Several agreements on the classifications of LBP have been documented. These classifications fall into three major domains described as 1) physical, 2) psychological, and 3) pathological. Several studies have reported the predictors of LBP, of which we site physical stress, [17], psychological stress [18, 19], personal characteristics [20],and physical characteristics [21] as predictors of LBP. These factors surround primarily ergonomic conditions in which body mechanics and extrinsic factors including work conditions play an important role in developing the pain.
Postural abnormalities may play a role in the occurrence of LBP by creating concentrations of stress. Nevertheless, this assumption remains speculative because of the absence of criteria for normal posture. Several studies have investigated sagittal spinal alignment and pelvic angle in lumbar disorders [22, 23]. In two studies evaluating sagittal lumbar alignment and LBP, no differences were found in the parameters of the lumbar or pelvic alignment in subjects with low back pain compared with normal individuals [24, 25]. In contrast, some individuals exhibited an increased lumbar lordosis compared with those without LBP [26]. The influence of sagittal spinal and pelvic alignment on LBP needs further elucidation.
Additionally, despite considerable study of the epidemiology of LBP, little is known about the factors related to LBP in adults in Tanzania [5], as studies in this population are lacking. In the present study, the results contribute to a better understanding of the relationship between sagittal alignment and LBP. This could potentially promote identification of subjects prone to develop LBP in Tanzania in the future based on their sagittal spinal and pelvic alignment.
This study found significant differences in pelvic angle and degree of thoracic segmental kyphosis between subjects with and without LBP. From this, we infer that a person with LBP symptoms in Tanzania has a larger anteversion of the pelvic angle and has a postural thoracic kyphosis. In contrast, no significant difference was observed in degree of lumbar lordosis between asymptomatic and symptomatic subjects. Therefore, we infer that large lumbar lordosis in Tanzania is not directly linked to the cause of LBP (Table 2).
The impact of sagittal vertebral alignment on the treatment of spinal disorders is of critical importance. The principles of sagittal balance are vital to achieve optimum outcomes when treating spinal disorders, since a failure to recognize malalignment in this plane can have significant consequences for the patient in terms of pain and deformity [27]. Normally, the spine is known to have a lordotic curves in the cervical and lumbar regions and a kyphotic curve in the thoracic region. A position correlation is found between thoracis kyphosis and lumbar lordosis. The degrees and shape of these curvatures allow an equal distribution of forces across the spinal column [28]. Pain and deformity result by imbalance and loss of equilibrium between these structures by pathological processes. A malalignment in the sagittal plane is presented as an exaggeration or deficiency of normal lordosis or kyphosis. This malalignment is usually accompanied by pain and functional disability [26, 29]. As a result, the pelvic and lower limb posture compensate for the imbalance to restore normal alignment.
A prior study [30] supports the concept that the pelvis and spine of asymptomatic adults can be considered in the sagittal plane as an open linear chain linking the head to the pelvis. Moreover, this concept implies that a change in shape or orientation at any level will effect a change on adjacent segments and will modify their shape. Therefore, several reports recommend muscle strength training of core muscles including the abdominal muscles aiming to improve hyperlordosis of the lumbar segment to prevent LBP [31,32,33]. Considering the results of the present study, this approach to improve trunk muscle strength is not enough to ameliorate LBP. Anterior and posterior pelvic muscles cause a disrupted pelvic angle when they are imbalanced. This imbalance is expressed by an anterior tilt of the pelvis by the quadriceps muscles and iliopsoas muscles, while the posterior tilt is caused by the hamstrings muscle pulling posteriorly [34]. Accordingly, for those who have LBP with lumbar hyperlordosis, correcting muscle flexibility and strength on abdominal and hip joint is necessary to improve anterior pelvic tilt [35, 36].
Our results suggest that excessive thoracic kyphosis is also associated with LBP in the residents of Moshi city, Kilimanjaro, Tanzania. Thoracic kyphosis contributes to positioning the center of gravity of the body behind. It is thought that when there is a thoracic kyphosis, the burden increases on the waist as a motion strategy is taken to ensure postural stability [37]. Therefore, evaluation such as the flexibility and stability that contribute to kyphosis of the thoracic vertebrae are indispensable for exploring the causes of people with LBP in Tanzania.
In addition, the results suggest that obesity seems to be one of the main reasons why the hyperlordosis of the lumbar vertebrae did not show a significant difference from LBP in this study. BMI was classified according to the World Health Organization as underweight (BMI < 18.5), normal weight (BMI = 18.5–24.9), overweight (BMI = 25–29.9), obesity I (BMI = 30–34.9) and obesity II (BMI = 34.9–39.9). From the BMI results in Table 1, the group with LBP has a significantly higher obesity rate. Additionally, previous studies have shown that overnutrition is increasing in some Sub-Saharan African societies, particularly in urbanized areas with western lifestyles [38]. Obesity causes tissue thickening. Therefore, due to the thick soft tissue, it could be considered that the Spinal Mouse used to measure along the body surface could not accurately capture the true lumbar vertebral curves in more obese subjects. In region where there is no equipment used for diagnostic imaging, it is very important to understand the features of the morphology of the body to give a treatment program. In this case, to replace the diagnostic images, it is appropriate to use indices of the thoracic vertebrae and pelvis with less influence of soft tissue in the anthropometric measurement, such as the methods we have used.
A majority of the current international community consists of developing countries with a lower standard of health service than that of developed countries. In developing regions like Tanzania, where diagnostic imaging and enough research are lacking, it is important to understand the morphological features to reduce the risk of many local populations’ musculoskeletal problems, to give an efficient treatment program and to promote the concept of prevention. As this study focuses on LBP in one of the areas in Africa where little research on the subject has been performed, our results will contribute to reducing the risk of many local populations’ musculoskeletal problems and promote the concept of prevention. Aside from improving the quality of health service, this research can bring a sizeable beneficial impact on larger populations.
However, this study is a cross-sectional study, the causes and results are unclear. And in this study, the alignment of the pelvis and lumbar spine is measured only in the sagittal plane. The alignment of the lumbar spine where no significant difference was seen in the sagittal plane may have been caused by rotation in the horizontal plane, scoliosis in the frontal plane, etc. Furthermore, backache has also been reported to be related to age, mental aspect such as depression, smoking history, etc. These measurements are also essential for a more detailed evaluation.
