Examination of the Role of Cells in Commercially Available Cellular Allografts in Spine Fusion: An in Vivo Animal Study

Autogenous Bilateral Cleft Alveolar Bone Grafting with rhBMP-2 and Cellular Bone Matrix

Alveolar bone grafting (ABG) in bilateral cleft lip and palate (BCLP) patients provides a reconstructive challenge. We present a novel technique of combining autologous iliac crest bone graft (ICBG) with recombinant human bone morphogenic protein 2 (rhBMP-2) and cellular bone matrix (CBM) for ABG in BCLP patients. Complete bone fill occurred in 90% of patients, with 100% having bilateral canine eruption. No patients required repeat ABG, and no significant complications were reported. The alveolar cleft gap volume significantly decreased with an improvement of 75.87%. ABG with autologous ICBG with rhBMP-2 and CBM is an effective technique for patients with BCLP.

Management and outcomes of surgical site tuberculosis infection due to infected bone graft in spine surgery: a single-institution experience and 1-year postoperative follow-up

OBJECTIVE

In 2021, several patients across the United States received bone allograft contaminated with Mycobacterium tuberculosis (TB). TB is typically a pulmonary infection with many possible extrapulmonary manifestations, including skeletal tuberculosis. However, TB is a rare causative organism of postoperative surgical site infection. Iatrogenic skeletal TB infections are not widely reported in the medical literature; therefore, treatment and associated outcomes are relatively unknown. In this series, the authors report 6 cases of patients who received a mesenchymal stem cell-enhanced bone graft infected with TB at their institution, including the clinical courses, imaging findings, management plans, and outcomes at 1 year postoperatively.

METHODS

A retrospective review was performed of 6 consecutive patients who underwent spinal fusion surgery at the authors' institution and received bone graft from a lot contaminated with TB. Collected data included patient demographic characteristics, indications for surgery, surgical procedures performed, timing of contamination discovery, medical treatment, and follow-up information including reoperation, healing progress, and imaging findings.

RESULTS

Five of 6 patients (83.3%) eventually tested positive for TB via interferon-gamma release assay or wound culture. They experienced significant complications, including surgical site infections with neck swelling, pain, dysphagia, and wound dehiscence. Extensive soft-tissue infection was common; however, significant bony involvement was not observed. Surgical wound debridement was required in 4 patients, and all patients received medical management with standard RIPE (rifampin, isoniazid pyrazinamide, pyridoxine, and ethambutol) therapy for 8 weeks with extension of rifampin and isoniazid for scheduled 12 months. All patients (excluding 1 patient who died of COVID-19) showed signs of improvement with adequately healing wounds at the most recent follow-up at a median (range) of 12 (6-13) months postoperatively. To date, no patients have developed pulmonary TB.

CONCLUSIONS

Direct inoculation with TB via contaminated bone grafts resulted in a high rate of severe soft-tissue infection, although extensive skeletal and pulmonary involvement has not been observed at 1 year postoperatively; this review includes the longest reported follow-up period for this TB outbreak. Medical management remains the mainstay of therapy for these patients, with most patients showing recovery with oral antibiotic therapy. The severity of these infections arising from mesenchymal stem cell-containing bone allografts that undergo an alternative sterilization process than standard allografts raises concerns regarding the added risks of infection, which should be weighed against the expected benefits of these grafts.

Commercial Bone Grafts Claimed as an Alternative to Autografts: Current Trends for Clinical Applications in Orthopaedics

In the last twenty years, due to an increasing medical and market demand for orthopaedic implants, several grafting options have been developed. However, when alternative bone augmentation materials mimicking autografts are searched on the market, commercially available products may be grouped into three main categories: cellular bone matrices, growth factor enhanced bone grafts, and peptide enhanced xeno-hybrid bone grafts. Firstly, to obtain data for this review, the search engines Google and Bing were employed to acquire information from reports or website portfolios of important competitors in the global bone graft market. Secondly, bibliographic databases such as Medline/PubMed, Web of Science, and Scopus were also employed to analyse data from preclinical/clinical studies performed to evaluate the safety and efficacy of each product released on the market. Here, we discuss several products in terms of osteogenic/osteoinductive/osteoconductive properties, safety, efficacy, and side effects, as well as regulatory issues and costs. Although both positive and negative results were reported in clinical applications for each class of products, to date, peptide enhanced xeno-hybrid bone grafts may represent the best choice in terms of risk/benefit ratio. Nevertheless, more prospective and controlled studies are needed before approval for routine clinical use.

Investigating the efficacy of allograft cellular bone matrix for spinal fusion: a systematic review of the literature

OBJECTIVE

The use of allograft cellular bone matrices (ACBMs) in spinal fusion has expanded rapidly over the last decade. Despite little objective data on its effectiveness, ACBM use has replaced the use of traditional autograft techniques, namely iliac crest bone graft (ICBG), in many centers.

METHODS

In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a systematic review was conducted of the PubMed, Cochrane Library, Scopus, and Web of Science databases of English-language articles over the time period from January 2001 to December 2020 to objectively assess the effectiveness of ACBMs, with an emphasis on the level of industry involvement in the current body of literature.

RESULTS

Limited animal studies (n = 5) demonstrate the efficacy of ACBMs in spinal fusion, with either equivalent or increased rates of fusion compared to autograft. Clinical human studies utilizing ACBMs as bone graft expanders or bone graft substitutes (n = 5 for the cervical spine and n = 8 for the lumbar spine) demonstrate the safety of ACBMs in spinal fusion, but fail to provide conclusive level I, II, or III evidence for its efficacy. Additionally, human studies are plagued with several limiting factors, such as small sample size, lack of prospective design, lack of randomization, absence of standardized assessment of fusion, and presence of industry support/relevant conflict of interest.

CONCLUSIONS

There exist very few objective, unbiased human clinical studies demonstrating ACBM effectiveness or superiority in spinal fusion. Impartial, well-designed prospective studies are needed to offer evidence-based best practices to patients in this domain.

Understanding the Future Prospects of Synergizing Minimally Invasive Transforaminal Lumbar Interbody Fusion Surgery with Ceramics and Regenerative Cellular Therapies

Transforaminal lumber interbody fusion (TLIF) is the last resort to address the lumber degenerative disorders such as spondylolisthesis, causing lower back pain. The current surgical intervention for these abnormalities includes open TLIF. However, in recent years, minimally invasive TLIF (MIS-TLIF) has gained a high momentum, as it could minimize the risk of infection, blood loss, and post-operative complications pertaining to fusion surgery. Further advancement in visualizing and guiding techniques along with grafting cage and materials are continuously improving the safety and efficacy of MIS-TLIF. These assistive techniques are also playing a crucial role to increase and improve the learning curve of surgeons. However, achieving an appropriate output through TLIF still remains a challenge, which might be synergized through 3D-printing and tissue engineering-based regenerative therapy. Owing to their differentiation potential, biomaterials such as stem/progenitor cells may contribute to restructuring lost or damaged tissues during MIS-TLIF, and this therapeutic efficacy could be further supplemented by platelet-derived biomaterials, leading to improved clinical outcomes. Thus, based on the above-mentioned strategies, we have comprehensively summarized recent developments in MIS-TLIF and its possible combinatorial regenerative therapies for rapid and long-term relief.