Toe Strength and Falling Among the Elderly

February 6, 2010 — My grandfather recently fell and broke his hip while “tinkering outside behind the workshop” on his Texas farm. Initially, the trauma of the incident and the painful surgery and rehabilitation blurred his memory of the specifics, but our suspicions that the real story included some quicker-than-most-octogenarians-can-handle movements away from a larger-than-expected flame were eventually confirmed when his recollection became clearer.  As it turns out, he’d used too much gasoline to start a fire in a burn barrel while disposing of some falling ceiling material from an old shed. Whether it was a reflexive jump away or the power of the blast itself that knocked him off balance, we’ll never know. The drama of Grandpa’s fall certainly isn't the norm, though, with many researchers suggesting that falls by the elderly are often due to something surprisingly simple: toe weakness and deformity.

Bunions—Banes of Aging

Usually accompanied by a bunion, hallux valgus, or the angling of the big toe toward the lesser toes, afflicts 35-74% of the elderly to some degree^1,2,3,4,5. The lesser toes often have problems⁵, too, most commonly hammer toe and claw toe. What causes these deformities? Numerous researchers have suggested that one factor may be weakness of the intrinsic flexor muscles of the toes^6,7,8,9.

Give Your Toes Their Due!

Before mentioning some of the studies which have related deformities, loss of strength, and falls, it’s worth thinking about what our toes are actually doing as we stand and walk. If you’re like me, you’ve probably never paid much attention to it—so try it out! You’ll find that they’re frequently flexing to help you adjust to shifts in your body weight, propel you forward with each step, and absorb the shock as your feet hit the ground^10,11. To be a bit more technical, during the stance phase of walking, the extrinsic toe flexors (flexor hallucis longus and flexor digitorum longus) are controlling the forward motion of your tibia (shin) over your foot and keeping your toes flat on the ground as your weight shifts from the back to the front of your foot. In the meantime, the intrinisic toes muscles are working to stabilize the medial longitudinal arch (the arch along the inside of your foot) and the toes¹⁰. Consider losing the toe strength needed for these basic functions, and you can image the problems that would be in store.

Now for the Studies

Solid research focused on toe deformations, flexor strength, or both and their relation to falling provides backing for our little experiment. Deformities have been tied to decreased balance², while retirement home residents who fall have been found to have more severe hallux valgus than those who don’t¹². Associations between low toe flexor strength and poor performance in balance and functional tests have been identified¹³, and the qualitative “paper grip test” for toe flexor strength has been a good predictor of falls in a group of men and women living in a retirement village¹⁴.

Focusing on both strength and deformities, an Australian study¹⁵ of 312 men and women who lived independently in the community, had good mental status, were capable of walking for at least 10 meters without use of an aid, and were between 60 and 90 years of age found that 35% of the study participants fell over the course of the next twelve months, with fallers exhibiting significantly less hallux (big toe) strength and lesser toe strength than participants who did not fall during the twelve months. Furthermore, fallers were more likely to have hallux valgus and lesser toe deformity than their non-falling counterparts. Note that toe strengths were analyzed relative to body weight for normalization and that age, gender, height, body mass index, and quadriceps strength did not statistically differ between fallers and non-fallers. Performing discriminant function analysis, the team identified hallux strength and the presence of lesser toe deformities as the most important factors in predicting whether a study subject would fall or not; and they suggested based on forward stepwise linear regression analysis that the odds of sustaining a fall drop by a whopping 6.7% for every 1% body weight increase in hallux strength.  The authors concluded that “interventions designed to increase strength of the toe flexor muscles combined with treatment of those older individuals with toe deformities may be beneficial.”

That, and not playing with fire!

References

1. J.E. Dunn, C.L. Link, D.T. Felson, M.G. Crincoli, J.J. Keysor and J.B. McKinlay, Prevalence of foot and ankle conditions in a multiethnic community sample of older adults, Am. J. Epidemiol. 159 (2004), pp. 491–498.
2. H.B. Menz and S.R. Lord, Gait instability in older people with hallux valgus, Foot Ankle Int. 26 (2005), pp. 483–489.
3. B. Munro and J. Steele, Foot-care awareness. A survey of persons aged 65 years and older, J. Am. Podiatr. Med. Assoc. 88 (1998), pp. 242–248.
4. E. Roddy, W. Zhang and M. Doherty, Prevalence and associations of hallux valgus in a primary care population, Arthritis Rheum. 59 (2008), pp. 857–862.
5. G. Scott, H.B. Menz and L. Newcombe, Age-related differences in foot structure and function, Gait Posture 26 (2007), pp. 68–75.
6. M.A. Caselli and D.H. George, Foot deformities: biomechanical and pathomechanical changes associated with aging, part I, Clin. Podiatr. Med. Surg. 20 (2003), pp. 487–509.
7. W.P. Garth and S.T. Miller, Evaluation of claw toe deformity, weakness of the foot intrinsics, and posteromedial shin pain, Am. J. Sports Med. 17 (1989), pp. 821–827.
8. M.S. Myerson and M.J. Shereff, The pathological anatomy of claw and hammer toes, J. Bone Joint Surg. Am. 71-A (1989), pp. 45–49.
9. C. Van Schie, C. Vermigli, A. Carrington and A. Boulton, Muscle weakness and foot deformities in diabetes: relationship to neuropathy and foot ulceration in Caucasian diabetic men, Diabetes Care 27 (2004), pp. 1668–1673.
10. R.A. Mann and J.L. Hagy, The function of the toes in walking, jogging and running, Clin. Orthop. 142 (1979), pp. 24–29.
11. M. Senda, Y. Takahara, Y. Yagata, K. Yamamoto, H. Nagashima, H. Tukiyama and H. Inoue, Measurement of the muscle power of the toes in female marathon runners using a toe dynamometer, Acta Med. Okayama 53 (1999), pp. 189–191.
12. H.B. Menz and M.E. Morris, Clinical determinants of plantar forces and pressures during walking in older people, Gait Posture 24 (2006), pp. 229–236.
13. Menz, H.B., Morris, M.E., Lord, S.R., 2005. Foot and ankle characteristics associated with impaired balance and functional ability in older people. J. Gerontol. A Biol. Sci. Med. Sci. 60, 1546–1552
14. Menz, H.B., Morris, M.E., Lord, S.R., 2006. Foot and ankle risk factors for falls in older people: a prospective study. J. Gerontol. A Biol. Sci. Med. Sci. 61A, 866–870.
15. Karen J. Mickle, Bridget J. Munro, Stephen R. Lord, Hylton B. Menz, Julie R. Steele, ISB Clinical Biomechanics Award 2009: Toe weakness and deformity increase the risk of falls in older people, Clinical Biomechanics, Volume 24, Issue 10, December 2009, Pages 787-791. Keywords:  Aging, Falling, Feet, Biomechanics, Gait