Evaluation of the neurological safety of epidurally-administered pregabalin in rats

Osteoconductivity and neurotoxicity of silver‐containing hydroxyapatite coating cage for spinal interbody fusion in rats

Background

The use of spinal instrumentation is an established risk factor for postoperative infection. To address this problem, we prepared silver-containing hydroxyapatite coating, consisting of highly osteoconductive hydroxyapatite interfused with silver. The technology has been adopted for total hip arthroplasty. Silver-containing hydroxyapatite coating has been reported to have good biocompatibility and low toxicity. However, no studies about applying this coating in spinal surgery have addressed the osteoconductivity and direct neurotoxicity to the spinal cord of silver-containing hydroxyapatite cages in spinal interbody fusion.

Aim

In this study, we evaluated the osteoconductivity and neurotoxicity of silver-containing hydroxyapatite-coated implants in rats.

Materials & Methods

Titanium (non-coated, hydroxyapatite-coated, and silver-containing hydroxyapatite-coated) interbody cages were inserted into the spine for anterior lumbar fusion. At 8 weeks postoperatively, micro-computed tomography and histology were performed to evaluate the osteoconductivity of the cage. Inclined plane test and toe pinch test were performed postoperatively to assess neurotoxicity.

Results

Micro-computed tomography data indicated no significant difference in bone volume/total volume among the three groups. Histologically, the hydroxyapatite-coated and silver-containing hydroxyapatite-coated groups showed significantly higher bone contact rate than that of the titanium group. In contrast, there was no significant difference in bone formation rate among the three groups. Data of inclined plane and toe pinch test showed no significant loss of motor and sensory function in the three groups. Furthermore, there was no degeneration, necrosis, or accumulation of silver in the spinal cord on histology.

Conclusions

This study suggests that silver-hydroxyapatite-coated interbody cages produce good osteoconductivity and are not associated with direct neurotoxicity.

Relationship between bone mineral density and the frequent administration of epidural steroid injections in postmenopausal women with low back pain

BACKGROUND

Epidural steroid injection (ESI) is one of the most common nonsurgical treatments for low back pain. In general, corticosteroid therapy often results in bone loss and osteoporosis. In previous studies, bone mineral density (BMD) was evaluated after epidural injections of relatively small numbers and relatively low total doses of corticosteroids. However, the relationship between BMD and multiple ESIs remains to be elucidated.

OBJECTIVE

To explore the relationship between BMD and multiple ESIs in postmenopausal women with low back pain.

METHODS

Medical records of postmenopausal women with low back pain treated with or without ESIs were reviewed. BMD was measured in the lumbar spine, femoral neck and total femur after the treatments. A total of 71 patients were divided into two groups: group 1 included patients who had received non-ESI medications; and group 2 included those who had received ESIs >10 times, with a cumulative administered triamcinolone dose >200 mg.

RESULTS

Patients in group 2 showed lower BMD in the femoral neck and total femur. However, no significant intergroup differences in the BMD of the lumbar spine were observed. The prevalences of osteoporosis and osteopenia in the lumbar spine and femoral neck were significantly higher in group 2; these patients also had lower femoral neck BMD Z-scores.

CONCLUSIONS

Multiple ESIs (approximately 14 injections with a cumulative triamcinolone dose of approximately 400 mg) can reduce BMD in postmenopausal women with low back pain.