Radiographic evaluation of bioactive glass-ceramic grafts in postero-lateral lumbar fusion

Characterization of patient population receiving bioactive glass bone graft substitute as intraoperative treatment for orthopaedic trauma fractures

Background

Bioactive glass synthetic bone grafts are used to treat osseous defects in orthopaedic surgery. Characterization of the clinical scenarios associated with bioactive glass use in the context of orthopaedic trauma, are not well established. This study aims to characterize population demographics, operative variables, as well as postoperative variables, for patients who required bone grafting for treatment of traumatic orthopaedic injuries and received a bioactive glass bone substitute intraoperatively.

Methods

The electronic medical record at a large Level I trauma center was queried for fracture patients between January 1st, 2019, and April 30th, 2022. Our retrospective cohort included fracture patients who received Fibergraft Matrix or Fibergraft Putty intraoperatively, and their respective control groups. This study ascertained patient demographic variables, operative variables, and postoperative variables. Differences in categorical variables were tested with Fischer's Exact Tests, while differences in continuous variables were tested with ANOVA. Statistical significance was determined as P < 0.05. If the overall Group model was significant for a given variable, post-hoc Fischer's Exact or Tukey HSD tests were used to assess pairwise significance between individual Group pairs.

Results

A total of four categories across our analysis of demographic, operative, and postoperative variables displayed significant differences amongst subject Groups (P ≤ 0.03). Individual groups were compared such that significant differences between subject groups could be appreciated for a specific variable. FM subjects had greater length of surgery, billable costs, and vitamin D supplementation at the time of surgery compared to FM controls. Similarly, FP subjects had greater length of surgery, billable cost, and implants used intraoperatively compared to FP controls.

Conclusion

This analysis revealed Fibergraft patients to have greater length of surgery and billable cost, with respect to their matched controls. These data suggest that Fibergraft patients had more severe orthopaedic fractures compared to matched controls.

Bioactive glass grants equivalent fusion compared to autologous iliac crest bone for ALIF: a within-patient comparative study

Purpose

To determine within-patient fusion rates of chambers filled with bioactive glass versus autologous iliac crest bone on computed tomography (CT) following anterior lumbar interbody fusion (ALIF).

Methods

A consecutive series of 40 patients (58 levels) that underwent single-level (L5-S1 only) or two-level (L5-S1 and L4-L5) ALIF were assessed. Indications for fusion were one or more of the following: degenerative disc disease with or without Modic changes, spondylolisthesis, and stenosis. Each intervertebral cage had a middle beam delimiting two chambers, one of which was filled with bioactive glass and the other with autologous iliac crest bone. CT scans were graded using the Bridwell classification (grade I, best; grade IV, worst). Patients were evaluated using the Oswestry Disability Index (ODI), and by rating pain in the lower back and legs on a Visual Analog Scale (pVAS); complications and reoperations were noted.

Results

At 15 ± 5 months follow-up, there were no significant differences in fusion across chambers filled with bioactive glass versus chambers filled with autologous bone (p = 0.416). Two patients with Bridwell grade III at both chambers of the L4-L5 cages required reoperation using posterior instrumentation. Clinical assessment of the 38 remaining patients (54 levels) at 25 ± 2 months, revealed ODI of 15 ± 12, lower back pVAS of 1.4 ± 1.5 and legs pVAS of 1.9 ± 1.6.

Conclusions

For ALIF at L5-S1 or L4-L5, within-patient fusion rates were equivalent for bioactive glass compared to autologous iliac crest bone; thus, bioactive glass can substitute autologous bone, avoiding increased operative time and blood loss, as well as donor site morbidity.

The effect of bioactive glasses on spinal fusion: A cross-disciplinary systematic review and meta-analysis of the preclinical and clinical data

Pseudarthrosis following spinal fusion is correlated with poorer patient outcomes and consequently is an area of continued interest within spinal research. Recently, bioactive glasses have been proposed as a means of augmenting fusion rates. Here, we present the first systematic review and meta-analysis of the existing preclinical and clinical literature on the effect of bioactive glasses on spinal fusion. Using the MEDLINE, Embase, and Web of Science databases, we queried all publications in the English-language literature examining the effect of bioactive glasses on spinal fusion. The primary endpoint was fusion rate at last follow-up and the secondary endpoint for clinical studies was the rate of deep wound infection. Random-effects meta-analyses were performed independently for the preclinical and clinical data. Twelve preclinical studies (267 animals) and 12 clinical studies (396 patients) evaluating a total of twelve unique bioactive glass formulations were included. Across clinical studies, fusion was seen in 84% treated with bioactive glass. On sub-analysis, fusion rates were similar for standalone autograft (91.6%) and bioactive glass-local autograft mixtures (89.6%). Standalone bioactive glass substrates produced inferior fusion rates relative to autograft alone (33.6% vs. 98.8%; OR 0.01, p < 0.02). Rates of deep wound infection did not differ between the bioactive glass and autograft groups (3.1%). The preclinical data similarly showed comparable rates of fusion between autograft and bioactive glass-treated animals. The available data suggest that bioactive glass-autograft mixtures confer similar rates of spinal fusion relative to standalone autograft without altering the risk of deep wound infection.

Behaviour of nonresorbable bioactive glass-ceramic implanted into long bone defects: comparison with cancellous allografts

INTRODUCTION

The goal of this retrospective study was to compare the long-term results after implantation of the nonresorbable glass-ceramic material and transplantation of the cancellous allografts into the defects of long bones.

METHOD

The bone cysts were excochleated and filled using granules of glass-ceramic material or cancellous allografts. Clinical, radiographic and scintigraphic examinations of 30 patients were carried out 2-14 years after their surgery.

RESULTS

Though signs of complete incorporation allowing full weight-bearing capacity were observed on plain radiographs, we detected pain in six out of nine patients after diaphyseal implantation of nonresorbable glass-ceramic. We found an increase in (99) (m)Tc-methylene diphosphonate uptake on the delayed images in the area of glass-ceramic implantation, mainly in its diaphyseal location. In patients after bone transplantation, the cancellous allografts were completely integrated and the scintigraphic findings were physiological.

CONCLUSION

The implantation of the nonresorbable glass-ceramic material into the diaphyseal defects of long bones is not suitable based on our study.

Hydroxyapatite granule graft combined with recombinant human bone morphogenic protein-2 for solid lumbar fusion

The purpose of this study was to evaluate the availability of recombinant human bone morphogenetic protein-2 (rhBMP-2) combined with hydroxyapatite (HA) and autogenous bone. Posterolateral intertransverse fusion between the fifth and sixth lumbar vertebrae was performed in 27 adult Japanese white rabbits. These 27 rabbits were classified into three groups: the autogenous bone group, the HA group, and the bone morphogenic protein (BMP) group. In the HA group, HA (0.5 g) mixed with iliac bone was grafted. In the BMP group, HA (0.5 g) soaked with rhBMP-2 (100 mg) and iliac bone was grafted. At 6 weeks after the procedure, bone union was evaluated. In the BMP group, all cases showed solid bone union, and fusion masses were stiffer than the masses obtained in the other group. Biomechanically and histologically, grafts of HA soaked with rhBMP-2 and iliac bone was clearly effective in obtaining a solid intertransverse arthrodesis.

A new resorbable bone void filler in trauma: early clinical experience and histologic evaluation

Six patients with traumatic bone injuries were treated by packing ultraporous beta-tricalcium phosphate (beta-TCP), a synthetic bone void filler, into defect sites using firm finger pressure. Radiographs showed new bone consolidating in treated sites after as little as 2 months. A biopsy obtained from a fractured calcaneus 9 months after surgery showed new bone growing within the ultraporous scaffold. Regions of newly mineralized bone and woven bone in the scaffold suggested that the defect site was undergoing repair. Some new bone had developed lamellar architecture. Higher radiodensity and slower resorption of ultraporous bone void filler in this human case, relative to that seen in a canine study, is attributed to slower metabolism in humans relative to dogs and to greater packing pressures used in the clinic. The histology specimen did not indicate untoward inflammatory response or significant foreign body reaction. Thus, this first human histology report supports the use of biocompatible ultraporous beta-TCP to enhance new bone formation in bone defects.