Bioabsorbable high-purity magnesium interbody cage: degradation, interbody fusion, and biocompatibility from a goat cervical spine model

Abstract

Background: Bioabsorbable Mg-based implants have been a focus of orthopedic researches due to their intrinsic advantages in orthopedics surgeries. This study aimed to investigate the performance of bioabsorbable high-purity magnesium (HP Mg, 99.98 wt.%) interbody cages in anterior cervical discectomy and fusion (ACDF) and to evaluate the degradation of HP Mg cages under an interbody microenvironment.Methods: ACDF was performed at C2-3 and C4-5, and a HP Mg cage or autologous iliac bone was randomly implanted. At 3, 6, 12 and 24 weeks after surgery, the cervical specimens were harvested to evaluate the fusion status, degradation and biocompatibility by CT, micro-CT, histological examinations and blood tests.Results: There was no significant difference in the CT fusion score between cage group and autogenous ilium group at 3 and 6 weeks. At 12 and 24 weeks, the mean CT fusion score in the cage group was markedly lower than in the autogenous ilium group. CT and histological examinations showed bony junctions formed through the middle hole of the cage between upper and lower vertebral bodies in the cage group, but the total fusion area was less than 30%. The degradation rate of cages was relatively rapid within the first 3 weeks and thereafter became stable and slow gradually. The HP Mg cage had good biosecurity and biomechanical characteristics.Conclusions: Implantation of Mg-based interbody cage achieves successful histological fusion, while the total fusion area needs to be improved. More studies are needed to improve the bone-cage interface.

Fluoride-coated high-purity magnesium cage promotes bone fusion in goat models

“…After 24 weeks, new bone tissue between endplates in graft segments was found in CT 3D reconstruction images (Figure 5B), while no fusion with a cage was observed (Figure 5C). ACDF surgery on a goat model, and achieved the first successful interbody fusion, indicating the possibility of Mgbased cage application in ACDF (8). However, this study also reported that the total area of interbody fusion was less than 30%.…”

“…Potential reasons include that co-implantation of titanium and Mg accelerates degradation of Mg cages, and hydrogen and excessively increasing pH value produced by rapid Mg corrosion negatively influence surrounding tissues healing. Recently, Guo et al claimed that they achieved histological fusion of HP-Mg cages in a goat model, although total fusion area was less than 30% (8).…”

Preliminary results in anterior cervical discectomy and fusion with the uncovertebral joint fusion cage in a goat model

“…The fusion rates in control group of our study were 41.7% (5/12) and 58.3% (7/12) at 12 and 24 weeks, respectively. In other studies, which used the same criteria for the evaluation of interbody fusion based on CT scoring in goat model, autologous iliac bone with titanium plate and screws fixation was performed as the control group and the fusion scores both in 12 and 24 weeks were higher than the present study [28,29]. Another goat study used PEEK cage filled with an autologous graft in the control group and 2/6 indicated arthrodesis with solid bone bridging the fusion area through radiographic analysis after 12 weeks [7].…”

Biomaterials for Interbody Fusion in Bone Tissue Engineering

“…Through degradation, interbody fusion, and biocompatibility testing of a goat cervical vertebra model, Guo et al found that Mg-based interbody fusion cage had better histological fusion, but the total fusion area needed to be improved. This is the first report of successful histological fusion of a Mg-based interbody fusion cage ( Guo et al, 2020 ). The main obstacle to limiting the clinical application of Mg-based cages is the adverse reactions caused by the rapid degradation of Mg.…”

“…The most commonly used interbody cages are made of non-absorbent materials, such as titanium (Ti) and poly-ether-ether-ketone (PEEK). Ti alloy may cause implant subsidence and segmental instability due to its high elastic modulus, and the use of PEEK is limited due to its poor biocompatibility leading to chronic inflammatory responses ( Guo et al, 2020 ). Absorbable materials include magnesium (Mg) and other polymer materials.…”