Relationship between typical fall patterns and fall-related fractures in older Japanese adults

Abstract

This study explored the relationship between fall patterns and fall-related fractures in older adults. A cross-sectional survey was conducted among community-dwelling older adults in Maibara City, Japan, focusing on falls over the past three years. Among the 1,695 reported falls, 176 fractures occurred in 120 individuals. Backward or straight-down and sideways falls were more likely to result in fractures compared to forward falls, with odds ratios (95％ confidence interval) of 3.23 (2.08-5.02) and 3.68 (2.35-5.76), respectively. Falls triggered by slipping or loss of balance had higher fracture rates than those triggered by tripping. Specific fall patterns were associated with particular fractures, such as forearm and patella fractures from forward falls, spine fractures from backward or straight-down falls, and hip fractures from sideways falls. We conclude that the fracture risk varies significantly based on fall patterns, providing insights for enhancing fall prevention strategies.

Introduction

Fall-related fractures are the most common and severe health problem in older adults. Approximately 30％ of older adults experience at least one fall per year,^1),2) and approximately 5％ of these falls result in fractures.³⁾ The average cost of injurious falls is relatively high,^4),5) with the medical cost per hip fracture estimated at 27,599 USD in Japan.⁶⁾ According to the Asian Federation of Osteoporosis Societies, the number of hip fractures and associated medical costs are expected to increase as the older population grows.⁷⁾ It is essential to implement systematic interventions to prevent hip fractures and other fall-related fractures that may be precursors to hip fractures.

Fall prevention and osteoporosis treatment are the most critical interventions for preventing fall-related fractures, and much work remains to be done, especially for the former. Over the past 60 years, numerous fall-related studies have been conducted worldwide, revealing various factors contributing to falls, and different fall prevention strategies have been reported.⁸⁾ However, the rate of falls has not changed over the past 60 years, and one in three older adults still falls at least once per year.^1),2) One reason the research results have not been fully reflected in society is that basic information on fall-related fractures is lacking, as comprehensive surveys have not been conducted.

Therefore, we conducted a comprehensive survey of 1,695 falls among 1,074 older adults who had experienced falls, identifying key characteristics. These included the timing (month and time), location, age of the individual, injury sustained, trigger, and direction of the fall.⁹⁾ These findings are essential for developing new ideas for fall prevention programs. Additionally, the survey found that fractures occurred in 10.4％ of falls. However, our previous study did not specifically analyze the characteristics of fracture-related falls.

Although several previous studies have investigated the characteristics of fracture-related falls, they are not comprehensive. This limitation is because they only focused on significant fractures such as hip fractures. Further, they only investigated frail older adults and examined the characteristics of falls from a single perspective.^10)-14) Fall-related fractures in older adults progress in stages, with prior fractures of the forearm, humerus, and spine increasing the risk of hip fractures, which are the most severe fall-related fractures.^12),15) Given this “fracture chain,” it is essential to understand the characteristics of falls that lead to even minor fractures that do not require surgery or hospitalization.

Therefore, this study explored the relationship between fall patterns and fall-related fractures. By identifying fall patterns more likely to result in fractures, this study enhances the effectiveness of fall-related fracture prevention, especially in preventing secondary fragility fractures.

Methods

Study design and participants.

We used cross-sectional observational survey data from the Maibara Study 2024, a survey of community-dwelling older adults aged ≥ 65 who lived independently and did not require long-term care. An observational mail survey was conducted in March 2024. The survey was sent to 5,567 older adults, of whom 3,795 responded. Among these, 132 were deemed incomplete, leaving 3,663 valid responses. Over the past three years, 1,074 individuals have experienced at least one fall. Of these, 663 fell once, 201 fell twice, and 210 fell thrice, resulting in 1,695 falls. Similarly, 120 individuals sustained at least one fracture during the same period. Of these, 88 had a single fracture, eight had two, and 24 had three, of which 176 were analyzed [Fig. 1]. This study was conducted per the guidelines of the Declaration of Helsinki. Moreover, the Ethics Committee of the Faculty of Human Sciences at the University of Tsukuba reviewed and approved the study protocol.

Fig. 1

Flow diagram for inclusion in the survey. In this study, 5,567 older adults were sent the survey, of whom 3,795 responded. Of these, 132 surveys were deemed incomplete, resulting in a final total of 3,663 valid responses. Over the past three years, 1,074 individuals have experienced at least one fall. Of these, 663 individuals fell just once, 201 fell twice, and 210 fell thrice, leading to 1,695 falls analyzed. Similarly, 120 individuals suffered at least one fracture during the same period. Of these, 88 had one fracture, eight had two, and 24 had three, totaling 176 fractures analyzed.

Investigation of fall and fall-related fracture characteristics.

We investigated the incidence of falls over the past three years using a self-administered mailed survey. Falls were defined as occasions when participants unintentionally and suddenly came to rest on the ground or a surface lower than their original position. This definition excludes falls triggered by extraordinary environmental factors, such as traffic accidents or falls while riding a bicycle.¹⁶⁾ Data on up to three memorable falls over the past three years were collected. For each fall, a thorough investigation was conducted to determine the month, time, location, direction, trigger, and the resulting injuries. This study used data on the direction and trigger of falls and the resulting fractures. The respondents were asked to choose their fall direction and trigger from predefined options. The list of directions for falling included the following options: forward, backward, sideways, straight-down, and inability to recall. The direction of the fall is defined as the direction in which the body is tilted with respect to the foot. For example, if the body is tilted forward with respect to the foot, this is classified as a forward fall, and if the body is tilted to either side, this is classified as a sideways fall. Similarly, the list of fall triggers included the following: trip, loss of balance, slip, tangled legs, misplaced steps, dizziness, leg-giving away, others, and inability to recall. The respondents were asked to indicate whether each fall resulted in a fracture. If a fracture was present, the patients were required to specify its location. The details of this fall-related survey have already been reported.⁹⁾

Demographic and covariate variables.

We investigated various demographic and covariate variables, including age, height, weight, sex, frailty status,^17),18) and specific comorbidities.

Statistical analyses.

A matrix of fall triggers and directions was created, and the number and percentage of falls and fall-related fractures in each category were tabulated. Multivariate logistic regression analysis was used to examine the association between the occurrence of fall-related fractures and each fall trigger and direction. In each analysis, the category with the lowest rate of fracture occurrence was used as the reference, and age, sex, presence of osteoporosis, and frailty status were included as covariates. Data were analyzed using SPSS Windows software version 28.0, with statistical significance as P ＜ 0.05.

Results

Of the 1,695 falls, 176 resulted in fractures in 10.4％ of cases. The forearm was the most common fracture site, occurring in 40 cases, followed by the spine in 34 cases and the patella in 16 cases. Hip fracture, one of the most severe fall-related health problems, occurred in 11 patients. Demographic and clinical variables are listed in Table 1. There were no differences in age, BMI, frailty status, or number of falls in the past three years between older adults with and without fractures (P ＞ 0.05). However, there were significant differences in sex distribution and presence of osteoporosis (P ＜ 0.001). Over the past three years, 120 individuals have experienced at least one fracture. Of these, 88 individuals fractured just once, eight fractured twice, and 24 fractured three times; 176 fractures were analyzed.

Table 1

Demographic characteristics

Impact of fall direction and trigger matrix on fall incidents [Table 2].

Tripping was the most common trigger for falls, accounting for 32.3％ of the 1,695 falls. Loss of balance and slipping accounted for 21.3％ and 16.0％ of falls, respectively. The most common direction of fall was forward (45.3％), followed by backward or straight-down (23.1％) and sideways (21.2％). In terms of the combination of triggers and direction of falls, the highest percentage of falls was forward due to tripping (25.9％), followed by sideways due to loss of balance (7.6％), and backward or straight-down due to slipping (7.3％).

Table 2

Impact of the fall direction and trigger matrix on fall incidents and fall-related fracture incidents

Impact of fall direction and trigger matrix on fall-related fractures [Fig. 2 and Table 2].

Loss of balance was the most common trigger for fall-related fractures, accounting for 32.4％ of 176 fractures. Slipping and tripping accounted for 18.8％ and 12.5％ of the fall-related fractures, respectively. Slipping (adjusted ORs: 3.00 [95％ CI: 1.69-5.32]) and loss of balance (adjusted ORs: 4.70 [95％ CI: 2.77-7.98]) were associated with a significantly elevated risk of incident fall-related fractures, according to the results of the multivariate analyses using tripping as the reference. The most common directions of the fall-related fractures were backward or straight-down (34.7％) and sideways (31.8％), followed by forward (21.0％). Backward or straight-down (adjusted ORs: 3.23 [95％ CI: 2.08-5.02]) and sideways (adjusted ORs: 3.68 [95％ CI: 2.35-5.76]) were associated with a significantly elevated risk of incident fall-related fractures. This was based on the results of the multivariate analyses using forward as the reference. Regarding triggers and directions combination for fall-related fractures, the highest percentage occurred sideways owing to loss of balance (12.5％), followed by backward or straight-down owing to loss of balance (11.9％), and backward or straight-down owing to slipping (9.7％).

Fig. 2

The impact of the fall trigger and direction on fall-related fractures. a: Slipping (adjusted ORs: 3.00 [95％ CI: 1.69-5.32]) and loss of balance (adjusted ORs: 4.70 [95％ CI: 2.77-7.98]) were associated with a significantly elevated risk of incident fall-related fractures, according to the results of the multivariate analyses using tripping as the reference. b: Backward or straight-down (adjusted ORs: 3.23 [95％ CI: 2.08-5.02]) and sideways (adjusted ORs: 3.68 [95％ CI: 2.35-5.76]) were associated with a significantly elevated risk of incident fall-related fractures, according to the results of the multivariate analyses using forward as the reference.

Relationship between fall direction and fracture site [Fig. 3].

In fractures resulting from forward falls the forearm was most frequently fractured (40.5％), followed by the patella (16.2％). Spinal fractures were the most common fractures resulting from backward or straight-down falls, accounting for 45.9％ of the fractures in this fall direction. Various fracture sites have been observed in fractures resulting from sideways falls, with a trend toward an increased proportion of hip fractures specific to this fall direction.

Fig. 3

The relationship between fall direction and fracture site. a: In fractures resulting from forward falls, the forearm was the most frequently fractured site, accounting for 40.5％ of cases, followed by the patella at 16.2％. b: For fractures resulting from backward or straight-down falls, spinal fractures were the most common, comprising 45.9％ of fractures in this category. c: Various fracture sites were observed in the case of sideway falls, with an increased proportion of hip fractures (10.7％) and ankle/foot fractures (17.9％) specific to this fall direction.

Discussion

Of the 1,695 falls among the 1,074 older adults who had experienced falls, 176 fractures occurred in 120. Two-thirds of all fractures were caused by backward, straight-down, or sideways falls. Compared to forward falls, backward, straight-down and sideway falls had a higher incidence of fractures, with adjusted ORs of 3.23 and 3.68, respectively. Approximately 50％ of all fractures are caused by falls triggered by slipping and losing balance. Compared with falls owing to trips, the incidence of fractures was higher for falls due to slips and loss of balance, with adjusted ORs of 3.00 and 4.70, respectively. Approximately 45％ of the falls were forward falls, with more than 25％ resulting from tripping. The percentage of fractures resulting from this fall pattern is relatively low. Among these, a high proportion involve fractures of the forearm and patella. Backward or straight-down falls accounted for approximately 23％ of the falls, most of which were due to slips or loss of balance. The proportions of fractures resulting from this fall pattern were relatively high at 9.7％ and 11.9％, respectively. Spinal fractures were exceptionally high when the fall was backward or straight-down. Sideways account for approximately 21％ of falls, primarily due to loss of balance. Fractures were the most common fall pattern, accounting for 12.5％ of all fractures. Sideway falls resulted in various fractures, with hip and ankle/foot fractures being more common, showing an increase compared to other types of fractures.

In this study, fractures occurred in 10.4％ of all falls, significantly higher than the 5％ reported in previous studies.³⁾ In our earlier report, we suggested that one possible reason for this is that Japanese older adults tend to have a lower BMI, resulting in reduced shock-absorbing capacity of soft tissues during falls.⁹⁾ Although a high rate of forward falls owing to tripping was observed in the present study, the rate of fractures associated with this pattern was relatively low. Conversely, the percentage of fractures increased when falls occurred sideways, backward, or straight-down, owing to slipping or losing balance. A more significant proportion of older Japanese adults may experience these fall patterns than older adults in Western countries. In a previous study on the triggers of falls among older American adults, 34％ of falls occurred due to tripping, similar to the 32.3％ observed in this study. In contrast, only 9％ were because of loss of balance, significantly lower than the 21.3％ observed in our study.¹⁹⁾ Although this information alone may not fully support the discussion above, it suggests the possibility of significant differences in fall patterns across countries and regions.

Older adults often fracture their forearms or patella when they fall forward owing to tripping. Maintaining sufficient toe clearance from the initial to middle swing phases of walking is essential to avoid tripping. If the toe contacts the ground or obstacle during this phase, it may induce a forward fall. Although minimum toe clearance does not differ significantly between younger and older adults, older adults tend to be more unstable than younger adults, particularly those who have experienced falls.²⁰⁾ This high instability is likely to increase the risk of tripping. In a forward fall, older adults may fracture their patella or forearm when the knee or hand first makes contact with the ground, often because of extending their hand to break the fall. This relationship is consistent with findings from a previous study.¹⁴⁾

Older adults often fracture their spines when they fall backward or straight-down because of slipping. The horizontal-to-vertical force ratio is the highest during heel contact while walking, which can trigger the foot to slip forward, inducing a backward fall.²¹⁾ Slipping may also be associated with environmental inadequacy and impaired environmental awareness. Improving environmental conditions can often prevent falls.²²⁾ Even in such inadequacies, falls may be avoided if older adults recognize and respond appropriately. Conversely, if the cognitive abilities related to the environment are impaired, avoiding falls becomes more complex.²¹⁾ During a backward fall triggered by these factors, older adults may strike their buttocks, leading to a spinal fracture.

When older adults experience sideways falls because of a loss of balance, fractures at various sites can occur, with a notable increase in hip fractures associated with this fall pattern. Balance is crucial for preventing falls and fall-related fractures. Among the various physical functions, one-leg standing time, a critical balance indicator declines significantly with age.²³⁾ The observed increase in hip fractures in this fall direction is consistent with the findings of previous studies.^10),11),14)

This study had three strengths. First, we investigated 1,695 falls among older adults, resulting in 176 fractures, and identified the characteristics of falls that lead to these fractures. Most studies on this topic have focused solely on individuals who experience fractures and lack information on those who fall without sustaining fractures. Second, this study included all types of fall-related fractures, not just severe fractures such as hip fractures. Given the concept of a “fracture chain,” it is significant that the characteristics of falls leading to forearm and spine fractures―considered precursors to hip fractures―were identified. Third, we analyzed falls from multiple perspectives, not just one aspect, and explored the relationship between fall patterns and fractures. By understanding these specific fall patterns, we collected information that could be directly applied to more effective fall prevention interventions.

This study had three limitations. First, although falls are influenced by internal, external, and behavioral factors, investigations of these factors are limited. Although frailty was assessed, key physical or cognitive function indicators such as muscle strength, balance, memory, and executive functions were not measured. Additionally, although environmental factors are believed to impact fall incidents significantly, this study did not examine these factors. Moreover, the risk of falling increases with significant indoor and outdoor activities; however, no detailed behavioral investigations have been conducted. Second, recall bias may have been present as the incidence of falls over the past three years was examined. Third, serious falls resulting in death or severe disability were not investigated, as this study focused on past falls. Consequently, the most critical and severe fall incidents may not have been included in this analysis.

In conclusion, we investigated 1,695 falls among older adults, resulting in 176 fractures, and identified the characteristics of the falls that led to these fractures. The incidence of fractures varies significantly depending on fall patterns. Each major fall-related fracture was associated with a specific fall pattern: falling forward due to tripping resulting in forearm and patella fractures, falling backward or straight-down due to slipping or loss of balance leading to spine fractures, and falling sideways due to loss of balance resulting in hip fractures. This information provides essential knowledge for developing effective fall fracture prevention strategies.

Acknowledgments

The authors acknowledge Ms. Sayuri Natsu-hara for her contributions to data collection.

Conflicts of interest

The authors have no potential conflicts of interest to disclose.

Author contributions

Minoru Yamada, Conceptualization, Investigation, Writing-original draft.

Yusuke Terao, Conceptualization, Investigation, Writing-review, and editing.

Iwao Kojima, Conceptualization, Investigation, Writing-review, and editing.

Shu Tanaka, Conceptualization, Investigation, Writing-review, and editing.

Hiroki Saegusa, Conceptualization, Investigation, Writing-review, and editing.

Miho Nanbu, Conceptualization, Investigation, Writing-review, and editing.

Shiho Soma, Conceptualization, Investigation, Writing-review, and editing.

Hiroki Matsumoto, Conceptualization, Investigation, Writing-review, and editing.

Masaya Saito, Conceptualization, Investigation, Writing-review, and editing.

Kohei Okawa, Conceptualization, Investigation, Writing-review, and editing.

Naoto Haga, Conceptualization, Investigation, Writing-review, and editing.

Hidenori Arai, Conceptualization, Writing-review, and editing.

Sponsor’s role

This work was supported by JSPS KAKENHI (Grant Numbers JP21H02834 and JP23K17565).

Notes

Edited by Tadao KAKIZOE, M.J.A.

Correspondence should be addressed to: H. Arai, National Center for Geriatrics and Gerontology, 7-430, Morioka-cho, Obu, Aichi 474-8511, Japan (e-mail: [e-mail]).

References

• 1)  Bergen, G., Stevens, M.R. and Burns, E.R. (2016) Falls and fall injuries among adults aged ≥ 65 years ― United States, 2014. MMWR Morb. Mortal Wkly. Rep. 65, 993-998.
• 2)  Sheldon, J.H. (1960) On the natural history of falls in old age. Br. Med. J. 2, 1685-1690.
• 3)  Kelsey, J.L., Procter-Gray, E., Hannan, M.T. and Li, W. (2012) Heterogeneity of falls among older adults: implications for public health prevention. Am. J. Public Health 102, 2149-2156.
• 4)  Davis, J.C., Robertson, M.C., Ashe, M.C., Liu-Ambrose, T., Khan, K.M. and Marra, C.A. (2010) International comparison of cost of falls in older adults living in the community: a systematic review. Osteoporos. Int. 21, 1295-1306.
• 5)  Newgard, C.D., Lin, A., Caughey, A.B., Eckstrom, E., Bulger, E.M., Staudenmayer, K. et al. (2021) The cost of a fall among older adults requiring emergency services. J. Am. Geriatr. Soc. 69, 389-398.
• 6)  Moriwaki, K., Komaba, H., Noto, S., Yanagisawa, S., Takiguchi, T., Inoue, H. et al. (2013) Cost-effectiveness of alendronate for the treatment of osteopenic postmenopausal women in Japan. J. Bone Miner. Res. 28, 395-403.
• 7)  Cheung, C.-L., Ang, S.B., Chadha, M., Chow, E.S.-L., Chung, Y.-S., Hew, F.L. et al. (2018) An updated hip fracture projection in Asia: The Asian Federation of Osteoporosis Societies study. Osteoporos. Sarcopenia 4, 16-21.
• 8)  Colón-Emeric, C.S., McDermott, C.L., Lee, D.S. and Berry, S.D. (2024) Risk assessment and prevention of falls in older community-dwelling adults: a review. JAMA 331, 1397-1406.
• 9)  Yamada, M., Terao, Y., Kojima, I., Tanaka, S., Saegusa, H., Nanbu, M. et al. (2024) Characteristics of falls in Japanese community-dwelling older adults. Geriatr. Gerontol. Int. 24, 1181-1188.
• 10)  Greenspan, S.L., Myers, E.R., Kiel, D.P., Parker, R.A., Hayes, W.C. and Resnick, N.M. (1998) Fall direction, bone mineral density, and function: risk factors for hip fracture in frail nursing home elderly. Am. J. Med. 104, 539-545.
• 11)  Hwang, H.-F., Lee, H.-D., Huang, H.-H., Chen, C.-Y. and Lin, M.-R. (2011) Fall mechanisms, bone strength, and hip fractures in elderly men and women in Taiwan. Osteoporos. Int. 22, 2385-2393.
• 12)  Klotzbuecher, C.M., Ross, P.D., Landsman, P.B., Abbott, T.A. and Berger, M. (2000) Patients with prior fractures have an increased risk of future fractures: a summary of the literature and statistical synthesis. J. Bone Miner. Res. 15, 721-739.
• 13)  Lim, S.-K., Beom, J., Lee, S.Y., Kim, B.R., Chun, S.-W., Lim, J.-Y. et al. (2020) Association between sarcopenia and fall characteristics in older adults with fragility hip fracture. Injury 51, 2640-2647.
• 14)  Nevitt, M.C. and Cummings, S.R. (1993) Type of fall and risk of hip and wrist fractures: the study of osteoporotic fractures. The Study of Osteoporotic Fractures Research Group. J. Am. Geriatr. Soc. 41, 1226-1234.
• 15)  Ariie, T., Yamamoto, N., Tsutsumi, Y., Nakao, S., Saitsu, A., Tsuge, T. et al. (2024) Association between a history of major osteoporotic fractures and subsequent hip fracture: a systematic review and meta-analysis. Arch. Osteoporos. 19, 44.
• 16)  Koski, K., Luukinen, H., Laippala, P. and Kivela, S.L. (1996) Physiological factors and medications as predictors of injurious falls by elderly people: a prospective population-based study. Age Ageing 25, 29-38.
• 17)  Arai, H. and Satake, S. (2015) English translation of the Kihon Checklist. Geriatr. Gerontol. Int. 15, 518-519.
• 18)  Satake, S., Senda, K., Hong, Y.-J., Miura, H., Endo, H., Sakurai, T. et al. (2016) Validity of the Kihon Checklist for assessing frailty status. Geriatr. Gerontol. Int. 16, 709-715.
• 19)  Berg, W.P., Alessio, H.M., Mills, E.M. and Tong, C. (1997) Circumstances and consequences of falls in independent community-dwelling older adults. Age Ageing 26, 261-268.
• 20)  Barrett, R.S., Mills, P.M. and Begg, R.K. (2010) A systematic review of the effect of ageing and falls history on minimum foot clearance characteristics during level walking. Gait Posture 32, 429-435.
• 21)  Lin, L.-J., Chiou, F.-T. and Cohen, H.H. (1995) Slip and fall accident prevention: A review of research, practice, and regulations. J. Safety Res. 26, 203-212.
• 22)  Clemson, L., Stark, S., Pighills, A.C., Fairhall, N.J., Lamb, S.E., Ali, J. et al. (2023) Environmental interventions for preventing falls in older people living in the community. Cochrane Database Syst. Rev. 3, CD013258.
• 23)  Mayhew, A.J., So, H.Y., Ma, J., Beauchamp, M.K., Griffith, L.E., Kuspinar, A. et al. (2023) Normative values for grip strength, gait speed, timed up and go, single leg balance, and chair rise derived from the Canadian longitudinal study on ageing. Age Ageing 52, afad054.