Ground reaction force complexity in hallux valgus.

BACKGROUND: Investigating the complexity of movement systems can be insightful in clinical decision making. The study conducted to evaluate whether complexity of ground reaction force is affected by hallux valgus grades and footwear or foot side conditions. METHODS: A sample of 120 females including 30 participants in each group of healthy and mild, moderate, and severe hallux valgus were recruited in this case-control study. Hallux valgus grades were assessed using Manchester scale. Ground reaction force were measured in bare foot and shod conditions for both feet and weighted permutation entropy was used to calculate the complexity. Nonparametric tests were employed for statistical inference. FINDINGS: The first important result was that hallux valgus caused loss of complexity of ground reaction force with a medium to large effect size. However, we did not find any difference between three grades of hallux valgus entropy. The second finding was that entropy of healthy group decreased from barefoot to shod condition with a large effect size and the third finding was that ground reaction force entropy were similar in both feet. INTERPRETATION: The findings are aligned with the theory that loss of complexity appears when the biological systems become functionally impaired. As soon as hallux valgus initiates, all potential risks related to the reduction of complexity appear. So, we suggest to administer conservative treatments in the early stages of hallux valgus. The study outcomes can be used for evaluation of foot function, classification of the foot types, or footwear selection.

Foot structural factors and ground reaction force in hallux valgus grades.

BACKGROUND: Little attention has been paid to foot structural factors and ground reaction force in hallux valgus. Investigating the structural factors in detail and determining their biomechanical effects can help to better manage hallux valgus. METHODS: In this case-control study, 120 females, 90 hallux valgus and 30 healthy, were recruited. Hallux valgus grades (mild, moderate, severe), first metatarsal mobility, foot pronation, hallux rotation, and pain were assessed by clinical tests. Ground reaction forces were measured in barefoot and shod conditions for both feet and analyzed using mixed within-between MANOVA. The association between structural factors and pain with force was analyzed using Spearman correlation coefficient. RESULTS: The frequency of foot structural factors and pain severity were reported in hallux valgus grades. A significant difference was seen in the force values between groups (P<0.001). Bonferroni post hoc test indicated that the mean of the first peak for the severe group was significantly higher than the mild group (P=0.013) and the mean of second peak for the moderate group was higher than that of the healthy group (P=0.009). The force values were affected by wearing shoe (P<0.001) but not by foot side (P=0.086). There was a medium, positive correlation between the hallux rotation and force in the moderate group (r=0.39, P=0.03) and also between the pronation and force in the severe group (r=0.36, P=0.04). CONCLUSION: Foot structural factors, pain, and force were different in each hallux valgus grads. Similar force in both feet, and increased force by wearing shoe were seen. The relationship between the pronation and hallux rotation with force revealed the importance of these factors from the biomechanical viewpoint.

A comparison of the hallux valgus angle, range of motion, and patient satisfaction after use of dynamic and static orthoses.

BACKGROUND: Conservative treatment is recommended for mild and moderate hallux valgus. The treatment may include two different types of orthoses: a dynamic orthosis and a static orthosis. The aim of this study was to compare the hallux valgus angle, hallux valgus range of motion, and patient satisfaction after the use of a dynamic and a static orthosis for the treatment of hallux valgus. METHODS: Twenty-four participants contributed to this cross-over study. Participants were randomly allocated to orthotic treatments at the start. The hallux valgus angle and range of motion were measured using a goniometer. Pain, signs and symptoms, function in activities of daily living (ADL), function in sport and recreation, and foot and ankle-related quality of life (QOL) were measured using the Foot and Ankle Outcome Score (FAOS) questionnaire. The participants then switched to using the other orthosis. A one-way repeated measure ANOVA was conducted to compare the measured variables in subjects at 4 conditions before and after of using each orthosis. RESULTS: There was a significant difference in the hallux valgus angle (p=0.001). The Bonferroni test indicated that both static and dynamic orthoses significantly decrease the angle of hallux valgus, respectively before static, after static (mean difference=-2.67, p=0.001) and before dynamic, after dynamic conditions (mean difference=-2.13, p=0.02). There was also a significant difference in subjects range of motion by using a dynamic orthosis in before dynamic, after dynamic conditions (mean difference=9.77, p=0.01). There was no significant difference in total FAOS score within the conditions (p=0.067). CONCLUSION: The use of both static and dynamic orthoses for 1 month can reduce the hallux valgus angle up to 2-3°. To achieve better results, it is suggested to wear orthoses for longer time. The dynamic orthosis also increases the passive range of motion of the first metatarsophalangeal joint and it seems to be effective during walking.

Comparison of plantar pressure distribution in CAD-CAM and prefabricated foot orthoses in patients with flexible flatfeet.

BACKGROUNDS: The effect of foot orthoses on plantar pressure distribution has been proven by researchers but there are some controversies about advantages of custom-made foot orthoses to less expensive prefabricated foot orthoses. METHODS: Nineteen flatfeet adults between 18 and 45 participated in this study. CAD-CAM foot orthoses were made for these patients according to their foot scan. Prefabricated foot orthoses were prepared according to their foot size. Plantar pressure, force and contact area were measured using pedar®-x in-shoe system wearing shoe alone, wearing CAD-CAM foot orthoses and wearing prefabricated foot orthoses. Repeated measures ANOVA model with post-hoc, Bonferroni comparison were used to test differences. RESULTS: CAD-CAM and prefabricated foot orthoses both decreased pressure and force under 2nd, 3-5 metatarsal and heel regions comparing to shoe alone condition. CAD-CAM foot orthosis increased pressure under lateral toe region in comparison to shoe alone and prefabricated foot orthosis. Both foot orthoses increased pressure and contact area in medial midfoot region comparing to shoe alone condition. Increased forces were seen at hallux and lateral toes by prefabricated foot orthoses in comparison with CAD-CAM foot orthoses and control condition, respectively. CONCLUSION: According to the results, both foot orthoses could decrease the pressure under heel and metatarsal area. It seems that the special design of CAD-CAM foot orthoses could not make great differences in plantar pressure distribution in this sample. Further research is required to determine whether these results are associated with different scan systems or design software.

Effects of unstable footwear on gait characteristic: A systematic review.

BACKGROUND: Over the last three decades, several designs of unstable footwear have been developed in the forms of shoes, sandals and boots. There are marketing claims related to the positive effects of these shoes on the training of lower limb muscles and improving gait. Many studies have been performed on the effects of unstable footwear on muscle activity, balance, posture, energy expenditure, lower extremity disorders, and biomechanical changes. The analysis of the kinetics and kinematics characteristics of gait would provide objective representation of body movement. OBJECTIVE: To systematically review available evidence on the use of unstable footwear on kinetic and kinematic parameters to make specific recommendation for practice and future studies. METHOD: A computer-based search was undertaken through PubMed, Cochrane Library, Embase, PEDro, Web of Science and Google Scholar from 2005 to 2015. The included studies were appraised using McMaster Critical Review Form for Quantitative Studies. RESULT: Ten studies (quasi-experimental design) were included. CONCLUSION: Considering kinetic and kinematic interaction of variables in the included studies revealed that confounding factors may have high impact on biomechanical findings of unstable footwear. Then, more homogeneous studies, considering these factors, should be implemented in future studies to inform the best clinical practice.

Effect of medial arch support foot orthosis on plantar pressure distribution in females with mild-to-moderate hallux valgus after one month of follow-up.

BACKGROUND: Higher plantar pressures at the medial forefoot are reported in hallux valgus. Foot orthoses with medial arch support are considered as an intervention in this pathology. However, little is known about the effect of foot orthoses on plantar pressure distribution in hallux valgus. OBJECTIVES: To investigate the effect of a foot orthosis with medial arch support on pressure distribution in females with mild-to-moderate hallux valgus. STUDY DESIGN: Quasi-experimental. METHODS: Sixteen female volunteers with mild-to-moderate hallux valgus participated in this study and used a medial arch support foot orthosis for 4 weeks. Plantar pressure for each participant was assessed using the Pedar-X(®) in-shoe system in four conditions including shoe-only and foot orthosis before and after the intervention. RESULTS: The use of the foot orthosis for 1 month led to a decrease in peak pressure and maximum force under the hallux, first metatarsal, and metatarsals 3-5 (p < 0.05). In the medial midfoot region, peak pressure, maximum force, and contact area were significantly higher with the foot orthosis than shoe-only before and after the intervention (p = 0.00). CONCLUSION: A foot orthosis with medial arch support could reduce pressure beneath the hallux and the first metatarsal head by transferring the load to the other regions. It would appear that this type of foot orthosis can be an effective method of intervention in this pathology. CLINICAL RELEVANCE: Findings of this study will improve the clinical knowledge about the effect of the medial arch support foot orthosis used on plantar pressure distribution in hallux valgus pathology.