Clinical and radiographic outcomes of extreme lateral approach to interbody fusion with β-tricalcium phosphate and hydroxyapatite composite for lumbar degenerative conditions

Ceramic bone graft substitute vs autograft in XLIF: a prospective randomized single-center evaluation of radiographic and clinical outcomes

Purpose of the Study

The objective of this prospective, parallel, randomized, single-center study is to evaluate the clinical success of a commercial ceramic bone graft substitute (CBGS) for autograft in eXtreme Lateral Interbody Fusion (XLIF) procedures. Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 1 Given name: [Cristiano Magalhães], Last name [Menezes]. Author 2 Given name: [Gabriel Carvalho], Last name [Lacerda]. Author 5 Given name: [Erica Godinho], Last name [Menezes]. Also, kindly confirm the details in the metadata are correct.yes

Methods

Forty-five adult subjects were consecutively enrolled and randomized into a single-level XLIF procedure using either CBGS or iliac crest bone graft autograft (30 and 15 subjects, respectively). The primary outcome was fusion rate at 12, 18, and 24 months. Secondary outcomes were pain and disability measured by HRQOL questionnaires. Kindly check and confirm whether the corresponding author and his corresponding affiliations is correctly identified.yes

Results

The fusion rates for both CBGS and autograft groups at the 24-month follow-up were 96.4% and 100%, respectively. For the CBGS group, mean ODI, mean back pain, and mean worst leg pain significantly improved at the 24-month follow-up by 76.7% (39.9–9.3), 77.6% (7.3–1.6), and 81.3% (5.1–1.0), respectively. For the autograft group, mean ODI, mean back pain, and mean worst leg pain significantly improved during the same time period by 77.1% (35.9–8.2), 75.6% (6.1–1.5), and 86.0% (6.6–0.9), respectively (all time points between groups, p < 0.05).

Conclusion

The results of this prospective, randomized study support the use of CBGS as a standalone bone graft substitute for autograft in single-level XLIF surgery. The clinical performance and safety outcomes reported here are consistent with published evidence on CBGS. Improvements in patient-reported back pain, leg pain, and disability outcomes were comparable between the CBGS and autograft groups.

Sustained local ionic homeostatic imbalance caused by calcification modulates inflammation to trigger heterotopic ossification

Heterotopic ossification (HO) is a condition triggered by an injury leading to the formation of mature lamellar bone in extraskeletal soft tissues. Despite being a frequent complication of orthopedic and trauma surgery, brain and spinal injury, the etiology of HO is poorly understood. The aim of this study is to evaluate the hypothesis that a sustained local ionic homeostatic imbalance (SLIHI) created by mineral formation during tissue calcification modulates inflammation to trigger HO. This evaluation also considers the role SLIHI could play for the design of cell-free, drug-free osteoinductive bone graft substitutes. The evaluation contains five main sections. The first section defines relevant concepts in the context of HO and provides a summary of proposed causes of HO. The second section starts with a detailed analysis of the occurrence and involvement of calcification in HO. It is followed by an explanation of the causes of calcification and its consequences. This allows to speculate on the potential chemical modulators of inflammation and triggers of HO. The end of this second section is devoted to in vitro mineralization tests used to predict the ectopic potential of materials. The third section reviews the biological cascade of events occurring during pathological and material-induced HO, and attempts to propose a quantitative timeline of HO formation. The fourth section looks at potential ways to control HO formation, either acting on SLIHI or on inflammation. Chemical, physical, and drug-based approaches are considered. Finally, the evaluation finishes with a critical assessment of the definition of osteoinduction. STATEMENT OF SIGNIFICANCE: The ability to regenerate bone in a spatially controlled and reproducible manner is an essential prerequisite for the treatment of large bone defects. As such, understanding the mechanism leading to heterotopic ossification (HO), a condition triggered by an injury leading to the formation of mature lamellar bone in extraskeletal soft tissues, would be very useful. Unfortunately, the mechanism(s) behind HO is(are) poorly understood. The present study reviews the literature on HO and based on it, proposes that HO can be caused by a combination of inflammation and calcification. This mechanism helps to better understand current strategies to prevent and treat HO. It also shows new opportunities to improve the treatment of bone defects in orthopedic and dental procedures.

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.

Role of oxidative metabolism in osseointegration during spinal fusion

Spinal fusion is a commonly performed orthopedic surgery. Autologous bone graft obtained from the iliac crest is frequently employed to perform spinal fusion. Osteogenic bone marrow stromal (a.k.a. mesenchymal stem) cells (BMSCs) are believed to be responsible for new bone formation and development of the bridging bone during spinal fusion, as these cells are located in both the graft and at the site of fusion. Our previous work revealed the importance of mitochondrial oxidative metabolism in osteogenic differentiation of BMSCs. Our objective here was to determine the impact of BMSC oxidative metabolism on osseointegration of the graft during spinal fusion. The first part of the study was focused on correlating oxidative metabolism in bone graft BMSCs to radiographic outcomes of spinal fusion in human patients. The second part of the study was focused on mechanistically proving the role of BMSC oxidative metabolism in osseointegration during spinal fusion using a genetic mouse model. Patients’ iliac crest-derived graft BMSCs were identified by surface markers. Mitochondrial oxidative function was detected in BMSCs with the potentiometric probe, CMXRos. Spinal fusion radiographic outcomes, determined by the Lenke grade, were correlated to CMXRos signal in BMSCs. A genetic model of high oxidative metabolism, cyclophilin D knockout (CypD KO), was used to perform spinal fusion in mice. Graft osseointegration in mice was assessed with micro-computed tomography. Our study revealed that higher CMXRos signal in patients’ BMSCs correlated with a higher Lenke grade. Mice with higher oxidative metabolism (CypD KO) had greater mineralization of the spinal fusion bridge, as compared to the control mice. We therefore conclude that higher oxidative metabolism in BMSCs correlates with better spinal fusion outcomes in both human patients and in a mouse model. Altogether, our study suggests that promoting oxidative metabolism in osteogenic cells could improve spinal fusion outcomes for patients.

Fusion rate for stand-alone lateral lumbar interbody fusion: a systematic review

BACKGROUND

Lateral lumbar interbody fusion (LLIF) is used to treat multiple conditions, including spondylolisthesis, degenerative disc disorders, adjacent segment disease, and degenerative scoliosis. Although many advocate for posterior fixation with LLIF, stand-alone LLIF is increasingly being performed. Yet the fusion rate for stand-alone LLIF is unknown.

PURPOSE

Determine the fusion rate for stand-alone LLIF.

STUDY DESIGN

Systematic review.

METHODS

We queried Cochrane, EMBASE, and MEDLINE for literature on stand-alone LLIF fusion rate with a publication cutoff of April 2020. LLIF surgery was considered stand-alone when not paired with supplemental posterior fixation. Cohort fusion rate differences were calculated and tested for significance (p<0.05). All reported means were pooled.

RESULTS

A total of 2,735 publications were assessed. Twenty-two studies met inclusion criteria, including 736 patients and 1,103 vertebral levels. Mean age was 61.7 years with BMI 26.5 kg/m². Mean fusion rate was 85.6% (range, 53.0%-100.0%), which did not differ significantly by number of levels fused (1-level, 2-level, and ≥3-level). Use of rhBMP-2 was reported in 39.3% of subjects, with no difference in fusion rates between studies using rhBMP-2 (87.7%) and those in which rhBMP-2 was not used (83.9%, odds ratio=1.37, p=0.448). Fusion rate did not differ with the addition of a lateral plate, or by underlying diagnosis. All-complication rate was 42.2% and mean reoperation rate was 11.1%, with 2.3% reoperation due to pseudarthrosis. Of the studies comparing stand-alone to circumferential fusion, pooled fusion rate was found to be 80.4% versus 91.0% (p=0.637).

CONCLUSIONS

Stand-alone LLIF yields high fusion rates overall. The wide range of reported fusion rates and lower fusion rates in studies involving subsequent surgical reoperation highlights the importance of proper training in this technique and employing a rigorous algorithm when indicating patients for stand-alone LLIF. Future research should focus on examining risk factors and patient-reported outcomes in stand-alone LLIF.

Spinal Biologics in Minimally Invasive Lumbar Surgery

As the use of minimally invasive spine (MIS) fusion approaches continues to grow, increased scrutiny is being placed on its outcomes and efficacies against traditional open fusion surgeries. While there are many factors that contribute to the success of achieving spinal arthrodesis, selecting the optimal fusion biologic remains a top priority. With an ever-expanding market of bone graft substitutes, it is important to evaluate each of their use as it pertains to MIS techniques. This review will summarize the important characteristics and properties of various spinal biologics used in minimally invasive lumbar surgeries and compare their fusion rates via a systematic review of published literature.

A Critical Analysis of Sagittal Plane Deformity Correction With Minimally Invasive Adult Spinal Deformity Surgery: A 2-Year Follow-Up Study

INTRODUCTION

Sagittal plane realignment is important to achieve desirable clinical outcomes after adult spinal deformity (ASD) surgery. This study evaluates the impact of minimally invasive (MIS) techniques on sagittal plane alignment and clinical outcomes in ASD patients.

METHODS

A retrospective, multi-center review of ASD patients (age ≥18 years, and with one of the following: coronal Cobb ≥20°, sagittal vertical axis [SVA] >5 cm, and/or pelvic tilt >25°), MIS surgery, and four or more levels instrumented. Patients were stratified by baseline SRS-Schwab global alignment modifier (GAM) into three groups: 0 (SVA <4 cm), + (SVA 4-9.5 cm), or ++ (SVA >9.5 cm). Radiographic and clinical outcomes measures were analyzed with a minimum of 2-year follow-up.

RESULTS

A total of 96 ASD patients were identified, and 63 met the study's inclusion criteria of circumferential MIS or posterior MIS only, with four or more levels instrumented (n: Group 0 = 37, Group + = 15, and Group ++ = 11). Group 0 was younger than ++ (56.8 vs. 69.6 years), with a higher proportion of females than Group + or ++ (83.8% vs. 66.7% and 54.5%, respectively). Baseline HRQoL was similar. Postoperatively, Groups 0 and + had improved Oswestry Disability Index (ODI) and numeric rating scale (NRS) back and leg scores. Group ++ only had improvement in NRS scores. At the latest follow-up, Groups 0 and ++ had similar sagittal measurements except for PT (21.6 vs. 23.6, p = .009). The + group had improvement in PI-LL (24.2 to 17; p = .015) and LL (30.9 to 38.3; p = .013). Eight of 27 (21.6%) Group 0 patients deteriorated (4 to Group +, 4 to Group ++). Three of 15 (20.0%) Group + patients deteriorated to Group ++, and 3 improved to Group 0. Six of 11 (54.5%) Group ++ patients improved (3 to Group + and 3 to Group 0).

CONCLUSIONS

MIS techniques successfully stabilized ASD patients with Group 0 and + deformities and improved HRQoL. This study suggests that severe sagittal imbalance is not adequately treated with MIS approaches.

Results of lumbar spondylodeses using different bone grafting materials after transforaminal lumbar interbody fusion (TLIF)

PURPOSE

Can a mixture of hydroxyapatite (HA) and autologous bone from decompression sites produce similar results when used for transforaminal lumbar interbody fusion (TLIF)? In the current literature, autologous iliac crest bone grafts (ICBGs) have been reported the gold standard for this procedure. Indeed, to date, no clinical data have confirmed that a mixture of equal volumes of HA and local autologous bone produce similar results in term of fusion as the same volume of autologous ICBG alone.

METHODS

Study design/setting This study was approved by the local ethics committee and completed in a prospective, randomized, single-blinded manner. The results of lumbar fusion using TLIF and different bone grafting materials were compared. Patient sample The patient sample included patients with spinal lumbar degenerative disease. Outcome measures The clinical outcome was determined using the Oswestry Low Back Pain Disability Questionnaire (ODI) and Visual Analog Scale (VAS). The radiological outcomes and fusion rates were determined with radiographs evaluated using the McAfee criteria and computed tomography (CT) data evaluated by the Williams criteria. Three blinded investigators (one radiologist and two orthopedic surgeons) assessed the data. The secondary variables included donor site morbidity. Methods The patients were admitted to our department for orthopedic surgery with degenerative lumbar pathologies (L2-S1) that required stabilization in one or two segments using a TLIF procedure. The patients were 18-80 years old. Only those patients who had degenerative lumbar pathologies and agreed to be educated about the study were included. The patients were divided into the following two randomized groups: group A: TLIF procedure using autologous ICBGs alone; and group B: TLIF procedure using local bone from decompression site mixed with hydroxyapatite. Each group received equal graft volumes. The mixture in group B consisted of equal volumes of local autograft (5 cc) and synthetic bone (5 cc). A graft volume of 10 cc was used at each fusion level. The patients were followed up at three appointments at 1.5, 6 and 12 months postoperatively. Every patient received detailed education about the course of the study.

RESULTS

Forty-eight patients finished the study (2 patients dropped out). The radiographic fusion rate did not significantly differ between the two groups. Based on the CT criteria, 83.3% of the patients showed fusion in both groups after 12 months. Furthermore, 95.3% of the patients in group A and 91.7% of the patients in group B showed bony spondylodeses according to the radiographic criteria at the 12-month follow-up. The donor site morbidity consisted of one patient with a wound infection and one with a hematoma in group A and two patients with persistent pain in group B. Group A also included one patient with cage subsidence of 4 mm and archived fusion after 12 months. In group B, one patient had a pedicle screw breakage and achieved fusion after 6 months. The clinical outcomes were similar between the two groups. In both groups, the VAS and ODI data improved during the follow-up period (p < 0.05). No patients required additional surgeries.

CONCLUSIONS

Both groups demonstrated equivalent clinical outcomes. HA and autologous bone from decompression sites can achieve similar fusion rates to those achieved with identical volumes of the gold standard autologous graft. The graft mixture can be used for one- or two-level lumbar spondylodeses to avoid donor site morbidity.

Comparison of a calcium phosphate bone substitute with recombinant human bone morphogenetic protein-2: a prospective study of fusion rates, clinical outcomes and complications with 24-month follow-up

PURPOSE

Recombinant human bone morphogenetic protein-2 (rhBMP-2) generally provides high rates of clinical improvement and fusion. However, rhBMP-2 has been associated with adverse effects. Recently, a beta tricalcium phosphate (β-TCP) bone substitute has been developed. The aim of this study was to determine the fusion rates and clinical outcomes of patients treated with β-TCP compared to rhBMP-2.

METHODS

One hundred and thirty-five consecutive patients who underwent lateral lumbar interbody fusion with β-TCP (n = 25) or rhBMP-2 (n = 110) in the interbody cage were included in the study. The 25 β-TCP patients were a group of consecutive patients from numbers 46 to 70. Clinical outcomes included back and leg pain, Oswestry Disability Index (ODI), and SF-36 physical and mental component scores (PCS and MCS). CT scans were performed at 6, 12, 18, and 24 months until confirmation of solid interbody fusion, with no further scans performed once fusion was achieved. Targeted CT at the operative level(s) was performed to reduce radiation exposure.

RESULTS

At 24 months there was no significant difference between clinical outcomes of the β-TCP or rhBMP-2 patients, with improvements in back pain (46% and 49%; P = 0.98), leg pain (31 and 52%; P = 0.14), ODI (38 and 41%; P = 0.81), SF-36 PCS (37 and 38%; P = 0.87), and SF-36 MCS (8 and 8%; P = 0.93). The fusion rate was significantly higher for rhBMP-2 with 96% compared to 80% for β-TCP (P = 0.01). Separating patients into those with a standalone cage and those with supplemental posterior instrumentation, there was no significant difference between instrumented fusion rates of the β-TCP and rhBMP-2 patients at 6 (P = 0.44), 12 (P = 0.49), 18 (P = 0.31) or 24 (P = 0.14) months. For standalone patients there was a significant difference at 6 (P = 0.01), 12 (P = 0.008) and 18 months (P = 0.004) with higher fusion rates in the rhBMP-2 group; however, by 24 months this was not significant (P = 0.18).

CONCLUSIONS

Comparable clinical outcomes and complication rates suggest that β-TCP is a viable alternative to rhBMP-2. The difference in fusion rates for the standalone patients suggests that β-TCP may require supplemental posterior instrumentation to enhance fusion.

Clinical outcomes after minimally invasive transforaminal lumbar interbody fusion and lateral lumbar interbody fusion for treatment of degenerative lumbar disease: a systematic review and meta-analysis

The surgical procedures used for arthrodesis in the lumbar spine for degenerative lumbar diseases remain controversial. This systematic review aims to assess and compare clinical outcomes along with the complications and fusion of each technique (minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) or minimally invasive lateral lumbar interbody fusion (MIS LLIF)) for treatment of degenerative lumbar diseases. Relevant studies were identified from Medline and Scopus from inception to July 19, 2016 that reported Oswestry Disability Index (ODI), back and leg pain visual analog score (VAS), postoperative complications, and fusion of either technique. Fifty-eight studies were included for the analysis of MIS-TLIF; 40 studies were included for analysis of LLIF, and 1 randomized controlled trial (RCT) study was included for comparison of MIS-TLIF to LLIF. Overall, there were 9506 patients (5728 in the MIS-TLIF group and 3778 in the LLIF group). Indirect meta-analysis, MIS-TLIF provided better postoperative back and leg pain (VAS), disabilities (ODI), and risk of having complications when compared to LLIF technique, but the fusion rate was not significantly different between the two techniques. However, direct meta-analysis between RCT study and pooled indirect meta-analysis of MIS-TLIF have better pain, disabilities, and complication but no statistically significant difference when compared to LLIF. In LLIF, the pooled mean ODI and VAS back pain were 2.91 (95% CI 2.49, 3.33) and 23.24 (95% CI 18.96, 27.51) in MIS approach whereas 3.14 (95% CI 2.29, 4.04) and 28.29 (95% CI 21.92, 34.67) in traditional approach. In terms of complications and fusion rate, there was no difference in both groups. In lumbar interbody fusion, MIS-TLIF had better ODI, VAS pain, and complication rate when compared to LLIF with direct and indirect meta-analysis methods. However, in terms of fusion rates, there were no differences between the two techniques.

Comparison of complication rates of minimally invasive transforaminal lumbar interbody fusion and lateral lumbar interbody fusion: a systematic review of the literature

OBJECT Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) and lateral lumbar interbody fusion (LLIF) are 2 currently popular techniques for lumbar arthrodesis. The authors compare the total risk of each procedure, along with other important complication outcomes. METHODS This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Relevant studies (up to May 2015) that reported complications of either MI-TLIF or LLIF were identified from a search in the PubMed database. The primary outcome was overall risk of complication per patient. Secondary outcomes included risks of sensory deficits, temporary neurological deficit, permanent neurological deficit, intraoperative complications, medical complications, wound complications, hardware failure, subsidence, and reoperation. RESULTS Fifty-four studies were included for analysis of MI-TLIF, and 42 studies were included for analysis of LLIF. Overall, there were 9714 patients (5454 in the MI-TLIF group and 4260 in the LLIF group) with 13,230 levels fused (6040 in the MI-TLIF group and 7190 in the LLIF group). A total of 1045 complications in the MI-TLIF group and 1339 complications in the LLIF group were reported. The total complication rate per patient was 19.2% in the MI-TLIF group and 31.4% in the LLIF group (p < 0.0001). The rate of sensory deficits and temporary neurological deficits, and permanent neurological deficits was 20.16%, 2.22%, and 1.01% for MI-TLIF versus 27.08%, 9.40%, and 2.46% for LLIF, respectively (p < 0.0001, p < 0.0001, p = 0.002, respectively). Rates of intraoperative and wound complications were 3.57% and 1.63% for MI-TLIF compared with 1.93% and 0.80% for LLIF, respectively (p = 0.0003 and p = 0.034, respectively). No significant differences were noted for medical complications or reoperation. CONCLUSIONS While there was a higher overall complication rate with LLIF, MI-TLIF and LLIF both have acceptable complication profiles. LLIF had higher rates of sensory as well as temporary and permanent neurological symptoms, although rates of intraoperative and wound complications were less than MI-TLIF. Larger, prospective comparative studies are needed to confirm these findings as the current literature is of relative poor quality.

Percutaneous injection of autologous bone marrow concentrate cells significantly reduces lumbar discogenic pain through 12 months

Degenerative disc disease (DDD) induces chronic back pain with limited nonsurgical options. In this open label pilot study, 26 patients (median age 40 years; range 18-61) received autologous bone marrow concentrate (BMC) disc injections (13 one level, 13 two levels). Pretreatment Oswestry disability index (ODI) and visual analog scale (VAS) were performed to establish baseline pain scores (average 56.5 and 79.3, respectively), while magnetic resonance imaging was independently scored according to the modified Pfirrmann scale. Approximately 1 ml of BMC was analyzed for total nucleated cell (TNC) content, colony-forming unit-fibroblast (CFU-F) frequency, differentiation potential, and phenotype characterization. The average ODI and VAS scores were reduced to 22.8 and 29.2 at 3 months, 24.4 and 26.3 at 6 months, and 25.0 and 33.2 at 12 months, respectively (p ≤ .0001). Eight of twenty patients improved by one modified Pfirrmann grade at 1 year. The average BMC contained 121 × 10(6) TNC/ml with 2,713 CFU-F/ml (synonymous with mesenchymal stem cells). Although all subjects presented a substantial reduction in pain, patients receiving greater than 2,000 CFU-F/ml experienced a significantly faster and greater reduction in ODI and VAS. Subjects older than 40 years who received fewer than 2,000 CFU-F/ml experienced an average pain reduction of 33.7% (ODI) and 29.1% (VAS) at 12 months, while all other patients' average reduction was 69.5% (ODI, p = .03) and 70.6% (VAS, p = .01). This study provides evidence of safety and feasibility in the nonsurgical treatment of DDD with autologous BMC and indicates an effect of mesenchymal cell concentration on discogenic pain reduction.