The influence of intervertebral disc tissue on anterior spinal interbody fusion: an experimental study on pigs

Abstract

Intervertebral disc has been shown to be related to low back pain and nerve root injury in pathologic conditions. However, little is known about its influence on spinal fusion. With the development of minimal invasive operations, such as laparoscopic anterior spinal fusion with cages, insufficient discectomy may occur. With its inflammatory properties, the residue nucleus pulposus may have an effect on spinal fusion. In this study, a two-level lumbar spine interbody fusion (L3/4, L5/6) with a Brantigan cage was performed on ten Danish Landrace pigs. Each level was randomly assigned to one of the following methods: (1) implantation of Brantigan cage filled with autogenous iliac crest bone graft, or (2) implantation of Brantigan cage filled with a mixture of autograft and the nucleus pulposus tissue harvested from the disc level in which it was to be inserted. Each level was stabilized with two staples. The pigs were followed for 12 weeks in the same standardized condition. After sacrifice, the lumbar spines were taken out, and plain X-ray, computed tomographic (CT) scanning and histomorphometry were performed to study the fusion mass inside the cages. From plain radiographs, new bone formation could be seen inside and around the cage. CT evaluation showed that the nucleus pulposus level had a 20% (2/10) fusion rate, while the pure autograft level had a 70% (7/10) fusion rate ( P=0.07). The histological fusion rate was even lower in the nucleus pulposus level (10%), and was significantly different from the autograft level (70%, P=0.02). Histomorphometric parameters of new bone formation, bone marrow space and fibrous tissue differed significantly between the two levels ( P=0.04; P=0.02; P=0.04 respectively). We conclude that when nucleus pulposus is mixed with the autogenous bone graft, it can delay or decrease the bone formation inside the cage, thus influencing the final fusion.

Disc Space Preparation in Transforaminal Lumbar Interbody Fusion: A Comparison of Minimally Invasive and Open Approaches

“…Inadequate removal of disc material and vertebral body endplate cartilage increases the risk of pseudarthrosis. Li et al [9] showed that nucleus pulposis mixed with bone graft slows down the rate of bony growth, possibly through inflammatory mediators. Lowe et al [10] asserted that total area of discectomy and endplate preparation play a role in fusion rate.…”

Anterior lumbar interbody fusion with carbon fiber cage loaded with bioceramics and platelet-rich plasma. An experimental study on pigs

“…A porcine model of three-level lumbar interbody fusion was employed in this study. The porcine model was described in our previous studies and had been shown to be a feasible model when human implants are to be engaged [12,29]. In the present experiment, the pigs had a mean serum platelet concentration of 398,400/µl, which is slightly higher than that among humans.…”

“…An early effect of the PRP was therefore expected at the start of the experiment, and the observation time was set at 3 months, during which a reasonable fusion rate for autograft levels has been observed in our previous study [12]. Based on the later histomorphometric evaluation, there remain about 14% unabsorbed β-TCP granules.…”

“…This controlled animal study was carried out on the pig interbody fusion model [12]. Ten Danish Landrace pigs were used and threelevel anterior lumbar interbody fusion with carbon fiber cages (Brantigan I/F cage, 8 mm posterior height and 15 mm depth; DePuy AcroMed, Raynham, MA, USA) was performed on each pig.…”

An overview on bone protein extract as the new generation of demineralized bone matrix

“…The lumbar spine fusion model was first built in pigs (Figure 2), which has a reported fusion rate close to that of humans [87,88]. Spinal fusion was evaluated by radiography, micro-CT and histomorphometry, and they concluded that BPE achieved the same fusion rate and the same percentage of new bone formation as that of an autologous iliac bone graft in this demanding porcine anterior spinal fusion model after 12 weeks (Figures 3 and 4) [45,78,89].…”