Plantar pressure relief using a forefoot offloading shoe

pressuRe: an R package for analyzing and visualizing biomechanical pressure distribution data

In many biomechanical analyses, the forces acting on a body during dynamic and static activities are often simplified as point loads. However, it is usually more accurate to characterize these forces as distributed loads, varying in magnitude and direction, over a given contact area. Evaluating these pressure distributions while they are applied to different parts of the body can provide effective insights for clinicians and researchers when studying health and disease conditions, for example when investigating the biomechanical factors that may lead to plantar ulceration in diabetic foot disease. At present, most processing and analysis for pressure data is performed using proprietary software, limiting reproducibility, transparency, and consistency across different studies. This paper describes an open-source software package, 'pressuRe', which is built in the freely available R statistical computing environment and is designed to process, analyze, and visualize pressure data collected on a range of different hardware systems in a standardized manner. We demonstrate the use of the package on pressure dataset from patients with diabetic foot disease, comparing pressure variables between those with longer and shorter durations of the disease. The results matched closely with those from commercially available software, and individuals with longer duration of diabetes were found to have higher forefoot pressures than those with shorter duration. By utilizing R's powerful and openly available tools for statistical analysis and user customization, this package may be a useful tool for researchers and clinicians studying plantar pressures and other pressure sensor array based biomechanical measurements. With regular updates intended, this package allows for continued improvement and we welcome feedback and future contributions to extend its scope. In this article, we detail the package's features and functionality.

The influence of partial weight bearing on plantar peak forces using three different types of postoperative shoes

BACKGROUND

Therapeutic shoes and partial weight bearing regimes are used after foot surgery to prevent the operated region from excessive load. It remains unclear to which extent partial weight bearing reduces the plantar peak forces. Therefore, we investigated the correlation of weight bearing and plantar peak forces in commonly used therapeutic shoes.

METHODS

Three different weight bearing regimes (20 kg, 40 kg, full weight) were investigated in 20 healthy volunteers. Sensor insoles were used to measure peak forces of the forefoot, midfoot, heel and the complete foot using four kind of shoes (bandage shoe, forefoot relief shoe, short walker and standard sneaker). Peak forces were compared between shoes using one-way ANOVA. The influence of partial weight bearing relative to the peak forces was examined by linear regression analysis.

RESULTS

All therapeutic shoes reduced significantly peak forces of the fore- and midfoot when compared to the reference shoe; the largest reduction was achieved by the forefoot relief shoe (-70 % at forefoot). Weight load and the resulting peak force showed a positive linear correlation for all regions and shoe types. Partial weight bearing significantly reduced the forefoot's force ratio compared to full weight bearing for all shoes except the forefoot relief shoe.

CONCLUSIONS

Partial weight bearing is a strong instrument to reduce plantar peak forces of the forefoot, additionally to the proven offloading effect of therapeutic shoes.

Plantar pressure distribution and wearing characteristics of three forefoot offloading shoes in healthy adult subjects

Forefoot offloading shoes are used to reduce pressure on specific regions of the foot. Aim of the pressure reduction is to aid healing of the soft and bony tissues and prevent complications by treating foot disorders. A great variety of forefoot offloading shoes are available. In a first step to investigate the appropriate use of these footwear in orthopedic settings, we studied plantar pressure distribution and wearing characteristics of three forefoot offloading shoes namely the Mailand, OrthoWedge and Podalux in a healthy population. Twenty subjects walked in a randomized order wearing three forefoot offloading shoes and a reference shoe for six minutes. The Pedar system was used to measure the pressure in 7 regions. Peak pressure and pressure time integral were analyzed as measures of pressure distribution. Furthermore, wearing characteristics were addressed using a Numeric Rating Scale. Pressure distribution and wearing characteristics of the forefoot offloading shoes were compared to a reference shoe. The Mailand and OrthoWedge shoes significantly reduced peak pressure with more than 80% under the hallux and more than 45% under MTH1 (p<.001). The Podalux did not show significant peak pressure reduction under the forefoot compared to the reference shoe. Under the lesser toes, the MTH4-5 region and heel region the Podalux shoe showed even a significant increase in peak pressure (p=.001). Looking at wearing characteristics, the Podalux and reference shoe scored significantly better than the other two forefoot offloading shoes (p<.01). In this study the differences between different forefoot offloading shoes was assessed. The Mailand and OrthoWedge shoes gave the best pressure reduction in the forefoot but are less comfortable in use. The Podalux rocker shoe showed opposite results. Next step is a patient study to compare our results in a patient population.

Clinical and Radiological Outcomes of Forefoot Offloading Versus Rigid Flat Shoes in Patients Undergoing Surgery of the First Ray

BACKGROUND

It is common clinical practice to use either flat or reverse camber shoes to protect the foot for up to 6 weeks after surgery for hallux valgus or hallux rigidus. To date there is a paucity of evidence as to whether there is any difference between these 2 postoperative shoes, in either patient satisfaction or clinical outcomes.

METHODS

One hundred consecutive patients undergoing scarf/Akin osteotomies or first metatarsophalangeal joint (MTPJ) arthrodesis were recruited. Patients were randomized 50:50 to either flat or reverse camber postoperative shoes. Patients undergoing ancillary lesser toe procedures were not excluded. Patient satisfaction was assessed by visual analog scale (VAS) pain score and Likert satisfaction survey. Radiographic outcomes were reviewed at 1 year observing differences in fusion rates or deformity recurrence. There were 47 patients in the reverse cam and 43 in the flat shoe group. No difference in primary forefoot operation, additional operation, age at surgery, or preop VAS pain score was seen.

RESULTS

At 6 weeks, there was no significant difference in postop VAS pain score. The flat shoe group was significantly more likely to be satisfied with their general mobility (86.0% vs 61.7%; P = .01) and with their stability in the shoe (90.7% vs 69.6%; P = .03). No significant difference was seen between groups for nonunion or hallux valgus recurrence rates.

CONCLUSION

Both forms of postoperative footwear were effective in enabling patients to mobilize and in preventing adverse outcomes. Patients were more likely to be satisfied with a flat postoperative shoe due to improved stability and ease of mobilizing. The results of this study aid surgeon decision making for postoperative footwear in forefoot surgery.

LEVEL OF EVIDENCE

Level II, prospective randomized controlled trial.

Plantar Partial Pressure Analysis in a Patient with Reverse Extensor Digitorum Brevis Flap for the Treatment of Hallux Injury

Introduction

An extensor digitorum brevis (EDB) flap can be used to cover a small soft-tissue defect and has been widely used as pedicled flap to cover defects around the ankle and foot. However, its post-operative functional recovery is unknown. Few reports have evaluated gait after foot flap surgeries, although gait assessment is considered to be necessary for functional evaluation after foot reconstruction. We performed a reverse EDB flap to treat a right hallux injury and conducted a plantar partial pressure (PPP) analysis as a postoperative functional evaluation.

Case Report

A 30-year-old laborer suffered an injury resulting in necrosis of the distal phalanx and soft-tissue defect of the proximal phalanx. After amputation, the proximal phalanx was covered with a reverse EDB flap. PPP analysis involved a 4-m-long platform system (P-Walk) and was conducted 3- and 12-month post-surgery. Walking velocity and the single-support phase on the affected limb had increased markedly after 12 months. After 12 months, the PPP of the first metatarsal head was greater than on the unaffected side, and the cadence and single-leg support rate were equal to the unaffected side.

Conclusion

A nearly normal gait was obtained by covering the basal part of the hallux with an EDB flap and preserving the metatarsophalangeal joint.

Lower-extremity dynamics of walking in neuropathic diabetic patients who wear a forefoot-offloading shoe

BACKGROUND

A forefoot-offloading shoes has a negative-heel rocker outsole and is used to treat diabetic plantar forefoot ulcers, but its mechanisms of action and their association with offloading and gait stability are not sufficiently clear.

METHODS

Ten neuropathic diabetic patients were tested in a forefoot-offloading shoe and subsequently in a control shoe with no specific offloading construction, both worn on the right foot (control shoe on left), while walking at 1.2m/s. 3D-instrumented gait analysis and simultaneous in-shoe plantar pressure measurements were used to explain the shoe's offloading efficacy and to define centre-of-pressure profiles and left-to-right symmetry in ankle joint dynamics (0-1, 1:maximum symmetry), as indicators for gait stability.

FINDINGS

Compared to the control shoe, peak forefoot pressures, vertical ground reaction force, plantar flexion angle, and ankle joint moment, all in terminal stance, and the proximal-to-distal centre-of-pressure trajectory were significantly reduced in the forefoot-offloading shoe (P<0.01). Peak ankle joint power was 51% lower in the forefoot-offloading shoe compared to the control shoe: 1.61 (0.35) versus 3.30 (0.84) W/kg (mean (SD), P<0.001), and was significantly associated with forefoot peak pressure (R²=0.72, P<0.001). Left-to-right symmetry in the forefoot-offloading shoe was 0.39 for peak ankle joint power.

INTERPRETATION

By virtue to their negative-heel rocker-outsole design, forefoot-offloading shoes significantly alter a neuropathic diabetic patient's gait towards a reduced push-off power that explains the shoe's offloading efficacy. However, gait symmetry and stability are compromised, and may be factors in the low perceived walking discomfort and limited use of these shoes in clinical practice. Shoe modifications (e.g. less negative heel, a more cushioning insole) may resolve this trade-off between efficacy and usability.

Analysis of Foot Kinematics with Unstable Sole Structure Using Oxford Foot Model

To determine the influence of the unstable sole structure on foot kinematics and provide theoretical basis for further application.12 healthy female subjects walked through a 10-meter experimental channel with normal speed wearing experimental shoes and control shoes respectively at the gait laboratory. Differences between the groups in triplanar motion of the forefoot, rearfoot and hallux during walking were evaluated using a three-dimensional motion analysis system incorporating with Oxford Foot Model (OFM). Compare to contrast group, participants wearing experimental shoes demonstrated greater peak forefoot dorsiflexion, forefoot supination and longer halluces plantar flexion time in support phase. Additionally, participants with unstable sole structure also demonstrated smaller peak forefoot plantarflexion, rearfoot dorsiflexion and range of joint motion in sagittal plane and frontal plane.. The difference mainly appeared in sagittal and frontal plane. With a stimulation of unstable, it may lead to the reinforcement of different flexion between middle and two ends of the foot model. The greater forefoot supination is infered that the unstable element structure may affect the forefoot motion on the frontal plane and has a control effect to strephexopodia people. The stimulation also will reflexes reduce the range of rearfoot motion in sagittal and frontal planes to control the gravity center of the body and keep a steady state in the process of walking.

Pedobarographic and kinematic analysis in the functional evaluation of two post-operative forefoot offloading shoes

BACKGROUND

Forefoot offloading shoes are special orthopaedic footwear designed to protect and unload the injured part of the foot after surgery and for conservative treatments. The offloading action is often achieved by transferring plantar load to the rearfoot via rocker shoes with reduced contact area between shoe and ground. While these shoes are intended to be worn only for short periods, a compromise must be found between functionality and the risk of alterations in gait patterns at the lower limb joints. In this study, the pedobarographic, kinematic and kinetic effects of a traditional half-shoe and a double-rocker full-outsole shoe were compared to those of a comfortable shoe (control).

METHODS

Ten healthy female participants (28.2 ± 10.0 years) were asked to walk in three different footwear conditions for the left/right foot: control/half-shoe, control/full-outsole, and control/control. Full gait analysis was obtained in three walking trials for each participant in each condition. Simultaneously a sensor insole system recorded plantar pressure in different foot regions. Normalized root-mean-square error, coefficient of determination, and frame-by-frame statistical analysis were used to assess differences in time-histories of kinematic and kinetic parameters between shoes.

RESULTS

The half -shoe group showed the slowest walking speed and the shortest stride length. Forefoot plantar load was significantly reduced in the half-shoe (maximum force as % of Body Weight: half-shoe = 62.1; full-outsole = 86.9; control = 93.5; p < 0.001). At the rearfoot, mean pressure was the highest in the full-outsole shoe. At the ankle, sagittal-plane kinematics in the full-outsole shoe had a pattern more similar to control.

CONCLUSIONS

The half-shoe appears significantly more effective in reducing plantar load at the forefoot than a double-rocker full-outsole shoe, which is designed to reduce forefoot loading by using an insole with a thicker profile anteriorly as to maintain the foot in slight dorsiflexion. However, the half-shoe is also associated with altered gait spatio-temporal parameters, more kinematic modifications at the proximal lower limb joints and reduced propulsion in late stance.

Use of Smart Toe(©) implant for small toe arthrodesis: A smart concept?

BACKGROUND

Arthrodesis of small joints for hammer and claw toe deformities is a common forefoot operative procedure. Our objective was to review patients who underwent small toe arthrodesis with Smart Toe(©) intramedullary monobloc implant. Our aim was to assess patient's surgical outcome and to ascertain implant suitability.

METHODS

This procedure was undertaken in 90 patients from February 2011 to December 2012. We present our review of 82 (91.1%) patients who attended the final six 6-month follow up. Mean age was 56.5 years. There were 7 (8.5%) males and 75 (8.5%) males and 75 (91.5%) females. Clinical and radiological evaluation was undertaken. A questionnaire was used to assess general symptoms, clinical outlook, deformity and patient's perceptions and acceptance. Foot and Ankle Outcome Score and Foot and Ankle Disability Index were used to judge outcome.

RESULTS

There were 71 (86.6%) proximal and 11 (13.4%) distal interphalangeal joints with 69 (84.1%) second, 7 (8.5%) third, 6 (84.1%) second, 7 (8.5%) third, 6 (7.3%) fourth toes. There was persistent swelling in 7 (8.5%) and tenderness in 1 (1.2%). Appearance of toes was symmetrical in 71 (86.6%) and 11 (13.4%) were asymmetrical but asymptomatic. The mean range of movement of the adjacent joint was 53.9°. Control of toes was good in 72 (87.8%) patients. Mean percentage of improvement was 76.1% with 100% in 17 (20.7%) and over 80% in 47 (57.3%). Seventy (85.3%) would recommend and undergo repeat surgery. There were 2 (2.4%) cases of metal cut out. There was one (1.2%) implant failure. Union was achieved in 79 (96.3%) patients.

CONCLUSION

We feel that Smart Toe(©) small toe arthrodesis is a safe and reliable technique with good patient outcome and acceptance.

FOOT LOADING PATTERNS WITH DIFFERENT UNSTABLE SOLES STRUCTURE

Foot loading patterns can be changed by using different unstable sole structures, detailed quantification of which is of great significance for research and technological development in falling prevention and lower limb disorders rehabilitation. In this study, unstable soles constructions are adjusted through unstable elements in heel and medial, neutral and lateral forefoot and the foot loading patterns are comparatively studied. A total of 22 healthy male subjects participated in this test. Subjects are asked to walk over a 12 m walkway with control shoes and experimental shoes in self-adapted speed. Significant peak pressure, contact area and pressure-time integral differences in middle foot are found between control shoes and experimental shoes. In addition, peak pressure and pressure-time integral are found to increase significantly with unstable elements adding to center forefoot. The results showed that adjusting the unstable elements in coronal plane of forefoot could effectively alter the distribution of plantar pressure, this could potentially offer a mechanism for preventing falling of elderly and rehabilitation of lower extremity malfunctions. This study also demonstrates a novel concept that unstable element could be effectively adjusted in terms of position to meet different functional requirement.

[Vacuum shoe system vs.forefoot offloading shoe for the management of metatarsal fractures. A prospective, randomized trial]

BACKGROUND

Metatarsal fractures are managed using different types of forefoot offloading orthosis. Theaim of this prospective study was to evaluate the clinical and pedographic results of a vacuum shoe system in comparison to a forefoot unloading shoe.

METHOD

20 patients (14 women/6 men--age: 36.4 +/- 14.1 years) were prospectively included in the study. The patients were followed up at four different time points. Detailed clinical and radiological examinations were carried out, functional scores were measured and a pedographic assessment was performed.

RESULTS

Between the study groups no differences were seen in functional scoring. A complete bony healing was achieved within the 3 months of followup in all patients. The heelstrike to heelstrike time was without significant differences in the pedographic analysis. Adequate forefoot unloading was achieved with both orthosis. The load sharing between fore-, mid- and hindfoot showed no significant differences in the pedographic analysis. Patients' satisfaction was rated with higher values for the vacuum shoe system, but without significance.

CONCLUSION

Both shoe systems show an adequate unloading of the forefoot. Therefore both orthosis may be used for the treatment of metatarsal fractures.