Custom-made foot orthoses with and without heel plugs and their effect on plantar pressures during treadmill walking.

BACKGROUND: Foot orthoses have consistently demonstrated an improvement in pain scores for plantar fasciitis. The fabrication of custom-made foot orthoses (CFOs) can vary between clinicians and may include the use of different materials and casting techniques. This cross-sectional study's objective was to quantify plantar pressure for two CFOs, one with a heel plug (HP) and one without. METHODS: Fourteen healthy participants (8 men and 6 women; 35.4 ± 7.7 years) were cast by the same practitioner. Both CFOs were made with the same materials and specifications, except for the HP orthosis, which replaced hard material under the heel with a softer blue PORON ® plug for added cushioning. Plantar pressures were recorded during treadmill walking for both devices in a running shoe. Average pressure, peak pressure, and pressure contact area were determined for three regions of the foot: hindfoot, midfoot, and forefoot. A paired samples t -test determined differences in each region ( P < 0.05). RESULTS: The HP orthosis reduced the overall means of average pressure, peak pressure, and pressure contact area in the hindfoot while tending to increase these measures in the midfoot and forefoot. The three measures showed statistically significant decreases in the hindfoot, whereas a statistically significant increase was seen in average and peak pressures in the midfoot ( P < 0.05). CONCLUSIONS: CFOs with HPs are more effective than regular CFOs in offloading plantar pressures in the hindfoot while increasing pressures in the midfoot. This is an important finding because offloading the hindfoot is critical in pathologies such as plantar fasciitis to decrease pain and increase function.

Arch Height Index, Arch Rigidity Index, and Arch Stiffness Values in a Symptomatic Population.

BACKGROUND: Studies of arch height index (AHI), arch rigidity index (ARI), and arch stiffness have primarily focused on healthy populations. Normative values of the aforementioned measurements in a pathologic sample may be useful in identifying relationships between arch structure and pathology. METHODS: AHI was obtained bilaterally at 10% and 90% weightbearing conditions using the AHI measurement system. ARI and arch stiffness were calculated using AHI measurements. Dependent t tests compared right and left, dominant and nondominant, and injured and noninjured limbs. Dominant feet were compared between sexes using independent t tests. Relationships between arch stiffness and subcategories were examined using the coefficient of determination (R2). One-way analyses of variance determined differences between arch structure and number of pathologies or body mass index (BMI). RESULTS: A total of 110 participants reported one (n = 55), two (n = 38), or three or more (n = 17) pathologies. Plantar fasciitis (n = 31) and hallux valgus (n = 28) were the most common. AHI, ARI, and arch stiffness did not differ between limbs or sexes for any comparisons. Between subgroups of BMI and number of pathologies, BMI influenced AHI (10% weightbearing) and arch stiffness (P < .05). Arch stiffness showed a weak relationship to AHI, where a higher AHI was associated with a stiffer arch (R2 = 0.06). CONCLUSIONS: Normative arch structure values were established in a pathologic sample with a large incidence of plantar fasciitis and hallux valgus. Understanding relationships between arch structure and pathology is helpful for clinicians and researchers.

Reliability of a multi-segment foot model in a neutral cushioning shoe during treadmill walking.

BACKGROUND: Detailed kinematics of the foot has been frequently reported on in the literature, specifically using various multi-segment foot models. It is important to identify the reliability of a multi-segment foot model in a population of mixed genders and activity levels, while walking in commonly used footwear. The main objective of this study was to investigate the between-day reliability and within-session variability of the Oxford Foot Model (OFM) while walking in a neutral cushioning shoe. METHODS: A 7-camera Vicon motion capture system was used along with 29 passive reflective markers, placed on the participant to examine the multi-segment foot kinematics of the left foot using the OFM. Windows were cut in New Balance 840 shoes following reports from a previous investigation to maintain shoe integrity during testing. Two walking sessions on separate days were collected for 12 healthy participants, with an average total of 22 gait cycles per day. RESULTS: ICCs ranged from 0.020 to 0.964 for between-day reliability, and within-session ICC values ranged from 0.268 to 0.985. Between-day ICC values of the relative measures (excursion and range of motion (ROM)) were higher than the absolute angle measures (angle at foot strike and peak angle). Largest differences were measured in the transverse plane, and the smallest differences in the sagittal plane. Bland-Altman plots revealed best agreement in the frontal and sagittal planes. SEM values ranged from 0.04 to 3.5 for the between-day reliability. CONCLUSIONS: Between-day reliability and within-session variability were comparable to previous studies for adults walking barefoot and shod. This research demonstrates that the OFM can produce reliable data when applied to the assessment of a shod foot.

Medial Longitudinal Arch Angle Presents Significant Differences Between Foot Types: A Biplane Fluoroscopy Study.

The structure of the medial longitudinal arch (MLA) affects the foot's overall function and its ability to dissipate plantar pressure forces. Previous research on the MLA includes measuring the calcaneal-first metatarsal angle using a static sagittal plane radiograph, a dynamic height-to-length ratio using marker clusters with a multisegment foot model, and a contained angle using single point markers with a multisegment foot model. The objective of this study was to use biplane fluoroscopy to measure a contained MLA angle between foot types: pes planus (low arch), pes cavus (high arch), and normal arch. Fifteen participants completed the study, five from each foot type. Markerless fluoroscopic radiostereometric analysis (fRSA) was used with a three-dimensional model of the foot bones and manually matching those bones to a pair of two-dimensional radiographic images during midstance of gait. Statistically significant differences were found between barefoot arch angles of the normal and pes cavus foot types (p = 0.036), as well as between the pes cavus and pes planus foot types (p = 0.004). Dynamic walking also resulted in a statistically significant finding compared to the static standing trials (p = 0.014). These results support the classification of individuals following a physical assessment by a foot specialist for those with pes cavus and planus foot types. The differences between static and dynamic kinematic measurements were also supported using this novel method.

The use of a low cost 3D scanning and printing tool in the manufacture of custom-made foot orthoses: a preliminary study.

BACKGROUND: Custom foot orthoses are currently recognized as the gold standard for treatment of foot and lower limb pathology. While foam and plaster casting methods are most widely used in clinical practice, technology has emerged, permitting the use of 3D scanning, computer aided design (CAD) and computer aided manufacturing (CAM) for fabrication of foot molds and custom foot orthotic components. Adoption of 3D printing, as a form of CAM, requires further investigation for use as a clinical tool.This study provides a preliminary description of a new method to manufacture foot orthoses using a novel 3D scanner and printer and compare gait kinematic outputs from shod and traditional plaster casted orthotics. FINDINGS: One participant (male, 25 years) was included with no lower extremity injuries. Foot molds were created from both plaster casting and 3D scanning/printing methods. Custom foot orthoses were then fabricated from each mold. Lower body plug-in-gait with the Oxford Foot Model on the right foot was collected for both orthotic and control (shod) conditions. The medial longitudinal arch was measured using arch height index (AHI) where a decrease in AHI represented a drop in arch height. The lowest AHI was 21.2 mm in the running shoes, followed by 21.4 mm wearing the orthoses made using 3D scanning and printing, with the highest AHI of 22.0 mm while the participant wore the plaster casted orthoses. CONCLUSION: This preliminary study demonstrated a small increase in AHI with the 3D printing orthotic compared to the shod condition. A larger sample size may demonstrate significant patterns for the tested conditions.