Abstract
Introduction
Retrograde extra-articular bone drilling is a common procedure in orthopaedic surgery and offers good results in the therapy of osteochondral defects. It induces an inflammatory reaction in the bone underneath cartilage defects leading to decompression, revascularization, and consequent cartilage healing. For the treatment of disk degeneration or injury such an approach has not been tested so far. Therefore, the goal of this study was to evaluate if retrograde extra-articular drilling can be transferred to the lumbar motion segment consisting of subchondral bone, vertebral endplate, and the disk.
Materials and Methods
We used an established porcine disk degeneration model. To induce disk degeneration, 12 animals received surgery over an anterolateral approach to pierce the annulus and perform a partial nucleotomy in a total of 48 lumbar disks. Total 24 disks served as internal controls. After 12 weeks, all nucleotomized disks were degenerated and a second surgery was done to perform retrograde drilling of the vertebral bone in 24 of the nucleotomized disks using a customized drilling device. Drilling was stopped at the vertebral endplate, to avoid additional endplate and disk damage. Animals were sacrificed 13 or 24 weeks after the first surgery.
Results
Drilling was accurate and reproducible, but five disks had to be excluded because vertebral endplates were reached with possible endplate damage. Compared to segments only nucleotomized, additional drilling did not cause statistically significant morphometric changes to the adjacent subchondral vertebral bone of the endplates in micro-CT-analysis (p > 0.05 for BV/TV and trabecular thickness). Disks from both groups showed equal disk height reduction, compared to internal controls and disk degeneration was not significantly different in segments with additional drilling (semi-quantitative histo-degeneration-score). Osteophytes were increased.
Conclusion
Retrograde bone drilling underneath the vertebral endplate did not result in disk regeneration or a limitation of the degeneration process induced by annular damage and partial nucleotomy. Contrary to articular cartilage, the degenerated disk may not be treatable by retrograde bone drilling.
Yes
None declared