INTRODUCTION
Posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) are common treatments for various lumbar spine conditions. However, complications like non-fusion and surgical site infections are issues, especially in older patients with surgical risks. To address these social and economic problems, we have developed silver (Ag)-containing hydroxyapatite(HA) coatings (Ag-HA), a combination of silver with strong antibacterial properties and hydroxyapatite with high osteoconductivity, offering both antimicrobial and osteogenic properties. This technology has been applied to titanium cages for PLIF (ResitageTM) and hip prostheses (AG-PROTEXTM). The purpose of this study was to investigate the degree of bone fusion in PLIF using this Ag-HA coatings for lumbar interbody fusion cage (Ag-HA cage) and the possibility of adverse events caused by Ag.
METHODS
The study was clinically applied at one university hospital from April 2020 to December 2022. During the 12-month postoperative observation period, fusion status was investigated as an indicator of efficacy and Ag-related adverse events, neuropathy, and postoperative complications were investigated as indicators of safety. Vertebral endplate cyst formation (VECF), loosening of pedicle screws (PSL), subsidence of cage (CS), and bone fusion were evaluated at 12 months postoperatively. Bone fusion was defined as bone continuity on CT-MPR images in sagittal and coronal views, and less than 3 degrees of mobility between fixed vertebrae on plain x-ray anteroposterior flexion imaging.
RESULTS
Seventy-two patients (24 males, 48 females, mean age 70.6 years) underwent lumbar interbody fusion using Ag-HA cages; no adverse effects (argyria and neuropathy by Ag) were observed during the 12-month observation period. There were no surgical site infections observed. VECF was present at 16 levels (22%) at 6 months and 14 levels (20%) at 12 months after surgery; PSL was present at 3 levels (4.2%) at 6 months and 6 levels (8.5%) at 12 months postoperatively; CS was present at 2 levels (2.8%) at 6 months and 5 levels (7.0%) at 12 months postoperatively. None of the patients underwent reoperation. Bone fusion was successfully completed at 56 levels (78%) at 6 months postoperatively and 59 levels (82%) at 12 months postoperatively.
DISCUSSION
The results of this study suggest that Ag-HA cages can be safely used in spinal fusion procedures and may prevent postoperative infection, prevent worsening quality of life, and provide favorable outcomes.
Ag-HA's safety well demonstrated, with low Ag concentrations avoiding adverse effects. No systemic or local adverse reactions occurred in this study, and no implant failures were observed. Radiological assessments showed improved a fusion rate of 82%. The Ag-HA cage was associated with an acceptable fusion rate. PSL and CS were low rate, and Ag-HA cages did not interfere with bone fusion, suggesting they contribute to reduced micromovement and better bone remodeling. No surgical site infections were occurred. In order to corroborate prevent postoperative infection, larger and longer follow-up studies are needed. This research paves the way for broader applications of Ag-HA cages in spinal surgery.