Sage Journals: Discover world-class research

Abstract

In this study, we developed and assessed band-embedded laterally wedged insoles designed to correct genu varum, a condition characterized by outwardly bent knees. The product was specifically developed to improve usability and wearability in both indoor and outdoor conditions, addressing the key limitations of existing correction products. The wedged insoles were integrated so the band could promote proper alignment by redistributing the body weight toward the medial side of the legs, thereby reducing knee strain. Through detailed testing, the band demonstrated an average reduction of 14.76% in the gap between the knees, indicating significant corrective efficacy. Among the three developed designs, the hooks-and-loop-based band appeared to be the most effective, achieving a 15.94% reduction in the gap between the knees and receiving the highest scores in user satisfaction regarding design, functionality, comfort, and ease of use. The use of breathable lightweight materials and a design that accommodates both barefoot and shod conditions ensures long-term comfort and practicality. This product provides a practical, versatile, and user-friendly solution for genu varum correction and a foundation for further advancements in corrective orthopedic design.

Keywords

Genu varum wedged insole band design long-term wearability knee gap reduction

Introduction

Genu varum is defined as a leg with knees that are not attached and bent outward, also known as an “O-shaped leg.” Previous studies have reported a 2.53%–16.33% global prevalence of genu varum, depending on the population group.^1,2 Furthermore, studies have revealed a 15%–20% prevalence of genu varum among the total population.^3,4 Vitamin D deficiency, resulting in rickets, osteochondrosis dissecans, and endocrine abnormalities, can cause genu varum. However, weakness of the muscles that support the knee, caused by poor lifestyle habits, poor posture, lower limb muscle weakness, and decreased bone density, is the primary cause of genu varum.^5,6 The presence of genu varum in the legs causes a range of musculoskeletal disorders and degenerative arthritis that affect the pelvis, lower back, and spine. Moreover, it contributes to irregular shoe heel wear, which is a significant concern because that causes severe pain and gait disorders over time.^5,7

Reportedly, women are ten times more prone to genu varum than men, primarily due to the prolonged use of high heels or other uncomfortable footwear, as well as the reduction in bone density that predominantly accompanies childbirth or menopause.^6,8

The number of patients who develop genu varum-related problems is constantly increasing, whereas research on genu varum correction products is limited.^4,7 Long-term use of corrective products is a crucial factor for genu varum correction; however, no existing product can be worn consistently for long periods, with or without shoes.

This study aimed to develop a product that can be worn both outdoors and indoors, regardless of whether the individual is wearing shoes. This study also aimed to verify the potential corrective effect using a band-design-centered approach. The product uses wedged insoles to correct genu varum. The results of this study will help a significant number of individuals with genu varum problems requiring a new correction product and is intended to contribute to the development of a body of relevant research data.

Literature review

Status and features of products for genu varum correction

With the increased demand for products designed to correct genu varum, an analysis of existing products has revealed their classification into three distinct categories, as illustrated in Table 1. The insole type, which is the most prevalent genu varum correction product, involves fabrication of an insole with greater height on the exterior than on the interior of the foot. These insoles, known as wedged insoles, help redistribute body weight from the outer to the inner portion of the foot in individuals with genu varum. The use of wedged insoles promotes an optimal gait by directing forces toward the medial side of the foot and leg.^9–12 When utilized in conjunction with footwear, these insoles mitigate the degree of wear and tear on the exterior soles of the shoes. A notable benefit of these insoles is their adaptability, which enables their use in diverse types of footwear. However, these insoles are limited by their incompatibility with indoor environments because the corrective effect is only achieved when wearing the shoe.

Table 1.

Overview of products for correcting genu varum.

Type	Advantages	Disadvantages	Reference
Insole type	- Prevents wear and tear on shoe insoles - Can be used with various shoes through a single product	- Corrective effects are only achieved when wearing shoes	21
Insole type	- Helps correct both genu varum (bowlegged) and genu valgum (knock–kneed) conditions	- Corrective effects are only achieved when wearing shoes	22
Leg band type	- Applies strong force to straighten legs by tightening them directly with a belt	- Poor usability due to restricted leg movement	13,14
Leg band type	- Increases belt pressure through a manual air pump, providing a strong straightening effect	- Poor usability due to restricted leg movement	23
Shoe type	- Features a 30-degree angle in the shoe design, helping to promote leg alignment - Improves effectiveness through exercise while wearing	- Limited to indoor use - Features an arch-supporting design with a focus on potentially preventing plantar fasciitis	16
Shoe type	- Designed with a higher outer side than the inner side, helping in shifting body weight inward	- Lacks a heel, making it suitable for indoor use only	15

Second is the leg-band product, which functions by directly extending the leg; this is caused by the tightness of the band that binds the entire leg. However, concerns have been raised about restricted leg movements and reduced usability and comfort owing to strong compression. Furthermore, this product can cause skin pressure based on the fabric used, and lack of ventilation is also an issue, making their use in people with sensitive skin difficult.^13,14

Third is when the shoe design incorporates a C-curve slipper type that does not fully contact the ground. It features a 30-degree angle interior that aims to correct genu varum by bringing the leg inward.^15,16 A notable benefit of this product is its compatibility with exercise regimens, which augments the efficacy of the corrective effect. However, without incorporating footlifting exercises, the design can only elevate the arch of the foot. Consequently, the product primarily functions to prevent plantar fasciitis rather than correct genu varum.

A review of currently marketed products indicates that genu varum correction products must be designed considering the wearer’s perspective. Lateral wedged insoles, in which the lateral side is higher than the medial side, are proven to reduce medial knee loading.^12,17,18 These insoles are affordable and easily accessible treatments for genu varum. Further, lateral wedged insoles have been efficacious in reducing pain in patients with medial compartment knee osteoarthritis.¹⁹ These insoles are recommended in 13 out of 14 international guidelines for knee osteoarthritis.²⁰

Consequently, this study aimed to contribute to the development of genu varum correction products by presenting a design that applies the effective height difference principle of wedged insole-type designs. This design addresses the limitations of existing products that can only be worn outdoors or indoors and improves their wearability.

Comparative study on the design of insoles and foot support bands

To develop a genu varum correction product that can be worn both indoors and outdoors by addressing the limitations of existing products, various types of insoles and foot supports with poor designs were investigated and analyzed. Table 2 lists the designs categorized into three types.

Table 2.

Analysis of related product designs.

Type	Design features	Purpose	Material	Reference
Socks type	- Suitable for both indoor and outdoor use Covers the heel and instep of the foot - Perforated for breathability - Not intended for genu varum correction	−2.5 cm height increase	- Silicone, unsuitable for sweaty feet	25
Socks type		−1.5–4.5 cm height increase, with arch support - Cushioning and bone protection effects due to heel pad	- Silicone and memory foam, unsuitable for sweaty feet	24
Foot support band type (fixing and support)	- Suitable for both indoor and outdoor use - Worn by wrapping over the instep of the foot - Not intended for genu varum correction	- Fixing and supporting the ball of the foot and instep	Thin nylon material	27
Foot support band type (fixing and support)		- Helps alleviate forefoot pain including metatarsalgia and Morton’s neuroma - Shock-absorbing cushioning effect	Elastic nylon, rubber threads, and gel cushion	26
Foot support band type (arch correction)	- Suitable for both indoor and outdoor use - Combines elastic bands and teardrop-shaped cushions - Not intended for genu varum correction	- For arch correction	Highly elastic bands, which may cause circulation issues	28
Foot support band type (arch correction)		- Provides arch correction and support - Alleviates flatfoot pain	Cushion covered with towel fabric, which is prone to abrasion along with shrinkage and deformation after washing	29

First, sock-type insoles are products made of silicone material, worn in socks to elevate height even indoors without shoes, and can be worn both indoors and outdoors.^24,25 All these designs are perforated for breathability; however, the thick silicone material makes them unsuitable for prolonged wear on sweaty feet.

Second, the foot support for fixing and the support band, which is made of nylon material, is a compression band designed to immobilize and support the ball of the foot and instep and provide stability to the foot to facilitate walking and movement.^26,27

Third, the foot support for the arch correction band, with a design that combines a stretchy elastic band with a drop-shaped cushion, supports the arch of the foot.^28,29 This design helps reduce foot fatigue during walking by supporting collapsed arches with cushioning. It uses a highly elastic band for better skin contact; however, overly elastic bands may impede circulation in the foot. Furthermore, the cushioning is wrapped in toweling fabric, which is easily damaged by friction between the foot and shoe or between the sock and shoe.

Based on related product design analysis results, this study designed a band that wraps around the insole with a soft fabric material that can be worn both indoors and outdoors. The band was designed to insert wedged insoles into fabric. In the present study, we developed a new product for genu varum correction.

Evaluation methods for improvement effects

Improvements in genu varum are evaluated using several methods. The three most common methods used in many studies are as follows. The first method involves the measurements of the gap between the knees.^5,7,30 The Global Postural System (GPS) device, which is a postural alignment analyzer, was used to assess the gap between the knees before and after elastic band exercise in participants with a 5–7 cm gap between the knees among women in their 20s and 30s⁷ Changes in the gap between the knees were measured through stretching and corrective exercises using bands.⁵ In this study, the gap between the knees was measured on a measuring board with graduated markings without equipment. A ruler, measuring board, and GPS were used to measure the gap between the most protruding parts of the patella.³⁰

The second method involves the assessment through interosseous angulation.^5,31,32 The intertrochanteric angle was measured in pediatric patients with rickets to evaluate its usefulness in diagnosing rickets.³¹ The genu varum effect was measured after radiography of the hip joint angle, the Q-angle, and the intertrochanteric angle.⁵ The hip joint angle is the angle between the femoral neck and the femur. The normal angle is 125°, and less than this angle is diagnosed as genu varum, whereas greater than this angle is diagnosed as genu valgum.⁵ The Q-angle is the angle formed by the line connecting the center of the patella and the anterior superior iliac spine and the line connecting the center of the patella in the tibial plane.⁵ The magnitude of the Q-angle varies depending on sex, as women (15°–23°) generally have a wider pelvis than men (10°–13°).³³ In genu varum, the Q-angle is reduced, which places unstable loads and forces on the joint, causing wear on the medial aspect of the knee.³⁴ The effectiveness of genu varum correction before and after training was compared by measuring the Q-angle using a tape measure and protractor.³²

The third method involves the measurement of the pressure distribution in the foot using plantar pressure measurement systems.^7,35,36 The plantar pressure characteristics of women in their 20s and 30s with genu varum were compared with those of the general population, revealing differences between the two groups.³⁵ A plantar pressure test was conducted to assess lower extremity imbalance caused by pronation in women with genu varum.⁷ Additionally, if the Q-angle is smaller than normal, there is increased pressure on the lateral plantar aspect of the foot, which causes varus of the foot and further elevates the pressure in this region.^36,37

Moreover, although not as much as the three methods, a study measured the effectiveness of genu varum improvement using electromyography (EMG), experimented with lateral insoles, and revealed no significant difference.³⁸ Other methods included measuring the cartilage volume, adduction moment of the knee joint, and body weight, as well as assessment of pain reduction through questionnaires. The difference between normal leg alignment and genu varum is illustrated in Figure 1.

Figure 1.

(a) Comparison of the gap between the knees in normal legs and genu varum. (b) Comparison of Q-angles between normal legs and genu varum (Left: normal alignment, right: genu varum).

Methods

After obtaining institutional review board approval (no. 7001988-202402-HR-2184-03), this study was conducted to assess the effectiveness of the developed genu varum correction band by measuring and comparing the gap between the knees. A satisfaction survey was conducted to evaluate the comfort and ease of use of the bands.

This study sought to evaluate the genu varum correction effect through a band design that prioritizes wearability and usability. All three insoles used in this study incorporated a 10° lateral wedge design, distinguished based on their band attachment methods (hook-and-loop, zipper, and elastic band). Furthermore, each insole was constructed using a stretch PU combined with velvet, providing a soft yet stable fit for optimal corrective function. The insole was manufactured from open-cell polyurethane foam (density 0.16 g cm^-3; hardness 35 ± 2 Asker C ≈ Shore A 30 ± 2, ASTM D2240; compression set < 5 %, ASTM D3574). A 0.05 mm velvet textile layer was thermally laminated to the foam surface to enhance tactile comfort and wear resistance. When placed on a flat surface, the lateral thickness of the insole is approximately 13 mm, whereas its medial thickness is approximately 5 mm, creating a 10° lateral wedge angle. In this study, the fabric selected for the band was tested for air permeability, elastic recovery, and abrasion resistance according to international standards (Table 4). These properties are essential for reducing the discomfort caused by perspiration and friction during prolonged wear and for ensuring durability.

The stage of genu varum is identified based on the gap between the knees: stage 1 (≤2.5 cm), which does not require treatment; stage 2 (2.5–5 cm), which requires exercise and bracing; and stages 3 (5–7.5 cm) and 4 (>7.5 cm), which require surgery as needed.⁵ The gap between the knees is the distance between the knees while standing foot with the feet together at the medial malleolus of the ankles.

This study included seven women in their 20s and 30s, all with genu varum stage 2 (2.5 cm), with an average foot size of 241 mm; they did not have severe genu varum, but wanted correction (Table 3). This number exceeded the standard of 2–3 female participants with genu varum in previous studies.³² The foot arch length of the participants was approximately 74 mm, which accounted for 30% of the total foot length. Therefore, in this study, insoles were designed and modified to match the arch length to approximately 80 mm, which was deemed sufficient to correct the condition.

Table 3.

Demographic and anthropometric characteristics of participants.

Characteristic	Value
Total participants	7
Mean age (range)	25.4 years (22–38 years)
Mean body mass index (range)	18.6 kg/m² (16.4–21.6 kg/m²)
Mean gap between the knees (range)	3.61 cm (2.8 –4.8 cm)
Proportion in genu varum stage 2 (2.5-5 cm)	100%

All participants were women living in South Korea. The testing room temperature was 23 ± 2°C, and the relative humidity was 45 ± 5%. The mean age of the participants was 25.4 years (range: 22–38 years) with a mean body mass index of 18.6 kg/m², which is within the normal weight range. For this study, women in their 20s and 30s were selected based on previous research showing that patients with medial knee osteoarthritis who were younger and weighed less were more likely to be satisfied with treatment with lateral wedge insoles.^39,40 Participants were recruited by posting an announcement on an offline bulletin board at a university and snowball sampling through personal networks. Women aged 20–30 years with stage 2 genu varum were included in the study.

To participate in the experiment, the participants’ gap between the knees (cm) was first measured while wearing socks before wearing the band. The participants checked the design of the band and wore it themselves to determine the performance of genu varum correction and their satisfaction with its use. The band was worn while wearing socks, and the participants took approximately 20 in-place steps, followed by a 3-m indoor flat walk.⁴¹ The participants’ gaps between the knees were measured again after in-place steps and indoor walking. The participants were then instructed to wear the shoes while still wearing the socks and bands. The same 20 in-place steps were performed with shoes on, followed by a 3-m indoor flat walk.

This process aimed to verify whether the participants could comfortably wear the band outdoors while wearing shoes, and the gap between their knees was measured again while wearing shoes. The participants repeated this process for all three designs, and the three band designs were assessed.

The experiment involved measuring the knee joint spacing (cm) before and after wearing the band.³⁶ The researchers directly measured the gap between the knees before and after wearing the band using a ruler. The gap measurement method and the overall experimental protocol are illustrated in Figure 2.

Figure 2.

(a) Measurement of the gap between the knees. (b) Experimental protocol.

A questionnaire was then administered to evaluate user satisfaction, which included 12 questions on design,^42,43 4 questions on function,^43–45 6 questions on comfort,^45,46 6 questions on safety,^42,45,47 6 items on perceived usability,⁴⁸ 4 items on perceived usefulness,⁴⁸ 3 items on purchase and usage intention,^43,45,48 10 items on demographic background, and two open-ended items on recommendations.

Participants were instructed to respond using a 7-point Likert scale (1 = strongly disagree, 7 = strongly agree). To measure the effectiveness of the program using the data obtained, descriptive analysis was conducted using Excel to obtain the mean, standard deviation, and percentage, and the analysis of variance was applied using the Statistical Package for the Social Sciences version 27.0.

Results and discussion

Developed design

This study developed a genu varum correction band combined with a wedged insole for genu varum correction. This design aimed to prevent the progression of genu varum in women with genu varum problems by allowing them to walk on the medial side of their feet and legs using the product. The principle was to use a wedged insole that was 10° higher on the outside than on the inside of the shoe to shift the weight of the body, including the feet, to the inside of the body.⁴⁹

Three band designs were developed that varied in terms of band attachment, band tightening, and insole removal methods. Hence, each band differs in terms of comfort, usability, washability, and durability. All three designs can be worn indoors and outdoors, with or without shoes, over the long term. The layered structure and versatile usage scenarios are illustrated in Figure 3.

Figure 3.

(a) Layered structure of the developed band. (b) Side view of the developed band in use (suitable for barefoot, socked, and shod conditions).

Design 1 is an oval shape with an E-band attached to an X-shaped cross to securely wrap the foot. The E-band used in this study is an elastic band with high elasticity and recovery properties. This material was selected because the e-band is elastic and can be stretched to fit various foot sizes while holding the foot firmly in place. Furthermore, the band is connected to the back to increase durability, and a double-row wrapping method was employed to increase friction with the ground to provide anti-slip protection without attaching a separate antislip fabric. Furthermore, this improves the durability by increasing the strength of the e-band and fabric. An opening is added to the center of the back for easy placement and removal of the insoles. This feature makes the bands washable for long-term hygiene use.

Design 2 has a long rectangular shape with rounded corners that can be easily adjusted to fit a wide range of foot widths and instep heights using a tri-glide buckle. Furthermore, the insole is placed at the bottom of the band, and a zipper is added to prevent the insole from separating during walking and to facilitate insole removal. The same fabric and e-band are utilized as in design 1.

Design 3 is a long rectangular shape with angled corners and can be adjusted to fit individual foot sizes by attaching hooks and loops to the bottom of the e-band. Similar to design 2, the insole is placed at the bottom of the band, and hooks and loops are used to prevent the insole from detaching and to easily put on and take off the insole. Design 3 uses the same fabric and e-band as design 1.

The crucial consideration in designing a genu varum correction product is its comfort when worn on the foot, which moves and sweats significantly, with the ability to be worn both indoors and with shoes for the product to be effective over a long period.

Therefore, a breathable and flexible fabric has been employed at the foot-contact interface to maintain comfort during extended periods of use. The detailed testing methods for this fabric are summarized in Table 4, and the material was selected to ensure the long-term usability of the corrective band and insole. The material selected for the foot-contact fabric was a blend of polyester and spandex with a high air permeability of 613 mm/s (ISO 9237:1995) and a soft texture (Table 5). The material is lightweight, breathable, suitable for sweaty feet, and has good tensile, burst, and abrasion strengths, confirming its suitability for long-term use. This helps reduce the build-up of perspiration and enhances long-term wear comfort, which are essential for maintaining a dry and comfortable foot environment and reducing the risk of foot diseases such as tinea pedis.^50,51 In addition, improved breathability helps minimize sweat accumulation, overheating, foot odor, and even the formation of blisters during prolonged wear.⁵² This finding aligns with previous research that reported improved foot comfort when breathable materials were used.^53,54 The Martindale abrasion test was conducted on the band fabric, and no holes appeared even after 500 abrasion cycles, indicating that the material possesses sufficient durability for repeated use in everyday corrective products.

Table 4.

Test analysis of fabrics used.

#	Test Item	Unit	Standard
1	Tensile strength	N	ISO 13934-2:2014 Grab method
2	Tensile elongation	%	ISO 13934-2:2014 Grab method, CRE TYPE Tensile tester
3	Elastic recovery	%	ASTM D 2594-2004 (2016)
4	Blend ratio	%	ISO 1833-2:2020
5	Bursting strength	kPa	ISO 13938-1:2019 Diaphragm method
6	Abrasion resistance	RUBS	ISO 12947-2:2016 Martindale method
7	Air permeability	mm/s	ISO 9237:1995

Table 5.

Performance evaluation results of materials.

Cate-gory	Fab-ric weig-ht	Tens-ile stre-ngth (N)	Tens-ile elon-gat-ion (%)	Elastic recovery (%)					Blend ratio (%)	Burst-ing strength (kPa)	Abras-ion resi-stance (rubs)	Air per-mea-bility (mmc;/ s)
		Tens-ile stre-ngth (N)	Tens-ile elon-gat-ion (%)	Elon-gat-ion rate	Resid-ual elong-ation (60 s)	Resid-ual elong-ation (60 min)	Elastic recov-ery (60 s)	Elastic recov-ery (60 min)
		wp/wt direc-tion	wp/wt direc-tion	w/cDirec-tion	w/cDirec-tion	w/cDirec-tion	w/cDirec-tion	w/cDirec-tion
Fab-ric	MG-3450 (320 g/yd)	378 318	111 152	35 46	2.9 9.3	6.7 1.9	92 84	81 97	PET 94.3 PU 5.7	544	Over 500 (End-point: when a hole app-ears in the fabric)	613
Sub-mater-ial	E-band 38 mm (725 g/m²)	770 -	113.7 -	132 -	2.1 -	1.3 -	98 -	99 -	PET 28.4 PP 46.9 PU 24.7	-	-	-

Polyester = PET, Polyurethane = PU, Polypropylene = PP.

Warp = wp, Weft = wt, Wale = w, Course = c.

Further, the e-band on the foot was selected because of its excellent tensile strength and elongation recovery rate, which enabled a stable and comfortable fit (Table 5). The e-band is 38 mm in width for comfort and fabric fixation.

The correction bands were designed to cut the length of the wedged insole so that it only touched the midfoot, based on previous research that indicated that providing an unstable support surface improves postural alignment compared to training on a stable support surface.^7,55 The band was developed and tested using a practical uncut insole, but the effect of helping to correct genu varum was felt to be weak because of the overly stable feeling; therefore, the overall length of the insole was modified, and the band with a shorter insole length may be used in different shoe types. Therefore, a genu varum correction band with increased usability was developed that could be worn for a long time in all situations, both indoors and outdoors, regardless of shoe wear. Figure 4 illustrates the schematic and wearing appearance.

Figure 4.

(a-c) Schematic examples of genu varum correction bands: (a) Design 1, (b) Design 2, (c) Design 3. (d-f) Mannequin wearing appearances: (d) Design 1, (e) Design 2, (f) Design 3.

Moreover, the design allows the insole to be inserted by rotating the band by 180°, which has the advantage of being highly versatile as it helps relieve genu valgum symptoms, known as X-shaped legs. This multipurpose design is significant because it makes the corrective band more versatile and enables its use as a customized orthotic.

Gap between the knees measurement results

In this study, the gap between the knees was measured to determine the performance of the genu varum correction band. This was performed to predict the future effectiveness of the correction when worn over a longer period. The participants had an average knee gap of 3.61 cm. All participants were in genu varum stage 2 (2.5–5 cm), and the average result was stage 2, which is the stage where exercise and bracing are recommended. All participants wore all three band designs, and designs 1, 2, and 3 caused an average reduction of approximately 13.83%, 14.49%, and 15.94% with an average of 3.11 cm, 3.09 cm, and 3.04 cm, respectively, with design 3 demonstrating the largest reduction. A paired-sample t-test was performed to determine the statistical significance of the difference in the gap between the knee reduction before and after band use. The means, standard deviations, and t-values before and after band use are listed in Table 6. A paired-samples t-test was conducted, and all three designs were found to have p < .01, confirming a difference between pre- and post-band wearing. Therefore, the gap between the knees after band wearing was significantly smaller than before band wearing.

Table 6.

Comparison of the gap between the knees according to design before and after band application.

Design type	Before	After	t
Design type	Mean (SD)	Mean (SD)	t
Design 1	3.61 (0.605)	3.11 (0.383)	4.065^**
Design 2		3.09 (0.249)	3.862^**
Design 3		3.04 (0.419)	4.028^**

*p < .05, **p < .01, ***p < .001

In conclusion, the gap between the knees of all participants decreased by an average of 14.76% when wearing the bands of all three designs. Furthermore, when the band was worn with shoes, the gap between the knees increased compared to the band alone because of the thickness of the shoes around the medial malleolus but decreased compared to the before condition, where no genu varum correction band was worn (Figure 5). These results indicate that wearing a band with a wedged insole decreases the gap between the knees, which helps alleviate genu varum symptoms. Lateral wedge insoles help reduce the external knee adduction moment.⁹ This is a variable that affects the genu varum because the knee adduction moment is also related to knee alignment.⁵⁶ Patients with genu varum can have a Q-angle that is smaller than the normal range, and a larger Q-angle is generally associated with reduced knee adduction moment.⁵⁷ Therefore, wearing a band with a lateral wedge insole may help reduce knee adduction moment, which may explain the decreased gap between the knees. The 14.76% average reduction in the gap between the knees indicates an improved alignment of the lower limbs, which may contribute to enhanced stability during movement and reduced strain on the knee joints. A decrease in the gap between the knees is associated with better biomechanical efficiency and may help prevent musculoskeletal discomfort or injury during prolonged physical activity.^12,58 Thus, this reduction is not only statistically meaningful, but also clinically relevant in promoting ergonomic benefits and physical well-being.

Figure 5.

Graph of the gap between knee measurements according to design.

The findings of this study are consistent with those of similar insole studies. A meta-analysis reported that lateral wedge insoles can improve femorotibial angle.⁵⁹ Additionally, foot orthoses with a lateral wedge alleviated pain and reduced the peak knee adduction moment, which is consistent with our observations of the reduced gap between the knees.⁶⁰ These comparisons support the accuracy and significance of our study’s findings.

User satisfaction evaluation results

The results of the user satisfaction evaluation revealed that the participants were generally satisfied with the new design of the genu varum correction bands, with an average score of 5.96 1, 5.17, and 6.20 for designs 1, 2, and 3, respectively, on a 7-point Likert scale for the positive survey questions. Design 3 achieved the highest user satisfaction and correction performance. Therefore, among the band designs, the participants preferred the use of hooks and loops to adjust the size to fit their instep and foot widths. Furthermore, the hooks and loops keep the insoles separate.

As shown in Figure 6, Design 3 was the most satisfactory in terms of design, function, comfort, usability, usefulness, and purchase or use intentions. Design 3 was the most satisfactory in all categories, except safety. Design 1 scored slightly higher than design 3 in the safety category, which may be due to the connection design of the e-band among the band designs. However, design 3 scored similarly, indicating a high level of safety and overall satisfaction with the bands. Furthermore, design 2 was much less preferred overall, especially in the comfort category, which was the only one in the 4-point range among all design categories, indicating that the use of a tri-glide buckle and zipper was less preferred. This indicates that the bulkiness of the buckle and zipper may have caused discomfort when wearing shoes and a band.

Figure 6.

Results of user satisfaction survey.

Satisfaction levels were expressed in the following order: safety, usability, function, design, usefulness, comfort, and purchase or use intention for design 1; safety, function, usefulness, design, usability, comfort, and purchase or use intention for design 2; and safety, comfort, function, usability, design, usefulness, and purchase or use intention for design 3.

Conclusion

Genu varum is an aesthetic problem of the legs accompanied by different types of pain and inflammation as people age, thereby requiring efforts to develop new types of corrective products. Various types of corrective products have been developed and sold; however, research is lacking on products that can be worn in both indoor and outdoor environments, as well as on their comfort and ease of use. Therefore, this study introduced a new design and developed a product by systematically considering design, function, wear comfort, and ease of use.

Based on our aims for this study, we applied a wedged insole with a higher height on the outer side than on the inner side to help correct genu varum and developed three different band designs on the fabric wrapped around the wedged insole. The fabric used for the correction bands is lightweight, soft, and breathable, making it suitable for use in foot areas that tend to sweat and become uncomfortable with movement, resulting in comfort when worn barefoot. The socks can be worn with other socks or inside shoes, and their compact design enables their use with existing shoes. Furthermore, insoles can easily be removed for washing, which enables their long-term use.

To assess the corrective performance of the band, objective data were collected by measuring the gap (cm) between the knees during standing and flat walking. This was followed by a questionnaire assessment to evaluate user satisfaction. All three designs achieved an average reduction of 14.76% in the gap between the knees compared to that before wearing the band, and user satisfaction was very high, with an average score of 5.78. In particular, the hook-and-loop design exhibited the best performance and satisfaction with a 15.94% reduction in the gap between the knees and a satisfaction score of 6.20.

This study is significant because it developed a new type of genu varum correction band and investigated its corrective effects and satisfaction. These results support the aim of confirming that a band design-centered approach could result in a statistically significant corrective effect for genu varum. The correction effect of wedged insoles is expected to be verified again through the experiment of wearing the developed band, and various problems caused by genu varum will be reduced by using the medial lower extremity muscles during walking. Genu varum correction can only be proven by long-term band wearing; thus, future studies should be conducted by setting a specific period in which the corrective effect can be confirmed.

In addition, extended wear tests can be performed to evaluate the durability of the bands under repeated use. To enhance the understanding of the functional performance of the product, it is necessary to investigate the characteristics of insole foam in terms of load distribution through both a foam property test and a separate plantar pressure test. Future research involving a larger and more diverse participant group will also help ensure that the findings can be generalized to a broader population.

The findings of this study can offer valuable insights for the development of corrective products targeting genu varum. These results may contribute to the advancement of practical interventions and promote the wider adoption of corrective solutions. As research in this area progresses, it is anticipated that innovative and effective products for the management of genu varum will become increasingly prevalent.

Footnotes

ORCID iDs

Jiwon Chung

Gayeon Lee

Sumin Helen Koo

Author contributions

J.C. as the first author executed the research and wrote the manuscript and S.M.K. as the corresponding author executed and supervised the research and edited the manuscript.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MIST) (No. RS-2023-00214474).

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data Availability Statement

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.*

References

Bukish

Alisha-tu-Zahra

Amja

, et al. Frequency of genu valgum and genu varum and its association with age, gender, BMI and knee angular deformities in young adults. Int J Health Prof. 2024; 1: 13–18.

Hidayatullah

Martanto

. Epidemiology of genu varum in pediatric patients in Dr. Soetomo general academic hospital surabaya 2010-2018: a retrospective study. J Orthop Traumatology Surabaya 2022; 11: 40–48.

Jang

Lee

. Analysis on the lower body shape of the varus-typed elderly women. Fashion & Text Res J 2017; 19: 569–578.

Lee

Kim

. Possible effects of applying rehabilitation program upon bowlegged undergraduates` cog (center of gravity) oscillation and its correction. J Sport Leisure Stud 2009; 35: 1061–1072.

Han

Lee

, et al. The effects of correction exercise on hip joint angle, Q angle, and the distance between knees of genu varum patients. Kinesiology 2011; 13: 83–90.

Jang

Lee

. A study on the lower body shape and life status of elderly women according to the progress group of varus. Fashion & Text Res J 2019; 21: 326–335.

Kwon

Jung

Yang

. Effects of elastic band exercise for 8 weeks on interval of knee joint, foot pressure and pain for adult women with genu varum according to surface. Korean J Sports Sci 2013; 22: 1109–1119.

Kim

. Increase and treatment methods for knee varus in women. The Korea Herald, 2012, vol A15.

Chapman

Parkes

Forsythe

, et al. Ankle motion influences the external knee adduction moment and may predict who will respond to lateral wedge insoles? an ancillary analysis from the SILK trial. Osteoarthr Cartil 2015; 23: 1316–1322.

10.

Crenshaw

Pollo

Calton

. Effects of lateral-wedged insoles on kinetics at the knee. Clin Orthop Relat Res 2000; 375: 185–192.

11.

Deng

Yang

, et al. Effect of lateral wedge-shaped orthopedic insole on patients with genu varus: a protocol for systematic review and meta-analysis. PLoS One 2022; 17: e0274789.

12.

Hinman

Payne

Metcalf

, et al.

Lateral wedges in knee osteoarthritis: what are their immediate clinical and biomechanical effects and can these predict a three‐month clinical outcome?

Arthritis Rheum 2008; 59: 408–415.

13.

Healifty . Posture corrector bow-legged correction. Amazon UK. https://www.amazon.co.uk/Healifty-Posture-Corrector-Bow-Legged-Correction/dp/B07L6VKYVT (accessed 24 January 2025).

14.

Hidden health . Hidden height bow leg correction belt. Coupang. https://www.coupang.com/vp/products/7387731705 (accessed 4 June 2024).

15.

Pinocoro . Slippers for pelvic and bow leg correction. Auction. https://itempage3.auction.co.kr/DetailView.aspx?itemno=B508151953 (accessed 24 January 2025)

16.

Savetime . Weight loss bow leg correction acupressure slippers. Coupang. https://www.coupang.com/vp/products/7534570240 (accessed 4 June 2024).

17.

Kerrigan

Lelas

Goggins

, et al. Effectiveness of a lateral-wedge insole on knee varus torque in patients with knee osteoarthritis. Arch Phys Med Rehabil 2002; 83: 889–893.

18.

Toda

Segal

Kato

, et al. Effect of a novel insole on the subtalar joint of patients with medial compartment osteoarthritis of the knee. J Rheumatol 2001; 28: 2705–2710.

19.

Sattari

Ashraf

. Comparison the effect of 3 point valgus stress knee support and lateral wedge insoles in medial compartment knee osteoarthritis. Iran Red Crescent Med J 2011; 13: 624–628.

20.

Zhang

Moskowitz

Nuki

, et al. OARSI recommendations for the management of hip and knee osteoarthritis, Part II: OARSI evidence-based, expert consensus guidelines. Osteoarthr Cartil 2008; 16: 137–162.

21.

Tenzero . Insole for correcting bowleg. Coupang. https://www.coupang.com/vp/products/6445724427 (accessed 24 January 2025).

22.

Heasoy . Bow leg corrector correction orthopedic Alignment. Amazon. https://www.amazon.com/Corrector-Correction-Heasoy-Orthopedic-Alignment/dp/B09WQRLVBH (accessed 24 January 2025).

23.

Agatige . Leg correction belt. Amazon. https://www.amazon.com/Correction-Adjustable-Corrector-Straightening-Deformity/dp/B09DV4NSXG (accessed 4 June 2024).

24.

Linyutech . Invisible height increases silicone socks. Amazon. https://www.amazon.co.uk/Insoles-Invisible-Increase-Silicone-Orthopedic/dp/B0BDW7X7VV (accessed 15 June 2024).

25.

Neo cosmetics . Height increase silicon insole. Lotte ON. https://www.lotteon.com/p/product/PD9381016 (accessed 15 June 2024).

26.

Brison . Metatarsal pads forefoot cushions for metatarsalgia. Amazon. https://www.amazon.co.uk/Metatarsal-Pads-Forefoot-Cushions-Metatarsalgia/dp/B07PMRFN3B (accessed 24 January 2025).

27.

Lime tree . Ball of foot pressure band. 11st. https://www.11st.co.kr/products/6176321147 (accessed 15 June 2024).

28.

Wobb life . Arch support band. Coupang. https://www.coupang.com/vp/products/1198393482 (accessed 24 January 2025).

29.

Wonderwin . Cushioned arch support for foot problems. Amazon. https://www.amazon.com/Compression-Fasciitis-Cushioned-Cushions-Problems/dp/B07XXP5RR4 (accessed 15 June 2024).

30.

Choi

Kim

Choi

, et al. The effects of exercise programs on genu varum persons. J Korean Soc Integr Med 2013; 1: 87–96.

31.

Feldman

Schoenecker

. Use of the metaphyseal-diaphyseal angle in the evaluation of bowed legs. J Bone Joint Surg 1993; 75: 1602–1609.

32.

Lee

. Comparison of Q-angle and muscle activity when elastic band and lunge are applied to people with genu varum. Int J Internet Broadcast Commun 2019; 19: 265–277.

33.

Houglum

Bertoti

(eds). Brunnstrom’s clinical kinesiology. 6th ed. F. A. Davis Company, 2012. https://fadavispt.mhmedical.com/content.aspx?bookid=2148&sectionid=162869570 (accessed 1 June 2024).

34.

Biedert

Warnke

. Correlation between the Q angle and the patella position: a clinical and axial computed tomography evaluation. Arch Orthop Trauma Surg 2001; 121: 346–349.

35.

Woo

Lim

. Foot position and foot pressure during the gait in female with genu varum. Asian J Phys Edu Sport Sci 2021; 9: 89–98.

36.

Kim

. The effects of the correction exercise program combined with stretching and elastic band exercise on femoral intercondylar distance, Q-angle, plantar pressure in undergraduate with genu varum. J Korea Acad Ind Coop Soc 2015; 16: 2064–2072.

37.

Braz

Carvalho

. Relationship between quadriceps angle (Q) and plantar pressure distribution in football players. Braz J Phys Ther 2010; 14: 296–302.

38.

Lee

Bae

Gong

. Effects of muscle activity of lower extremity with contact laterally wedged insoles with strapping of varying elevations. J Korean Soc Phys Med 2006; 1: 37–47.

39.

Toda

Segal

Kato

, et al. Correlation between body composition and efficacy of lateral wedged insoles for medial compartment osteoarthritis of the knee. J Rheumatol 2002; 29: 541–545.

40.

Baker

Goggins

Xie

, et al. A randomized crossover trial of a wedged insole for treatment of knee osteoarthritis. Arthritis Rheum 2007; 56: 1198–1203.

41.

Peters

Middleton

Donley

, et al. Concurrent validity of walking speed values calculated via the GAITRite electronic walkway and 3 meter walk test in the chronic stroke population. Physiother Theory Pract 2014; 30: 183–188.

42.

Cho

Lee

. Transactions: the development of usability evaluation criterion for sensor based smart clothing. Fashion & Text Res J 2008; 10: 473–478.

43.

Kwon

Lee

, et al. Energy efficiency and patient satisfaction of gaitwith knee-ankle-foot orthosis and robot (rewalk)-assisted gait in patients with spinal cord injury. Ann Rehabil Med 2020; 44: 131–141.

44.

Joo

Han

Kim

. Analysis of consumer behavior and influence variables of smart clothing for body dimension measurement. J Korean Soc Des Cult 2022; 28: 423–433.

45.

Park

Lee

Kim

, et al. A study on the satisfaction level of Rewalk use of people with spinal cord injury. In: Proceedings of the Autumn Conference of the Ergonomics Society of Korea, Gangwon, Korea, 29 November-2 December 2017. ESK, pp.463–467.

46.

Wang

Hwang

. A Study on satisfaction and intention of use of wrist-worn wearable devices. J Bus Converg 2022; 7: 41–47.

47.

Eom

Lee

. Comfort evaluation by wearing a gait-assistive rehabilitation robot. J Korean Soc Cloth Text 2020; 44: 1107–1119.

48.

Siagian

Tarigan

ZJH

Basana

, et al. The effect of perceived security, perceived ease of use, and perceived usefulness on consumer behavioral intention through trust in digital payment platform. Int J Data Network Sci 2022; 6: 861–874.

49.

Jung

Kim

Kwon

. The Influence of wedged insole and foot progression angle on lateral thrust of knee during walking. J Korean Acad Univ Trained Phys Ther 2004; 11: 27–34.

50.

Ning

Yick

, et al. Effects of textile-fabricated insole on foot skin temperature and humidity for enhancing footwear thermal comfort. Appl Ergon 2022; 104: 103803.

51.

Yick

Yip

, et al. Influence of upper footwear material properties on foot skin temperature, humidity and perceived comfort of older individuals. Int J Environ Res Public Health 2022; 19: 10861.

52.

Putra

Nagano

Watanabe

, et al. Footwear upper breathability: an understudied yet critical aspect for physical activity. JSM Foot Ankle 2025; 6: 1054.

53.

Peixoto

Souto

Flores

. Breathable, impermeable and odourless lining for orthopaedic footwear application. In: Proceedings of the International Textile, Clothing & Design Conference, Dubrovnik, Croatia, 7 October-10 October 2012.

54.

Kwan

Yick

Yip

, et al. The immediate effects of hallux valgus orthoses: a comparison of orthosis designs. Gait Posture 2021; 90: 283–288.

55.

Silsupadol

Lugade

Chou

, et al. Effects of single-vs dual-task training in older adults with balance impairment. J Biomech 2007; 40: S124.

56.

Lewinson

Stefanyshyn

. Wedged insoles and gait in patients with knee osteoarthritis: a biomechanical review. Ann Biomed Eng 2016; 44: 3173–3185.

57.

Park

Stefanyshyn

. Greater Q angle may not be a risk factor of patellofemoral pain syndrome. Clin Biomech 2011; 26: 392–396.

58.

Kakavandi

Sadeghi

Abbasi

. The effects of genu varum deformity on the pattern and amount of electromyography muscle activity lower extremity during the stance phase of walking. J Clin Physiother Res 2017; 2: 110–118.

59.

Zhang

Liang

, et al. Is the wedged insole an effective treatment option when compared with a flat (placebo) insole: a systematic review and meta‐analysis. Evid Based Complement Alternat Med 2018; 1: 8654107.

60.

Dessery

Belzile

Turmel

, et al. Effects of foot orthoses with medial arch support and lateral wedge on knee adduction moment in patients with medial knee osteoarthritis. Prosthet Orthot Int 2017; 41: 356–363.

Development and evaluation of band-embedded laterally wedged insoles for people with genu varum

Abstract

Keywords

Introduction

Literature review

Status and features of products for genu varum correction

Comparative study on the design of insoles and foot support bands

Evaluation methods for improvement effects

Methods

Results and discussion

Developed design

Gap between the knees measurement results

User satisfaction evaluation results

Conclusion

Footnotes

ORCID iDs

Author contributions

Funding

Declaration of conflicting interests

Data Availability Statement

References