Distal radial fracture is the most common upper-extremity fracture in elderly women1,2, and a lifetime risk of the fracture in premenopausal woman is no less than 15% to 20%2. Patients with a fragility fracture of the distal radius have a twofold to fourfold higher risk of a subsequent fracture than those with no prior fracture3,4, and distal radial fractures occur on average fifteen years earlier than hip fractures5. To reduce the risk of future fractures, it would be useful to identify the risk factors for patients sustaining their first distal radial fracture.
Distal radial fractures usually result from a fall during daily activities in susceptible individuals1,6,7. Accordingly, risk factors of distal radial fracture are expected to be associated with an increased risk of falling in general8. However, little is known regarding factors associated with increased risk of falls in patients with distal radial fracture. Silman found that women who walked regularly had a higher risk of distal radial fracture than those who did not walk regularly2, and Kelsey et al. found that patient-reported difficulty in performing physical functions was associated with a decreased risk of distal radial fracture8. These results suggest that distal radial fractures may be associated with increased activity level in contrast to hip fractures, which occur in less active and more debilitated patients9-11. However, Mallmin et al. found a protective effect of moderate daily physical activity or leisure activity on the occurrence of distal radial fracture12. Therefore, it may be the combination of maintained physical activity with subtle declines in physical performance that increase risk of distal radial fracture. The goal of our study was to compare physical performance measures and fall risk factors in patients with recent distal radial fractures compared with age-matched control patients.
Materials and Methods
This study was approved by the institutional review board of our hospital. From January 2011 to January 2012, we prospectively recruited patients with a distal radial fracture who had been treated surgically or non-surgically at our institution six months prior to enrollment for the study. Inclusion criteria were postmenopausal women more than fifty years old who agreed to participate in the study and had fractured their wrist with a fall on an outstretched hand. Exclusion criteria included (1) associated physical injuries, (2) cognitive impairment, and (3) medical conditions such as neuromuscular disease or chronic debilitating disease that were considered to affect muscle strength. Of 124 patients who were treated for a distal radial fracture during the study period, eighty-five consecutive patients who fulfilled the six-month follow-up assessment were screened for enrollment for this study, and fifty-five patients met our inclusion criteria. Of those fifty-five patients, we excluded fifteen according to the exclusion criteria; thus, a total of forty patients were included as the patient group. The controls were postmenopausal women with a unilateral upper-extremity condition such as carpal tunnel syndrome, tenosynovitis, or epicondylitis of the elbow within the same period. The same exclusion criteria for patient group were applied. A history of a fall within the last two years or a prior distal radial fracture was additional exclusion criteria for the control group. A total of 325 postmenopausal women with unilateral upper-extremity condition were screened for enrollment, and 196 individuals were identified as meeting our criteria. Among these individuals, forty controls were randomly selected and were individually matched for age (within one year) to patients. Demographic information of the two groups is presented in the Appendix.
Assessment of Physical Performance
Physical performance was evaluated with the Short Physical Performance Battery and grip strength13-15. In addition, the level of physical activity was evaluated on the basis of the daily amount of time spent walking1,2,9. The Short Physical Performance Battery, which mainly assesses lower-extremity function, is composed of three components: standing balance, walking speed, and the ability to rise from a chair (chair stand)13. The test of standing balance included tandem, semi-tandem, and side-by-side stands13. Walking speed was tested by having each subject walk a 2.4-m (8-foot) straight course at a self-selected normal walking speed13. To test the chair stand, the subject was asked to stand up and to sit down five times as quickly as possible, and was timed from the initial sitting position to the final standing position13. A summary performance score was created by summing each score (see Appendix). A higher score signifies a better performance13. We separately analyzed direct time measurements of the chair stand and the walking speed test. The grip strength of the unaffected hand was measured with use of a Jamar dynamometer (Asimow Engineering, Los Angeles, California) with the elbow flexed at 90° and the forearm in a neutral rotation16. The mean values of three trials were recorded in kilograms. For the adjustment of hand dominance, the grip strength of the left hand was multiplied by 1.1 according to the simple rule that the dominant hand is approximately 10% stronger than the nondominant hand for right-handed subjects17. This rule was not applied to left-handed subjects. The Short Physical Performance Battery and grip strength were measured by a single orthopaedic surgeon (C.H.S.), who was not blind to study groups. The amount of time spent daily on walking was evaluated by asking the subjects to provide the self-estimated amount of time per day that they spent walking. On the basis of walking hours per day, patients were categorized into three groups: walking less than thirty minutes, walking from thirty minutes to one hour, or walking more than one hour.
Assessment of Other Fall Risk Factors
A number of risk factors for falls have been described in the literature6,8,18-22. Aside from risk factors regarding physical performance, fall risk factors that were assessed in this study include low body mass index, dizziness or vertigo, osteoarthritis, arrhythmia, depression, visual disturbance, hypotension, use of antihypertensive drugs, sedatives or hypnotics, or antidepressants, and use of four or more medications18-21. Subjects with a history of fragility fractures, which has been consistently identified as an isolated risk factor of distal radial fracture6,8,22, were excluded from this study as we excluded those with a history of distal radial fracture from the control group. Height and weight of the subject were measured with stadiometers and scales in the clinics. Information on risk factors was obtained with use of an interviewer-administered questionnaire. The interviewer (C.H.S.) was not blinded to the groups. Patients with dizziness or vertigo were asked about the presence of subjective symptoms within the last year. However, only physician-diagnosed osteoarthritis, arrhythmia, and depression were considered valid. Visual capability was assessed by asking subjects if they had subjective symptoms of visual disturbance or were diagnosed as having visual deficiency by an ophthalmologist. Medications that subjects were currently using were ascertained by requested prescriptions or medications brought into the clinics.
For the determination of sample size, we used the Short Physical Performance Battery summary score as the primary outcome and attempted to detect a difference of 1 point between the groups. A previous study showed that the mean value (and standard deviation) of the Short Physical Performance Battery summary score of community-dwelling elderly adults was 8.8 ± 1.5 points23. On the basis of these normative data, we calculated that the inclusion of forty participants in each group would provide 80% power and a two-sided alpha level of 0.05 with use of a t test.
Continuous variables were compared between the two groups with use of the Student t test. The chi-square test was used for categorical variables. A conditional logistic regression test was used to analyze the odds ratios with 95% confidence intervals (95% CIs) for the occurrence of distal radial fracture. Significance was set at p < 0.05.
Source of Funding
This study was supported by a grant (Grant No. 06-2011-051) by Ildong Pharmaceutical to one author (H.S.G.). Funds were used to pay for laboratory fees and salaries.
Comparison of Physical Performance
No significant differences were found in the Short Physical Performance Battery summary score (including walking speed score and standing balance score) and walking hours per day between the two groups (Table I). However, the patient group had a significantly lower chair stand score and grip strength than the control group (Table I). The mean chair stand score (and standard deviation) was 3.3 ± 0.8 points for the patient group and 3.6 ± 0.6 points for the control group (p = 0.034). The mean direct measurement (and standard deviation) of the chair stand test was 11.2 ± 1.9 seconds for the patient group and 10.4 ± 1.5 seconds for the control group (p = 0.018). The mean grip strength (and standard deviation) was 14.4 ± 3.5 kg for the patient group and 16.7 ± 5.9 kg for the control group (p = 0.038).
Comparison of Other Potential Fall Risk Factors
No significant differences were found in other potential fall risk factors between the two groups (Table II).
Logistic Regression Analyses
Conditional logistic regression analysis showed that a decreased incidence of distal radial fracture was associated with higher chair stand score (odds ratio, 0.316 [95% CI, 0.126 to 0.794]) and higher grip strength (odds ratio, 0.881 [95% CI, 0.773 to 0.980]) (Table III).
Several studies have shown contradictory results regarding the level of physical activity in patients with distal radial fracture1,2,12. However, no studies have evaluated the level of physical performance in patients with distal radial fracture using direct measurement. We were not able to demonstrate a significant difference of the Short Physical Performance Battery summary score between the two groups. However, chair stand ability and grip strength were significantly lower in the patient group with distal radial fracture. Given the overlapping standard deviations in chair stand ability and grip strength between the two groups, its clinical implication is unclear. However, there is a possibility that the differences in chair stand ability and grip strength might represent a subtle decrease in physical performance level that was not reflected in the Short Physical Performance Battery summary score.
The chair stand test has been associated with lower-extremity strength, balance, sensorimotor function, psychological factors, and cardiopulmonary function24,25. Nevitt et al. found that difficulty in standing up from a chair is a risk factor of a fall in their prospective study26. Although grip strength assesses primarily muscle function in the upper extremity, it has been described as a reasonable surrogate measure for general physical function such as nutritional status, strength of other muscle groups, fatigue, and susceptibility to injury14,15,27,28. Stalenhoef et al. found that low hand grip strength increases risk of recurrent falls in their prospective cohort study29. Therefore, decreased chair stand ability and lower grip strength of the patient group might suggest subtle changes in general physical performance level.
In fragility hip fractures, the effect of deficient physical performance on the occurrence of fractures has been well described9,11. Cummings et al. identified thirteen risk factors for hip fractures in their prospective study9. Among these risk factors, those that primarily reflect physical performance include poor self-rated health, standing less than four hours per day, inability to rise from a chair without using one’s arms, poor depth perception, and poor contrast sensitivity. Grisso et al. found that increased risk of hip fractures is associated with lower-limb dysfunction and visual impairment30. Nevertheless, studies concerning risk factors of distal radial fracture have concluded that distal radial fractures do not tend to occur in individuals exhibiting poorer physical performance, based on inference from questionnaires about physical activity or medical conditions8,10. However, the direct measurements of our study suggest that although distal radial fractures are not associated with a reduction in overall physical performance level, they are associated with a small but significant difference in grip strength and chair stand test scores.
In this study, no significant associations were identified with regard to previously known fall risk factors. This result is in close agreement with those of earlier studies1,2,12,22. Given that distal radial fractures tend to occur at a relatively young age compared with other osteoporotic fractures6, these negative results were expected to some extent. It is possible that changes in physical performance might have been initiated prior to the appearance of other fall risk factors in the patient group with distal radial fracture.
Randomized controlled trials and meta-analyses have demonstrated that strength and balance training for healthy elderly people can significantly reduce the risk of falling3,19,25,31. However, these studies largely examined patients over sixty-five years of age31. Furthermore, the evidence of effectiveness regarding exercise for the prevention of osteoporotic fractures is not yet sufficient32. Further studies are warranted on whether exercise would be helpful for preventing subsequent fractures in patients experiencing their first distal radial fracture.
In this study, the control group was not recruited from the normal healthy population. The general characteristics of physical performance levels of the patients who visit an orthopaedic hand surgeon’s office have not been well validated. However, a number of upper-extremity conditions are related to chronic medical conditions. For instance, individuals with diabetes, alcohol abuse, obesity, or thyroid disease are susceptible to compressive neuropathies33. Although we excluded subjects with known chronic medical conditions, some of the controls might have been affected by undiagnosed medical conditions. In addition, the level of physical performance of controls could be influenced by their upper-extremity conditions. Therefore, it is possible that a comparison with normal healthy controls may have revealed greater differences in the levels of physical performance or other risk factors.
Our study had some limitations. First, the sample size was rather small for assessing many fall risk factors. Furthermore, our sample size determination was performed on the basis of the Short Physical Performance Battery summary score in which we failed to prove significant difference. Consequently, the findings regarding chair stand ability and grip strength could be opportunistic, and the possibility of increased type-I error should be considered. However, we separately calculated the sample size with use of previous data on chair stand score and grip strength, which showed that the current sample size could produce about 80% power with use of the t test when the target difference was 0.5 point34,35. Second, the interviewer (C.H.S.) and the physician (H.S.G.) who examined patients were not blinded to the study groups, which may have introduced bias. Third, this is a cross-sectional study, so the association between physical performance measures and falls may not have been causally related. A longitudinal study would be necessary to demonstrate causality.
In summary, this study suggests that overall physical performance level is not different between women with a distal radial fracture and those with no distal radial fracture. However, differences in chair stand test scores and grip strength may imply early subtle decrease in physical performance level in patients with distal radial fracture. Further studies are warranted on whether preventive measures such as muscle strengthening exercise would be helpful for preventing future fall events and fractures in patients with a distal radial fracture.
Tables showing demographic information and the Short Physical Performance Battery are available with the online version of this article as a data supplement at jbjs.org.
A commentary by Leon S. Benson, MD, is linked to the online version of this article at jbjs.org.
Investigation performed at the Department of Orthopedic Surgery, Seoul National University Bundang Hospital, Seongnam, South Korea
Peer Review: This article was reviewed by the Editor-in-Chief and one Deputy Editor, and it underwent blinded review by two or more outside experts. It was also reviewed by an expert in methodology and statistics. The Deputy Editor reviewed each revision of the article, and it underwent a final review by the Editor-in-Chief prior to publication. Final corrections and clarifications occurred during one or more exchanges between the author(s) and copyeditors.
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Disclosure: One or more of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of an aspect of this work. None of the authors, or their institution(s), have had any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, no author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.