Functional and radiological outcomes of semi-rigid dynamic lumbar stabilization adjacent to single-level fusion after 2 years

To prospectively evaluate the functional and radiological outcomes of Isobar semi-rigid dynamic posterior stabilization adjacent to single-level fusion up to and including 24 months postoperatively.

A prospective follow-up for 24 months of 36 patients who underwent posterior Isobar dynamic stabilization due to single-level degenerative lumbar discopathy and instability (DLDI) with mild adjacent level degeneration, with collection of functional [visual analog scale (VAS) and Oswestry Disability Index (ODI)] and radiological data (resting, functional X-rays and MRI).

Functional outcomes at 24 months showed significant improvement in mean VAS score by 38.9 points (P < 0.01) and ODI by 22.4 points (P < 0.01). Compared with data preoperatively, disc height at the index and adjacent levels and intervertebral angle (IVA) at the index level showed a slight decreasing trend at each follow-up (P > 0.05), while IVA at the adjacent level showed a slight increasing trend (P > 0.05). Range of motion averaged 2.84° at the index level and remained unchanged at the adjacent level (P > 0.05). The mean Pfirrmann score changed from 2.86 preoperatively to 2.92 at 24 months postoperatively at the index level (P > 0.05), and from 1.92 preoperatively to 1.96 at 24 months postoperatively at the adjacent level (P > 0.05). No reoperation, loosening of screws or infection was recorded.

Patients with single-level DLDI and mild adjacent level degeneration treated with Isobar stabilization show a clinical improvement after 2 years. However, disc degeneration at the index and adjacent levels seems to continue despite using semi-rigid dynamic stabilization.