Can Wallis topping-off surgery reduce radiographic adjacent segment degeneration? a single-center study with at least 8 years of long-term follow-up.

OBJECTIVE

To compare the long-term clinical outcomes and radiographic changes between the Topping-off technique and lumbar fusion surgery for lumbar degenerative diseases, and to evaluate their effects on Adjacent Segment Degeneration (ASD).

METHODS

A retrospective analysis was conducted on 97 patients who underwent lumbar fusion surgery at Dongzhimen Hospital of Beijing University of Chinese Medicine from January 2010 to October 2013, with a minimum of 8 years of follow-up data. Patients were divided into the Topping-off group and the Fusion group based on whether a Wallis interspinous device was implanted at the adjacent upper segment. Clinical outcomes were assessed using the Visual Analogue Scale (VAS), Japanese Orthopaedic Association (JOA) score, Oswestry Disability Index (ODI), and reoperation rate. Radiographic progression of ASD was evaluated by range of motion (ROM) of the adjacent upper segment, intervertebral disc height (IDH), intervertebral foramen height (IFH), ligamentum flavum thickness, dural sac sagittal diameter, University of California at Los Angeles (UCLA) grading of intervertebral space degeneration, Pfirrmann classification of disc degeneration, and Pathria-CT grading of facet joint degeneration.

RESULTS

The mean follow-up duration for the 97 patients was 107.4 ± 13.0 months. At the final follow-up, all patients showed significant improvement in VAS, JOA, and ODI scores compared to preoperative values. Between groups, the Topping-off group had better ODI and VAS scores than the Fusion group (P < 0.05). At the final follow-up, ROM, IDH, IFH, and dural sac sagittal diameter at the adjacent upper segment decreased in all patients compared to preoperative measurements. However, the Topping-off group showed significantly smaller ROM (P < 0.05) and greater IDH, IFH, and dural sac sagittal diameter (P < 0.05) compared to the Fusion group. The ligamentum flavum thickness did not increase significantly in the Topping-off group (P = 0.078), while it increased significantly in the Fusion group (P < 0.05). The Topping-off group demonstrated significantly less radiographic degeneration in UCLA grading of intervertebral space, Pfirrmann classification of disc degeneration, and Pathria-CT grading of facet joint degeneration (P < 0.001). The incidence of ASD in the Topping-off group (31.1%) was lower than in the Fusion group (59.6%) (P < 0.05). The reoperation rate was also lower in the Topping-off group compared to the Fusion group (15.6% vs. 23.1%, respectively).

CONCLUSION

Both the Topping-off technique and lumbar fusion surgery achieved satisfactory clinical outcomes in treating lumbar degenerative diseases. Although the Wallis-implanted segment showed decreased ROM, IDH, IFH, and dural sac sagittal diameter, the implantation of Wallis effectively delayed the progression of ASD compared to the adjacent upper segment in conventional lumbar fusion surgery.