There is wide-ranging evidence to show that although the risk of falls is multifactoral, it can however, be greatly influenced by footwear and foot characteristics. The National Institute for Health and Clinical Excellence (NICE) recognise the health risk of falls in older adults, annually a significant number of adults aged 65 or older have falls resulting in serious injuries such as fractures, head injuries or even death. Hospital admission from fall related accidents in older individuals are a growing burden on the NHS, but these statistical findings are not confined to the UK, this is an international problem (NICE, 2011).
It is not just the physical injuries that falls cause, they can have adverse psychological consequences on older adults too, resulting in reduced confidence and feelings of lost of independence (NHS, 2005). Furthermore, there is a high statistical risk that someone who has a fall will suffer further falls within six months of the first (ibid).
The following sections will discuss the roles of foot characteristics and footwear in reducing fall risk and conclude with a comparison of the increased risk factors older adult have when compared to adults below 65 years old. Finally, a summary of the findings and recommendations for fall reduction in an older population will be given.
Foot characteristics and their role in falls
The foot and ankle are complex biomechanical structures comprised of over 150 separate parts (bones, ligaments, tendons and muscles), evolved to help support and balance the body mass during standing and motion. A great many musculoskeletal foot pathologies have a biomechanical basis that can interfere with gait and movement, increasing the risk of falls. In conjunction with this, foot pain is also associated with increased risk of falls and can be unrelated or connected to foot and toe deformities.
Badlissi et al. (2005) found that many foot disorders did not cause functional limitation, for example Hallux valgus, bunionette and lesser toe deformities caused not significant loss of function. However, plantar fasciitis and pes cavus were associated with significant foot-related functional limitation and that these limitations could be independent of the associated foot pain. They postulated that the associated structural deformity seen in plantar fasciitis leads to biomechanical transformations of the foot, such as the tightening of the achillies tendon would cause pain during normal functioning of the foot in ambulation. These changes may lead to adjusted gait tendencies to reduce pain and discomfort during walking, which may in turn further reduce muscle strength and flexibility. Pes cavus was found to limit functional abilities to a lesser degree compared with plantar fasciitis; however, these limitations may be caused by asymmetrical distribution of pressure in the plantar foot, as well as the disparity in elevation between the forefoot and hindfoot, thus limiting foot function (Badlissi et al. 2005).
Balance is a vital component in risk of falls, balance is associated with more than just foot function, for example eye sight and ear problems can also affect balance. However, foot problems can impair balance; Menz et al. (2005) measured foot characteristics in relationship to balance. They found that tactile sensitivity of the plantar foot had high correlation with balance and postural sway as did strength and flexibility of the ankle, Spink et al. (2011a) had similar findings. Contraire to Badlissi et al. (2005) they found that toe deformities such as hallux valgus were associated with balance and functional ability if considered separate to ankle flexibility and toe strength, when these were considered in the model, toe deformities had no bearing on functional abilities associated with balance, in accord with the findings of Badlissi et al. (2005). Spink et al. (2011a) found that foot posture was an independent predictor in balance and functional test performance, which was inconsistent with findings by Menz et al. (2005), although this may be attributed to Menz not using foot pain as part of the test criteria, while both research groups and other research found that ankle dorsiflexion range and toe plantar ?exor strength were significantly correlated to balance (Mickle et al. 2010 and 2011).
Tactile sensitivity lost during aging cannot be medically corrected; however, Menz et al. (2005) suggest the use of specific shoe inserts with raised projections could augment lack of sensitivity in the aging foot. Furthermore, they found older individuals have increased pressure in the large toe during functional use when compared with younger people, suggesting that this change in foot position during balance may compensate for lack of sensitivity in the plantar foot, thus increasing neurological signalling. This change of balance to greater pressure towards the toes, rather than using the whole plantar surface of the foot, would put the body position greater risk of falling as the body mass would not be evenly distributed over the whole foot, in conjunction with reduced ankle and toe strength, this would go some way to explaining the greater risk of fall seen in older individuals.
Badlissi et al. (2005) did not find significant relationships connecting foot pain to the walk test, which were inconsistent many others (Spink et al. 2011a and 2011b; Mickle et al. 2011), but they believed this was due to the limited protocol employed as their test covered indoor distances. Spink et al. (2011b) found that specially made orthoses and correct footwear, in conjunction with light stretching and exercise strengthened ligaments and muscles, as well as reducing pain. While exercise may be difficult for all older adults, some forms of stretching would aid the individual to remain mobile.
Footwear and its role in falls
Footwear can have some bearing on risk factors in fall. Incorrect or poorly fitting footwear can increase the individual’s risk of falls. Lord et al. (1999) found that elevated heels increased the risk of falls, whereas increased sole contact area reduced this, these findings have been consistently back up by later research (Spink et al. 2011b; Sherrington et al. 2005; Tencer et al. 2004; Menant et al. 2008; Menz et al. 2006). This fact is not only known and accepted by research, but also the general community, so much so that Menz et al. 2006 stated that warning people of this risk factor was no longer relevant. Whilst some research has found there is significant difference between footwear, with the recommended footwear consisting of high-collar heeled shoes with a heel height of less than 4.5 cm, adequate fixation to ensure the foot is snugly held in place, with good sole to floor contact and hard soles (Menant et al. 2008; Sherrington et al. 2003; Spink et al. 2011b). Others have found that going bare foot or in slippers created the highest risk factors for falling. Sherrington et al. (2003) found that the highest number of falls during their study was in the group wearing slippers (22%), this could be due to slippers having little fixation and allowing the foot to move around within the footwear. There is no mechanism to explain why lack of footwear is so deleterious, Lord et al. (1999) found that balance in females was better in barefoot compared with any footwear; however, these tests were for standing and not ambulating. Others have found that shoelessness was associated with greater risk of fall, perhaps this might be due to increased risk of slipping or foot trauma as the plantar foot is unprotected from uneven ground (Menz et al. 2006). Furthermore, some have found there is no significance associated between footwear characteristics and the risk of falls (Menz et al. 2006, Tencer et al. 2004; Spink et al. 2011b; Sherrington et al. 2005; Menant et al. 2008;).
The perfect shoe features
This section summarises the perfect shoe according to the research used. The shoe would have a heel height of lower than 4.5cm, above this height there is a significant increase in postural sway and impaired balance, perhaps due to the shift in total body centre of mass, thus modifying posture and plantar pressure distribution. There is also a lateral instability caused by the smaller critical tipping angle. Hard soles are seen as lesser risk than soft-soled shoes, hard soled shoes may transmit plantar sensory signals better than soft-soled shoes, reducing sway and improving balance. High heel-collared shoes have outperformed low heel-collared shoes, which may be due to the heel collar supporting and strengthening the ankle posture as well as increasing tactile sensory signals in the ankle. Adequate fixation would ensure that the foot stays snugly held within the shoe, preventing loss of posture in both the foot and ankle and reducing the risk of losing the shoe during ambulation (Menz et al. 2006; Tencer et al. 2004; Lord et al. 1999;).
Strengths and limitations
The strength of this literature review is that in using secondary data is that it is easily available and allows a greater population to be evaluated for relatively small financial outlay and time. It enables the author to compare and contrast previous studies and examine trends within the data. The key challenge in using secondary data is ensuring the right data is chosen to aptly address the research question. The limitations are that the data may be flawed without the author’s knowledge, or there may be missing data. Further limitations within all the studies used is the inability for the studies to take into account and model all factors within a fall, also data about the falls is discussed much later than the fall occurred and some factors may be wrongly remembered by the individual faller.
Recommendations for podiatrists
Older adults are at greater risk of injury from a fall. There are multiplicities of risk factors, some of which cannot always be taking into account, such as drug interactions and various foot deformities. Research has shown that there are a number of age related changes happen in the foot and ankle that reduce the strength and flexibility of the older foot, leading to reduced posture and balance. Tactile sensitivity can be reduced in the older foot and this is more so for those with specific diseases such as diabetes. Strengthening exercises can be used to increase balance, posture, flexibility and coordination in older adults (Spink et al. 2011a and b).
Pain can increase the risk of fall, some foot deformities can have an adverse affect on gait and balance, for example plantar fasciitis and pes cavus can reduce functional ability in the foot. Hallux valgus can decrease mobility due to pain, although asymptomatic foot disorders do not require medical intervention.
The perfect shoe is one that has a low heel (4.5cm or less), with adequate fixation that moulds to the foot to reduce movement of the foot within the shoe. High heel-collared shoes are preferable to low heel-collars and flat hard sole, rather than soft soles, reduce the risk of falls. Orthoses can be used to reduce pain by directing weight away from painful areas of the foot, while raised bed insoles can help correct tactile insensitivity in the plantar foot, reducing fall risk.
Unanswered questions within this study would be how the aging foot compares with the younger foot and how those differences translate to increased risk of falling. Do younger people have fewer falls than older peopleThe main risk to older people is that falls can lead to severe injury which is not seen in younger people, is this because younger people trip as often but are able to prevent an injurious fall because they have better reflexes or balance?
Falls can have severe consequences to older adults that are not seen in younger people and so the risk factors are significantly higher in this section of the population. There is a multiplicity of factors in fall risk that have no connection to footwear or foot characteristics such as medication, visual impairment and unsafe environment. The increased risk of injury in older adults is related to a number of factors when compared to younger people.
Of the risk factors that can be controlled, older adults are at higher risk of osteoporosis and have decreased bone density. They take less regular exercise, which results in a lack of muscle tone and flexibility, as well as decreased strength and bone mass, when compared to their younger counterparts, Aging adults should be encouraged to exercise regularly to increase basic strength and flexibility. Ensuring footwear is ‘sensible’ lower heeled with good foot position, sole contact and adequate fixation can reduce fall risk. Foot conditions and deformities should be dealt with appropriately if they are symptomatic; however, asymptomatic disorders require no medical interventions and unnecessary medical interventions can be detrimental overall. The main conclusion from this study is that there are still many factors that have not been taken into account and more research in this area is required that can build a more comprehensive model of fall risks in older adults.
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