Abstract
Introduction
Clinical effectiveness of the PEEK nonfusion interspinous device is well documented. However, there is a lack of evidence on the long-term behavior of this implant in regard to bone in general and especially its influence on structural changes of bone elements of the lumbar spine. Aim of our study was to investigate histomorphometric and radiographic changes in the BB.4Sd1 rat model after implantation of an interspinous PEEK implant.
Materials and Methods
Total 24 male BB.4Sd1 rats 11-week old underwent surgery for implantation of an interspinous PEEK device or for a sham procedure in three groups of eight animals each viz: (1) implantation at level L4-5, (2) implantation at level L5-6, and (3) sham surgery. Total 11 weeks postoperatively osteolyses at the implant-bone interface were measured via X-ray, bone mineral density of vertebral bodies was analyzed using osteodensitometry, and bone mineral content as well as osteolyses of the spinous processes examined by histomorphometry.
Results
Osteolyses of the spinous processes at the site of the interspinous implant were found in all treated segments. There was no significant difference in either bone density of vertebral bodies or histomorphometric structure of the spinous processes.
Conclusion
Osteolyses of spinous processes as a result of the implant becoming unsecure inhibit the targeted load redistribution through the interspinous PEEK device in the lumbar spinal segment of the rat. This leads to reduced long-term benefits of the implant in the animal model. These results suggest that the interspinous PEEK implants should only be used under strict indication and in consideration of their time-limited effects.
Yes
None declared
Holinka J, Krepler P, Matzner M, et al. Stabilising effect of dynamic interspinous spacers in degenerative low-grade lumbar instability. International Orthopaedics 2011;35:395–400