BACKGROUND CONTEXT: The nonunion rate after lumbar spinal fusion is as high as 25%. Recombinant human bone morphogenetic protein 2 (rhBMP2) has been used as a biological adjunct to promote bony fusion. However, recently there have been concerns about BMP2. Oxysterol 133 (Oxy133) has been shown to promote excellent fusion rates in rodent lumbar spine models and offers a potential alternative to rhBMP2.PURPOSE: The purpose of this study was to compare the fusion rate of rhBMP2 and Oxy133 in a randomized controlled trial using a posterolateral lumbar rabbit spinal fusion model.STUDY DESIGN: This was a randomized control animal study.METHODS: Twenty-four male adult white New Zealand rabbits (3-3.5 kg) underwent bilateral posterolateral lumbar spinal fusion at L4-L5. Rabbits were divided into four groups: control (A), 30-mg rhBMP2 (B), 20-mg Oxy133 (C), and 60-mg Oxy133 (D). At 4 weeks, fusion was evaluated by fluoroscopy, and at 8 weeks, the rabbits were sacrificed and fusion was evaluated radiographically, by manual palpation, and with microcomputed tomography.RESULTS: Fusion rates by radiographic analysis at 8 weeks were Group A, 40.0%; Group B, 91.7%; Group C, 91.7%; and Group D, 100%. Evaluation of fusion masses by manual palpation of excised spines after sacrifice showed the following fusion rates: Group A, 0%; Group B, 83.3%; Group C, 83.3%; and Group D, 90%. Microcomputed tomography scanning confirmed these findings.CONCLUSIONS: These findings in a rabbit model demonstrate that both 20- and 60-mg Oxy133 doses promote fusion that is equivalent to fusion induced by 30-mg rhBMP2 and significantly greater than the control group. The present findings confirm that Oxy133 is a promising candidate for therapeutic development as an alternative to rhBMP2 to promote spinal fusion. (C) 2015 Elsevier Inc. All rights reserved.

ABSTRACT Osteogenic factors are often used in orthopedics to promote bone growth, improve fracture healing, and induce spine fusion. Osteogenic oxysterols are naturally occurring molecules that were shown to induce osteogenic differentiation in vitro and promote spine fusion in vivo. The purpose of this study was to identify an osteogenic oxysterol more suitable for clinical development than those previously reported, and evaluate its ability to promote osteogenesis in vitro and spine fusion in rats in vivo. Among more than 100 oxysterol analogues synthesized, Oxy133 induced significant expression of osteogenic markers Runx2, osterix (OSX), alkaline phosphatase (ALP), bone sialoprotein (BSP), and osteocalcin (OCN) in C3H10T1/2 mouse embryonic fibroblasts and in M2-10B4 mouse marrow stromal cells. Oxy133-induced activation of an 8X-Gli luciferase reporter, its direct binding to Smoothened, and the inhibition of Oxy133-induced osteogenic effects by the Hedgehog (Hh) pathway inhibitor, cyclopamine, demonstrated the role of Hh pathway in mediating osteogenic responses to Oxy133. Oxy133 did not stimulate osteogenesis via BMP or Wnt signaling. Oxy133 induced the expression of OSX, BSP, and OCN, and stimulated robust mineralization in primary human mesenchymal stem cells. In vivo, bilateral spine fusion occurred through endochondral ossification and was observed in animals treated with Oxy133 at the fusion site on X-ray after 4 weeks and confirmed with manual assessment, micro-CT (µCT), and histology after 8 weeks, with equal efficiency to recombinant human bone morphogenetic protein-2 (rhBMP-2). Unlike rhBMP-2, Oxy133 did not induce adipogenesis in the fusion mass and resulted in denser bone evidenced by greater bone volume/tissue volume (BV/TV) ratio and smaller trabecular separation. Findings here suggest that Oxy133 has significant potential as an osteogenic molecule with greater ease of synthesis and improved time to fusion compared to previously studied oxysterols. Small molecule osteogenic oxysterols may serve as the next generation of bone anabolic agents for therapeutic development. © 2014 American Society for Bone and Mineral Research.

BACKGROUND:Previous studies have suggested that the co-expression of two different bone morphogenetic protein (BMP) genes can result in the production of heterodimeric BMPs that may be more potent than homodimers. In this study, combined BMP-2 and BMP-7 gene transfer was performed ex vivo to compare the resulting new bone formation with that of single-BMP gene transfer in a rat spinal fusion model. METHODS:Forty-four athymic rats underwent posterolateral fusion at L4-L5 and were implanted with a collagen sponge containing human adipose-derived stem cells. Group A received untreated cells, and the remaining groups received cells transfected with various genes in a lentivirus vector. The transferred genes were GFP (green fluorescent protein) in Group B, BMP-2 in Group C, BMP-7 in Group D, and both BMP-2 and BMP-7 in Group E. In vitro production of BMP-2 and BMP-7 was quantified by means of an enzyme-linked immunosorbent assay (ELISA) specific to BMP-2 or BMP-7. Osseous fusion was quantified with use of radiography and microcomputed tomography. RESULTS:ELISA demonstrated that Group E, which was treated with both BMP-2 and BMP-7, produced less than one-fourth as much BMP as the groups treated with a single transfected BMP (Groups C and D). Radiographs showed that all of the spines in Groups C, D, and E appeared to be fused by eight weeks; the spines in Groups A and B showed minimal evidence of new bone formation. Measurements confirmed that the mean bone formation area was significantly greater in Groups C, D, and E compared with Groups A and B (p < 0.001). In addition, the bone formation area was significantly greater in Group E compared with Groups C and D (p < 0.001). CONCLUSIONS:Combined BMP-2 and BMP-7 ex vivo gene transfer was found to be significantly more effective for inducing new bone formation compared with ex vivo gene transfer of an individual BMP in a rat spinal fusion model. CLINICAL RELEVANCE:Combined BMP-2 and BMP-7 therapy may lead to efficient bone regeneration.

Study Design:A retrospective study.Objective:To evaluate whether recombinant human bone morphogenetic protein (rhBMP-2) can improve fusion rates and time to fusion in high-risk patients when compared with autograft in lumbar posterolateral fusion.Summary of Background Data:The use of rhBMP-2 in the general population for posterolateral fusion has resulted in relatively good reported outcomes; however, it is currently considered off-label use. Few studies, however, have determined the outcomes of rhBMP-2 when used in patients with numerous risk factors for a pseudarthrosis.Methods:One hundred ninety-five patients were divided into 4 groups depending on fusion material and the presence/absence of fusion-related risk factors for nonunions; group A was defined as rhBMP-2 used in the presence of high-risk factors (FRRF), group B was defined as rhBMP-2 used in the absence of FRRF, group C was defined as autograft used in the presence of FRRF, and group D was defined as autograft used in the absence of FRRF. The time to fusion, fusion rate were compared between each group.Results:The time to fusion was significantly faster in group B than in group D in patients with no history of smoking (P<0.05), hypertension (P<0.01), or other significant comorbidity (P<0.05). The time to complete fusion was also significantly faster in group B than in group D in patients under the age of 65 (P<0.05), patients undergoing primary surgery (P<0.05), single-level surgery (P<0.01), no smoking history (P<0.05), no diabetes mellitus (P<0.01), no hypertension (P=0.001), no osteoporosis (P<0.01), and no significant comorbidity (P<0.01). Although the fusion rate was higher in group B than in group D, with the exception of sex and single-level surgery, there were no significant differences between groups B and D. Although initial fusion mass and time to solid fusion was faster in group A than in group C, there were no significant differences between groups A and C. In addition, fusion rates were higher in group C than in group A, looking at all factors except revision surgery, but the differences were not statistically significant.Conclusions:With relative low dosage of rhBMP-2 compared with the dose used in Food and Drug Administration trial, in patients without fusion-related risk factors, rhBMP-2 may lead to acceptable fusion rates and faster fusion time when compared with autograft. Therefore, rhBMP-2 may serve as an acceptable alternative to autogenous bone graft in patients without fusion-related risk factors undergoing instrumented posterolateral lumbar fusions. When compared with patients with fusion-related risk factors, the use of rhBMP-2 was comparable with autograft but was not sufficient to overcome all aspects of the weakened osteoinductive capacity encountered in patients with these risk factors.

The ideal treatment for posterior cruciate ligament (PCL) injuries is controversial and remains an active area of orthopedic research. The indications for surgery and the ideal method of reconstruction continue to be evaluated in biomechanical and clinical studies. Recent research has provided information on the anatomy and biomechanics of the PCL, and the merits and drawbacks of the transtibial compared with the tibial inlay technique, the use of single vs double-bundle reconstruction, and different graft options for reconstruction. This review discusses important factors in the surgical treatment of PCL injuries, with attention to the most current literature on these topics.

Osteogenic factors are often used in orthopedics to promote bone growth, improve fracture healing, and augment spine fusion. We have previously reported the novel osteogenic activity of specific oxysterols and investigated their potential for use in clinical applications requiring bone formation.

BACKGROUND CONTEXT:Bone morphogenetic protein (BMP)-2 and BMP-7 are used to enhance bone formation in spine surgery, but the use of these materials is associated with side effects including inflammation, especially in the soft tissues of the neck. Bone morphogenetic protein-binding peptide (BBP) binds BMP-2 and BMP-7 and imparts a "slow-release" property to collagen carrier. PURPOSE:To test the hypothesis that the addition of BBP will reduce the soft-tissue inflammation induced by the implantation of BMP-2 and BMP-7 on a collagen sponge. STUDY DESIGN/SETTING:Prospective in vivo rodent model of inflammation. METHODS:We implanted six different materials absorbed onto collagen sponges: absorbable collagen sponge (ACS) alone; BBP alone; recombinant human bone morphogenetic protein (rhBMP)-2 alone; rhBMP-2 plus BBP; rhBMP-7 alone; and rhBMP-7 plus BBP. Sponges were implanted bilaterally (subcutaneously [SC] and intramuscularly [IM]) into the backs of rats. Using magnetic resonance imaging, inflammation was assessed in terms of soft-tissue edema volume at 3 hours and at 2, 4, and 7 days. The animal subjects were killed on Day 7, and the dimensions of the inflammatory mass were measured manually in the case of SC tissue and those of the inflammatory zone were determined subsequently by microscopic examination in the case of muscle. RESULTS:Both the SC and the IM soft-tissue edema volumes in the rhBMP-2 plus BBP and the rhBMP-7 plus BBP groups were significantly lower than those observed in the rhBMP-2 alone and rhBMP-7 alone groups. The edema volume associated with BBP alone was greater than that associated with ACS alone but less than that associated with the other treatment groups. The measurements of inflammatory masses and zone yielded similar results. CONCLUSIONS:Bone morphogenetic protein-binding peptide may reduce the inflammatory response associated with the use of rhBMP-2 and rhBMP-7 in a rodent model of inflammation and in a form that has previously been shown to enhance the activity of BMPs. These preliminary studies suggest that BBP may have the potential to be used in the future to improve healing and reduce soft-tissue swelling in surgical applications of BMPs.

Purpose The Scoliosis Research Society-22 (SRS-22) questionnaire is a widely accepted questionnaire used to assess the health-related quality of life for scoliosis patients in the United States. However, its adaptation in other languages is necessary for its multinational use. A cross-sectional study was performed to evaluate the validity and reliability of an adapted Thai version of the SRS-22 questionnaire. Methods An expert committee performed translation/retranslation of the English version of the SRS-22 questionnaire, as well as a cross-cultural adaptation process. Later, SRS-22 questionnaires and previously validated Short Form-36 version 2 (SF-36v2) outcome instruments were given to patients treated for idiopathic scoliosis with a minimum of 1 year of follow-up. Internal consistency and reproducibility were determined by Cronbach's alpha statistics and the intraclass correlation coefficient, respectively. Concurrent validity was measured by comparing SRS-22 results with a previously validated questionnaire (SF-36v2). Measurement was made using the Pearson correlation coefficient ( r). Results The study showed satisfactory internal consistency with Cronbach's alpha values for all of the corresponding domains (pain, 0.72; self-image/appearance, 0.87; mental health, 0.83; satisfaction with management, 0.63; and function/activity, 0.83). The test–retest reproducibility was also excellent or good for all domains (pain, 0.72; self-image/appearance, 0.85; mental health, 0.82; satisfaction, 0.62; and function/activity, 0.81). For concurrent validity, excellent correlation was found in two domains, good in six domains, moderate in five domains, and poor in five domains of the 18 relevant domains. Conclusions The Thai version of the SRS-22 outcome instrument has satisfactory internal consistency, excellent reproducibility, and acceptable validity.

Stimulation of bone formation by osteoinductive materials is of great clinical importance in spinal fusion surgery, repair of bone fractures, and in the treatment of osteoporosis. We previously reported that specific naturally occurring oxysterols including 20(S)‐hydroxycholesterol (20S) induce the osteogenic differentiation of pluripotent mesenchymal cells, while inhibiting their adipogenic differentiation. Here we report the characterization of two structural analogues of 20S, Oxy34 and Oxy49, which induce the osteogenic and inhibit the adipogenic differentiation of bone marrow stromal cells (MSC) through activation of Hedgehog (Hh) signaling. Treatment of M2‐10B4 MSC with Oxy34 or Oxy49 induced the expression of osteogenic differentiation markers Runx2, Osterix (Osx), alkaline phosphatase (ALP), bone sialoprotein (BSP), and osteocalcin (OCN), as well as ALP enzymatic activity and robust mineralization. Treatment with oxysterols together with PPARγ activator, troglitazone (Tro), inhibited mRNA expression for adipogenic genes PPARγ, LPL, and aP2, and inhibited the formation of adipocytes. Efficacy of Oxy34 and Oxy49 in stimulating bone formation in vivo was assessed using the posterolateral intertransverse process rat spinal fusion model. Rats receiving collagen implants with Oxy 34 or Oxy49 showed comparable osteogenic efficacy to BMP2/collagen implants as measured by radiography, MicroCT, and manual inspection. Histological analysis showed trabecular and cortical bone formation by oxysterols and rhBMP2 within the fusion mass, with robust adipogenesis in BMP2‐induced bone and significantly less adipocytes in oxysterol‐induced bone. These data suggest that Oxy34 and Oxy49 are effective novel osteoinductive molecules and may be suitable candidates for further development and use in orthopedic indications requiring local bone formation. J. Cell. Biochem. 112: 1673–1684, 2011. © 2011 Wiley‐Liss, Inc.

Bone morphogenetic proteins (BMPs) and transforming growth factor-beta (TGF-beta) contribute to the growth of some skeletal metastases through autocrine stimulation. Secreted phosphoprotein 24 kDa (spp24) has been shown to bind to both BMP-2 and TGF-beta and to markedly inhibit the osteogenic properties of rhBMP-2. We hypothesized that the addition of spp24 would sequester autocrine growth factors (especially BMP-2) and reduce tumor growth in a system (A549 human non-small cell lung cancer cell line) where autocrine stimulation by BMP-2 is known to be important. A549 cells were injected into two sites (subcutaneous and intraosseus) in SCID mice with and without the co-injection of BMP-2 and spp24. Tumor growth after 8 weeks was assessed through gross examination, radiological imaging, and histological analysis. Spp24 attenuated the tumor growth enhancing effects of rhBMP-2 and reduced the tumor growth when added to tumor cells that were not treated with BMP-2. We conclude that spp24 can reduce A549 cell tumor growth in both soft tissue and intraosseus environments. We hypothesize that the mechanism for this inhibition is interruption of autocrine stimulation through the sequestration of BMP-2. Spp24 can be developed into a therapeutic agent that can be employed in clinical situations where the inhibitions of BMPs and related proteins is advantageous. (C) 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:1712-1718, 2011

Spinal arthrodesis continues to expand in clinical indications and surgical practice. Despite a century of study, failure of bone formation or pseudarthrosis can occur in individual patients with debilitating clinical symptoms. Here we review biological and technical aspects of spinal fusion under active investigation, describe relevant biomechanics in health and disease, and identify the possibilities and limitations of translational animal models. The purpose of this article is to foster collaborative efforts with researchers who model bone hierarchy. The induction of heterotopic osteosynthesis requires a complex balance of biologic factors and operative technique to achieve successful fusion. Anatomical considerations of each spinal region including blood supply, osteology, and biomechanics predispose a fusion site to robust or insufficient bone formation. Careful preparation of the fusion site and appropriate selection of graft materials remains critical but is sometimes guided by conflicting evidence from the long-bone literature. Modern techniques of graft site preparation and instrumentation have evolved for every segment of the vertebral column. Despite validated biomechanical studies of modern instrumentation, a correlation with superior clinical outcomes is difficult to demonstrate. In many cases, adjuvant biologic therapies with allograft and synthetic cages have been used successfully to reproduce the enhancement of fusion rates observed with cancellous and tricortical autograft. Current areas of investigation comprise materials science, stem cell therapies, recombinant growth factors, scaffolds and biologic delivery systems, and minimally invasive surgical techniques to optimize the biologic response to intervention. Diverse animal models are required to approach the breadth of spinal pathology and novel therapeutics.

Pharyngoesophageal diverticulum after anterior cervical spine surgery is a rarely reported but potentially life-threatening complication. A case report of pharyngoesophageal diverticulum 7 years after anterior cervical spine surgery is presented. The patient suffered from dysphagia, odynophagia, recurrent fever, weight loss, and also an impressive bulging in the neck with swallowing. After careful examination and preparation, he underwent revision surgery via an open procedure, had the implants removed, pouch excised, and esophagus reconstructed reinforced by a sternohyoid muscle flap as well as an omohyoid muscle flap. The post-operative period was uneventful, and he experienced a satisfactory recovery. At last follow up, 2.5 years post surgery, the patient remained symptom free. Upon review of the literature, only six such previous reports with seven cases were found. Diagnostic tools, possible mechanism, correlative factors and treatment are discussed. This patient was fortunate that although his symptoms developed long after the initial anterior cervical operation and the pouch grew impressively large almost perforating, he still recovered well. It again proves the necessity of long-term X-ray follow up, and also reminds the surgeons to be alert of the possibility of esophageal injury even when the esophageal symptoms are mild and occur long after the initial operation.

The osteoinductive properties of recombinant human bone morphogenetic protein-2 (rhBMP-2) have been well documented and studied. In addition to these properties recent in vitro data suggests that rhBMP-2 may also have a positive anabolic effect on the intervertebral disc. However, conclusive in vivo evidence of this effect is still lacking and further study is necessary.

Bone morphogenetic binding peptide (BBP) is an 18.5 kDa fragment of a bone matrix protein peptide. A rat femoral defect model was used to test the effect of BBP combined with recombinant human bone morphogenetic protein‐7 (rhBMP‐7) to induced bone healing. Two doses of BBP (500 and 1000 µg) were tested with two doses of rhBMP‐7 (2 and 5 µg), and the results were compared with a positive control (10 µg rhBMP‐7). Bone healing was evaluated by radiology, manual palpation, microcomputed tomography, and histology. The high dose of 10 µg of rhBMP‐7 resulted in a consistent 100% bone union rate and a mature histological appearance on histology, and was used as a positive control. When 1000 µg of BBP was combined with lower doses of BMP‐7 (2 µg rhBMP‐7 or 5 µg rhBMP‐7) significant differences were seen in radiographic scores, manual palpation, and bone volume, when compared to 2 µg rhBMP‐7 or 5 µg rhBMP‐7 alone. The combination of 1000 µg of BBP and 5 µg rhBMP‐7 also achieved 100% fusion rate, induced a larger amount of bone formation, and yielded similar maturity of bone marrow when compared with the high dosage 10 µg rhBMP‐7 group. This study demonstrated that when combined together, BBP can enhance the bone healing of rhBMP‐7. Improved healing imparted by the addition of BBP may result in lesser amounts of rhBMP‐7 needed to achieve union in the clinical setting. © 2010 OrthopaedicResearchSociety.PublishedbyWileyPeriodicals, Inc.JOrthopRes29:753–759,2011

BACKGROUND CONTEXT: The rat caudal disc has been increasingly used in studying of disc degeneration because of its simplicity, low cost, and efficiency. However, the reproducibility and standardization are essential to facilitate the investigations of biologic therapeutics at different stages of degeneration.PURPOSE: To identify the effect of different needle gauges to the degenerative response in rat caudal discs and to examine its pathogenesis by looking at the cellular and matrix changes.STUDY DESIGN: In vivo study of injury-induced rat caudal disc degeneration using needle puncture.PATIENT SAMPLE: Thirty-six Lewis rats aged 12-14 weeks.OUTCOME MEASURES: The induced degenerative discs were analyzed by plain radiograph, magnetic resonance imaging (MRI) and histological examination. Proteoglycan content was assessed by alcian blue stain. Immunohistochemistry using aggrecan, collagen II, and Sox-9 was also evaluated to investigate cell differentiation and matrix changes.METHODS: All rats were divided into three groups according to different needle gauges (180, 20G, and 220). Caudal discs were punctured percutaneously under image guidance. Radiographs and MRI were obtained at 2 weeks interval until 8 weeks. At each time point, three rats from each group were sacrificed for histological analysis and immunohistochemistry.RESULTS: Larger needle gauges, especially 180, produced more deterioration of the disc when compared with smaller sizes, particularly with time. Significant differences were identified in almost all parameters compared between 180 and 220 at the 8-week time point. For the effect of time in the same needle size, the differences occurred between 2- or 4-week and 8-week time point in the 18G and 20G groups. The proteoglycan and aggrecan stain gradually decreased over time. Chondrogenic differentiation was identified within the degenerative disc by detecting Sox-9 positive cells and collagen II accumulation increased as degeneration progressed.CONCLUSIONS: The puncture-induced degenerative changes in rat caudal discs can imitate the human degenerative cascade as observed in plain radiograph, MRI, histology, and immunohistochemistry. We suggest that needle size affects the occurrence of progression of degeneration; thus, the large needle size was required to accelerate the deterioration. The size of needle and time point after injury should be considered when investigating the effect of therapeutic materials to retard degeneration or regenerate the intervertebral disc. Published by Elsevier Inc.