To date, little attention has been paid to imaging of the fascia of the lumbar spine. Langewin et al. employed ultrasound elastography on 71 patients with chronic back pain and found that the FTL plays a critical role in the normal movement of the spine [
9]. Restricted mobility of the lumbar spine was associated with thickening and adhesion of the FTL with the EM [
10]. By contrast, we were able to differentiate the FTL and the EM in all cases. Moreover, limitations of lumbar spine mobility, such as spondylodesis, spondylolisthesis, and scoliosis, were associated with various degrees of thickening of the FTL and EM. Both FTL and EM could be clearly visualized and differentiated from each other and adhesions between them were detectable.
For the interpretation of MRI findings, it is important to consider the underlying anatomy [
15,
16,
19]. Anatomically, epimysial and aponeurotic fasciae can be distinguished. The epimysial fascia is directly adjacent to and intertwined with the muscle (Fig.
1; [
4]). The aponeurotic fasciae encompass several muscles together in groups. In the lumbar spine, the FTL represents the aponeurotic fascia, which surrounds the autochthonous musculature similar to a sac, which extends from the occipital bone to the sacrum. At the level of SVB 1 and near the spinous processes, the EM and FTL fuse together [
15,
16,
19]. Medially, it is connected to the ligamentum nuchae, the ligamentum supraspinale and the spinous processes from CVB 7 to LVB 4. The fasciae not only envelop the muscles, but are important for gliding of the muscles against each other [
10]. However, they also transmit tensile forces longitudinally along the entire spine. Thus, 30–40% of the muscle force is not transferred to the tendons, but is distributed directly to the fascia system [
1‐
3,
16]. Furthermore, the FTL connects different myofascial complexes. Specifically, this means that the fascia of the shoulder and the latissimus dorsi muscle are connected to the fascia of the gluteus maximus muscle via the FTL [
15,
19]. At the level of LVB 4, the fibers of the FTL cross to the opposite side [
5,
16,
17]. This is what makes walking with opposing oscillations of the arms possible in the first place. A degenerative process in the vertebral column leads to disorders of movement that increase the biomechanical malfunction at the same level and then extend to those of adjacent components [
6,
11]. Ranger at al. described that a shorter length of the FTL around the paraspinal compartment was significantly associated with high-intensity low back pain and/or disability [
14]. Kang et al. found a flattened lumbar fascia to be associated with lumbar degenerative kyphosis [
8]. After hemilaminectomy, a fascial gap with herniation of fat and muscle tissue was found in four of six cases. This may result in disruption of forces and tensions and finally leads to chronic postoperative myofascial pain. Wilke et al. found that a clear macroscopic hernia in the FTL is a rare exception representing a small minority of patients with low back pain [
18]. Whenever there is a mismatch between the forces affect the fasciae and their ability to resist them, the fasciae would react with fibrosis and adhesions between them so that movement of various components would be restricted [
8,
12,
13]. A sagging FTL was found in a study of 68 postoperative patients. They considered a sagging posterior FTL if it showed an abrupt bulging appearance on the parasagittal image and correlated it with adjacent lumbar segment [
7].
Various observations of this study have not been reported previously, such as the increase in thickness of the EM associated with adhesion or scarring of the FTL. Segmental movement restrictions, as found in the patients with spondylodesis or spondylolisthesis, result in bilateral thickening of the EM and adhesions between the EM and the FTL. In patients with scoliosis, this occurred unilaterally. Another observation not previously described is denticulation of the EM near the spinous process (Fig.
2). Since this was also detectable in group B, it could be due to contraction of the muscle in the supine position and have no pathological meaning.