Introduction
Plantar fasciitis is defined as inflammation or destructive changes in the plantar fascia. Pain and stiffness in the soles of the feet are often a common symptom of the disease, which is often felt when standing after a long period of sitting or sleeping. This complication has a negative effect on foot function and limits a person’s daily activities [1, 2]. In general, 10% -15% of people in the world suffer from plantar fasciitis [1, 2].
Surgical and non-surgical treatments are available for this complication which among non-surgical interventions, orthotic (protective) treatments are widely used to treat plantar fasciitis [3]. Among orthotic treatments, custom-made insoles and prefabricated insoles are significantly prescribed in the treatment of plantar fasciitis [4]. Both custom-made and prefabricated insoles are effective in reducing pain and increasing patient function, but there are conflicting studies about the superiority of custom-made insoles and prefabricated insoles [5].
In these studies, the effect of custom insole with Computer-aided Design-Computer-aided Manufacturing (CAD-CAM) device in the treatment of patients with plantar fasciitis was not investigated [6]. In a review study, it was shown that computer insole fabrication is a valid method that can be used in the field of medical insole fabrication to achieve the best fit between the insole and the patient’s foot [7]. Custom-made medical insole is a factor that is directly related to the proper placement of the insole in the sole of the foot and is associated with reducing the amount of damage to the sole of the foot [8]. The main purpose of using this type of medical insole is to change the pressure distribution of the sole of the foot from a specific point to a wider surface [9, 10]. 
Insoles made by CAD-CAM method reduce the force applied to high pressure areas through full contact with increasing the level and it was shown during the studies that the mentioned insole reduced the pressure of high-risk points for diabetic wounds [11]. Recent studies have also shown that computer-made insoles reduce pain in people with flat feet [12]. Another study that examined the effect of custom-made insoles made by CAD-CAM method in people with pes cavus foot, the use of this insole was said to reduce the pain of these people due to the proportional distribution of pressure and force distribution from the heel [13].
Considering the reviewed studies and the significant prevalence of plantar fasciitis and its negative impact on patient performance and activity and due to the fact that in these studies, the effect of the insole made by CAD-CAM method in people with plantar fasciitis has not been studied and Reports of other complications, such as diabetes and flat feet, suggest that custom-made insoles distribute pressure evenly across high-risk areas, therefore, in this study, we reviewed and compared the custom insole made by computer method with the prefabricated insole [14].
Materials and Methods
This quasi-experimental study was performed in 2018 in the medical centers of Tehran University of Social Welfare and Rehabilitation Sciences on 14 patients with plantar fasciitis (five women and nine men) with an average age of 40 years. The inclusion criteria of the research were being aged 25-45 years, diagnosis of plantar fasciitis by an orthopedist, existence of flexible flatfoot complication, no neurological disorders or any pathology in the foot such as diabetes and osteoarthritis and lack of surgery on the lower limb joints in the past month and the ability to walk independently without an aid [11, 15-18]. Exclusion criteria were people with a history of surgery on the plantar fasciitis and patients were also excluded from the study if insoles were not used during the study and if they were professional athletes [18].

The tool used to measure the variables of symptoms, pain, daily activities, sports and recreational activities and quality of life before and after the test was the Foot and Ankle Outcome Score (FAOS) questionnaire. The scoring of this questionnaire was from 0 to 100, which 0 refers to the worst situation and 100 refers to the best situation.
After the diagnosis of plantar fasciitis by an orthopedist and the evaluation of the patient by an orthopedist and prosthetist based on the reported history (for example, the first step is accompanied by pain in the leg area), clinical tests (such as local pain when touched in the anterior-internal part of the heel tuberosity) or pain during plantar fasciitis of patients if they meet the inclusion criteria to enter the study, 14 patients were assigned by non-probability simple (available) method and were randomly divided into two groups of 7 using custom insole with CAD-CAM device and using conventional (prefabricated) insole group. Patients were initially given a FAOS questionnaire to determine their pain, symptoms, daily activities, sports and recreational activities, and quality of life before using the insole. Then, in both groups, the necessary measurements were performed on each person’s foot. The map of each person’s foot was taken in equal weight bearing condition on both feet and the patients were scanned by EMED Foot Pressure scanner [19].

In the group of patients selected to make custom insoles for by CAD-CAM method, after taking a compression scan of the patient’s foot, the compression scan information of each patient was evaluated separately. Then, based on the scan report in these patients, a custom-made insole was designed for each patient separately using Rhinoceros computer software by the therapist. In the next step, the data obtained from the design in the form of a set of codes called G-code, was given to the CNC (Computer Numerical Control) machine made by Paya-Fanavaran Company and as can be seen in Figure 1, the medical insole was shaved on a foam block made of ethyl vinyl acetate with 50% saline. The height of the longitudinal-internal arch in the custom-made insole was considered to be 15 mm [20]. The length of the medial longitudinal arch was also calculated based on the size of the patient’s foot from the talus to the first metatarsus [21]. The width and length of the metatarsal pad were also based on a study by Hastings et al. [10] and based on the foot size of each patient, the length of the metatarsal pads were chosen to be between 65-75 mm and their width were between 63-51 mm and their height were between 9-11 mm and they were made based on these dimensions [22]. 
In the second group, conventional insoles were prepared based on the measurement of each person’s foot. The mentioned prefabricated insole is made of polyurethane and has a longitudinal-inner arch and metatarsal pad (Figure 2). Patients in both groups were then asked to put insoles inside their shoes. To avoid discrepancies in shoes, patients were asked to provide shoes with laces and appropriate size that have a suitable space in the front of the foot and after the patients’ shoes were approved by the therapist, both groups of patients were told to use insoles for 7-10 hours every day while working and walking outdoors for 6 weeks. At the end of the treatment period, the patients were given the questionnaire again to re-report the studied variables. Then, we calculated the score related to each of the sub-scales of the questionnaire according to its formula in the questionnaire guide, before using the insole and after using the insole for each individual.
The final scores of both groups at the time before the study and also 6 weeks after the study, which were obtained from the questionnaires completed by individuals, were entered into SPSS software V. 22. After calculating the mean scattering indices and standard deviation and measuring the normality of the data using Shapiro–Wilk, Mann-Whitney U and Wilcoxon tests were used to evaluate the data.
Results
The study was performed on 14 patients with plantar fasciitis who referred to the clinic that half of them were studied by conventional insole and the other half by custom insole made using CAD-CAM device. The Mean±SD age of patients in the custom-made insole group was 40.14±5.98 years and the Mean±SD of patients in the conventional insole group was 37.86±5.58 years. The Mean±SD of BMI of patients in the custom-made insole group was 26.07±1.76 and the Mean±SD of BMI of patients in the conventional insole group was 27.04±2.46.
First, the 5 main factors of FAOS questionnaire including pain, symptoms, daily activities, sports and recreational activities, and quality of life in patients with plantar fasciitis were evaluated separately in both types of insole groups and finally, we compared all the factors between the two insole groups. The scoring of FAOS questionnaire factors was such that the higher the score, the more desirable and the lower, the more undesirable.
According to Table 1, which is the result of Wilcoxon statistical test, it can be seen that the rate of improvement of pain, symptoms, daily activities, sports and recreational activities, and quality of life before and after 6 weeks of using custom-made insoles was significant.
According to Table 2, which is the result of Wilcoxon statistical test, it can be seen that the rate of improvement of pain, symptoms, daily activities, sports and recreational activities and quality of life before and after 6 weeks of using the conventional insole is significant.
According to the result of Mann-Whitney test in Table 3, we see that in the rate of improvement of pain, symptoms, daily activities, sports and recreational activities and quality of life after 6 weeks of using both types of custom insoles using CAD-CAM and conventional insoles, no significant differences were shown.

Discussion
The results of the present study were in line with the study of Bonanno et al. [23]. They stated that the prefabricated insole distributes the force evenly over a wider area due to full contact with the patient’s sole [24]. Full-length insoles with longitudinal-internal arch reduce these forces further by reducing the vertical forces on the heel and due to the wider surface, they create, and as a result, the pain in this area is reduced [25].
Our study was in line with the study of Michelle Drake [26]. The author stated in this study that custom insoles reduced tensile stress in plantar fascia due to sufficient longitudinal-internal arch height [27, 28] and as a result, pain and disability were significantly reduced [26].
The result of the present study was in line with the result of Burns study [13]. In the Burns study, a significant improvement in pain was reported in a group of patients with pes cavus. The orthosis used in this study was a custom insole using the CAD-CAM system [13], insoles made with CAD-CAM system distributed pressure peak and maximum force distribution from the heel to the inner part of the midfoot area and were used to reduce the maximum pressure concentration at a specific point [14]. Because the sole of the foot is the heel and the removal of pressure from this area helps to improve pain and increase the function of patients with the sole of the foot, it is likely that the custom insole made by our study also distributes the maximum pressure from the heel.
The reduction of pain observed after using both insoles in the present study may also be due to the support of the longitudinal-internal arch of the foot by the insole, including the heel area and also the support of the transverse arch of the foot by the metatarsal pad. According to a Burns study in 2005, these three factors also caused a proportional distribution of plantar pressure and reduced load applied to the heel area, followed by pain in this area [29].
The result of the present study was inconsistent with the study of Pfeffer Glenn; in Glenn’s study, the silicone heel as a prefabricated insole caused more pain in the heel area than the custom insole made in this study, which was made of polypropylene [30]. The author stated that if the custom-made insole used more shock-absorbing material, it might have worked better than the propylene insole to reduce pain [31]. In the study, the author considered the use of soft and shock-absorbing materials as the reason for the superiority of silicone heels and stated that the propylene used is a hard material. Of course, the custom insole made in our study was made of EVA and had less shore than polypropylene (shore=70) [32].
In the field of daily activities and sports and recreational activities of patients with plantar fasciitis, the custom insole made the study by Oliveira et al. more comfortable because it matched the patient’s foot and due to the use of soft foam in the heel area, it was more comfortable for this part [6]. Based on the results obtained in this study, the insole reduced the forces applied to the heel and subsequently reduced the pain and improved performance [26]; we can say that a person’s activity increases due to the reduction of heel pain. Also, the insole we studied improves the performance and thus increases the activity of the person for the same reasons as the study of Oliveira.
In a study by Roos et al., A custom insole was reported to be a better choice in the treatment of plantar fasciitis and was able to increase the level of performance of people with plantar fasciitis compared to nocturnal splints [4]. In a study by Drake Michelle et al., using a custom insole for 2 weeks improved the performance and ability of patients with plantar fasciitis [26]. In a study by Drake Michelle et al., using a custom insole for 2 weeks improved the performance and ability of patients with plantar fasciitis and it was reported that using the insole with daily stretching improved its effects. In a study by Burns et al., Custom-made orthoses were able to increase the level of performance of people with pes cavus [13]. Novak et al. Also concluded that functional orthoses compared to flat insoles (without arch) had a significant effect on increasing the function of patients with rheumatoid arthritis [33].
The results of the present study were consistent with the studies mentioned above. In the prefabricated insole of the present study, due to the presence of the longitudinal-internal arch and the inclusion of the entire surface of the foot, it causes the distribution of force on a larger surface, followed by removal of pressure from the heel area (which is the source of the sole). In addition to all the items mentioned in the prefabricated insole, the softer foam in the substrate can be mentioned in the custom insole made by the patients in this case, which creates a better fit.
Regarding the quality of life of plantar fasciitis patients, Ross et al. measured the effect of insoles and night splints in people with plantar fasciitis and in both groups, an improvement in quality of life was observed [4]. In the Burns study, orthoses improved the quality of life of people with pes cavus and there was a significant difference in the quality of life variable between the group that used orthoses and the control group [13]. In his study, Burns compared a study group that had a custom insole made using the CAD-CAM system with another group that did not have an insole (a simple placebo insole) and therefore, it can be said that it is similar to the present study and their results are in one direction.
Conclusion
Both insoles were effective in improving all subscales of the FAOS questionnaire (pain, symptoms, daily activities, sports and leisure activities, and quality of life) after use for six weeks, but comparing the two insoles numerically, despite The custom insole showed more improvement using the CAD-CAM device than the conventional insole in most subscales, but there was no statistically significant difference between the two insoles and both insoles improved foot and ankle outcomes. Therefore, due to the lack of significant differences between the two types of insoles and their effectiveness in improving the variables mentioned in the treatment of patients, this study suggests the use of both types of insoles in medical centers.
Ethical Considerations
Compliance with ethical guidelines
This study was approved by the University of Social Welfare and Rehabilitation Sciences Medical Center. The principles are considered in this article. The participants were informed about the purpose of the research and its implementation stages; they were also assured about the confidentiality of their information; moreover, they were free to leave the study whenever they wished, and if desired, the research results would be available to them.
Funding
The present paper was extracted from the MSc. thesis of the first author, Department of Orthotics and Prosthetics, School of Rehabilitation Sciences, University of Social Welfare and Rehabilitation Sciences.
Authors' contributions
All authors contributed in preparing this article.
Conflicts of interest
The authors declared no conflict of interest.