Measurement of dynamic pressures at the shoe-foot interface during normal walking with various foot orthoses using the FSCAN system

Testing protocols and measurement techniques when using pressure sensors for sport and health applications: A comparative review

Plantar pressure measurement systems are routinely used in sports and health applications to assess locomotion. The purpose of this review is to describe and critically discuss: (a) applications of the pressure measurement systems in sport and healthcare, (b) testing protocols and considerations for clinical gait analysis, (c) clinical recommendations for interpreting plantar pressure data, (d) calibration procedures and their accuracy, and (e) the future of pressure sensor data analysis. Rigid pressure platforms are typically used to measure plantar pressures for the assessment of foot function during standing and walking, particularly when barefoot, and are the most accurate for measuring plantar pressures. For reliable data, two step protocol prior to contacting the pressure plate is recommended. In-shoe systems are most suitable for measuring plantar pressures in the field during daily living or dynamic sporting movements as they are often wireless and can measure multiple steps. They are the most suitable equipment to assess the effects of footwear and orthotics on plantar pressures. However, they typically have lower spatial resolution and sampling frequency than platform systems. Users of pressure measurement systems need to consider the suitability of the calibration procedures for their chosen application when selecting and using a pressure measurement system. For some applications, a bespoke calibration procedure is required to improve validity and reliability of the pressure measurement system. The testing machines that are commonly used for dynamic calibration of pressure measurement systems frequently have loading rates of less than even those found in walking, so the development of testing protocols that truly measure the loading rates found in many sporting movements are required. There is clear potential for AI techniques to assist in the analysis and interpretation of plantar pressure data to enable the more complete use of pressure system data in clinical diagnoses and monitoring.

Commercially available pressure sensors for sport and health applications: A comparative review

Pressure measurement systems have numerous applications in healthcare and sport. The purpose of this review is to: (a) describe the brief history of the development of pressure sensors for clinical and sport applications, (b) discuss the design requirements for pressure measurement systems for different applications, (c) critique the suitability, reliability, and validity of commercial pressure measurement systems, and (d) suggest future directions for the development of pressure measurements systems in this area. Commercial pressure measurement systems generally use capacitive or resistive sensors, and typically capacitive sensors have been reported to be more valid and reliable than resistive sensors for prolonged use. It is important to acknowledge, however, that the selection of sensors is contingent upon the specific application requirements. Recent improvements in sensor and wireless technology and computational power have resulted in systems that have higher sensor density and sampling frequency with improved usability - thinner, lighter platforms, some of which are wireless, and reduced the obtrusiveness of in-shoe systems due to wireless data transmission and smaller data-logger and control units. Future developments of pressure sensors should focus on the design of systems that can measure or accurately predict shear stresses in conjunction with pressure, as it is thought the combination of both contributes to the development of pressure ulcers and diabetic plantar ulcers. The focus for the development of in-shoe pressure measurement systems is to minimise any potential interference to the patient or athlete, and to reduce power consumption of the wireless systems to improve the battery life, so these systems can be used to monitor daily activity. A potential solution to reduce the obtrusiveness of in-shoe systems include thin flexible pressure sensors which can be incorporated into socks. Although some experimental systems are available further work is needed to improve their validity and reliability.

Gait-Specific Optimization of Composite Footwear Midsole Systems, Facilitated through Dynamic Finite Element Modelling

Objective

During the last century, running shoes have been subject to drastic changes with incremental however improvements as to injury prevention. This may be, among others, due to the limited insight that experimental methodologies can provide on their 3D in situ response. The objective of this study was to demonstrate the effectiveness of finite element (FE) modelling techniques, in optimizing a midsole system as to the provided cushioning capacity.

Methods

A commercial running shoe was scanned by means of micro computed tomography and its gel-based midsole, reverse-engineered to a 200 μm accuracy. The resulting 3D model was subjected to biorealistic loading and boundary conditions, in terms of time-varying plantar pressure distribution and shoe-ground contact constraints. The mesh grid of the FE model was verified as to its conceptual soundness and validated against velocity-driven impact tests. Nonlinear material properties were assigned to all entities and the model subjected to a dynamic FE analysis. An optimization function (based on energy absorption criteria) was employed to determine the optimum gel volume and position, as to accommodate sequential cushioning in the rear-, mid-, and forefoot, of runner during stance phase.

Results

The in situ developing stress fields suggest that the shock dissipating properties of the midsole could be significantly improved. Altering the position of the gel pads and varying their volume led to different midsole responses that could be tuned more efficiently to the specific strike and pronation pattern.

Conclusions

The results suggest that midsole design can be significantly improved through biorealistic FE modelling, thus providing a new platform for the conceptual redesign and/or optimization of modern footwear.

Foot Pressure Changes Before and After Ankle Fusion: A Pedobarograph Study

We performed a case-control study with the purpose of establishing the pressure patterns in the soles of the feet of patients with ankle osteoarthritis, determining whether the pattern changed after treating the arthritis with ankle joint fusion (arthrodesis), and whether the change is significant. We also studied the benefits of ankle fusion with respect to the Short-Form 36-item Health Survey and the American Orthopaedic Foot and Ankle Society Ankle-Hindfoot scale. The study included 18 participants (9 in the study group and 9 in the control group) to reach statistical significance with a 95% confidence interval (CI). A demonstrable increase was found in both forefoot and hind-foot pressures in the study group preoperatively compared with the control group. Also, a demonstrable increase was found in the pressure in both the forefoot (mean difference 50.56 ± 267.39 kPa) and the hindfoot (mean difference 57.44 ± 160.27 kPa) from preoperatively to postoperatively. This difference was not statistically significant (p = .59 [t(8) = 0.57]; 95% CI 256.10 to -154.98) for the forefoot pressures and for the hindfoot pressures (p = .31 [t(8) = 1.08]; 95% CI 180.64 to -65.76). The Short-Form 36-item scores significantly improved from preoperatively to postoperatively (p = .000054 for the physical component and p = .018 for the mental component). The American Orthopaedic Foot and Ankle Society Ankle-Hindfoot scale score also improved significantly (p = .0000005). The foot pressures, as measured by using the insole sensors, showed an increase in forefoot and hindfoot pressures that was not statistically significant.

The effects of total contact insole with forefoot medial posting on rearfoot movement and foot pressure distributions in patients with flexible flatfoot

The purpose of this study is to evaluate the therapeutic effect of total contact insole with forefoot medial posting (TCIFMP) orthosis in patients with flexible flatfoot. The TCIFMP insole was custom- mode, made from semi-rigid plastazote and PPT. Using the gait analysis and the plantar-pressure measure systems, we investigate rearfoot motion and plantar pressure redistribution in these patients. The results of this study showed that the excessive valgus movement of the rearfoot can be reduced significantly by the TCIFMP insole in these patients. Besides, there were significant decreases in the peak pressure under the toe, lateral metatarsal, lateral foot and heel areas. Therefore, we suggested that the TCIFMP insole is an effective orthotic device for rearfoot motion control, plantar pressure reduction and re-distribution in patients with flexible flatfoot.

Plantar pressure relief under the metatarsal heads: therapeutic insole design using three-dimensional finite element model of the foot

Therapeutic footwear with specially-made insoles is often used in people with diabetes and rheumatoid arthritis to relieve ulcer risks and pain due to high pressures from areas beneath bony prominences of the foot, in particular to the metatarsal heads (MTHs). In a three-dimensional finite element study of the foot and footwear with sensitivity analysis, effects of geometrical variations of a therapeutic insole, in terms of insole thicknesses and metatarsal pad (MP) placements, on local peak plantar pressure under MTHs and stress/strain states within various forefoot tissues, were determined. A validated musculoskeletal finite element model of the human foot was employed. Analyses were performed in a simulated muscle-demanding instant in gait. For many design combinations, increasing insole thicknesses consistently reduce peak pressures and internal tissue strain under MTHs, but the effects reach a plateau when insole becomes very thick (e.g., a value of 12.7mm or greater). Altering MP placements, however, showed a proximally- and a distally-placed MP could result in reverse effects on MTH pressure-relief. The unsuccessful outcome due to a distally-placed MP may attribute to the way it interacts with plantar tissue (e.g., plantar fascia) adjacent to the MTH. A uniform pattern of tissue compression under metatarsal shaft is necessary for a most favorable pressure-relief under MTHs. The designated functions of an insole design can best be achieved when the insole is very thick, and when the MP can achieve a uniform tissue compression pattern adjacent to the MTH.

The Correlation between Dynamic Balance Measures and Stance Sub-phase COP Displacement Time in Older Adults during Obstacle Crossing

[Purpose] This study examined the relationship between the center of pressure (COP) displacement time during the stance subphases and dynamic balance ability when elderly cross obstacles 0, 10, and 40 cm in height. [Subjects] Fifteen older adults were enrolled in this study (≥65 years of age). [Methods] An F-Scan System was used to measure the COP displacement time when subjects crossed obstacles 0, 10, and 40 cm in height, and the Dynamic Gait Index, Berg Balance Scale, and Four Square Step Test were used to measure dynamic balance ability. [Results] The Dynamic Gait Index, Berg Balance Scale, and Four Square Step Test were correlated with each other. Dynamic balance tests were correlated with the COP displacement time during the stance phase. At obstacle heights of 10 and 40 cm during loading response and at all heights during pre-swing, there were correlations with dynamic balance ability. However, dynamic balance ability did not affect the COP displacement time during mid-stance and terminal stance. [Conclusion] People with a lower dynamic balance ability show a larger COP displacement time during loading response and pre-swing. Therefore, dynamic balance ability can be predicted by measuring the COP displacement time.

Evaluation of combined prescription of rocker sole shoes and custom-made foot orthoses for the treatment of plantar fasciitis

BACKGROUND

It is a routine practice to prescribe a combination of rocker shoes and custom-made foot orthoses for patients with plantar fasciitis. Recently, there has been a debate on this practice, and studies have shown that the individual prescription of rocker shoes or custom-made foot orthoses is effective in treating plantar fasciitis. The aim of this study was to evaluate and compare the immediate therapeutic effects of individually prescribed rocker sole shoes and custom-made foot orthoses, and a combined prescription of them on plantar fasciitis.

METHODS

This was a cross-over study. Fifteen patients with unilateral plantar fasciitis were recruited; they were from both genders and aged between 40 and 65. Subjects performed walking trials which consisted of one 'unshod' condition and four 'shod' conditions while wearing baseline shoes, rocker shoes, baseline shoes with foot orthotics, and rocker shoes with foot orthotics. The study outcome measures were the immediate heel pain intensity levels as reflected by visual analog scale pain ratings and the corresponding dynamic plantar pressure redistribution patterns as evaluated by a pressure insole system.

RESULTS

The results showed that a combination of rocker shoes and foot orthoses produced a significantly lower visual analog scale pain score (9.7 mm) than rocker shoes (30.9 mm) and foot orthoses (29.5 mm). With regard to baseline shoes, it also significantly reduced the greatest amount of medial heel peak pressure (-33.58%) without overloading other plantar regions when compared to rocker shoes (-7.99%) and foot orthoses (-28.82%).

DISCUSSION

The findings indicate that a combined prescription of rocker sole shoes and custom-made foot orthoses had greater immediate therapeutic effects compared to when each treatment had been individually prescribed.

The effects of safety handrails and the heights of scaffolds on the subjective and objective evaluation of postural stability and cardiovascular stress in novice and expert construction workers

Work performed on scaffolds carries the risk of falling that disproportionately threatens the safety and health of novice construction workers. Hence, objective measures of the postural stability, cardiovascular stress, and subjective difficulty in maintaining postural balance were evaluated for four expert and four novice construction workers performing a manual task in a standing posture on a scaffold with and without safety handrails at two different elevation heights. Based on a multivariate analysis of variance, the experience, scaffold height, and presence of a handrail were found to significantly affect measures of the postural stability and cardiovascular stress. At a lower level of worker experience, a higher scaffold height, and in the absence of a handrail (which may correspond to higher risk of a fall), postural stability was significantly reduced, while cardiovascular stress and subjective difficulties in maintaining postural balance increased. We emphasize the importance of training and handrails for fall prevention at construction sites.

THE EFFECTS OF CHANGES IN STEP WIDTH ON PLANTAR FOOT PRESSURE PATTERNS OF YOUNG FEMALE SUBJECTS DURING WALKING

The aim of this study was to investigate the foot plantar pressure distribution and the effect of different step width during walking. Methods: Nineteen female volunteers who aged 18~30 years old and with no history of lower extremity injury were considered. Subjects walked at a pre-determined set speed with varied step width (5 cm, 10 cm, and 20 cm) for three trials at each step width. This study used an in-sole plantar pressure measurement system to collect the peak pressure, maximum ground reaction force, pressure–time integral, and force–time integral data of eight different foot regions. Results: The data revealed that the peak plantar foot pressure on the medial arch increased with wider step width (p < 0.05). In contrast, maximum ground reaction force, peak plantar pressure, pressure–time integral, and force–time integral on the lateral arch and lateral side of the metatarsals decreased with wider step width (p < 0.05). Conclusion: The results of this study revealed that smaller step width during walking result in decreasing the pressure on the medial arch of the foot. It may have the relieving effect for clients with pes planus and it can be a reference for rehabilitation clinicians while treating the above-mentioned subjects.

An in-shoe device to measure plantar pressure during daily human activity

In this work, we report the development of a novel device, integrated into a shoe, to monitor plantar pressure under real-life conditions by reducing the spatial and temporal resolution. The device consists of a shoe insole with seven pressure-sensitive conductive rubber sensors and a wireless data transmission unit incorporated into a smaller measurement unit. One advantage of this approach is that the mass and volume of the measurement unit are less than 1/10th and 1/50th, respectively, of that reported for other devices. A comparison experiment was conducted for validation of the device using the F-scan system, and the initial test of the device was conducted by recording unobstructed gaits of one young adult subject and two elderly subjects. Each subject performed a straight, level walking trial at a comfortable speed for 7 m without any assistive device while wearing the in-shoe device. Changes in the plantar pressure during gait were recorded. Compared with the young subject, the pressure under the heel of the elderly subject was found to be smaller and less steep. This in-shoe device can be used to monitor plantar pressure during daily living and is expected to be useful in various clinical applications.

The modified oblique keller capsular interpositional arthroplasty for hallux rigidus

BACKGROUND

Hallux rigidus is a common problem characterized by localized osteoarthritis and limited range of motion of the hallux. First metatarsophalangeal joint arthrodesis has been the accepted procedure for the treatment of late-stage disease. Despite the success of arthrodesis, some patients object to the notion of eliminating motion at the metatarsophalangeal joint. For this reason, motion-sparing procedures such as the modified oblique Keller capsular interpositional arthroplasty have been developed.

METHODS

We compared a cohort of ten patients (ten toes) who had undergone the modified Keller arthroplasty with a group of twelve patients (twelve toes) who had undergone a first metatarsophalangeal joint arthrodesis at an average of sixty-three and sixty-eight months, respectively. Clinical outcomes were evaluated, and range of motion, great toe dynamometer strength, plantar pressures, and radiographs were assessed.

RESULTS

Clinical outcome differences existed between the groups, with the American Orthopaedic Foot and Ankle Society score being significantly higher for the arthroplasty group than for the arthrodesis group. The arthroplasty group had a mean of 54 degrees of passive and 30 degrees of active range of motion of the first metatarsophalangeal joint. The plantar pressure data revealed significantly higher pressures in the arthrodesis group under the great toe but not under the second metatarsal head.

CONCLUSIONS

The modified oblique Keller capsular interpositional arthroplasty appears to be a motion-sparing procedure with clinical outcomes equivalent to those of arthrodesis, and it is associated with a more normal pattern of plantar pressures during walking.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.

Diabetic foot biomechanics and gait dysfunction

BACKGROUND

Diabetic foot complications represent significant morbidity and precede most of the lower extremity amputations performed. Peripheral neuropathy is a frequent complication of diabetes shown to affect gait. Glycosylation of soft tissues can also affect gait. The purpose of this review article is to highlight the changes in gait for persons with diabetes and highlight the effects of glycosylation on soft tissues at the foot-ground interface.

METHODS

PubMed, the Cochrane Library, and EBSCOhost on-line databases were searched for articles pertaining to diabetes and gait. Bibliographies from relevant manuscripts were also searched.

FINDINGS

Patients with diabetes frequently exhibit a conservative gait strategy where there is slower walking speed, wider base of gait, and prolonged double support time. Glycosylation affects are observed in the lower extremities. Initially, skin thickness decreases and skin hardness increases; tendons thicken; muscles atrophy and exhibit activation delays; bones become less dense; joints have limited mobility; and fat pads are less thick, demonstrate fibrotic atrophy, migrate distally, and may be stiffer.

INTERPRETATION

In conclusion, there do appear to be gait changes in patients with diabetes. These changes, coupled with local soft tissue changes from advanced glycosylated end products, also alter a patient's gait, putting them at risk of foot ulceration. Better elucidation of these changes throughout the entire spectrum of diabetes disease can help design better treatments and potentially reduce the unnecessarily high prevalence of foot ulcers and amputation.

Plantar pressure pain thresholds and touch sensitivity in rheumatoid arthritis

BACKGROUND

In-shoe pressure redistribution to provide relief of forefoot pain in rheumatoid arthritis (RA) is based on assumed links between pressure and pain. However, little is known about the size of the pressure change required to reduce pain or the capacity of other plantar regions to bear increased pressure. Our primary aim was to quantify the plantar pressure pain threshold (PPT) in RA and compare it to age- and gender-matched control participants.

MATERIALS AND METHODS

This controlled trial involved 10 RA participants and 10 age- and gender-matched control subjects. PPT, measured using a force gauge, and touch sensitivity, measured via Semmes-Weinstein monofilaments, were tested in 19 plantar regions.

RESULTS

RA plantar PPTs were significantly reduced in eight foot regions (p < 0.05) and were more uniform across the plantar surface. Touch sensitivity was not different between groups. Plantar PPT was significantly related to age (p < 0.05) and to touch sensitivity (p < 0.05) in multiple foot regions of the control group but not in RA. PPT was significantly correlated with disease duration (p < 0.05).

CONCLUSION

Plantar PPTs in RA were 60% to 80% of the control group and may be helpful in predicting the amount of pressure reduction needed to relieve pain. This study provides further evidence that RA disturbs normal pain sensory mechanisms.

Detection of gait events using an F-Scan in-shoe pressure measurement system

A portable system capable of accurate detection of initial contact (IC) and foot off (FO) without adding encumbrance to the subject would be extremely useful in many gait analysis applications. Force platforms represent the gold standard method for determining these events and other methods including foot switches and kinematic data have also been proposed. These approaches, however, present limitations in terms of the number of steps that can be analysed per trial, the portability for outdoor measurements or the information needed beforehand. The purpose of this study was to evaluate the F-Scan((R)) Mobile pressure measurement system when detecting IC and FO. Two methods were used, one was the force detection (FD) in-built algorithm used by F-Scan software and a new area detection (AD) method using the loaded area during the gait cycle. Both methods were tested in ten healthy adults and compared with the detection provided by a kinetic detection (KT) algorithm. The absolute mean differences between KT and FD were (mean+/-standard deviation) 42+/-11 ms for IC and 37+/-11 ms for FO. The absolute mean differences between KT and AD were 22+/-9 ms for IC and 10+/-4 ms for FO. The AD method remained closer to KT detection for all subjects providing sufficiently accurate detection of both events and presenting advantages in terms of portability, number of steps analysed per trial and practicality as to make it a system of choice for gait event detection.

Comparison of plantar pressure distribution patterns between foot orthoses provided by the CAD-CAM and foam impression methods

Foot orthotic treatment is one of the major conservative methods used to handle foot problems. Total plantar contact foot orthoses are used to reduce and redistribute peak pressures. For the fabrication of a total plantar contact foot orthosis, the computer-aided design and computer-aided manufacturing (CAD-CAM) method has been applied. In this study, the plantar foot-orthosis interface pressure data during walking were collected by the Novel Pedar-mobile in-shoe plantar pressure measuring system. The data were collected under three conditions: (i) Flat insole, (ii) foot orthosis provided by the CAD-CAM method, and (iii) foot orthosis provided by the foam impression method. The Swiss Comfort CAD-CAM foot orthotics system was used in this study. For conditions (ii) and (iii), foot shapes were collected in partial weight bearing and subtalar neutral conditions. Thirty normal subjects were recruited for this study. The plantar foot surface was divided into eight plantar foot regions and then was investigated. These regions included the heel, the medial and lateral arches, the medial, mid and lateral forefoot, the hallux, and the lateral toes. The results showed that the orthoses provided by both the CAD-CAM and foam impression methods could decrease the peak pressure and the maximum force in the heel region, and increase the peak pressure and the maximum force in the medial arch region. Both orthoses redistributed the peak pressure and the maximum force from the heel to the medial arch region. The peak pressure in the mid forefoot region was different between the orthoses provided by the CAD-CAM and foam impression methods.

Custom therapeutic insoles based on both foot shape and plantar pressure measurement provide enhanced pressure relief

OBJECTIVE

The purpose of this study was to determine whether custom insoles tailored to contours of the barefoot pressure distribution and shape of a patient's foot can reduce plantar pressures in the metatarsal head (MTH) region to a greater extent than conventional custom insoles.

RESEARCH DESIGN AND METHODS

Seventy regions of elevated barefoot pressures (mean peak 834 kPa under MTHs) were identified in 20 subjects with diabetes. Foam box impressions of their feet were sent to three different orthotic supply companies for fabrication of custom insoles. One company was also given plantar pressure data, which were incorporated into the insole design. Measurements of in-shoe plantar pressures were recorded during gait for the three custom insoles in a flexible and a rocker-bottom shoe. Peak pressure and force-time integral were extracted for analysis.

RESULTS

In 64 of 70 regions, the shape-plus-pressure-based insole in the flexible shoe achieved superior unloading compared with the two shape-based insoles. On average, peak pressure was reduced by 32 and 21% (both P <or= 0.0001) and force-time integral by 40 and 34% (both P < 0.0001) compared with the shape-based insoles. At the midfoot, force-time integral was increased by 51 and 33% (both P < 0.01). Similar trends were found using the rocker-bottom shoe.

CONCLUSIONS

Compared with insoles based only on shape, the use of foot shape with barefoot plantar pressure measurements in designing custom insoles results in enhanced offloading of high-pressure areas under the forefoot. This offloading was achieved by a greater transfer of load to the midfoot without additional loading of other forefoot structures.

Subtalar release in clubfeet: a retrospective study of 10-year outcomes

BACKGROUND

Optimal management of congenital talipes equinovarus continues to be controversial. There is a dramatically renewed emphasis on non-operative management partly because there has been a high recurrence rate among operated feet. Our hypothesis is that early, extensive subtalar ligament release as the cornerstone of aggressive hindfoot realignment prevents recurrence and retains mobility.

MATERIALS AND METHODS

Twenty-two congenital clubfeet (14 patients) corrected by one surgeon were evaluated using two validated patient-based outcome instruments, dynamic pedobarographic analysis, hindfoot mobility, and weightbearing radiographs. Pedobarographic analysis consisted of quantifying peak plantar forces and pressures during the gait cycle in 22 corrected feet and 24 control feet using the FSCAN in-shoe device.

RESULTS

The mean age at surgery was 8 months and mean followup was 10 years. No patients experienced recurrence of deformity. Reported foot function and satisfaction were very high for all patients and were comparable to reported normal population values. AP and lateral talocalcaneal angles for each foot were within normal limits for age. Hindfoot range of motion, including dorsiflexion, was preserved in all feet. Peak regional forces throughout the gait cycle and plantar pressures at foot flat were mildly, but statistically significantly, higher in the midfoot of corrected feet suggesting slight flattening of the arch. One patient had tendon transfers for bilateral calcaneal deformity and one patient had surgical correction of a bilateral valgus deformity.

CONCLUSION

Aggressive hindfoot realignment provides definitive treatment of an equinovarus deformity, but care must be taken to avoid overcorrection.

Effect of metatarsal pad placement on plantar pressure in people with diabetes mellitus and peripheral neuropathy

BACKGROUND

Standard prevention and treatment strategies to decrease peak plantar pressure include a total contact insert with a metatarsal pad, but no clear guidelines exist to determine optimal placement of the pad with respect to the metatarsal head. The purpose of this study was to determine the effect of metatarsal pad location on peak plantar pressure in subjects with diabetes mellitus and peripheral neuropathy.

METHODS

Twenty subjects with diabetes mellitus, peripheral neuropathy, and a history of forefoot plantar ulcers were studied (12 men and eight women, mean age=57+/-9 years). CT determined the position of the metatarsal pad relative to metatarsal head and peak plantar pressures were measured on subjects in three footwear conditions: extra-depth shoes and a 1) total contact insert, 2) total contact insert and a proximal metatarsal pad, and 3) total contact insert and a distal metatarsal pad. The change in peak plantar pressure between shoe conditions was plotted and compared to metatarsal pad position relative to the second metatarsal head.

RESULTS

Compared to the total contact insert, all metatarsal pad placements between 6.1 mm to 10.6 mm proximal to the metatarsal head line resulted in a pressure reduction (average reduction=32+/-16%). Metatarsal pad placements between 1.8 mm distal and 6.1 mm proximal and between 10.6 mm proximal and 16.8 mm proximal to the metatarsal head line resulted in variable peak plantar pressure reduction (average reduction=16+/-21%). Peak plantar pressure increased when the metatarsal pad was located more than 1.8 mm distal to the metatarsal head line.

CONCLUSIONS

Consistent peak plantar pressure reduction occurred when the metatarsal pad in this study was located between 6 to 11 mm proximal to the metatarsal head line. Pressure reduction lessened as the metatarsal pad moved outside of this range and actually increased if the pad was located too distal of this range. Computational models are needed to help predict optimal location of metatarsal pad with a variety of sizes, shapes, and material properties.

[A baropodometric parameter to analyze the gait of hemiparetic patients: the path of center of pressure]

PURPOSE

Hemiparetic gait has been previously evaluated by several biomechanical methods, but plantar pressure distribution has been much less studied. Our purpose was to analyze the changes in the path of the center of pressure (COP) following the occurrence of hemiparesis using an F-Scan in-shoe transducer.

MATERIALS AND METHODS

Twenty patients, mean age 50 years [26-67] with hemiparesis due to vascular causes underwent gait analysis (by the F-Scan system). All patients had steady neurological status and were self-sufficient for gait. Podo-orthoses were removed during the test. Five to six cycles of gait, about 8 m, were recorded. Comparison of the COP path was performed between hemiparetic and healthy foot. The group control consisted of 9 healthy volunteer subjects.

RESULTS

Differences in the COP path were found in the hemiparetic foot of patients: a significant decrease for the anteroposterior displacement (P=0.002) and the lateral displacement (P=0.04) and a significant anterior displacement of the more posterior contact COP (P=0.005). The "gait line" was irregular, with slowing down going forward and, for some, going back. These results are likely consistent with the equine of the foot. No change was observed in the control group.

CONCLUSION

The use of an F-Scan in the shoe transducer allows for revealing the importance of the COP path in analyzing hemiparetic gait; this noninvasive investigation would be helpful for evaluating the best therapy to propose to and to follow-up patients with hemiparesis.

Influence of heel height and shoe insert on comfort perception and biomechanical performance of young female adults during walking

BACKGROUND

The possible negative effects of high-heeled shoes on subjective comfort perception and objective biomechanical assessment have been noted. Although shoe inserts have been widely applied in footwear to increase comfort and to reduce the frequency of movement-related injury, no study has attempted to identify insert effectiveness in high heels. The purpose of this study was to determine the effects of heel height and shoe inserts on comfort and biomechanics as represented by plantar pressure and ground reaction force (GRF).

METHODS

Twenty young female adults performed the test conditions formed by the cross-matching of shoe inserts (shoe without insert and shoe with total contact insert [TCI]) and heel height (a flat, a low heel [3.8 cm] and a high heel [7.6 cm]). Two-way analyses of variance for repeated measures design were used to test condition effects on comfort rating, plantar pressure, and GRF during gait. To determine the biomechanical variables that can predict comfort, a multiple linear regression with stepwise method was done.

RESULTS

The results showed that discomfort increased with heel height. In high heels, the plantar pressure in the heel and midfoot shifted to the medial forefoot, and the vertical and anteroposterior GRF increased. Use of the TCI reduced the peak pressure in the medial forefoot. Interestingly, the effectiveness of the TCI was greater in the higher heels than in the lower heels and in flat heels. The peak pressure in the medial forefoot, impact force, and the first peak vertical GRF could explain 75.6% of the variance of comfort in high-heeled gait.

CONCLUSIONS

These findings suggest that higher heels result in decreased comfort, which can be reflected by both the subjective rating scale and biomechanical variables. Use of a TCI altered the biomechanics and therefore improved the comfort in high-heeled shoes.

The effect of terrain on foot pressures during walking

BACKGROUND

High plantar pressures are associated with the development of foot ulcers in people with diabetic neuropathy. The effect of terrain on plantar pressures during walking has not been fully explored.

METHODS

Twenty 23- to 40-year-old subjects with no known musculoskeletal pathology walked across three terrains: padded carpet (R), grass (G), and concrete (C) while wearing Novel Pedar (Novel Electronics Inc. GMBH, Munich, Germany) insoles with and without shoes. Pressures were collected at 50 Hz. The sole of the foot was divided into: heel (H), lateral midfoot (LM), medial midfoot (MM), big toe and first metatarsal head (BT), and lateral toes and metatarsal heads (LT). Repeated measures ANOVA identified differences in pressures, forces, and contact areas across terrains. Post hoc Bonferroni adjustments were used to accept an overall alpha level of 0.05.

RESULTS

Peak pressure (PP), maximal mean pressure (MMP) and pressure time integral (PTI) were significantly higher (p < 0.01) when walking barefoot on concrete than on grass or carpet for all foot regions except MM and LM. The percent increase in the three pressure variables ranged from 21% to 43%. Grass and carpet PP, MMP, and PTI were similar for the BT and LT. Wearing shoes significantly increased contact area and decreased all pressure variables on all three terrains.

CONCLUSION

Walking barefoot, especially on concrete was associated with higher plantar pressure variables. Wearing shoes eliminated terrain differences in pressure except under the lesser toes. Persons with insensate feet should avoid walking barefoot on hard surfaces to avoid excessive plantar pressures. Wearing shoes and covering hard floors with nonslip, padded rugs may decrease plantar pressures and the risk of ulceration.

Pressure relief and load redistribution by custom-made insoles in diabetic patients with neuropathy and foot deformity

OBJECTIVE

To study the effects of custom-made insoles on plantar pressures and load redistribution in neuropathic diabetic patients with foot deformity.

DESIGN

Cross-sectional.

BACKGROUND

Although custom-made insoles are commonly prescribed to diabetic patients, little quantitative data on their mechanical action exists.

METHODS

Regional in-shoe peak pressures and force-time integrals were measured during walking in the feet of 20 neuropathic diabetic subjects with foot deformity who wore flat or custom-made insoles. Twenty-one feet with elevated risk for ulceration at the first metatarsal head were analysed. Load redistribution resulting from custom-made insoles was assessed using a new load-transfer algorithm.

RESULTS

Custom-made insoles significantly reduced peak pressures and force-time integrals in the heel and first metatarsal head regions; pressures and integrals were significantly increased in the medial midfoot region compared with flat insoles. Custom-made insoles successfully reduced pressures in and integrals at the first metatarsal head in 7/21 feet, were moderately successful in another seven, but failed in the remaining seven. Load transfer was greatest from the lateral heel to the medial midfoot regions.

CONCLUSIONS

Custom-made insoles were more effective than flat insoles in off-loading the first metatarsal head region, but with considerable variability between individuals. Most off-loading occurred in the heel (not a region typically at risk). The load transfer algorithm effectively analyses custom-made-insole action.

RELEVANCE

Because similar insole modifications apparently exert different effects in different patients, a comprehensive evaluation of custom designs using in-shoe pressure measurement should ideally be conducted before dispensing insoles to diabetic patients with neuropathy and foot deformity.

The influence of walking speed and footwear on plantar pressures in older adults

OBJECTIVE

To identify the influence of walking velocity and footwear condition on plantar pressure variables in healthy older adults.

DESIGN

Single session data collection during varying speed and footwear conditions.

BACKGROUND

Elevated plantar pressures are concerning due to the risk of tissue injury, ulceration, and pain. In young adults, increases in plantar pressure have been documented with faster walking speeds and when walking barefoot compared to wearing shoes. These relationships have not been systematically explored in older adults.

METHODS

Key plantar pressure factors were recorded as subjects walked barefoot and in comfortable walking shoes across a 10 m walkway at three predetermined velocities (57, 80, 97 m/min). Separate 3x2 analyses of variance with repeated measures identified significant differences in pressure, force, and contact area in eight anatomically defined foot regions across walking speeds and between footwear conditions.

RESULTS

Faster walking resulted in higher pressures under all foot regions except for the arch and lateral metatarsal (P</=0.001), due primarily to greater forces under the heel, medial metatarsal and toes (P</=0.001). Compared to wearing shoes, barefoot heel pressure was elevated (P</=0.001) due to reduced heel contact area (P<0.001); pressure under the central metatarsals was higher (P</=0.001) owing to greater central metatarsals force (P<0.001).

CONCLUSIONS

Two conditions were associated with higher plantar pressures in the older adults studied: faster speeds and barefoot walking.

Effects of total contact insoles on the plantar stress redistribution: a finite element analysis

OBJECTIVE

To investigate the effects of total contact insoles on the plantar stress redistribution using three-dimensional finite element analysis.

DESIGN

The efficacies of stress reduction and redistribution of two total contact insoles with different material combinations were compared with those of a regular flat insole used as a baseline condition.

BACKGROUND

Many specially designed total contact insoles are currently used to reduce the high plantar pressure in diabetic patients. However, the design of total contact insoles is mostly empirical and little scientific evidence is available to provide a guideline for persons who prescribe such insoles.

METHODS

To use three-dimensional finite element models of the foot together with insoles to investigate the effects of total contact insoles on the foot plantar pressure redistributions. Nonlinear foam material properties for the different insole materials and the contact behavior in the foot-insole interface were considered in the finite element analysis.

RESULTS

Results showed that the peak and the average normal stresses were reduced in most of the plantar regions except the midfoot and the hallux region when total contact insoles were worn compared with that of the flat insole condition. The reduction ratios of the peak normal stress ranged from 19.8% to 56.8%.

CONCLUSIONS

Finite element analysis results showed that the two sets of total contact insoles used in the current study can both reduce high pressures at regions such as heel and metatarsal heads and can redistribute the pressure to the midfoot region when compared with the flat insole condition.

RELEVANCE

It is possible to simulate foot deformities, change in material properties, different ambulatory loading conditions, and different orthotic conditions by altering the finite element model in a relatively easy manner and these may be of interests to the medical professionals who treat foot-related problems.

Is there a reliable outcome measurement for displaced intra-articular calcaneal fractures?

BACKGROUND

The treatment of displaced intra-articular calcaneal fractures remains controversial, because of difficulties in assessing the outcome. The goal of this study, therefore, was to compare different outcome measurements with gait analysis, using dynamic pedography.

METHODS

Twenty patients with operatively treated displaced intra-articular calcaneal fractures were followed up clinically and radiographically. In addition, foot pressure was measured using dynamic pedography.

RESULTS

No significant difference was found between the two clinical outcome scores used (p = 0.08); both revealed good results. Dynamic pedography, however, showed a shift of the maximum impact and roll-off of the foot to the lateral side, as well as a widening of these zones in the heel and on the sole in 14 of 20 patients.

CONCLUSION

These results indicate that traditional outcome measurements underestimate functional deficits in our patients. Monitoring plantar pressure distribution might therefore be a useful tool for assessing foot function in these patients.

Mechanical comparison of cyclic loading in five different first metatarsal shaft osteotomies

The purposes of the current study were: 1. to analyze the relative fatigue endurance of five different first metatarsal shaft osteotomies (proximal crescentic, proximal chevron, Ludloff, Mau, and Scarf), as performed on sawbone models using the most common fixation techniques (part I); and 2. to compare the two more commonly used techniques (per part I results) in matched-pair cadaver specimens (part II). In part I, the proximal chevron and Mau osteotomies were significantly more stable (P < or = 0.005) than all other osteotomies except the Ludloff. In part II, there was no significant difference in fatigue endurance between the proximal chevron and Ludloff osteotomies.

Stress distribution of the foot during mid-stance to push-off in barefoot gait: a 3-D finite element analysis

OBJECTIVE

To quantify stress distribution of the foot during mid-stance to push-off in barefoot gait using 3-D finite element analysis.

DESIGN

To simulate the foot structure and facilitate later consideration of footwear. Finite element model was generated and loading condition simulating barefoot gait during mid-stance to push-off was used to quantify the stress distributions.

BACKGROUND

A computational model can provide overall stress distributions of the foot subject to various loading conditions.

METHODS

A preliminary 3-D finite element foot model was generated based on the computed tomography data of a male subject and the bone and soft tissue structures were modeled. Analysis was performed for loading condition simulating barefoot gait during mid-stance to push-off.

RESULTS

The peak plantar pressure ranged from 374 to 1003 kPa and the peak von Mises stress in the bone ranged from 2.12 to 6.91 MPa at different instants. The plantar pressure patterns were similar to measurement result from previous literature.

CONCLUSIONS

The present study provides a preliminary computational model that is capable of estimating the overall plantar pressure and bone stress distributions. It can also provide quantitative analysis for normal and pathological foot motion.

RELEVANCE

This model can identify areas of increased pressure and correlate the pressure with foot pathology. Potential applications can be found in the study of foot deformities, footwear, surgical interventions. It may assist pre-treatment planning, design of pedorthotic appliances, and predict the treatment effect of foot orthosis.

Six first metatarsal shaft osteotomies: mechanical and immobilization comparisons

Because malunion (usually with dorsal elevation of the first metatarsal) has been reported after the treatment of severe hallux valgus deformities by proximal osteotomies, the current study was designed to compare the sagittal stability of six different metatarsal shaft osteotomies: the proximal crescentic, proximal chevron, Mau, Scarf, Ludloff, and biplanar closing wedge osteotomies. A plate was used in the biplanar closing wedge osteotomy; all others used screws for fixation. Ten fresh-frozen, human anatomic lower extremity specimens were used for each osteotomy. Failure loads were measured as units of force (newtons) and converted to pressure (kilopascals). Then the F-Scan system, which uses a thin insole to measure plantar pressure, was used to evaluate the pressure under the first metatarsal of seven volunteers using four types of shoes. According to the results, in patients with normal bone stock who are compliant, any of the four shoe types tested may be used after a Ludloff, Scarf, biplanar wedge (plantar screw fixation), or Mau osteotomy, but the wedge-based shoe should be used after a proximal crescentic or chevron osteotomy or for patients with severe osteopenic bone.

Quantification of the path of center of pressure (COP) using an F-scan in-shoe transducer

By tracking the path of the center of pressure (COP) during the stance phase, the balance and pattern of progression can be determined. The path of COP is frequently used in clinical practice, although it is not quantified. In this study, an F-scan pressure sensitive insole system was used to quantify the path of COP. The COP of initial contact and the average during the stance phase corresponded to the center of the heel and to the center of the total plantar surface, respectively. The COP displacement corresponded to 83% of foot contact length and 18% of forefoot contact width. When the longitudinal axis of the insole was plotted as the Y-axis and the transverse axis of the insole as X-axis, the slopes of the COP coordinates during stance phase was 6 degrees inward. Velocities of the COP during each functional rocker action were even and 22-27 cm/s. The changes of quantified COP parameters according to the biomechanical alteration of the foot were confirmed by high-heeled gait.

novel Award First Prize Paper. Orthotic management of plantar pressure and pain in rheumatoid arthritis

OBJECTIVE

To investigate the effectiveness of foot orthoses in the management of plantar pressure and pain in subjects with rheumatoid arthritis.

DESIGN

A repeated measures study in which the independent variable was orthosis design. Dependent variables, including pressure, gait and pain parameters, were examined using analysis of variance and correlation statistics.

BACKGROUND

The aim of orthotic management of the rheumatoid foot is to relieve metatarsalgia through the reduction of metatarsal head pressure. Few studies have investigated the relative effectiveness of different orthosis designs. To date, no studies have examined the relationship between plantar pressure and second metatarsal head pain in rheumatoid arthritis subjects.

METHODS

Twelve rheumatoid arthritis subjects with foot involvement and second metatarsal head pain were tested. Four styles of foot orthosis (prefabricated, standard custom moulded, custom with metatarsal bar, custom with metatarsal dome) were compared to a shoe only control. An EMED Pedar system was used to measure plantar pressure during repeated trials of comfortable cadence walking and quiet standing. Reports of subjective pain were recorded for each orthosis as were orthosis preferences.

RESULTS

All orthoses significantly reduced pressure beneath the first and second metatarsal heads compared to the shoes only control. The custom moulded orthosis with metatarsal dome was the most effective orthosis for reducing subjective ratings of pain. A significant correlation (r=0.562) was found between ratings of pain and average pressure beneath the second metatarsal head.

CONCLUSIONS

Results from this study suggest that average pressure measurement may be a useful indicator in the management of metatarsalgia in RA. Further study is required to improve understanding of the relationship between rheumatoid foot mechanics and pain.

RELEVANCE

Appropriate foot orthosis design can substantially improve comfort in RA patients with symptomatic feet. A custom moulded foot orthosis incorporating a metatarsal dome was the most effective design for subjects with painful second metatarsal heads. Foot pressure measurement technology can be a useful adjunct to research and clinical management of the painful rheumatoid foot.

Conventional patellar-tendon-bearing (PTB) socket/stump interface dynamic pressure distributions recorded during the prosthetic stance phase of gait of a trans-tibial amputee

Force sensing resistors (FSR) have been used to measure dynamic stump/socket interface pressures during the gait of a trans-tibial amputee. A total of 350 pressure sensor cells were attached to the inner wall of a patellar-tendon-bearing (PTB) socket. Data was sampled at 150 Hz during the approximate 0.8 seconds of prosthetic stance of gait. A total of 42,000 pressures were recorded during a single prosthetic stance. This paper describes the distribution of the pressure patterns monitored during the prosthetic stance phase of gait.

Foot asymmetry in healthy adults: elliptic fourier analysis of standardized footprints

The size and shape of paired structures differ in the left and right sides of the body. Shape characteristics should be analyzed separately from size to supply information about the normal variations of human organs. In the present study, the within-subject normal symmetry of footprint shape and size was analyzed from a mathematical standpoint. On the standardized left and right footprints of 46 healthy adults (23 women and 23 men; 19-26 years old), the outline of each foot excluding the toes was identified and its shape was quantified independently from size by the elliptic Fourier analysis. The symmetry in shape was quantified on an intra-subject basis by calculating a morphologic distance D between the mathematical reconstructions of the left and right footprints of each subject. Symmetry in size was assessed by the right-to-left area ratio and found to be very good for all subjects; it ranged from 0.948 to 1.049. The subjects were also grouped by sex, and mean values were calculated. Within-subject symmetry in the footprint shape appeared high, with morphologic distances ranging between 8.94 and 2.66 in men and between 7.15 and 3.09 in women. No consistent associations between footprint symmetry and age, body height and weight, or shoe size were found. On average, women had more symmetric size-standardized footprints than did men (women: mean 4.57, SD 1.14; men: mean 5.46, SD 1.7; p < 0.05). Mean size-independent shapes of male and female left and right footprints were also calculated. Together with the analysis of individual asymmetry, they could be used for the quantitative diagnosis of borderline patients.

Calibration problems encountered while monitoring stump/socket interface pressures with force sensing resistors: techniques adopted to minimise inaccuracies

Force sensing resistors (FSR) have been used to measure dynamic pressures at the interface between appliance and patient. Inaccuracies using FSRs have been reported. This paper summarises both the calibration problems encountered and the techniques adopted to minimise inaccuracies. It is considered that, by calibrating the transducers attached to the socket, and by adopting a strict test protocol, FSRs may provide a guide to the dynamic pressure distribution applied to the trans-tibial stump during gait.