Eun et al. [
15] reported an average disc height reduction of 18.8% at 11 years after endoscopic discectomy. Our surgical technique was able to obtain a visual angle of the dorsal structure of nerve tissue, for which it can safely be managed under the monitoring of microscopic visual field, including hypertrophic ligament tissue and the cohesive hyperplastic articular process. If necessary, the nerve structure can even be pushed medially to complete the treatment of its lateral and ventral compression [
16]. In our series, we removed the hypertrophic ligamentum flavum and some lumbar facet joints during the operation, Lumbar facet joints play an important role in regulating the range of motion of the lumbar spine, carrying and transmitting the axial compression load of the spine, and maintaining the mechanical stability of the spine [
17‐
19]. Biomechanical testing of isolated spinal segments has demonstrated that up to 33% of the total axial load of the spine segment can be borne by facet joints [
20,
21]. Mechanical stress controls intervertebral disc matrix metabolism by affecting the biological behavior of intervertebral disc cells [
22,
23] and mechanical stress plays an important role in the progression of intervertebral disc degeneration .so we want to know whether the change of axial load of the spine caused by partial resection of the facet joint in our endoscopic surgery will affect the intervertebral disc, so we detected the changes of IHI and CDS of the intervertebral disc. Fortunately, the postoperative IHI was basically unchanged from its preoperative value: the IHI had decreased slightly (no statistical significance) at more than 1 year after the operation. However, we do not consider that the slight decrease in disc height was due to degenerative processes and invasiveness of the discectomy [
24,
25], as the central spinal canal stenosis in most of the patients was caused by hypertrophy of the ligamentum flavum or joint facet osteophytes in the spinal canal. And we just simply removed the hypertrophic ligamentum flavum or proliferative osteophyte rather than the normal intervertebral disc. Overall, our surgical technique is not suitable for patients with intervertebral foramen compression or stenosis, and we prefer to use a transforaminal approach for patients with intervertebral foramen stenosis with unilateral symptoms. The water content of the normal intervertebral discs was high, and the signal was evenly distributed on T2WI. When the synthesis and decomposition of the extracellular matrix become unbalanced due to a variety of factors [
26], changes in the biochemical components of the nucleus pulposus, dehydration of intervertebral disc tissue and proteoglycan decomposition cause intervertebral disc degeneration. The degree of lumbar intervertebral disc degeneration was evaluated according to the signal intensity of the intervertebral disc on T2WI. In addition, Imai Y et al. [
27] showed that the frequency and intensity of biomechanical load has an important influence on the degeneration of the lumbar intervertebral discs. In the present study, there were no significant changes in the CDS on follow-up compared to before the surgery. Combined with the analysis of IHI and lumbar stability, the stability of the lumbar spine was not damaged, and There is no significant change in the strength, direction and frequency of biomechanical loads.
Thus, we believe that this surgery will not accelerate the degeneration of the intervertebral disc in the short term, though the medium- and long-term effects on the intervertebral discs need further follow-up.