Original articlePostural taping decreases thoracic kyphosis but does not influence trunk muscle electromyographic activity or balance in women with osteoporosis
Introduction
Vertebral fractures are the hallmark of osteoporosis, and are associated with significant physical impairments (Greendale et al., 1995; Huang et al., 1996; Hall et al., 1999). One such impairment is increased thoracic kyphosis, which itself is associated with increased spinal loading, back extensor muscle weakness, limitations in functional activities, and increased risk of further fracture. The relationship between vertebral fracture and thoracic kyphosis is recognised in the literature, with agreement that greater numbers of vertebral fractures are associated with increases in thoracic kyphosis (Ensrud et al., 1997; Cortet et al., 2002). Considering this association, interventions that decrease thoracic kyphosis may reduce spinal load, and therefore may potentially decrease the risk of further fracture. However, whether thoracic kyphosis and the associated risk for vertebral fracture can be changed with conservative interventions is unclear.
Thoracic kyphosis is associated with increased compression loading through the spine, which results in greater vertebral and intervertebral disc loads (Keller et al., 2003). In a vertebral fracture population, thoracic kyphosis is correlated with increased vertebral loading (Briggs et al., 2007). Thus, theoretically, a reduction in thoracic kyphosis may have the potential to reduce fracture risk. In addition to kyphosis, spinal loading is also increased by co-contraction of trunk flexor and extensor muscles (Marras et al., 2001; Dieën et al., 2003). Recently, we have shown that individuals with osteoporosis, both with and without vertebral fracture, have increased co-contraction of trunk muscles in association with tasks that challenge balance (Greig, 2006). Together, greater thoracic kyphosis and co-contraction of trunk muscles would substantially increase spinal loading, and when this occurs in individuals with fragile bones and vertebral fracture, this may predispose the individual to further fracture. Thus interventions would ideally modify both thoracic kyphosis and trunk muscle activity.
A further issue that complicates the association between thoracic kyphosis and vertebral fracture is that increased thoracic kyphosis is also associated with impaired balance control in individuals with osteoporosis (Lynn et al., 1997; Cook, 2002; Balzini et al., 2003), and this may further contribute to the development of fracture as a result of falling. It has been argued that increased forward curvature of the spine displaces the centre of mass anteriorly towards the limits of stability, and thus increases the likelihood of loss of balance (Horak et al., 1989; Yuan et al., 2004). However, the relationship between thoracic kyphosis and balance is unclear as we have recently shown that impaired balance is more closely associated with vertebral fracture than thoracic kyphosis (Greig et al., 2006). When testing interventions that change thoracic kyphosis to reduce risk for further fracture, it is essential to also investigate the potential for these interventions to concurrently affect balance.
In light of the previous research, treatments that aim to reduce thoracic kyphosis and alter trunk muscle activity may have positive effects on vertebral loading, trunk control, and balance, which in turn may reduce the risk for fracture. Conservative management techniques which aim to reduce thoracic kyphosis, such as therapeutic postural taping, spinal orthoses and postural retraining, warrant further investigation. Positive outcomes have been found after combined interventions of spinal orthoses and exercise (Sinaki and Lynn, 2002; Pfeifer et al., 2004; Sinaki et al., 2005). These studies report decreased thoracic kyphosis in association with reduced back extensor muscle activity, and positive effects on pain, mobility, and quality of life.
Postural taping is used by physiotherapists in conjunction with exercise to manage individuals with increased thoracic kyphosis (Bennell et al., 2000). Like spinal orthoses, postural taping aims to decrease forward curvature of the spine, reduce pain associated with thoracic kyphosis, and facilitate activity of the postural muscles in a more optimal spinal position. However, few studies have investigated the effect of taping on spinal posture, and no studies have investigated the effects of thoracic kyphosis on trunk muscle activity or other functional outcomes, such as balance. Therefore, the primary aim of this study was to investigate whether therapeutic postural taping changes thoracic posture in women with osteoporosis and vertebral fracture. The secondary aims were to explore whether changes in posture, if present, are associated with changes in trunk muscles activity and balance ability.
Section snippets
Participants
Fifteen participants with osteoporotic vertebral fractures were recruited through advertisements in local newspapers, osteoporosis support groups, osteoporosis clinics, endocrinologists, and general practitioners. Sample size was calculated a-priori. Change in posture was selected as the outcome measure in which we based our calculation, as it was the primary aim of the postural taping. Based on previous literature reporting intervention-based changes in thoracic kyphosis (Wang et al., 1999;
Results
A significant main effect was found for the influence of tape on thoracic kyphosis (p=0.026). Post hoc analysis revealed that thoracic kyphosis was decreased immediately after application of therapeutic tape (mean±SD: 55.3±13.5°) compared with control tape (57.2±13.8°), (p=0.043) and no tape (58.2±12.3°), (p=0.024). There was no difference between control tape and no tape (p=0.377). Application of therapeutic tape reduced kyphosis by 5.2±0.9%, whereas control taping was associated with a mean
Discussion
The results of this study demonstrate that the application of postural therapeutic tape to the thoracic spine induces an immediate reduction in thoracic kyphosis in a population with osteoporotic vertebral fractures. However, this reduction in kyphosis is not associated with significant changes in the activity of the trunk muscles or balance parameters.
The reduction in thoracic kyphosis associated with the therapeutic tape may have been mediated by either passive support from the tape, active
Conclusions
The results of this study demonstrate that the application of therapeutic postural tape induces an immediate reduction in thoracic kyphosis in individuals with osteoporotic vertebral fracture. However, the reduction in thoracic kyphosis is not associated with any changes in trunk muscle activity or balance during a quiet standing task. Future studies may consider investigating the underlying mechanisms associated with the reduction in thoracic kyphosis from postural taping, with an emphasis on
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