Assessment of in-shoe pressure: Development of a clinical user guide based on a DELPHI-derived consensus

BACKGROUND

The F-Scan (F-Scan System by Tekscan, Boston, USA) is an in-shoe pressure measurement device used to provide dynamic pressure, force and timing information to guide appropriate offloading of plantar foot ulcers. Despite the clinical utility of an in-shoe pressure measuring device there are some limitations in the validity and reliability of the output of the F-Scan. The aim of this study was to develop a consensus-based guideline following information provided by experienced clinicians, synthesis of research evidence and manufacturer's guidelines on the most appropriate use and interpretation of the data generated by the F-Scan to manage plantar foot ulceration.

METHODS

Using the Delphi method a series of sixteen consensus statements were developed following a two-step questionnaire utilising clinicians feedback, a review of evidence and the manufacturer's guidelines.

FINDINGS

Seventeen clinicians responded to the first questionnaire and 11 to the second, that included 8 podiatrists and 9 pedorthists working in the public and private sectors. Of the sixteen statements there was strong consensus for ten and moderate consensus for a further four. Only two statements failed to reach consensus and the feedback from the respondents was of great value providing sound clinical rationale for their rejection.

INTERPRETATION

The objective of this study has been achieved in developing a clear and concise set of guiding statements (Table 1) to standardise use of the F-Scan. The application of the guiding statements will encourage standardisation of practice with the aim of highlighting the limitations of the system and reducing potential systematic error in measurement from output produced.

The influence of population characteristics and measurement system on barefoot plantar pressures: A systematic review and meta-regression analysis

BACKGROUND

The measurement of plantar pressure distributions during gait can provide insights into the effects of musculoskeletal disease on foot function. A range of hardware, software, and protocols are available for the collection of this type of data, with sometimes disparate and conflicting results reported between individual studies. In this systematic review and meta-regression analysis of dynamic regional peak pressures, we aimed to test if 1) the system used to obtain the pressure measurements and 2) the characteristics of the study populations had a significant effect on the results.

METHODS

A systematic review of the literature was undertaken to identify articles reporting regional peak plantar pressures during barefoot walking. A mixed-effects modeling approach was used to analyze the extracted data. Initially, the effect of the system used to collect the data was tested. Following this, the effect of participant characteristics on the results were analyzed, using moderators of cohort type (defined as the primary health characteristic of the participants), age, sex, and BMI.

RESULTS

115 participant groups were included in the analysis. Sufficient cohorts were available to test those that consisted of healthy individuals, and those with diabetes and diabetic neuropathy. Significant differences were found between results reported by studies using different pressure measurement systems in 8 of the 16 regions analyzed. The analysis of participant characteristics revealed a number of significant relationships between regional peak pressures and participant characteristics, including: BMI and midfoot plantar pressures; elevated forefoot pressures as a result of diabetic neuropathy; and sex-differences in regional loading patterns.

CONCLUSIONS

At the level of the literature, we confirmed significant effects of disease status, age, BMI, and sex on regional peak plantar pressures. Researchers and clinicians should be aware that measurements of peak plantar pressure variables obtained from different collection equipment are not directly comparable.

Plantar forefoot pressures in psoriatic arthritis-related dactylitis: an exploratory study

Dactylitis is a common feature of psoriatic arthritis (PsA); local physical trauma has been identified as a possible contributing factor. The aim of this study was to explore differences in forefoot plantar pressures in patients with PsA with and without dactylitis and compare to healthy controls. Thirty-six participants were recruited into three groups: group A PsA plus a history of dactylitis; group B PsA, no dactylitis; group C control participants. Forefoot plantar pressures were measured barefoot and in-shoe at the left second and fourth toes and corresponding metatarsophalangeal joints. Temporal and spatial parameters were measured and data from the foot impact scale for rheumatoid arthritis (FIS-RA), EQ5D and health assessment questionnaire (HAQ) were collected. Pressure time integral peak plantar pressure, and contact time barefoot and in-shoe were not significantly different between groups. Temporal and spatial parameters reported no significant differences between groups. ANOVA analysis and subsequent post hoc testing using Games-Howell test yielded significance in FIS-RA scores between both PsA groups versus controls, A p ≤ 0.0001 and PsA group B p < 0.0001 in the FIS-RA impairment and footwear domain, PsA group A p < 0.03 and PsA group B p ≤ 0.05 in the FIS-RA activity and participation domain compared to controls. This is the first exploratory study to investigate forefoot plantar pressures in patients with and without historical dactylitis in PsA. FIS-RA scores indicate PsA patients have significant limitations compared to controls, although a history of dactylitis does not appear to worsen patient reported outcomes.

Dose-response effects of customised foot orthoses on lower limb muscle activity and plantar pressures in pronated foot type

Customised foot orthoses (FOs) featuring extrinsic rearfoot posting are commonly prescribed for individuals with a symptomatic pronated foot type. By altering the angle of the posting it is purported that a controlled dose-response effect during the stance phase of gait can be achieved, however these biomechanical changes have yet to be characterised. Customised FOs were administered to participant groups with symptomatic pronated foot types and asymptomatic normal foot types. The electromyographic (EMG) and plantar pressure effects of varying the dose were measured. Dose was varied by changing the angle of posting from 6° lateral to 10° medial in 2° steps on customised devices produced using computer aided orthoses design software. No effects due to posting level were found for EMG variables. Significant group effects were seen with customised FOs reducing above knee muscle activity in pronated foot types compared to normal foot types (biceps femoris p=0.022; vastus lateralis p<0.001; vastus medialis p=0.001). Interaction effects were seen for gastrocnemius medialis and soleus. Significant linear effects of posting level were seen for plantar pressure at the lateral rearfoot (p=0.001), midfoot (p<0.001) and lateral forefoot (p=0.002). A group effect was also seen for plantar pressure at the medial heel (p=0.009). This study provides evidence that a customised FOs can provide a dose response effect for selected plantar pressure variables, but no such effect could be identified for muscle activity. Foot type may play an important role in the effect of customised orthoses on activity of muscles above the knee.