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TDR likely not superior to ALIF for degeneration of the posterior paraspinal muscles
Researchers of this prospective randomized study found patients who underwent either motion restriction via stand-alone anterior lumbar interbody fusion or motion preservation via total disc replacement experienced postoperative degeneration of the posterior paraspinal muscles.
The study included 50 patients with chronic low back pain caused by single-level intervertebral disc degeneration and/or osteochondrosis without symptomatic facet joint degeneration. Half of the patients underwent anterior lumbar interbody fusion (ALIF) and half underwent total disc replacement (TDR). Researchers noted the resident muscle tissue volume at 12 months and changes in the fat content were compared between the groups at final follow-up.
All patients demonstrated statistically significant clinical improvement for back pain and function. However, all patients experienced a decrease in absolute muscle tissue volume and an increase in relative fat content from 1-week to 12-months follow-up. There was no difference between the groups for resident muscle tissue volume and change in the relative fat content at the index segment, researchers wrote.
“Based on the results of our study, we did not find TDR to be superior. In addition, to our knowledge, neither the long-term superiority of a motion-preserving stabilization system in comparison with fusion, nor the long-term benefit of muscle-sparing surgical approaches to the lumbar spine, have been clinically demonstrated. Therefore, the controversy over the benefits of motion-preserving techniques and implants and the superiority of muscle-sparing approaches could not be resolved,” researchers wrote in the study. – by Robert Linnehan.
Disclosure: The researchers report no relevant financial disclosures.
Perspective
Back to TopStrube and colleagues published this well-designed randomized, prospective study investigating postoperative muscular tissue volume and relative fat content of the paraspinal muscles following anterior lumbar interbody fusion (ALIF) and total disc replacement (TDR). Contrary to the general belief, there were similar small decreases of paraspinal muscle volume and increases of fatty degeneration in the TDR group compared to the ALIF group. Furthermore, significantly less paraspinal muscular atrophy and smaller increase of fatty degeneration was observed at the superior adjacent levels of the ALIF, which theoretically would sustain more stress. It seems that, although range of motion was preserved, TDR did not seem to provide the fringe benefit of preserving the anatomical integrity of the paraspinal muscles. That being said, the paraspinal muscular changes were not clinically relevant and patients from both groups showed significant improvement of pain (VAS) and function (Oswestry Disability Index). The current study did not demonstrate the expected negative influence of a motion restricting procedure on the posterior muscles compared with motion preserving one. Additionally, we could speculate muscle atrophy/degeneration might be more related to a direct splitting/deinsertion and mobilization during the posterior approaches. A larger scale study with longer follow-up might provide more information.