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Comparison of the Effect of Cane, Tripod Cane Tip, and Quad Cane on Postural Steadiness in Healthy Older Adults

Bateni, Hamid PhD; Collins, Prisca PT, PhD; Odeh, Christina PT, DHSc

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Journal of Prosthetics and Orthotics: April 2018 - Volume 30 - Issue 2 - p 84-89
doi: 10.1097/JPO.0000000000000176
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Assistive devices, such as walking frames (walkers) and canes, often are prescribed to help individuals maintain balance while performing activities of daily living, by reducing fatigue, pain due to clinical pathologies (e.g., hip fractures), and weight bearing on the lower limbs.1–4 Such devices are intended to improve balance control, either through direct mechanical stabilization or indirectly, through the additional haptic sensory information to the user.5,6 Some researchers, however, have suggested that the use of assistive devices actually may jeopardize stability and increase risk of falling in certain situations.7–9 It is estimated that nearly 50,000 older adults (65 years and older) are treated yearly in emergency rooms in the United States because of falls associated with assistive devices.9 These findings are in agreement with previous reports on potential disadvantages of the use of mobility aids and the possibility of mobility aids impeding performance of compensatory reactions.10–12

Previous studies also have suggested that one problem contributing to an increased risk of falling pertains to the potential for walking frames or canes to interfere with or constrain lateral movement of the legs. Such interference can impair the user's capacity to execute compensatory stepping reactions during a lateral loss of balance.10–12 Stepping reactions are prevalent and functionally important responses to a loss of balance13,14 and often represent the only recourse in the event that the stability limits established by the walker or cane are exceeded. Researchers also have suggested that walkers, because of their design and the fact that they can limit performance of compensatory reactions more than canes can, increase the risk of falls.10–12 In fact, a more recent study showed that approximately 12% of falls associated with the use of mobility aids were associated with use of canes and 87% were associated with the use of walkers.9 When a new walker was designed with a larger arch to allow a better performance of compensatory reactions, tests indicated a significantly lower collision with the moving foot.15 These findings lead to a conclusion that although walkers provide more stability, they also can limit the stepping reactions more than canes and raise the risk of falling to a higher level.

Quad canes are known to provide a better stability than straight canes owing to an increased base of support.16 It is highly likely, however, that quad canes also increase the chance of falling in certain situations when compared with canes because of an increased potential for foot-device collisions. It is also expected that quad canes do not increase chance of falling as much as walkers do when performance of stepping reactions are imperative for controlling upright posture.

Recently, a tripod cane tip was introduced with a promising design benefiting from a small base as compared with the quad cane. The tip design provides a larger base of support and presumably better stability and haptic information than a straight cane. Similar to the quad cane, the tripod also allows individuals to release the cane when not needed, leaving it to stand alone in an upright position. When compared with the quad cane, however, the tripod may reduce the chance of falling because of its smaller size and, therefore, reduced risk of collision with the moving foot. It is not yet clear, however, whether the use of a tripod cane tip improves postural stability over use of straight cane. A first step in testing the tripod design, therefore, is to identify its potential benefits on postural control as compared with that of straight canes and quad canes. The purpose of this study was to compare the impact of the tripod cane tip, the straight cane, and the quad cane on postural stability in older adults as defined by changes in time and frequency domain variables of postural sway. The time and frequency domain variables of postural sway were assessed to establish differences for mean distance, root-mean-square distance, 95% confidence circle area of sway, power, 95% power frequency, and centroidal frequency of postural sway signal as defined by movement of center of pressure (COP).


A written consent form was obtained from all participants before participating in the study. After approval from the institutional review board of Northern Illinois University was obtained, 16 healthy older adults (8 men and 8 women) between the ages of 62 and 84 years (mean [SD], 73.5 [7.3] years) were recruited to participate in the study. Participants were included if they were right-handed and right-legged and had no physical or cognitive disability that could potentially affect postural balance. Individuals with any uncorrected visual or vestibular deficits and those with a history of injury or surgery of the lower limbs in the past 6 months were excluded from participation. A Kistler-9287BA force platform (Kistler Co, Winterthur, Switzerland) was used to collect COP data at 100 Hz. During testing, participants stood barefoot on the force platform with either tandem (Romberg position) or double-limb support (heels together, approximately 7° toe out for each foot), with the knees extended and the arms relaxed. For each trial, subjects were instructed to stand straight and look straight ahead. Data were collected for 30 seconds for each trial. In some trials, participants were instructed to apply a load on the cane as suggested in literature.10 This load was recorded using a load cell embedded in each cane and was monitored throughout the trials. When participants failed to apply the proper range of load throughout a trial, the trial was repeated.

Three cane types were compared: a) a straight cane, b) a quad cane, and c) a straight cane fitted with a tripod cane tip (AbleTripod from L.A. Care Industries, West Hartford, CT, USA; see Figure 1). In subsequent references to this device (AbleTripod), the term “tripod cane” is used. To compare the three different canes, participants were randomly assigned (block randomization) to 54 cane trials (six conditions, three different canes, three repetitions) and three additional trials where they stood in a bilateral stance with no cane in hand (no-device condition). Conditions were 1) eyes open, standing heels together (double stance), less than 5% body weight (BW) load on the cane (no load), cane on the side (named “open eyes, double stance, cane on the side” hereafter); 2) same as condition 1, but with eyes closed (named “closed eyes, double stance, cane on the side” hereafter); 3) same as condition 1, but applied a load of approximately 15% to 25% of BW on the cane (named “open eyes, double stance, cane on the sidewl” hereafter); 4) same as condition 1, but standing in tandem position with the dominant leg in the back (named “open eyes, tandem stance, cane on the side” hereafter); 5) same as condition 4, but the cane was located approximately 35 cm anterior to midcoronal plane (named “open eyes, tandem stance, cane in front” hereafter); 6) same as condition 4, but the cane was located approximately 35 cm posterior to the midcoronal plane (named “open eyes, tandem stance, cane in back” hereafter); and 7) eyes open, standing heels together (double stance) and no device being held. To simulate a condition of walking with short steps, the cane was placed 35 cm ahead of or behind the subject in selected trials. The center of the tip of the cane was located 20 to 25 cm lateral to the midsagittal plane (depending on the comfort of the participants). Conditions 1 to 6 were repeated three times for each of the cane types. Anteroposterior and mediolateral time series data acquired from the force platform were filtered through a fourth-order zero-phase Butterworth low-pass filter with a cutoff frequency of 5 Hz.17 The first 10 seconds and the last 2 seconds of each 30-second data acquisition trial were discarded.17 A detailed explanation of time and frequency domain variables computed in this study is available in the literature.17–21 Mean distance of the movement of the COP from the central point was computed as defined in the literature17 using following equations:

Figure 1:
AbleTripod (L.A. Care Industries; used with permission) along with a schematic of straight cane and quad cane.


N = total number of data point and n = individual data point

= mean position of COP in the anteroposterior direction

= mean position of COP in the mediolateral direction

ML[n] = mediolateral (and AP[n] for anteroposterior) position of each point referenced to the mean position of COP

ML[n] = resultant distance between each two points

Mean_dist = mean distance from the mean COP position

Root-mean-square distance (RDIST) was computed as17

The 95% confidence circle area of sway was computed as17:


Z0.05 = Z statistic at the 95% confidence level

SRD = standard deviation of resultant distance

Power of sway signal was computed as the integrated area of power spectrum and 95% power frequency was determined as the point below which 95% of the total power is placed.17 Centroidal frequency of center was computed as square root of the ratio of the second to zeroth spectral moment.17

Matlab (Release 2012b; The MathWorks, Inc, Natick, MA, USA) and SAS/STAT software (version 9.4; SAS Institute Inc. Cary, NC, USA.) statistical analysis software were used for data processing and analysis. Resultant and directional characteristics of postural sway were compared using one-way repeated-measures analysis of variance to identify any significant differences in time and frequency domains (p < 0.05) for each condition separately.

Analyses were focused on mean distance from the central point of COP, root-mean-square distance from the mean COP position, 95% confidence circle area, total power (integrated area of the power spectrum), 95% power frequencies (the frequencies below which 95% of total power is found), and centroidal frequency of the sway signal.


The values of all variables in no device condition were always close to the values of “open eyes, double stance, cane on the side” condition when the straight cane was held (Figure 2). Significant differences between the straight cane, the tripod cane, and the quad cane persisted in all variables in “open eyes, double stance, cane on the side” condition (Table 1). Mean and root-mean-square distance variables, power, centroidal frequency, and 95% confidence circle area were significantly reduced when the tripod cane was held (vs. the straight cane) and reduced more when the quad cane was held. The 95% power frequency increased significantly from straight cane trials to tripod cane trials and from tripod cane trials to quad cane trials. When eyes were closed, a similar pattern was observed, with the exception that differences in 95% confidence circle area and power were not statistically significant between the tripod cane and the other cane types. Although the same pattern was again observed in the “open eyes, tandem stance, cane on the side” and “open eyes, double stance, cane on the sidewl” conditions, only total power values were significantly different between use of the regular and tripod cane types. When the cane was held in front, the differences between the tripod cane and the quad cane were significant for all values, whereas the differences between the straight cane and the tripod cane were significant only for values of root-mean-square distance and 95% confidence circle area. When the device was held in back, the straight cane and the tripod cane did not show significant differences. The tripod cane and the quad cane were not significantly different, except for the values of root-mean-square distance, 95% power frequencies, and centroidal frequency. Overall, it appears that a pattern of performance was established in our findings where tripod cane values always fell between straight cane and quad cane values.

Figure 2:
Average values of mean distance from COP (MDIST), resultant distance (RDIST), 95% confidence circle area (AREA_CC), resultant power (POWER), 95% power frequency (PFREQ95), and centroidal frequency (CFREQ). Each figure shows six different conditions of 1) open eyes, double stance, cane on the side (ODS), 2) closed eyes, double stance, cane on the side (CDS), 3) ODS with load application (ODSwl), 4) open eyes, tandem, cane on the side (OTS), 5) open eyes, tandem, cane in front (OTF), and 6) open eyes, tandem, cane in the back (OTB). Each line represents measurements of three different devices being held (i.e., cane, tripod, and quad cane). The horizontal line depicts the average value of the variable for double stance position with no device held (labeled as Nd). Note that Nd values were always close to the cane values in the ODS condition.
Table 1:
Comparison of mean values for cane, tripod, and quad cane in different conditions and for different variables


The purpose of this study was to compare the impact of tripod cane tip, straight cane, and quad cane on postural stability in older adults as defined by changes in time and frequency domain variables of postural sway. The time and frequency domain variables of postural sway assessed to established differences were mean distance, root-mean-square distance, 95% confidence circle area of sway, power, 95% power frequency, and centroidal frequency of COP movement signal. The mean and root-mean-square distances of sway signal are shown to increase substantially by deterioration of postural steadiness as evident from the changes between young and older adults and also the changes between open eyes and close eyes conditions.17 The findings of this study indicate that use of the quad cane (vs. straight cane) substantially reduces both mean and root-mean-square distances of sway. It also shows that compared with the straight cane, the tripod cane significantly improves postural steadiness in the double stance position, as shown by a reduction in both mean and root-mean-square distance values of sway.

The 95% confidence circle area of sway models the area of stabilogram with a circle that includes approximately 95% of the COP distances from mean COP position. The 95% confidence circle area of sway also is significantly reduced when the tripod cane was held, indicating a steadier posture, as compared with the straight cane. The circle area of sway was reduced even more when the quad cane was held.

In frequency domain analysis, total power, 95% power frequency, and centroidal frequency also showed significant changes when the held device was changed. The total power is the integrated area of the power spectrum and, along with other variables in the frequency domain, indicates activities of postural subsystems. A unified decrease in total power and centroidal frequency and an increase in 95% power frequency, as observed in all but the “open eyes, tandem stance, cane in front” and “open eyes, tandem stance, cane in back” trials, are consistent with the changes reported for increased postural stability.17

Changes in values of all variables for the three conditions of “open eyes, tandem stance, cane in front,” “open eyes, tandem stance, cane in back,” and “open eyes, double stance, cane on the sidewl” did not always follow the same pattern of changes as occurred with all other conditions. That is, in most cases, the tripod cane values fell between the values of the straight cane and the quad cane. Unfortunately, there are not enough data in the literature to address the significance of cane performance when the cane is located in front or in the back. The only studies that specifically addressed the issue of foot-device collision in an experimental design were set up to have the cane on the side and reported that loading cane (by 10% of BW) does not affect the rate of foot-device collision.10–12 In this study, however, whereas the tripod cane values were always in the range between the straight cane and quad cane values, only the power of the sway signal was significantly different between straight cane and tripod cane. Significant total power reduction that was observed when using tripod cane instead of straight cane may indicate an improved postural stability, both when the cane was unloaded and loaded.

One limitation of this study is that we recruited only healthy older adults who were not in a need of a cane for standing or ambulation. Although we anticipate that the observed differences would be augmented if the person was in need of a cane for standing (cane users), that information is not available. We recruited healthy older adults who were not cane users, however, to be able to attribute changes of the postural steadiness directly to the change in cane type. This would eliminate potential interference of any present pathology with our outcome measures. Another limitation arises from the fact that all participants were tested barefoot, although this may not be the case in real life. The decision was made to avoid potential interference of the type and design of footwear on our results.22 Furthermore, considering that use of footwear could potentially improve postural stability,23,24 having participants tested barefoot could be more challenging, and therefore, changes in postural steadiness could be better detected. An additional limitation of this study is that all tripod cane tests were performed using the AbleTripod cane tip. Other similar cane tips available on the market may produce different results, as the mechanical and geometrical characteristics of AbleTripod materials may be different. Therefore, our findings cannot be generalized to all different types of cane tips.

In conclusion, it appears that use of the tripod cane tip improves postural steadiness compared with use of the straight cane. In addition, considering the small design of the cane tip, the tripod cane may not interfere with the foot movements any more than the straight cane does. Further studies are needed, however, to identify the effect of the tripod cane on the rate of foot-device collision and/or its benefits for individuals with known physical limitations that potentially can affect postural control.


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assistive devices; cane; cane tip; tripod cane tip; quad cane; physical activity; rehabilitation; postural steadiness; older adults; postural balance

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