Lumbar fusion for lytic spondylolisthesis: Is an interbody cage necessary?

Expandable versus static cages in unilateral biportal endoscopy lumbar interbody fusion (ULIF) for treating degenerative lumbar spondylolisthesis (DLS): comparison of clinical and radiological results

BACKGROUND

In recent years, early rehabilitation after spinal fusion and the recovery of physiological curvature have attracted much attention. Therefore, expandable cages have entered the field of vision of scientists. The goal of the current study was to compare the clinical and radiological results of unilateral portal endoscopic lumbar interbody fusion (ULIF) in the treatment of degenerative lumbar spondylolisthesis (DLS) with expandable versus static cages.

METHODS

We retrospectively analysed patients who received ULIF treatment for DLS from May 2019 to February 2021. Patients were categorized by cage type (static vs. expandable), and the main study was the preop and postop clinical and radiological index changes of the patients.

RESULTS

Eighty-four patients were included (38 in the static cages group; 46 in the expandable cages group). There was no difference in the preop results between the two groups. The VAS scores for low back and leg pain and ODI scores in the expandable cages group 7 d postop were significantly superior to those in the static cages group (P < 0.05), and the segmental angle and PDH in the expandable cages group postop were significantly higher than those in the static cages group (P < 0.05). The fusions at 6 m postop in the expandable cages group were superior to those in the Static Cages group (P < 0.05).

CONCLUSIONS

The results of this study showed that compared with the stable cage group, the expandable cage group had unique advantages in restoring the physiological curvature of the lumbar spine, increasing the fusion rate, and relieving pain in the early postoperative period. ULIF can be used to treat single-segment, mild lumbar spondylolisthesis patients using expandable cages instead of static cages.

Preliminary Results of Expandable Transforaminal Lumbar Interbody Fusion Cages

Background:

Compared with static cages, expandable cages for Transforaminal Lumbar Interbody Fusion (TLIF), are thought to require less posterior bony removal and nerve root retraction. They may allow the creation of a greater lordotic angle and lordosis restoration.

Objective:

This study investigated whether TLIF using an expandable lordotic interbody cage facilitates an improvement in both segmental lordosis and the restoration of intradiscal height.

Methods:

A total of 32 patients with 40 operated segments underwent TLIF surgery for lumbar degenerative disc disease and were consecutively included in this prospective observational study. Of those patients, 25 received monosegmental treatment, six were treated bisegmentally, and one was treated trisegmentally. All patients were assessed clinically and radiographically preoperatively, as well as one week, six months, and two years postoperatively.

Results:

Two patients required revision for screw loosening and pseudarthrosis. In four patients, the endplate was violated intraoperatively due to cage placement. Postoperatively, cage subsidence was observed in four patients. Significant improvement in the mean degree of spondylolisthesis was noted at the two-year mark. Mean segmental lordosis improved postoperatively. A significant increase in mean disc height of the treated segment was also found. Overall, with the exception of pain, no significant clinical or radiographic changes were reported between the first postoperative week and the two-year year follow-up mark. The mean pain, functional, and quality of life outcomes improved significantly from the preoperative to postoperative period, with no deterioration between six months and two years.

Conclusion:

This study demonstrates that favorable outcomes can be achieved by using an expandable titanium cage in TLIF procedures.

Graft Materials and Biologics for Spinal Interbody Fusion

Spinal fusion is the most widely performed procedure in spine surgery. It is the preferred treatment for a wide variety of pathologies including degenerative disc disease, spondylolisthesis, segmental instability, and deformity. Surgeons have the choice of fusing vertebrae by utilizing cages containing autografts, allografts, demineralized bone matrices (DBMs), or graft substitutes such as ceramic scaffolds. Autografts from the iliac spine are the most commonly used as they offer osteogenic, osteoinductive, and osteoconductive capabilities, all while avoiding immune system rejection. Allografts obtained from cadavers and living donors can also be advantageous as they lack the need for graft extraction from the patient. DBMs are acid-extracted organic allografts with osteoinductive properties. Ceramic grafts containing hydroxyapatite can be readily manufactured and are able to provide osteoinductive support while having a long shelf life. Further, bone-morphogenetic proteins (BMPs), mesenchymal stem cells (MSCs), synthetic peptides, and autologous growth factors are currently being optimized to assist in improving vertebral fusion. Genetic therapies utilizing viral transduction are also currently being devised. This review provides an overview of the advantages, disadvantages, and future directions of currently available graft materials. The current literature on growth factors, stem cells, and genetic therapy is also discussed.