Lumbar Interbody Spinal Fusion Research Articles

Comparison of C-Arm-Free Oblique Lumbar Interbody Fusion L5-S1 (OLIF51) with Transforaminal Lumbar Interbody Fusion L5-S1 (TLIF51) for Adult Spinal Deformity.

Background and Objectives: Adult spinal deformity (ASD) surgery, L5-S1 lordosis is very important factor. The main objective of the research is to retrospectively compare symptomatic presentation and radiological presentation in the sequelae of oblique lumbar inter-body spinal fusion at L5-S1 (OLIF51) and transforaminal lumbar interbody fusion (TLIF) for ASD. Materials and Methods: We retrospectively evaluated 54 patients who underwent corrective spinal fusion for ASD between October 2019 and January 2021. Thirteen patients underwent OLIF51 (average 74.6 years old, group O) and 41 patients underwent TLIF51 (average 70.5 years old, group T). Mean follow-up period was 23.9 months for group O and 28.9 months for group T, ranging from 12 to 43 months. Clinical and radiographic outcomes are assessed using values including visual analogue scale (VAS) for back pain and Oswestry disability index (ODI). Radiographic evaluation was also collected preoperatively and at 6, 12, and 24 months postoperatively. Results: Surgical time in group O was less than that in group T (356 min vs. 492 min, p = 0.003). However, intraoperative blood loss of both groups were not significantly different (1016 mL vs. 1252 mL, p = 0.274). Changes in VAS and ODI were similar in both groups. L5-S1 angle gain and L5-S1 height gain in group O were significantly better than those of group T (9.4° vs. 1.6°, p = 0.0001, 4.2 mm vs. 0.8 mm, p = 0.0002). Conclusions: Clinical outcomes were not significantly different in both groups, but surgical time in OLIF51 was significantly less than that in TLIF51. The radiographic outcomes showed that OLIF51 created more L5-S1 lordosis and L5-S1 disc height compared with TLIF 51.

Cement discoplasty for managing lumbar spine pseudarthrosis in elderly patients: a less invasive alternative approach for failed posterior lumbar spine interbody fusion.

A retrospective cohort study was performed to evaluate pseudoarthrosis treatment results by injection of cement in disc space of failed fusion in posterior lumbar interbody fusion in patients above 65years. Forty-five patients above 65years with symptomatic pseudarthrosis after lumbar spine fusion were treated by cement injection in the affected disc space. There were 30 females and 15 males. The mean age at the operation was 74 ± 6.5years (range 65-89). Discoplasty was performed after the primary fusion operations after a mean of 14 ± 1.3months (range 12-24). The mean preoperative VAS was 7.5 (range 6-9), and ODI was 36 (range 30-45). Cement injection was done at one level in most of the cases (35 patients). In seven cases, two injection levels were done, and in three cases, three levels. Twenty-three patients had discoplasty only, while 22 had discoplasty and screws change, including 14 cases of extension of the instrumentation. The mean postoperative follow-up was 32 ± 6.5months. The VAS improved to 3.5 (range 2-5) (p = 0.02) and ODI to 12.3 (range 5-35) (p = 0.001). Reoperation was indicated in two (4%) patients by screws loosening. Asymptomatic cement leakage occurred in the paravertebral space in seven cases (15.5%). Cement discoplasty offers a less invasive reliable surgical solution in elderly patients with symptomatic lumbar pseudarthrosis in the elderly patients. In cases with screw loosening, discoplasty should be combined with screw revision.

Bone marrow mesenchymal stem cells with low dose bone morphogenetic protein 2 enhances scaffold-based spinal fusion in a porcine model.

High doses bone morphogenetic protein 2 (BMP-2) have resulted in a series of complications in spinal fusion. We previously established a polyelectrolyte complex (PEC) carrier system that reduces the therapeutic dose of BMP-2 in both rodent and porcine spinal fusion models. This study aimed to evaluate the safety and efficacy of the combination of bone marrow mesenchymal stem cells (BMSCs) and low dose BMP-2 delivered by PEC for bone regeneration in a porcine model of anterior lumbar interbody spinal fusion (ALIF) application. Six Yorkshire pigs underwent a tri-segmental (L2/L3; L3/L4; L4/L5) ALIF in four groups, namely: (a) BMSCs+25μg BMP-2/PEC (n=9), (b) 25μg BMP-2/PEC (n=3), (c) BMSCs (n=3), and (d) 50μg BMP-2/absorbable collagen sponge (n=3). Fusion outcomes were evaluated by radiography, biomechanical testing, and histological analysis after 12weeks. Mean radiographic scores at 12weeks were 2.7, 2.0, 1.0, and 1.0 for Groups 1 to 4, respectively. μ-CT scanning, biomechanical evaluation, and histological analysis demonstrated solid fusion and successful bone regeneration in Group 1. In contrast, Group 2 showed inferior quality and slow rate of fusion, and Groups 3 and 4 failed to fuse any of the interbody spaces. There was no obvious evidence of seroma formation, implant rejection, or any other complications in all groups. The results suggest that the combination of BMSCs and low dose BMP-2/PEC could further lower down the effective dose of the BMP-2 and be used as a bone graft substitute in the large animal ALIF model.

Evaluation of lumbar spinal fusion utilizing recombinant human platelet derived growth factor-B chain homodimer (rhPDGF-BB) combined with a bovine collagen/β-tricalcium phosphate (β-TCP) matrix in an ovine model.

Background contextWhile the clinical effectiveness of recombinant human Platelet Derived Growth Factor‐B chain homodimer combined with collagen and β‐tricalcium phosphate (rhPDGF‐BB + collagen/β‐TCP) treatment for indications involving hindfoot and ankle is well‐established, it is not approved for use in spinal interbody fusion, and the use of autograft remains the gold standard.PurposeThe purpose of this study was to compare the effects of rhPDGF‐BB + collagen/β‐TCP treatment on lumbar spine interbody fusion in an ovine model to those of autograft bone and collagen/β‐TCP treatments using biomechanical, radiographic, and histological assessment techniques.Study designThirty‐two skeletally mature Columbian Rambouillet sheep were used to evaluate the safety and effectiveness of rhPDGF‐BB + collagen/β‐TCP matrix in a lumbar spinal fusion model. Interbody polyetheretherketone (PEEK) cages contained either autograft, rhPDGF‐BB + collagen/β‐TCP, collagen/β‐TCP matrix, or left empty.MethodsAnimals were sacrificed 8‐ or 16‐weeks post‐surgery. Spinal fusion was evaluated via post‐sacrifice biomechanical, micro‐computed tomography (μCT), and histological analysis. Outcomes were statistically compared using a two‐way analysis of variance (ANOVA) with an alpha value of 0.05 and a Tukey post‐hoc test.ResultsThere were no statistically significant differences between groups within treatment timepoints for flexion‐extension, lateral bending, or axial rotation range of motion, neutral zone, neutral zone stiffness, or elastic zone stiffness. μCT bone volume fraction was significantly greater between treatment groups independent of timepoint where Autograft and rhPDGF‐BB + collagen/β‐TCP treatments demonstrated significantly greater bone volume fraction as compared to collagen/β‐TCP (P = .026 and P = .038, respectively) and Empty cage treatments (P = .002 and P = .003, respectively). μCT mean bone density fraction was most improved in rhPDGF‐BB + collagen/β‐TCP specimens at the 8 week and 16‐week timepoints as compared to all other treatment groups. There were no statistically significant differences in histomorphometric measurements of bone, soft tissue, or empty space between rhPDGF‐BB + collagen/β‐TCP and autograft treatments.ConclusionsThe results of this study indicate that the use of rhPDGF‐BB combined with collagen/β‐TCP promotes spinal fusion comparable to that of autograft bone.Clinical significanceThe data indicate that rhPDGF‐BB combined with collagen/β‐TCP promotes spinal fusion comparably to autograft bone treatment and may offer a viable alternative in large animal spinal fusion. Future prospective clinical studies are necessary to fully understand the role of rhPDGF‐BB combined with collagen/β‐TCP in human spinal fusion healing.

Assessment of Great Vessels for Anterior Access of L5/S1 Using Patient Positioning

Study Design This was a prospective cross-sectional study.Purpose The aim was to describe the effect of patient positioning, from supine to lateral decubitus position, on the width of the L5/S1 anterior disk space defined by the great vessels.Overview of Literature The application of the lateral decubitus position interbody fusion has been rapidly increasing; however, there are concerns regarding the access to the lumbosacral region due to the great vessels, which necessitates further morphometric data.Methods A total of 20 consecutive live patients awaiting lumbar surgery were subjected to two magnetic resonance imaging scans on the same day in both supine and lateral decubitus positions at a single center to investigate the anterior L5/S1 disk space.Results The bare anterior L5/S1 disk window was present in all patients of this study population, and the mean width was 27 mm in the supine and 22 mm in the lateral decubitus position, with a mean reduction of 5.2 mm between the positions. The oblique corridor angle was measured at a mean of 33°.Conclusions The bare window of L5/S1 disk space was present within this population group, and it was found to be mobile and changed significantly with patient positioning. Therefore, the spine surgeon or the access surgeon must consider the increased potential vascular risk during disk access in lateral decubitus anterior lumbar interbody spinal fusion surgery.

Associations Between Preoperative Hyponatremia and 30-Day Perioperative Complications in Lumbar Interbody Spinal Fusion.

Retrospective population database study. To investigate the relationship of preoperative hyponatremia to postoperative morbidity and mortality in lumbar interbody fusion patients. Optimization of preoperative patient selection and perioperative management can improve patient outcomes in spinal surgery. Hyponatremia, incidentally identified in 1.7% of the US population, has previously been tied to poorer postoperative outcomes in both the general surgery and orthopedic surgery populations. Using the National Surgical Quality Improvement Program database, the authors identified all lumbar interbody fusion patients treated between 2012 and 2014. Patients were classified as hyponatremic (Na<135 mEq/L) or as having normal sodium levels (135-145 mEq/L) preoperatively. The primary outcome was major morbidity and secondary endpoints were prolonged hospitalization, 30-day readmission, and reoperation. Multivariable linear regression was used to find independent predictors of these outcomes. Of 10,654 patients, 45.6% were male individuals, 5.5% were hyponatremic, and 4.2% experienced a major postoperative complication. On multivariable analysis, preoperative hyponatremia was independently associated with major morbidity (odds ratio, 1.22; 95% confidence interval, 1.03-1.44; P<0.05) and prolonged hospitalization (odds ratio, 1.14; 95% confidence interval, 1.02-1.27). Here the authors provide the first evidence suggesting preoperative hyponatremia is an independent predictor of major morbidity after lumbar interbody fusion. Hyponatremia may represent a modifiable risk factor for improved patient care and preoperative risk counseling.

Advances in Techniques and Technology in Minimally Invasive Lumbar Interbody Spinal Fusion.

Minimally invasive lumbar interbody fusion has had a surge in popularity in the last decade. Minimally invasive surgery (MIS) techniques reduce muscle dissection and soft-tissue disruption, offering faster recovery, reduced blood loss, and shorter hospital stays compared with open techniques. There is, however, a substantial learning curve associated with MIS techniques. MIS approaches to the lumbar spine involve anterior, posterior, and combined options. This article reviews patient selection, techniques, outcomes, and complications of the common MIS approaches, including the MIS posterior approach (a transforaminal lumbar interbody fusion) and 3 MIS anterior approaches (a mini-open anterior lumbar interbody fusion, a lateral lumbar interbody fusion, and an oblique lumbar interbody fusion).

Mini-Open Access for Lateral Lumbar Interbody Fusion: Indications, Technique, and Outcomes.

Lateral lumbar interbody fusion (LLIF) is a relatively new procedure. It was established as a minimally invasive alternative to traditional open interbody fusion. LLIF allows the surgeon to access the disc space via a retroperitoneal transpsoas muscle approach. Theoretical advantages of the LLIF technique include preservation of the longitudinal ligaments, augmentation of disc height with indirect decompression of neural elements, and insertion of large footprint cages spanning the dense apophyseal ring bilaterally1,2. The original 2-incision LLIF technique described by Ozgur et al., in 2006, had some inherent limitations3. First, it substantially limited direct visualization of the surgical field and may have endangered nerve and vascular structures. Additionally, it often required multiple separated incisions for multilevel pathologies. Finally, for surgeons with experience in traditional open retroperitoneal surgery, utilization of their previously acquired skills may have been difficult with this approach. To overcome these limitations, we adopted the mini-open lateral approach, which allows for visualization, palpation, and electrophysiologic neurologic confirmation during the procedure4. As detailed below, the patient is positioned in the lateral decubitus position and a single incision is carried out centered between the target discs. For single-level LLIF, the incision spans approximately 3 cm and can be lengthened in small increments for multilevel procedures. After blunt dissection, the retroperitoneal space is entered. The psoas muscle is split under direct visualization, carefully avoiding the traversing nerves with neurosurveillance5. A self-retaining retractor is used, and after thorough discectomy, the disc space is sized with trial components. The implant is filled with bone graft materials and is introduced using intraoperative fluoroscopy. The 2-incision LLIF technique or traditional anterior or posterior lumbar spine interbody fusion techniques might be used instead. LLIF offers the reported advantages of minimally invasive surgery, such as reduced tissue trauma during the approach, low blood loss, shorter length of stay, decreased recovery time, and less postoperative pain. LLIF allows for the placement of a relatively larger interbody cage spanning the dense apophyseal ring bilaterally. The lateral approach preserves the anterior longitudinal ligament and posterior longitudinal ligament. These structures allow for powerful ligamentotaxis and provide extra stability for the construct. Compared with other approaches, LLIF has a reduced risk of visceral and vascular injuries, incidental dural tears, and perioperative infections. Although associated with approach-related complications such as motor and sensory deficits, LLIF can be a safe and versatile procedure1,2.

A cross-sectional study of surgical glove perforation during the posterior lumbar interbody spinal fusion surgery: Its frequency, location, and risk factors.

Lumbar fusion surgery was known to pose a greater risk of surgical glove perforation. However, there has been no study on the glove perforation that can transmit the blood-borne disease to the patient and surgical staff members in the posterior lumbar interbody fusion surgery (PLIFs).We performed a cross-sectional study to investigate the glove perforation during the PLIFs. The study included 37 consecutive patients (10 males and 27 females). All used gloves of surgical staff members, which included the surgeon, assistant surgeons, bone trimmer (who performed local bone trimming and interbody cage preparation), and scrub nurse were collected and were performed to the pinhole water infusion test. The characteristics (i.e., frequency and location of perforated glove) and relative risk of glove perforation were investigated for each participant. The independent risk factors influencing glove perforation were analyzed by multiple logistic regression analysis.The overall operative perforation rate which is a percentage of detected more than one glove perforated event in all cases was 51.4%. The overall glove perforation rate which is the percentage of perforated gloves in all gloves used for surgery was 3.8%. The relative risk of glove perforation by each participant was 2.38 in the surgeon (P = .002), 1.36 in the bone trimmer (P = .04), 1.36 in the scrub nurse (P = .04), and 1.19 in assistant surgeons (P = .13). And, the volume of trimmed local bone was analyzed as an independent risk factor for glove perforation (ORs = 1.310, P = .02).The overall operative perforation rate in PLIFs is higher than 50%. The surgeon, scrub nurse and bone trimmer were observed as a significant risk factor for glove perforation. And, the volume of trimmed local bone was analyzed as independent risk factor. Since the preparation of the interbody cage is essential for successful lumbar fusion surgery, the bone trimmer must pay attention to the glove perforation during this procedure.

Using Provocative Discography and Computed Tomography to Select Patients with Refractory Discogenic Low Back Pain for Lumbar Fusion Surgery.

Background ContextControversy remains over the use of provocative discography in conjunction with computed tomography (CT) to locate symptomatic intervertebral discs in patients with chronic, low back pain (LBP). The current study explores the relationship between discogenic pain and disc morphology using discography and CT, respectively, and investigates the efficacy of this combined method in identifying surgical candidates for lumbar fusion by evaluating outcomes.Methods43 consecutive patients between 2006 and 2013 who presented with refractory low back pain and underwent discography and CT were enrolled in the study. For this study, "refractory LBP" was defined as pain symptoms that persisted or worsened after 6 months of non-operative treatments. Concordant pain was defined as discography-provoked LBP of similar character and location with an intensity of ≥ 8/10. Fusion candidates demonstrated positive-level discography and concordant annular tears on CT at no more than two contiguous levels, and at least one negative control disc with intact annulus. Surgical outcomes were statistically analyzed using Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and Short Form-36 (SF-36) for back-related pain and disability preoperatively, and 2 weeks, 3, 6, 12, and 24 months postoperatively.ResultsAnnular tears were found in 87 discs. Concordant pain was reported by 9 (20.9%) patients at L3-L4, 21 (50.0%) at L4-L5, and 34 (82.9%) at L5-S1; pain occurred significantly more often in discs with annular tears than those without (p<0.001). Painless discs were independent of annulus status (p=0.90). 18 (42%) of the original 43 patients underwent lumbar fusion at L3-L4 (n=1(6%)), L4-L5 (n=6 (33%)), L5-S1 (n=5 (28%)), and two-level L4-S1 (n=6 (33%)) via a minimally invasive transforaminal lumbar interbody fusion (MITLIF) approach with the aim to replace the nucleus pulposus with bone graft material. Median follow-up time was 18 months (range: 12–78 months). VAS, ODI, and SF-36 scores demonstrated significant improvements at 10 out of 12 postoperative time points compared with preoperative baseline.ConclusionsLumbar discography with post-discography CT can be an effective method to evaluate patients with discogenic back pain refractory to non-operative treatments. Those patients with one- or two-level high concordant pain scores with associated annular tears and negative control disc represent good surgical candidates for lumbar interbody spinal fusion.

Influence of Obesity on Access-Related Complications During Anterior Lumbar Spine Interbody Fusion

The anterior lumbar spine approach has gained in popularity in recent years, but the associated access-related complications for obese patients have not been clearly established. This study aimed to analyze the relationship between obesity or overweight and the safety of the anterior lumbar spine approach. Eighty-four consecutive patients admitted for lumbar spine surgery by anterior approach between 2011 and 2014 were included. The surgical approach consisted of left lateral minilaparotomy and retroperitoneal dissection. The patients were categorized into 3 different groups according to their body mass index (BMI). The studied outcomes measures included medical history, BMI, the number of fused levels, surgery duration, blood loss, vascular injury, day of discharge, surgical revision, and wound infection. No significant difference was found across the BMI groups with regard to vascular or infectious complications. The duration of surgery was significantly higher in the obese group. Because BMI does not seem to increase the overall risk of complications, the anterior lumbar spine approach should be considered in obese or overweight patients, as in nonoverweight patients.

Is dibotermin alfa a cost-effective substitute for autologous iliac crest bone graft in single level lumbar interbody spine fusion?

Objectives:To evaluate the cost-effectiveness of dibotermin alfa compared with autologous iliac crest bone graft (ICBG) for patients undergoing single level lumbar interbody spinal fusion in a UK hospital setting.Methods:An individual patient data (IPD) meta-analysis of six randomized controlled clinical trials and two single arm trials compared dibotermin alfa on an absorbable collagen implantation matrix (ACIM) (n = 456) and ICBG (n = 244) on resource use, re-operation rates, and SF-6D (Short form 6-dimension) health utility (total N = 700). Failure-related second surgery, operating time, post-operative hospital stay, and quality-adjusted life years (QALYs) derived from the IPD meta-analysis were included as inputs in an economic evaluation undertaken to assess the cost-effectiveness of dibotermin alfa/ACIM versus ICBG for patients undergoing single level lumbar interbody spinal fusion. A four year time horizon and the United Kingdom (UK) National Health Service (NHS) and Personal Social Services (PSS) perspective was adopted in the base case, with sensitivity analyses performed to gauge parameter uncertainty.Results:In the base case analysis, patients treated using dibotermin alfa/ACIM (12 mg pack) accrued 0.055 incremental QALYs at an incremental cost of £737, compared with patients treated with ICBG. This resulted in an incremental cost-effectiveness ratio (ICER) of £13,523, indicating that at a willingness-to-pay threshold of £20,000, dibotermin alfa/ACIM is a cost-effective intervention relative to ICBG from the NHS and PSS perspective.Conclusions:In a UK hospital setting, dibotermin alfa/ACIM is a cost-effective substitute for ICBG for patients who require lumbar interbody arthrodesis.

Allogeneic mesenchymal precursor cells (MPCs) combined with an osteoconductive scaffold to promote lumbar interbody spine fusion in an ovine model

BackgroundAdvances in immunomagnetic cell sorting have enabled isolation and purification of pleuripotent stem cells from marrow aspirates and have expanded stem cell therapies to include allogeneic sources. PurposeThis study aimed to determine the safety and efficacy of allogeneic mesenchymal precursor cells (MPCs) combined with an osteoconductive scaffold in lumbar interbody spinal fusion using an ovine model. Study DesignThirty-two skeletally mature ewes underwent a single-level interbody fusion procedure using a Polyetheretherketone fusion cage supplemented with either iliac crest autograft (AG) or an osteconductive scaffold (Mastergraft Matrix, Medtronic, Memphis, TN, USA) with 2.5×106 MPCs, 6.25×106 MPCs, or 12.5×106 MPCs. MethodsPlain radiographs and computed tomography scans were scored for bridging bone at multiple points during healing and at necropsy. The biomechanical competency of fusion was scored by manual palpation and quantified using functional radiographs at necropsy. Postnecropsy histopathology and histomorphometric analysis assessed the local response to MPC treatment and quantified the volume and connectivity of newly formed bridging bone. Safety was assessed by serum biochemistry, hematology, and organ histopathology. ResultsMesenchymal precursor cell treatment caused no adverse systemic or local tissue responses. All analyses indicated MPCs combined with an osteoconductive scaffold achieved similar or better fusion success as AG treatment after 16 weeks, and increasing the MPC dose did not enhance fusion. Manual palpation of the fusion site indicated more than 75% of MPC-treated and 65% of AG-treated animals achieved rigid fusion, which was corroborated with functional radiography. Computed tomography fusion scores indicated all animals in the MPC- and AG-treatment groups were fused at 16 weeks, yet X-ray scores indicated only 67% of the AG-treated animals were fused. Histomorphometry analyses showed equivalent outcomes for fusion connectivity and bony fusion area for MPC- and AG-treated groups. Approximately 6% residual graft material remained in the MPC-treated fusion sites at 16 weeks. ConclusionsAdult allogeneic MPCs delivered using an osteoconductive scaffold were both safe and efficacious in this ovine spine interbody fusion model. These results support the use ofallogeneic MPCs as an alternative to AG for lumbar interbody spinal fusion procedures.

Bilateral pulmonary emboli associated with intraoperative use of thrombin-based hemostatic matrix following lumbar spine interbody fusion

Here we describe a patient with bilateral pulmonary emboli (PE) associated with thrombin-based hemostatic matrix (TBHM) use in the setting of a possible venous injury during transforaminal lumbar interbody fusion in the treatment of degenerative spondylolisthesis at L4–5. TBHM products are gelatin granules mixed with human or bovine thrombin. They have been used in a wide variety of surgical procedures to facilitate local hemostasis though their use is not without complications. This is the first reported patient, to our knowledge, with a TBHM-related PE following spinal fusion. As TBHM is a widely used intraoperative hemostatic agent, surgeons should be aware of the risk of TBHM-associated PE, particularly when there is the potential for intravascular injection or dissemination. While our experience indicates that common pharmacological prophylaxis such as subcutaneous heparin is likely ineffective in reducing occurrence of PE in the setting of TBHM use, the PE was successfully treated with standard systemic anticoagulation. The authors would also add that when iliac injury is encountered during discectomy or interbody fusion through a posterior approach, use of TBHM may be a life-saving technique. Postoperatively, vascular surgery consultation is recommended and consideration should be given to systemic anticoagulation.

Sequestration of rhBMP-2 into Self-Assembled Polyelectrolyte Complexes Promotes Anatomic Localization of New Bone in a Porcine Model of Spinal Reconstructive Surgery

Efficient and therapeutically safe delivery of recombinant human bone morphogenetic protein 2 (rhBMP-2) continues to be a central issue in bone tissue engineering. Recent evidence indicates that layer-by-layer self-assembly of polyelectrolyte complexes (PECs) can be used to recreate synthetic matrix environments that would act as tuneable reservoirs for delicate biomolecules and cells. Although preliminary in vitro as well as small-animal in vivo studies support this premise, translation into clinically relevant bone defect volumes in larger animal models remains unreported. Here we explored the use of native heparin-based PEC, deposited on a hydrated alginate gel template, to load bioactive rhBMP-2 and to facilitate lumbar interbody spinal fusion in pigs. We observed that triple PEC deposits with the highest protein sequestration efficiency and immobilization capacity promoted higher volume of new bone formation when compared with single PEC with low sequestration efficiency and immobilization capacity. This also resulted in a significantly enhanced biomechanical stability of the fused spinal segment when compared with PEC carriers with relatively low protein sequestration and immobilization capacities (p<0.05). Most importantly, PEC carriers showed a more orderly pattern of new bone deposition and superior containment of bone tissue within implant site when compared to collagen sponge carriers. We conclude that this growth factor sequestration platform is effective in the healing of clinically relevant bone defect volume and could overcome some of the safety concerns and limitations currently associated with rhBMP-2 therapy such as excessive heterotopic ossification.

Rough titanium alloys regulate osteoblast production of angiogenic factors

Background contextPolyether-ether-ketone (PEEK) and titanium-aluminum-vanadium (titanium alloy) are used frequently in lumbar spine interbody fusion. Osteoblasts cultured on microstructured titanium generate an environment characterized by increased angiogenic factors and factors that inhibit osteoclast activity mediated by integrin α2β1 signaling. It is not known if this is also true of osteoblasts on titanium alloy or PEEK. PurposeThe purpose of this study was to determine if osteoblasts generate an environment that supports angiogenesis and reduces osteoclastic activity when grown on smooth titanium alloy, rough titanium alloy, or PEEK. Study designThis in vitro study compared angiogenic factor production and integrin gene expression of human osteoblast-like MG63 cells cultured on PEEK or titanium-aluminum-vanadium (titanium alloy). MethodsMG63 cells were grown on PEEK, smooth titanium alloy, or rough titanium alloy. Osteogenic microenvironment was characterized by secretion of osteoprotegerin and transforming growth factor beta-1 (TGF-β1), which inhibit osteoclast activity and angiogenic factors including vascular endothelial growth factor A (VEGF-A), fibroblast growth factor 2 (FGF-2), and angiopoietin-1 (ANG-1). Expression of integrins, transmembrane extracellular matrix recognition proteins, was measured by real-time polymerase chain reaction. ResultsCulture on titanium alloy stimulated osteoprotegerin, TGF-β1, VEGF-A, FGF-2, and angiopoietin-1 production, and levels were greater on rough titanium alloy than on smooth titanium alloy. All factors measured were significantly lower on PEEK than on smooth or rough titanium alloy. Culture on titanium alloy stimulated expression of messenger RNA for integrins that recognize Type I collagen in comparison with PEEK. ConclusionsRough titanium alloy stimulated cells to create an osteogenic-angiogenic microenvironment. The osteogenic-angiogenic responses to titanium alloy were greater than PEEK and greater on rough titanium alloy than on smooth titanium alloy. Surface features regulated expression of integrins important in collagen recognition. These factors may increase bone formation, enhance integration, and improve implant stability in interbody spinal fusions.

Osteoblasts exhibit a more differentiated phenotype and increased bone morphogenetic protein production on titanium alloy substrates than on poly-ether-ether-ketone

Multiple biomaterials are clinically available to spine surgeons for performing interbody fusion. Poly-ether-ether-ketone (PEEK) is used frequently for lumbar spine interbody fusion, but alternative materials are also used, including titanium (Ti) alloys. Previously, we showed that osteoblasts exhibit a more differentiated phenotype when grown on machined or grit-blasted titanium aluminum vanadium (Ti6Al4V) alloys with micron-scale roughened surfaces than when grown on smoother Ti6Al4V surfaces or on tissue culture polystyrene (TCPS). We hypothesized that osteoblasts cultured on rough Ti alloy substrates would present a more mature osteoblast phenotype than cells cultured on PEEK, suggesting that textured Ti6Al4V implants may provide a more osteogenic surface for interbody fusion devices. The aim of the present study was to compare osteoblast response to smooth Ti6Al4V (sTiAlV) and roughened Ti6Al4V (rTiAlV) with their response to PEEK with respect to differentiation and production of factors associated with osteogenesis. This in vitro study compared the phenotype of human MG63 osteoblast-like cells cultured on PEEK, sTiAlV, or rTiAlV surfaces and their production of bone morphogenetic proteins (BMPs). Surface properties of PEEK, sTiAlV, and rTiAlV discs were determined. Human MG63 cells were grown on TCPS and the discs. Confluent cultures were harvested, and cell number, alkaline phosphatase-specific activity, and osteocalcin were measured as indicators of osteoblast maturation. Expression of messenger RNA (mRNA) for BMP2 and BMP4 was measured by real-time polymerase chain reaction. Levels of BMP2, BMP4, and BMP7 proteins were also measured in the conditioned media of the cell cultures. Although roughness measurements for sTiAlV (S(a)=0.09±0.01), PEEK (S(a)=0.43±0.07), and rTiAlV (S(a)=1.81±0.51) varied, substrates had similar contact angles, indicating comparable wettability. Cell morphology differed depending on the surface. Cells cultured on Ti6Al4V had lower cell number and increased alkaline phosphatase specific activity, osteocalcin, BMP2, BMP4, and BMP7 levels in comparison to PEEK. In particular, roughness significantly increased the mRNA levels of BMP2 and BMP4 and secreted levels of BMP4. These data demonstrate that rTiAlV substrates increase osteoblast maturation and produce an osteogenic environment that contains BMP2, BMP4, and BMP7. The results show that modifying surface structure is sufficient to create an osteogenic environment without addition of exogenous factors, which may induce better and faster bone during interbody fusion.

AxiaLIF system: minimally invasive device for presacral lumbar interbody spinal fusion

Lumbar fusion is commonly performed to alleviate chronic low back and leg pain secondary to disc degeneration, spondylolisthesis with or without concomitant lumbar spinal stenosis, or chronic lumbar instability. However, the risk of iatrogenic injury during traditional anterior, posterior, and transforaminal open fusion surgery is significant. The axial lumbar interbody fusion (AxiaLIF) system is a minimally invasive fusion device that accesses the lumbar (L4–S1) intervertebral disc spaces via a reproducible presacral approach that avoids critical neurovascular and musculoligamentous structures. Since the AxiaLIF system received marketing clearance from the US Food and Drug Administration in 2004, clinical studies of this device have reported high fusion rates without implant subsidence, significant improvements in pain and function, and low complication rates. This paper describes the design and approach of this lumbar fusion system, details the indications for use, and summarizes the clinical experience with the AxiaLIF system to date.

Lumbar Disk Herniation and Degenerative Disk Disease in Athletes

This work reviews the epidemiology, evaluation, treatment, and return-to-play guidelines for athletes with degenerative disk disease and herniated nucleus pulposus. Although most athletes with degenerative disk disease and herniated nucleus pulposus improve with conservative treatment, athletes with persistent symptoms may benefit from lumbar discectomy surgery. Lumbar interbody spinal fusion or disk-replacement surgery should only be considered after all other treatment options have been exhausted. Although some general consensus exists, return-to-play guidelines for the athlete with lumbar degenerative disk disease or disk herniation are not well-defined and require further investigation.

Complications Related to Osteobiologics Use in Spine Surgery

Systematic review. The objectives of this systematic review were to identify the character and rates of complications in patients after the use of BMP in spine fusion surgery and to determine whether there is a dose-response relationship of BMP with complications. BMP is used on-label for ALIF with LT-CAGE and off-label for various spine fusion applications in the cervical, thoracic, and lumbar spines because of its effectiveness in promoting arthrodesis. Multiple studies published over the past several years have highlighted complications associated with BMP in a variety of clinical fusion scenarios. There are no systematic reviews on this topic, and thus, the complication profile of off-label use or physician directed use of BMP in spinal fusion surgery is not well characterized. Some of the reported complications are unique to BMP, which underscores the need for this thorough literature review. A systematic review of the English language literature was performed for articles published between 1990 and June 2009. Electronic databases and reference lists of key articles were searched to identify articles examining the use of BMP in spine surgery. Two independent reviewers assessed the level of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria and disagreements were resolved by consensus. Two hundred forty-' articles that assessed outcomes after BMP use in spinal surgery were identified from the literature; of these, 31 articles were selected for inclusion. We determined that multiple complications are associated after the use of rhBMP-2 in both cervical and lumbar spine fusion surgery. There is a mean incidence of 44%, 25%, and 27% of resorption, subsidence, and interbody cage migration reported for lumbar spine interbody fusion surgery although reoperation or long-term detrimental effect was rare. Cervical studies report a mean 5.8% of postoperative soft tissue problems, including dysphagia, when rhBMP-2 is used for ventral cervical fusion. It was determined that the strength of evidence of the peer-reviewed literature that report on types of complications is high for the lumbar and low for the cervical spine, respectively, and that the current strength of evidence on rates of complications with BMP is moderate and low, respectively. The complication profile of BMP-2 for ALIF with LT-CAGE is well characterized. Because of the lack of substantive data, the same is not true for other types of lumbar fusions, or for cervical or thoracic fusion applications. BMP has been associated with a variety of unique complications in the ventral cervical and lumbar spines. The published data on BMP fail to precisely profile this product's use in fusion surgery; hence, it should be used only after a careful consideration of the relevant data. Well-designed and executed studies are necessary to completely define the incidence of various complications relative to type of BMP, type and region of fusion, surgical technique, dose, and carrier, and importantly, to define the natural history and management of associated complications.