Age and Falls History-Related Differences in the Biomechanics of 360º Pivot Turns

INTRODUCTION: Older adults who fall during turning
are eight times more likely to experience a hip
fracture than from a fall during walking in a straight
line [1]. The ability to turn has been identified as an
important task of daily living, and the evaluation of
turning has been included in many clinical
assessments to determine those at risk of falling [2-
4]. Therefore, the comparison of turning
biomechanics in fallers and non-fallers in the older
population is essential if we are to understand the
mechanisms underlying falls. The aims of this study
were to compare time to turn, number of steps
utilised to turn, and segmental reorientation onset in
groups of young adults and older non-fallers, single
fallers and multiple fallers during a 360º standing
turn
METHODS: Fifteen young adults (age 25.7 ± 3.2
years), and older non-fallers (n = 15, age 70.7 ± 6.2
years), single fallers (n = 11, age 70.2 ± 6.1 years)
and multiple fallers (n = 14, age 71.5 ± 6.9 years)
participated in this study. Participants completed
three 360º turn trials at their own speed, and the
participants self-selected their turning direction to
make the movement as natural as possible. A 14-
camera Vicon M2 (624) system was used to collect
3-D marker trajectory data sampled at 60 Hz, and
the head, thorax and pelvis segments were defined.
Thoracic and pelvic onset latencies were calculated
with respect to head rotation onset, and pelvic onset
latency with respect to thoracic rotation onset was
also calculated. Group differences were
investigated using one-way ANOVA.
RESULTS: The young adults completed the turn in
significantly less time than the multiple fallers (F =
3.636, p = 0.019), and utilised significantly fewer
steps to turn (F = 3.693, p = 0.018). All of the
participant groups demonstrated head yaw as the
first movement in the initiation of the 360º turn.
There was a significant difference between groups
for pelvic turn onset latency with respect to the
thorax (F = 5.968, p = 0.001), post-hoc tests showed
the multiple fallers to have significantly shorter
latency between the thorax and the pelvis than all
other groups.
CONCLUSIONS: The multiple fallers demonstrated a
more en-bloc strategy for turning than the other
groups characterized by a shorter latency between
reorientation onset of the thorax and the pelvis at
the initiation of the turn. Interestingly, en-bloc
turning strategy of the thorax and pelvis has been
previously observed in both stroke and Parkinson
disease patients; patient groups who also are at
increase risk of falling during turning. In combination
these results suggest that studying the
biomechanics of pivot turns is a useful tool for
elucidating the mechanisms underlying falls and
diagnosis of increased falls-risk.