect sizes. Binary logistic regressions were used to adjust for age, sex and body mass index.

FINDINGS

People with foot ulcers had a smaller plantar flexion (Cohen's d=-0.6 vs. diabetes controls and d=-0.8 vs. healthy controls), knee flexion (d=-0.6 vs. diabetes controls and d=-1.0 vs. healthy controls) and pelvic obliquity (d=-0.9 vs. diabetes controls and d=-0.7 vs. healthy controls) (all P<0.05). They also had a significantly greater range of anterior-posterior ground reaction force (d=1.0 vs. diabetes controls and d=1.7 vs. healthy controls) and total vertical ground reaction force (d=0.9 vs. diabetes controls and d=1.1 vs. healthy controls) and significantly slower walking speed and smaller step length compared to controls (all P<0.05).

INTERPRETATION

People with plantar foot ulcers have considerably different gait parameters to controls. Whether the observed gait parameters contributed to the ulcer development or are a response to the ulcer is currently unclear and needs further investigation.