In our study of community dwelling older adults, past shoewear among women was a predictive, statistically significant, factor for hind-foot pain; however, no significant associations were seen in men. In women, we found an increased risk between foot pain at the hind-foot location and shoewear. This was the only site-specific association in women and none were seen among the men in our sample, or among generalized foot pain. In our study, weight was significantly associated with foot pain for both the men and women. Age was not significantly associated with foot pain in our sample, but we included it as a covariate in order to compare to other studies and to address possible residual confounding. Even after taking age and weight into account, past shoewear in women remained associated with hind-foot pain.
We found that 25% of participants (19% of men and 29% of women) reported the presence of generalized foot pain on most days, which is in line with other studies examining foot pain. Similar to our study, Garrow et al. found that 20% of men and 24% of women reported foot pain13
. Menz et al also found that more women report foot pain than men10, 11
In men, less than 2% of our population reported wearing Poor shoe types. This could make seeing any possible relation between foot pain and shoewear very difficult due to sparse statistical power to detect a possible difference. We also observed several protective, non-significant associations in men between shoewear and foot pain. Despite the large numbers of men in our study, very few reported wearing Good or Poor shoes. It may well be that other studies with larger numbers of men reporting good or poor shoe types (57 % and 92% of men in our study reported average shoes for current shoewear and past shoewear, respectively) could have sufficient power to examine these possible protective effects further and in more detail.
No statistically significant associations were found in a study by Manna et al21
that evaluated the relation between foot troubles and type of footwear (shoe, sandal or slipper) in 300 men and women. While this study was limited by their definition of ‘foot troubles’, their null results between foot troubles and shoe, sandal or slipper use are in agreement with our results. A study by Dawson et al22
examined the association of age at which heels were first worn for different heel heights and maximum heel height in relation to foot pain and other foot problems in women. While no statistically significant associations were observed between age at which heels were first worn and foot pain, the authors found statistically significant associations between maximum heel height worn for going out socially and for dancing with foot pain (P
< .05). These associations of high heel use and foot pain were not seen in our study, which found no association between shoewear and generalized foot pain. It is quite interesting to note, however, that Poor shoewear (including high heels) was associated with hind-foot pain.
It is interesting to note that we observed an association with foot pain at specific locations in the foot but not with generalized foot pain. The definition of good shoes (athletic shoe or casual sneaker) used in this study implies a shoe design with better fit, foot posture and shock absorption characteristics. Each heel strike during walking may produce a biomechanical shock of 3–7 g (note: 1 g = 1 times the acceleration due to gravity). “Good shoes” often have softer out-soles, mid-soles, or insoles which may use elements of gel, foamed polyurthethane, or air chambers which serve to smooth (low pass filter) the raw shock wave. Attenuation of shock could be responsible for the reduction in perceived pain at the hind-foot. It is important to note that the hind-foot receives the largest shock wave within the foot at each and every heel strike. Thus, it makes sense that “Good shoes” will protect for pain within the hind-foot. It is also possible that the lone association seen at the hind-foot is due to the tightness of the heelcords that might result from sustained use of high heels. If this is the case, it is possible that interventions with stretching exercises could mitigate the influence of the “poor” shoes.
Given that no correction for multiple comparisons was made, the results should be conservatively interpreted; specifically, note that there is only one significant association and thus other studies are needed to confirm or extend these results.
Our study has several limitations that should be addressed. Since our population was predominately Caucasian adults, we have limited ability to generalize to other racial populations. The cross sectional study design limited our ability to infer causality. Thus, we cannot note whether the choice of shoewear caused the foot pain or if the foot pain caused the participant to select a particular type of shoe.
In addition, participants were given a list of eleven, non-specific, categories from which to choose the one shoe type that was worn most often currently and at past age groupings. Since these categories were broad and inadequately specified, there is, without a doubt, misclassification that has occurred in the categorization of footwear. Due to the time constraints of the study, we were forced to limit the choices of categories and were not able to measure this as accurately or specifically as would have been ideal. This probable misclassification would lead to results that are biased towards the null. Sandals, in particular, are likely to be misclassified given the fact that some sandals may actually provide excellent support for the foot. Due to the time constraints in this study, only one category for sandals was used. Despite this limitation, it is important to realize that regular sandal use in the North Eastern United States is not particularly common (4% in this study), and therefore may not be a major factor. There was also opportunity for recall bias when participants were asked to remember what type of shoe they were wearing as long ago as 60 years.
Also, part of what makes this analysis more complicated may be the precise category in which we placed certain shoe types. For example, a work shoe that was categorized as 'average' may be steel toed for construction and very uncomfortable and might actually be better classified as 'poor'. Even an athletic shoe which was classified as 'good' may have pronatory control elements and the person may actually have pes cavus and hence be an over supinator - so the shoe was a 'poor' match for that person. Furthermore, previous work on specific qualities of shoewear has suggested that foot structure and shoe structure interact with foot function23–26
. This implies that the shoe may actually dominate this relationship so the issue is not simply if one is wearing a 'good' shoe but if they are wearing a 'good' shoe for their foot type. We were not able to account for this possibility in our analysis, as we did not have a reliable measure of the subject’s foot type.
Despite the aforementioned limitations, our study also has several strengths. To our knowledge, this is one of the first studies to examine the association between shoewear, beyond just high heel use, and foot pain. Our study sample includes both men and women, which enables us to generalize the results to both genders. Foot pain was measured across multiple sites of the foot. We obtained information on nail pain, toe pain, forefoot pain, hind-foot pain, heel pain, pain in the arch, and pain in the ball of the foot, in addition to the measure of generalized foot pain. This allows us to conduct more specified analyses of a particular pain location. The foot examination was conducted by a trained examiner and was not simply self-report. This information is likely to be more reliable and should result in less misclassification or recall bias than a simple self-report of foot conditions.
Further research is needed to address the specific support features of shoewear such as arch support, toe box width and toe box depth. Also, future studies should examine the relationship between the severity of foot pain and whether the subject has a pes planus, rectus or pes cavus foot type. Furthermore, examining the relationship between foot type, shoe structure, the presence or absence of foot pathologies and associated pain would be of keen interest to the rheumatology and podiatric community.
In conclusion, our study found that in women, past shoewear is a statistically significant, predictive factor for hind-foot pain, but there no such association was found in men. In men, less than 2% wore Poor shoe types, making it difficult to see any relation. Given the small percentage of men wearing Poor shoes, it appears that shoe type may not be a major factor for developing foot pain in men. Past shoewear in women is associated with hind-foot pain, regardless of age or weight. Thus, young women should make careful choices regarding their shoe type in order to potentially avoid hind-foot pain later in life, or perform stretching exercises to alleviate the effect of high heels on hind-foot pain.