Full length articleContinuous lumbar spine rhythms during level walking, stair climbing and trunk flexion in people with and without lumbar disc herniation
Introduction
Low back pain (LBP) is recognized as the leading cause of disability, which is ahead of 290 other health-related conditions [1]. The lifetime prevalence is reported to be more than 70% [2]. It also causes the activity limitation and work absence globally. In the US, the annual direct costs are estimated between $20 billion and $98 billion and the indirect costs are as high as $200 billion [3,4]. Accordingly, it is essential to explore the abnormal spinal movement and the underlying mechanism responsible for the LBP.
The observation of the lumbopelvic movement is a basic component of the physical exam in people with LBP because of the common belief that back pain and activity limitation could be improved by identifying and correcting movement aberration [5,6]. Lumbopelvic rhythm (LPR) describes the contribution of the pelvis and lumbar spine to the total trunk movement [7]. Extensive studies have reported the characteristics of the LPR in healthy people. Michio et al. has found that the mean of the LPR was different between forward phase and backward phase during trunk flexion [8]. Jie Zhou et al. has also reported more in-phase and stable LPR during trunk extension than trunk flexion [9]. In addition, the LPR varied with the position when conducting trunk flexion [10]. In people who were suffering LBP, the LPR might be changed due to pain or fear. Several studies investigating the trunk flexion have found significant differences in the LPR between healthy participants and LBP patients [[11], [12], [13], [14]]. The contribution of the whole lumbar spine, which is part of the LPR, has been reported to have significant reduction in patients with LBP [11,12].
In the examination of the LPR, the lumbar spine is deemed a lumped rigid body. However, there are regional differences in the lumbar movement [15]. Therefore, apart from observing the adaptation in the LPR, understanding the lumbar spine rhythm (LSR) may reveal more adaptive mechanism in LBP patients.
Similar to the definition of the LPR, the LSR expresses the segmental contribution of each lumbar vertebra to the total lumbar rotation. However, most previous investigations mainly focused on the lumbar intervertebral motion (LIVM). Gombatto et al. conducted multi-segment analysis to explore the continuous spinal motion of the upper lumbar and lower lumbar between healthy people and LBP patients during activities of daily living (ADLs) [16,17]. In these studies, the lumbar spine was only subdivided into two segments. In order to quantify the five LIVMs, the computerized image analysis method based on radiographs were mainly applied [[18], [19], [20]]. However, the calculation of LIVM mainly depended on the static maximal flexion radiograph and maximal extension radiograph. Detailed information during trunk flexion and extension was unknown. In patients with LBP, no significant change of LIVM was found among all the five segments at several discrete positions during trunk flexion [21]. But whether the continuous lumbar spine rhythms would be affected by LBP was still unknown.
Level walking and stair climbing are more frequent than trunk flexion for most people. Investigation on the lumbar spine rhythm during level walking and stair climbing might contribute to the clinical diagnosis and the prevention of back pain. However, based on the authors’ knowledge, none of the previous literature has reported the continuous lumbar spine rhythms during the two ADLs and their alteration caused by LBP.
Thus, the aim of this study was to investigate the characteristics of the continuous lumbar spine rhythms in people with and without lumbar disc herniation (LDH) during level walking, stair climbing and trunk flexion. It was hypothesized that 1) the lumbar spine rhythm would be constant during trunk flexion and variant during level walking and stair climbing. 2) LDH patients would demonstrate different lumbar spine rhythms with healthy people during the three ADLs.
Section snippets
Subjects
The study population was selected from patients with LDH aged from 22 to 35 years. Inclusion criteria for the LDH group were as follows, 1) the herniation occurred in the lower lumbar region. 2) the symptom had reached the criteria for surgery and the patients were waiting for surgery. 3) the patients had the ability to perform the functional task in this study. Twenty-six healthy adults who matched the age were recruited for the control group. The enroll criteria were as follows, 1) there was
The continuous lumbar spine rhythms in the LDH group and the control group during the three ADLs
In level walking (Fig. 3(A)) and stair climbing (Fig. 3(B)), L5S1 and L4L5 contributions were roughly constant (Range in level walking, L5S1 = 2.98%, L4L5 = 5.26%, Range in stair climbing, L5S1 = 2.77%, L4L5 = 4.89%) throughout the gait cycle in the control group. The other three segmental contributions varied over time point. But the maximum range of segmental contributions was less than 9%. In the LDH group, all the five segmental contributions fluctuated over time point in both level walking
Discussion
The objective of this study was to explore continuous lumbar spine rhythms and how the LDH affected them during level walking, stair climbing, and trunk flexion. The constant lumbar spine rhythms were only found in trunk flexion for both groups, supporting the first hypothesis. The LDH group significantly reallocated the segmental contributions during stair climbing and trunk flexion. The fluctuation was different between the two groups during the three ADLs. In addition, antiphase lumbar spine
Conclusion
The continuity of the lumbar spine rhythm and the segmental contribution were altered in the LDH group. The difference in the continuity or segmental contribution between the control group and the LDH group was associated with the ADL. The lumbar spine rhythm fluctuated during level walking and stair climbing, indicating the complexity of motor control in the two ADLs. Therefore, the spinal stability in the two ADLs was susceptible to be affected by LDH, which was also proved by the big
Funding
This research was funded by the Economy, Trade and Information Commission of Shenzhen Municipality (Grant No. SMJKPT20140417010001), the Innovation Commission of Science and Technology of Shenzhen Municipality (Grant No. JCYJ20151030160526024，Grant No. KJYY20170405161248988) and Guangdong provincial department of science and technology (Grant No. 2014A020212655).
Conflicts of interest statement
Nothing to declare.
Acknowledgements
The authors thank Shenzhen Second People’s Hospital and Research Institute of Tsinghua University in China. They provided the equipment and helped to collect the experimental data. The authors also thank all the participants.
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