Footwear characteristics and factors influencing footwear choice in patients with gout
Gout is associated with foot pain, impairment, and disability. The aim of this study was to assess footwear characteristics and key factors influencing footwear choice in patients with gout. We also wanted to evaluate the relationship between footwear characteristics and foot disability.
Fifty patients with a history of acute gout were recruited from rheumatology clinics during the summer months. Clinical characteristics, global function, and foot impairment and disability measures were recorded. Footwear characteristics and the factors associated with choice of footwear were identified using validated assessment tools. Suitability of footwear was assessed using predetermined criteria for assessing adequacy of footwear, based on a previous study of foot pain.
The patients had moderate to severe foot pain, impairment, and disability. Poor footwear characteristics included poor cushioning, lack of support, lack of stability, and motion control. More than 50% of shoes were ≥12 months old and demonstrated excessive wear patterns. Patients reported comfort (98%), fit (90%), support (90%), and cost (60%) as important factors in choosing their own footwear. No correlation was found between footwear characteristics (length and width) and foot characteristics (foot pain, impairment, and disability). Patients with poor footwear reported higher foot-related impairment and disability.
Use of poor footwear is common in patients with chronic gout and is associated with foot disability and impairment.
Gout is the most prevalent inflammatory arthropathy in men, caused by formation of monosodium urate crystals in joints and other tissues (1). Gout typically presents as recurrent self-limiting flares of acute joint inflammation, and in the presence of persistent hyperuricemia, chronic tophaceous disease may also develop (2). Gout displays a striking predilection to affect the feet, particularly the first metatarsophalangeal (MTP) joint, midfoot, and ankle (2–6). We have recently reported that patients with chronic gout have changes in gait parameters focused on the midfoot and the hallux, consistent with a pain-avoidance strategy (7). It is likely that these gait changes contribute to altered loading patterns and impaired foot function in chronic gout.
Footwear has been developed and modified to provide protection from the environment, conform to fashion, assist function, accommodate foot deformities, and treat musculoskeletal injury (8). Various footwear characteristics have been linked to the development of musculoskeletal disorders such as osteoarthritis of the foot and knee, low back pain, foot ulceration, hallux valgus, and hammer toes (8). Poorly fitting shoes have also been linked to foot pain in rheumatoid arthritis (9, 10). In addition to shoe features, previous studies have reported that the individual fit of a shoe is important; loose-fitting shoes can also cause excessive foot slippage within the shoe during walking and altered contact area between the foot and shoe, impairing foot stability and walking parameters (11–13).
To date, the choice of footwear and factors impacting the choice of footwear have not been reported in patients with chronic gout. The aim of this study was to assess footwear characteristics and key factors influencing footwear choice in patients with gout. We also wanted to examine the relationships between footwear and foot characteristics (pain, disability, and impairment).
Significance & Innovations
Poor footwear is a major problem in patients with gout.
Foot pain, impairment, and disability may contribute to the problem.
Patients reported comfort, fit, support, and cost as important factors in choosing their own footwear.
Future research should be focused on assessing the role of competitively priced footwear with adequate cushioning, motion control, and sufficient width at the forefoot.
PATIENTS AND METHODS
This was a cross-sectional observational study of 50 adult patients with a history of gout attacks recruited from rheumatology outpatient clinics at Auckland and Counties Manukau District Health Boards, Auckland, New Zealand. All patients had a physician diagnosis of gout and a history of acute gout according to American College of Rheumatology (ACR) classification criteria (14). Ethical approval was obtained by the Northern X Ethics Committee, Auckland, New Zealand (NTX/10/EXP/231), and local institutional approval was also obtained. Participants were excluded if they were experiencing an acute gout flare at the time of assessment or had lower extremity amputation. Patients with diabetes mellitus or neurologic disease associated with gout were not excluded from the study. A single podiatrist (MF) assessed all of the patients at a single study visit.
The following data were collected: age, sex, ethnicity, body mass index (BMI), disease duration, current pharmacologic management, and history of cardiovascular disease and diabetes mellitus. Foot type was assessed using the Foot Posture Index, which is a validated method for quantifying standing foot type with scores above +4 suggesting a flatfoot type (15).
Disease impact was measured using the Leeds Foot Impact Scale (LFIS) (16). This self-administered questionnaire comprises 2 subscales for impairment/footwear (LFISIF) and activity limitation/participation restriction (LFISAP). The former contains 21 items related to foot pain and joint stiffness as well as footwear-related impairments, and the latter contains 30 items related to activity limitation and participation restriction. Turner et al (17) report that an LFISIF score >7 points and an LFISAP score >10 points indicate a high to severe level of foot impairment and disability.
Foot pain was assessed using the Foot Function Index (FFI) domain (17). The FFI is a self-administered questionnaire consisting of 23 items grouped in 3 domains: foot pain (9 items), disability (9 items), and functional limitation (5 items). All items are rated using 100-mm visual analog scales, and higher scores indicate greater pain, disability, and limitation of activity, and therefore poorer foot health (18).
An objective assessment of footwear was conducted by the examiner to ascertain the type, structural components, and fit of the participant's footwear at the time of the study visit (8, 19). Patients did not receive any instructions about their footwear prior to the study visit. Six aspects of footwear are evaluated and include: 1) fit (length, width, and depth), 2) general (age of shoe, footwear style, weight, and length), 3) general structure (heel height, fixation, forefoot height, forefoot sole flexion point, and last), 4) motion control properties (density, fixation, heel counter stiffness, midfoot sole sagittal, and frontal stability), 5) cushioning (presence of lateral, medial, and heel sole hardness), and 6) wear patterns (upper, midsole, tread, and outsole wear pattern).
Based upon previous studies of patients with foot pain and rheumatoid arthritis, we classified current footwear into poor, average, and good footwear (10, 20). The poor footwear group consisted of footwear that lacks support and sound structure, including sandals, flip-flops, slippers, mules, and moccasins. The average footwear group included shoes such as hard- or rubber-soled shoes and work boots. The good footwear group consisted of athletic shoes, walking shoes, therapeutic footwear, and Oxford-type shoes. Foot dimensions (foot length and width) were measured using a Brannock measuring device (Liverpool). The device allows the weight-bearing measurement of foot length and width. Each patient was also asked by the examiner to identify the most important feature on a validated checklist that included comfort, style, fit, sole, costs, weight, and color (21).
All analyses were performed using SPSS, version 17.0. Sex, ethnicity, clinical characteristics such as current pharmacologic management, history of hypertension, cardiovascular disease, diabetes mellitus, and renal impairment, and general footwear scores are described as the number (percentage). All other demographic characteristics are described as the mean ± SD. The association of changes with foot characteristics (pain, disability, and impairment) with footwear characteristics (shoe length and width) were evaluated using Spearman's rho correlation coefficients. We examined significant differences between shoe category (good, poor, and average) and foot characteristics (pain, disability, and impairment) using one-way analysis of variance. We undertook secondary analysis using independent t-tests to evaluate significant differences in all footwear characteristics between participants with diabetes mellitus and those without diabetes mellitus. All tests were 2-tailed and P values less than 0.05 were considered significant.
Clinical and foot characteristics.
The clinical and foot characteristics are summarized in Table 1. Patients were predominantly middle-aged men with longstanding disease. Obesity and cardiovascular disease were common comorbidities. The majority of patients (n = 27 [54%]) had a low foot profile (flatfoot). Patients had high to severe (LFISIF >7 points: n = 27 [54%], LFISAP >10 points: n = 30 [60%]) levels of foot impairment and disability (Table 1). The FFI pain domain showed a moderate level of pain.
Table 1. Clinical and foot characteristics
|Age, mean ± SD years||63.1 ± 13.2|
|Male sex, no. (%)||42 (84)|
|Ethnicity, no. (%)|| |
| White||26 (52)|
| Pacific Island||13 (26)|
| Maori||8 (16)|
| Asian||1 (2)|
| Indian||2 (4)|
|Disease duration, mean ± SD years||17.9 ± 14.4|
|Cardiovascular disease, no. (%)||20 (40)|
|Diabetes mellitus, no. (%)||7 (14)|
|Diuretic use, no. (%)||10 (20)|
|Allopurinol use, no. (%)||28 (56)|
|Body mass index, mean ± SD kg/m2||31.9 ± 7.8|
|Tophi present, no. (%)||8 (16)|
|Serum urate, mean ± SD mmoles/liter||0.43 ± 0.14|
|Crystal-confirmed diagnosis, no. (%)||18 (36)|
|Foot Posture Index, mean ± SD||4.1 ± 2.9|
|Leeds Foot Impact Scale (impairment), mean ± SD||8.3 ± 5.3|
|Leeds Foot Impact Scale (activities), mean ± SD||13.3 ± 10.7|
|Foot Function Index (pain), mean ± SD||34.0 ± 28.3|
|Foot Function Index (disability), mean ± SD||33.4 ± 29.1|
|Foot Function Index (activities), mean ± SD||18.1 ± 24.7|
Table 2 summarizes the footwear types observed. Overall, 28 patients (56%) wore good footwear that included walking, athletic, and Oxford-type shoes, with 42% of patients wearing shoes that were defined as “poor.” No participants wore high-heeled shoes.
Table 2. Footwear type
|Good||28 (56)|| |
| Oxford shoe|| ||9 (18)|
| Walking shoe|| ||4 (8)|
| Athletic shoe|| ||13 (26)|
| Therapeutic footwear|| ||2 (4)|
|Average||1 (2)|| |
| Boot|| ||1 (2)|
|Poor||21 (42)|| |
| Sandal|| ||6 (12)|
| Flip-flop|| ||7 (14)|
| Slipper|| ||4 (8)|
| Backless slipper|| ||3 (6)|
| Moccasin|| ||1 (2)|
Table 3 describes footwear characteristics. Footwear characteristics demonstrated that shoes were frequently either too long or too short. A similar finding was also found for shoe width, although shoe depth was deemed to be good in more than 62% of patients. We found that 24% (n = 12) of shoes had no fixation. More than 60% (n = 30) of shoes demonstrated no cushioning and only 36% (n = 18) of shoes had heel/forefoot cushioning. Minimal motion control properties were found in the current study, with only 26% (n = 13) wearing shoes that had adequate heel counter stiffness, 50% (n = 25) of shoes with midfoot sole sagittal stability, and a further 42% (n = 21) with midfoot sole frontal stability. We observed that 64% (n = 32) of patients wore shoes with a heel height ranging between 2.6 and 5.0 cm; of those, 13 (41%) wore athletic shoes, 9 (28%) wore Oxford-type shoes, 7 (22%) wore open shoes, 2 (6%) wore bespoke footwear, and 1 (3%) wore boots. Forefoot sole flexion point demonstrated 54% (n = 27) of shoes before the level of the first MTP joint. More than one-half of the patients wore shoes that were aged more than 12 months old.
Table 3. Footwear construction characteristics*
|Fit of shoe|| |
| Length|| |
| Good||21 (42)|
| Too short||12 (24)|
| Too long||17 (34)|
| Width|| |
| Good||20 (40)|
| Too narrow||27 (54)|
| Too wide||3 (6)|
| Depth|| |
| Good||31 (62)|
| Too shallow||19 (38)|
|Heel height, cm|| |
| 0–2.5||15 (30)|
| 2.6–5.0||32 (64)|
| >5.0||3 (6)|
|Forefoot height, cm|| |
| 0–0.9||11 (22)|
| 1.0–2.0||33 (66)|
| >2.0||6 (12)|
|Age, months|| |
| <6||17 (34)|
| 6–12||7 (14)|
| >12||26 (52)|
|Width, mean ± SD mm||23.7 ± 2.44|
|Length, mean ± SD mm||271.6 ± 18.9|
|Motion control properties|| |
| 1. Midfoot sole sagittal stability|| |
| Minimal||25 (50)|
| Moderate||16 (32)|
| Rigid||9 (18)|
| 2. Midfoot sole frontal stability|| |
| Minimal||21 (42)|
| Moderate||17 (34)|
| Rigid||12 (24)|
| 3. Heel counter stiffness|| |
| Not available||13 (26)|
| Minimal||21 (42)|
| Moderate Rigid||3 (6)|
| Rigid||13 (26)|
| 4. Density|| |
| Single||48 (96)|
| Dual||2 (4)|
| 5. Fixation|| |
| None||12 (24)|
| Laces||21 (42)|
| Straps/buckles||17 (34)|
|Presence of cushioning|| |
| None||30 (60)|
| Heel||2 (4)|
| Heel/forefoot||18 (36)|
|Forefoot sole flexion point|| |
| At level of first MTP joint||23 (46)|
| Before first MTP joint||27 (54)|
|Wear patterns|| |
| Upper wear|| |
| Medial tilt||21 (42)|
| Neutral||27 (54)|
| Lateral tilt||2 (4)|
| Midsole wear|| |
| Medial compression signs||10 (20)|
| Neutral||37 (74)|
| Lateral compression signs||3 (6)|
| Tread pattern|| |
| Not worn||14 (28)|
| Partly worn||34 (68)|
| Fully worn||2 (4)|
| Outerwear pattern|| |
| None||14 (28)|
| Normal||23 (46)|
| Lateral||4 (8)|
| Medial||9 (18)|
Table 4 shows the factors patients perceived as important; most commonly identified factors were comfort (98%), fit (90%), support (90%), cost (60%), and weight (63%). Patients reported style (36%) and color (33%) as being less important.
Table 4. Factors relating to footwear choice*
Factors influencing changes in foot characteristics and footwear.
Shoe width and depth did not correlate with foot pain, impairment, and disability (data not shown). However, patients with poor footwear reported higher foot-related impairment and activities, particularly in the scores of the LSISAP (P = 0.01) and the FFI impairment domain (P = 0.02) (Table 5). Secondary analysis demonstrated no significant differences in any of the footwear characteristics between participants with diabetes mellitus (n = 7) and those without diabetes mellitus (n = 43; P > 0.05).
Table 5. Differences between shoe fit category and foot characteristics
|Leeds Foot Impact Scale (impairment)||9.9 ± 6.5||6.5 ± 4.5||0.05|
|Leeds Foot Impact Scale (activities)||17.2 ± 11.3||8.2 ± 8.7||0.01|
|Foot Function Index (pain)||43.5 ± 33.7||27.4 ± 22.4||0.07|
|Foot Function Index (impairment)||45.9 ± 29.2||24.2 ± 26.4||0.02|
|Foot Function Index (limitation)||24.3 ± 25.3||24.1 ± 26.4||0.20|
The aim of this study was to identify current footwear styles, footwear characteristics, and factors that influence footwear choice experienced by patients with chronic gout. Overall, we found severe impairment and limited activity scores, consistent with significant foot disability and impairment associated with gout. A previous study has reported similar findings of foot pain, impairment, and disability relating to chronic gout (7).
More than 40% of patients in the current study wore sandals, moccasins, and flip-flops. A previous study (22) reported that gait changes were observed in an asymptomatic population wearing flip-flops and suggested that the shoe construction may contribute to lower extremity leg pain and is counterproductive to alleviating pain. The wearing of open-type footwear should be interpreted with caution in the current study. It is important to understand that open-type footwear, such as flip-flops and sandals, are commonly worn in New Zealand. However, wearing open-type footwear may reflect the issue of finding appropriate footwear, in particular relating to finding footwear that has adequate foot width and length.
Analysis of patient footwear illustrated signs of detrimental changes. Minimal motion control was found in the current study and since the midfoot is required to form a rigid lever during propulsion, footwear instability may contribute to foot problems in patients with chronic gout. The current study found more than 50% of shoes with a flexion point distal to the level of the first MTP joint. This may limit gait efficiency due to altered kinematics that result from inhibition of normal first MTP joint function (8). We can postulate that a flexion point proximal may jeopardize the shoe's stability and may exacerbate the problem of efficient toe-off observed in patients with chronic gout (7).
Heel height greater than 2.5 cm has been associated with hallux valgus, plantar callus, and postural instability in older adults (8). In our study, more than 40% of those with high heel height wore athletic shoes. Athletic shoes vary significantly with midsole construction that may use elements of gel, foamed polyurethane, or air chambers that serve to aid cushioning (20). The elevated heel height of athletic shoes may go some way to explain the high heel height observed in this study.
The lack of cushioning found in shoes demonstrates the inadequate amount of structural support for the foot and lower extremity. Wear patterns on the footwear provided some indication that they were partially worn, and there were considerable amounts of medial compression signs. The poor midfoot sole stability and poor heel counter stiffness found suggest that the current footwear does not stabilize the foot during walking. The definition of poor shoes (sandals, slippers, and flip-flops) used in this study implies a shoe design with poor fit, poor foot posture, and a lack of shock absorption characteristics. The lack of shock attenuation has the potential to increase loads on plantar tissues, potentially leading to foot pain. Combined with the presence of a flatfoot type, patients with gout wear footwear that gives no support or cushioning and is prone to unstableness. Therefore, footwear that has inadequate stability, poor cushioning, and limited stability may exacerbate foot pain in patients with gout.
In the current study, the participants reported that fit and comfort were important factors in choosing footwear, suggesting that patients with gout may prioritize these factors due to their condition. More than one-half of the patients reported cost as a factor contributing to their footwear choice. The wearing of poor shoes may be due to financial restrictions when purchasing footwear. Furthermore, gout is a painful and distressing condition that can have a major impact on economically active adults who may be forced to give up work either temporarily or permanently due to their condition (23, 24). These data highlight the barriers related to costs that patients with gout may encounter when purchasing footwear.
We found no relationship between foot length and width and foot pain, disability, and impairment. Previous studies have found similar findings in older adults with arthritis (20) and rheumatoid arthritis (10). However, we found significant differences between shoe fit category and foot characteristics, with higher scores associated with foot impairment and disability in the poor shoe category. Poor footwear may exacerbate the problem. Lindsay et al (25) reported that gout may impede the patients' lower extremity function, particularly with recreational activities.
In the current study, we found high mean BMIs indicative of obesity. The findings in the patients with gout are consistent with a previous gout study (7). The sustained repetition of such loading in these activities makes significant demands on the feet in normal-weight individuals, and these demands are likely to be magnified in those with gout, obesity, and poor footwear. It is possible that the increased demand related to obesity, coupled with the structural changes associated with chronic gout and poor cushioning and control, contributes to foot disability in patients with gout.
This study has several limitations. The study was conducted in the summer and in an urban environment, and the results may not be generalizable to other seasons or geographic locations. The footwear questionnaire contains both objective and subjective data and not all footwear meets the criteria (8). For example, open-type footwear such as mules, flip-flops, and sandals is difficult to assess and does not have all of the footwear features to evaluate. Furthermore, the category for the subjective measure of heel height is based on an arbitrary range (i.e., 0–2.5 cm, 2.6–5.0 cm, and >5.0 cm). Therefore, future research is needed to develop a more objective measure to evaluate heel height. The current study was cross-sectional and future work using prospective studies is needed to evaluate causative relationships before any definitive conclusions can be made regarding the role of poor footwear in contributing to foot pain, impairment, and disability in patients with chronic gout. We did not exclude patients with diabetes mellitus from this study. Diabetes mellitus is frequently associated with gout (26) and this combination may contribute to more severe foot problems. These patients were not excluded as we wished to ensure that patients with a wide spectrum of disease severity and comorbidities were included, consistent with gout that is managed in clinical practice. Importantly, subanalysis of patients with and without diabetes mellitus did not show major changes between the groups. Not all of the patients in this study had microscopically proven gout. The rates of microscopically proven gout are consistent with our previous studies of patients with chronic gout (27, 28). Although it is possible that misclassification may have occurred, all of the patients included in the study had a physician diagnosis of gout and also fulfilled the ACR diagnostic classification for acute gout.
In summary, patients with chronic gout experience foot pain, disability, and impairment. This study has demonstrated that fit, comfort, and costs were perceived by patients to be important factors in choosing footwear, although patients' current footwear was objectively poor. Overall, the current footwear demonstrated a lack of cushioning, control, and stability as well as excessive wear. The majority of shoes worn by patients were also more than 12 months old. For patients with gout, this might explain the problems of purchasing adequate footwear due to foot pain, impairment, and disability. Based upon the current findings, we suggest that footwear should be considered in the management plan of patients with gout. Future research should be focused on assessing the role of competitively priced footwear with adequate cushioning, motion control, and sufficient width at the forefoot.
All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be published. Dr. Rome had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study conception and design. Rome, Frecklington, McNair, Gow, Dalbeth.
Acquisition of data. Frecklington.
Analysis and interpretation of data. Rome, Frecklington, McNair, Gow, Dalbeth.