The Effectiveness of Hard Insoles for Plantar Pressure in Cycling: A Crossover Study

BACKGROUND

Hard insoles have been proposed to decrease plantar pressure and prevent foot pain and paresthesia due to repetitive loading. The aim of this research was to analyze the effect of three different hard insoles in cycling on healthy subjects.

METHODS

A crossover randomized trial was carried out. The mean age of the subjects was 35 ± 3.19 years, and all of them were men. While the subjects were cycling on a stationary bicycle, their plantar pressure was recorded with nine in-shoe sensors placed in nine specific foot areas to test a standard ethylene-vinyl-acetate 52° Shore A hardness insole, a polypropylene 58° Shore D insole, and a polypropylene 58⁰ Shore D insole with selective aluminum 60 HB Brinell hardness in the metatarsal head and hallux.

RESULTS

The maximum plantar pressure decreased significantly with the polypropylene insole containing selective aluminum in the metatarsal head and hallux areas. The maximum plantar data of the polypropylene aluminum insole in the M2 area (5.56 kgF/cm²), fifth metatarsal styloid process (6.48 kgF/cm²), M3-M4 area (4.97 kgF/cm²), and hallux (8.91 kgF/cm²) were of particular interest compared to the other insoles.

CONCLUSIONS

The use of insoles made of polypropylene with aluminum in the metatarsal head and hallux areas decreases the maximum plantar pressure in cycling compared to standard EVA and polypropylene insoles.

Radiologic changes of long term foot insole use in symptomatic pediatric flatfoot

Clinically, flatfoot, known as pes planus, is quite prevalent. It is classified into 2 types: flexible and rigid, both of which may or may not have symptoms. If a flexible flatfoot is symptomatic, it must be treated to prevent subsequent complications. In principle, most physicians initially use conservative methods, such as foot insoles. This study aimed to demonstrate the effect of long term use of a foot insole using plain radiography as an objective measurement in children with symptomatic flexible flatfoot (SFFF) in large samples. This study analyzed the medical records of 292 children aged < 18 years who were diagnosed with SFFF. Of these, 200 children (62 boys and 138 girls, mean age: 6.49 ± 2.96 years) were selected and conservatively treated with foot insoles. They were periodically followed up within 3 to 4 months to modify the foot insole and perform radiologic evaluations, such as foot radiography. The calcaneal pitch angle (CPA) and talo first metatarsal angle were measured and compared individually using foot lateral radiographs, which were pictured in a bilateral barefoot state. The treatment was terminated by repeating the same procedure until the symptoms disappeared. A significant improvement (P < .001) was observed in the radiological indicators, both CPA and talo first metatarsal angle, regardless of age, after the application of soft foot insoles. However, the right foot CPA in the group with valgus deformity was an exception (P = .078). This study showed that in children diagnosed with SFFF under 18 years of age, wearing a periodically revised foot insole as conservative treatment could not only decrease the symptoms, but also improve the radiologic indices.

Evaluation of standing stability in individuals with flatfeet

OBJECTIVE

Flatfoot is one of the most common foot disorders, which not only influences the performance of the foot but also affects the alignments of the ankle, knee, and hip joints. The performance of the flat-arched individuals differs from that of normal individuals during walking. However, there is not enough information in the literature regarding their standing stability. Moreover, the influence of use of foot insole on standing stability has not been evaluated. Therefore, the aim of this study was to evaluate standing stability in individuals with flatfoot with and without insole.

METHODS

Two groups of normal and flat-arched individuals were recruited into this study. A Kistler force plate was used to measure the center of pressure (CoP), which is recognized as a good approximation of sway of center of gravity in a horizontal plane. Stability was determined by calculating the CoP excursions, path length, and velocity in the mediolateral and anteroposterior directions. The difference between stability in normal individuals and those with flatfoot was examined using the independent t test. The paired t test was used to determine the difference between stability in each group with and without insole. Significant P value was set at α ≤.05.

RESULTS

There was a significant difference between stability of flat-arched and normal individuals based on CoP velocity and total velocity. In addition, there was no direct correlation between the severity of flatfoot and instability during quiet standing. However, the mean values of CoP total velocity during standing with and without insole were significantly different (P < .001).

CONCLUSION

This study suggests that individuals with flatfoot are more unstable when compared with normal individuals during quiet standing. It seems that the foot insole improves the alignment of foot structure and reduces the forces applied on the ligament, thus, improving standing stability. Therefore, stability assessment in patients with flatfoot may be important, and the insole is a useful modality that can be used to improve stability in this patient group.

LEVELS OF EVIDENCE

Therapeutic, Level II: Prospective, comparative trial.