Foot Musculoskeletal Disorders, Pain, and Foot-Related Functional Limitation in Older Persons

Fadi Badlissi, MD, MSc; Julie E. Dunn, PhD; Carol L. Link, PhD; Julie J. Keysor, PhD, PT; John B. McKinlay, PhD; David T. Felson, MD, MPH

Disclosures

J Am Geriatr Soc. 2005;53(6):1029-1033. 

In This Article

Discussion

This study demonstrated that, of the studied foot disorders, only plantar fasciitis and, to a lesser degree, pes cavus were associated with foot-related functional limitation. According to these results, these two foot disorders might be associated with functional limitation independent of their relationship with foot pain.

A validation study showed that FHFS scale scores differed between three groups of patients, one with minor foot pathology (e.g., hyperkeratosis and nail pathology; mean FHFS scale score 88.8), a second with morphological disorders (e.g., hammertoes; mean FHFS scale score 77.9), and a third with acute disease (e.g., plantar fasciitis; mean FHFS scale score 53.9).[8] The decrements associated with foot disorders and foot pain in the current study were in the range of 10 to 20 points, similar to the differences reported earlier[8] and suggesting that the effects found in the current for foot disorders on foot function are clinically relevant.

There is empirical evidence that foot pain is associated with functional limitation and disability. A previous study reported that women with chronic and severe foot pain had more difficulty walking and greater risk of disability in activities of daily living (bathing, dressing, eating, bed-to-chair transferring, and using the toilet).[3] A community-based study found that foot pain was associated with disability in instrumental activities of daily living, including shopping, walking, and heavy housework.[4] The association between foot disorders and disability regardless of foot pain was not the focus of either study.

Regardless of pain, plantar fasciitis and pes cavus might be associated with functional limitation. One explanation to consider is that there is a structural deformity associated with plantar fasciitis leading to biomechanical changes in the foot such as the association with a tight Achilles tendon.[12,13] It might be that persons with plantar fasciitis adjust their gait to avoid pain, leading to decreasing muscle strength and flexibility, resulting in a slower gait that continues after the pain has resolved. In the case of pes cavus, this could be due to the uneven distribution of pressure, the difference in height between the forefoot and the hindfoot, and its association with a tight plantar fascia.[12,13,14,15] Nevertheless, the association between plantar fasciitis and pes cavus and functional limitation independent of pain may reflect unmeasured characteristics of foot pain in this study, elements such as pain severity, or pain with walking.

It was found that covariates (age; sex; race/ethnicity; BMI; ingrown toenail; claudication; diabetes mellitus; foot or hip fracture; hip, knee, and low-back pain; assistive devices; and the role-emotional scale) accounted for much more of the variance explained in the FHFS scale and walk test than did foot disorders themselves. Thus, foot function is complex, and for those in the community, the presence of foot disorders explains only a small portion of its variability. Other factors, especially those affecting lower limb function, play a major role.

This study did not show a statistically significant association between foot pain and the walk test, a result inconsistent with previous findings.[3,4] Different foot pain definitions, different study populations, and a possible ceiling effect of the walk test scores in this community-living sample could explain this. In addition, the walk test protocol used in this study was designed for in-home use, and thus the employed distances may not have been long enough to detect limitations related to foot disorders and pain.

The cross-sectional design of this study limits the ability to draw etiological conclusions. Among the limitations are the lack of foot pain severity and the missing data on severity of foot disorders. Although there was no formal reliability study of the foot examinations, items found to have poor inter- or intraexaminer reliability during the training or certification process were dropped from the final protocol. In addition, although multiple variables were adjusted for in the analytic models, the models were still somewhat limited in explaining the functional outcomes (the FHFS scale and walk test scores).

The strengths of this study include the large community-based sample, its racial and ethnic diversity, and the variety of individual foot musculoskeletal disorders evaluated.

One of the implications of this study is that hallux valgus, lesser digits deformities, and bunionette, when asymptomatic, may not be of great clinical importance. Even subjects who have number of those foot deformities did not have foot-related functional limitation (analyses not shown). Those disorders are sometimes of concern to clinicians during physical examination, and it is time-consuming to document them. These findings raise questions about the necessity of devoting attention to those disorders. An exception would be in patients with diabetes mellitus who have increased risk of ulceration. Another area of potential importance that needs further investigation in relation to foot disorders is falls. A study showed that subjects with a history of multiple falls had a higher number of foot disorders (including foot pain and cutaneous conditions), but there was no higher rate of individual foot disorders in fallers than in nonfallers. The study concluded that foot problems might have a cumulative effect in relation to the risk of falls.[16] This is especially relevant to frail older persons with multiple comorbidities.

The effect of plantar fasciitis on foot function merit further study, as do its risk factors. Among those are arch deformities that might be associated with an increased risk of developing plantar fasciitis by increasing the tension on the plantar fascia.[12,13]

In conclusion, commonly assessed foot musculoskeletal disorders were not associated with foot pain or foot-related functional limitation. Only plantar fasciitis and pes cavus were associated with foot pain and foot-related functional limitation. Further longitudinal investigations are needed to confirm and clarify the clinical implications of these results.

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