Einsatz von Knochenersatzmaterialien bei Fusionen der Wirbelsäule

A model approach to show that monocytes can enter microporous β-TCP ceramics

β-TCP ceramics are versatile bone substitute materials and show many interactions with cells of the monocyte-macrophage-lineage. The possibility of monocytes entering microporous β-TCP ceramics has however not yet been researched. In this study, we used a model approach to investigate whether monocytes might enter β-TCP, providing a possible explanation for the origin of CD68-positive osteoclast-like giant cells found in earlier works.We used flow chambers to unidirectionally load BC, PRP, or PPP into slice models of either 2 mm or 6 mm β-TCP. Immunofluorescence for CD68 and live/dead staining was performed after the loading process.Our results show that monocytes were present in a relevant number of PRP and BC slices representing the inside of our 2 mm slice model and also present on the actual inside of our 6 mm model. For PPP, monocytes were not found beyond the surface in either model.Our results indicate the possibility of a new and so far neglected constituent in β-TCP degradation, perhaps causing the process of ceramic degradation also starting from inside the ceramics as opposed to the current understanding. We also demonstrated flow chambers as a possible new in vitro model for interactions between blood and β-TCP.

Anterior Cervical Discectomy and Fusions Supplemented With Cellular or Noncellular Allografts Have Similar Radiographic Fusion and Clinical Outcomes

STUDY DESIGN

A retrospective, single-center study.

OBJECTIVE

The aim of this study was to assess radiographic fusion after anterior cervical discectomy and fusion (ACDF) supplemented with either demineralized bone matrix or ViviGen in a polyetheretherketone biomechanical interbody cage.

SUMMARY OF BACKGROUND DATA

Cellular and noncellular allografts are utilized as adjuncts in attempts to improve fusion after ACDF. The purpose of this study was to assess radiographic fusion and clinical outcomes after ACDF supplemented with cellular or noncellular allografts.

MATERIALS AND METHODS

A single surgeon's clinical practice database was interrogated for consecutive patients who underwent a primary ACDF using cellular or noncellular allograft from 2017 to 2019. These subjects were matched by age, sex, body mass index, smoking status, and levels operated. Patient demographic and preoperative and postoperative patient-reported outcome measures (PROMs) including Visual Analog Scale Pain, Neck Disability Index, EuroQol-5 Dimension (EQ-5D), Patient-Reported Outcomes Measurement Information System (PROMIS), and Eating Assessment Tool 10 were collected preoperatively and at 3, 6, and 12 months postoperatively. Radiographic evidence of fusion was determined by <2 mm motion between spinous processes on flexion and extension radiographs and assessing bony bridging at 3, 6, and 12 months postoperatively.

RESULTS

There were 68 total patients, with 34 patients in each group, and 69 and 67 operative levels in the cellular and noncellular allograft groups, respectively. There was no difference in age, sex, body mass index, or smoking status between groups ( P >0.05). There was no difference in number of 1-level, 2-level, 3-level, or 4-level ACDFs between cellular and noncellular groups ( P >0.05). At 3, 6, and 12 months postoperatively, there was no difference in the percent of operated levels with <2 mm motion between spinous processes, complete bony bridging, or both <2 mm motion and complete bony bridging in the cellular and noncellular groups ( P >0.05). There was no difference in the number of patients fused at all operated levels at 3, 6, or 12 months postoperatively ( P >0.05). No patient required revision ACDF for symptomatic pseudarthrosis. There was no significant difference in PROMs between the cellular and noncellular groups at 12 months postoperatively except for improved EQ-5D and PROMIS-physical in the cellular compared with noncellular group ( P =0.03).

CONCLUSIONS

Similar radiographic fusion rates were achieved with cellular and noncellular allografts at all operated levels with similar PROMs in the cellular and noncellular groups at 3, 6, and 12 months postoperatively. Thus, ACDFs supplemented with cellular allograft demonstrate adequate radiographic fusion rates when compared with noncellular allografts with similar patient outcomes.

LEVEL OF EVIDENCE

Level III.

Sustained delivery of PlGF-2123-144*-fused BMP2-related peptide P28 from small intestinal submucosa/polylactic acid scaffold material for bone tissue regeneration

Bone morphogenetic protein 2 (BMP-2) is one of the most important factors for bone tissue formation. However, its use over the past decade has been associated with numerous side effects. This is due to the fact that recombinant human (rh) BMP-2 has several biological functions, as well as that non-physiological high dosages were commonly administered. In this study, we synthesized a novel BMP-2-related peptide (designated P28) and fused a mutant domain in placenta growth factor-2 (PlGF-2123-144*) that allowed for the "super-affinity" of extracellular matrix proteins to P28, effectively controlling the release of low dosage P28 from small intestinal submucosa/polylactic acid (SIS/PLA) scaffolds. These have been shown to be excellent scaffold materials both in vivo and in vitro. The aim of this study was to determine whether these scaffolds could support the controlled release of P28 over time, and whether the composite materials could serve as structurally and functionally superior bone substitutes in vivo. Our results demonstrated that P28 could be released slowly from SIS/PLA to promote the adhesion, proliferation, and differentiation of bone marrow stromal cells (BMSCs) in vitro. In vivo, radiographic and histological examination showed that SIS/PLA/P28/PlGF-2123-144* completely repaired critical-size bone defects, compared to SIS/PLA, SIS/PLA/PlGF-2123-144*, or SIS/PLA/P28 alone. These findings suggest that this controlled release system may have promising clinical applications in bone tissue engineering.

Biphasic calcium phosphate with submicron surface topography in an Ovine model of instrumented posterolateral spinal fusion

As spinal fusions require large volumes of bone graft, different bone graft substitutes are being investigated as alternatives. A subclass of calcium phosphate materials with submicron surface topography has been shown to be a highly effective bone graft substitute. In this work, a commercially available biphasic calcium phosphate (BCP) with submicron surface topography (MagnetOs; Kuros Biosciences BV) was evaluated in an Ovine model of instrumented posterolateral fusion. The material was implanted stand-alone, either as granules (BCPgranules) or as granules embedded within a fast-resorbing polymeric carrier (BCPputty) and compared to autograft bone (AG). Twenty-five adult, female Merino sheep underwent posterolateral fusion at L2-3 and L4-5 levels with instrumentation. After 6, 12, and 26 weeks, outcomes were evaluated by manual palpation, range of motion (ROM) testing, micro-computed tomography, histology and histomorphometry. Fusion assessment by manual palpation 12 weeks after implantation revealed 100% fusion rates in all treatment groups. The three treatment groups showed a significant decrease in lateral bending at the fusion levels at 12 weeks (P < 0.05) and 26 weeks (P < 0.001) compared to the 6 week time-point. Flexion-extension and axial rotation were also reduced over time, but statistical significance was only reached in flexion-extension for AG and BCPputty between the 6 and 26 week time-points (P < 0.05). No significant differences in ROM were observed between the treatment groups at any of the time-points investigated. Histological assessment at 12 weeks showed fusion rates of 75%, 92%, and 83% for AG, BCPgranules and BCPputty, respectively. The fusion rates were further increased 26 weeks postimplantation. Similar trends of bone growth were observed by histomorphometry. The fusion mass consisted of at least 55% bone for all treatment groups 26 weeks after implantation. These results suggest that this BCP with submicron surface topography, in granules or putty form, is a promising alternative to autograft for spinal fusion.

Biological properties of calcium phosphate biomaterials for bone repair: a review

This article reviews the recent advances and various factors affecting the improvement of the biological properties of calcium phosphate for bone repair.

Efficacy of cortico/cancellous composite allograft in treatment of cervical spondylosis

This was a prospective comparative study.The aim of this study was to compare the clinical and radiologic outcomes of patients treated with cortico/cancellous composite allograft or autoiliac bone graft in anterior cervical discectomy and fusion.Several methods have been developed to fuse the cervical spine for treatment of cervical spondylosis. Cortico/cancellous composite allograft might be another alternative.A total of 46 patients who underwent surgery for treatment of cervical spondylosis were evaluated between September 2010 and January 2015. The duration of operation, blood loss, perioperative complications, neck disability index (NDI), visual analogue scale (VAS), and fusion rates were compared between the 2 groups.There were no significant differences in clinical or radiologic outcomes between the patients treated with cortico/cancellous composite allograft and those treated with autoiliac bone graft. The 2 groups showed similar improvements in clinical symptoms and fusion rates. Although not statistically significant, the subsidence rate was lower in the cortico/cancellous composite group.Cortico/cancellous composite allograft is an effective alternative to conventional allograft or autograft in anterior cervical discectomy and fusion.

Effectiveness and safety of recombinant human bone morphogenetic protein-2 for adults with lumbar spine pseudarthrosis following spinal fusion surgery: A systematic review

Objectives

We performed a systematic review of the literature to determine the safety and efficacy of bone morphogenetic protein (BMP) compared with bone graft when used specifically for revision spinal fusion surgery secondary to pseudarthrosis.

Methods

The MEDLINE, EMBASE and Cochrane Library databases were searched using defined search terms. The primary outcome measure was spinal fusion, assessed as success or failure in accordance with radiograph, MRI or CT scan review at 24-month follow-up. The secondary outcome measure was time to fusion.

Results

A total of six studies (three prospective and three retrospective) reporting on the use of BMP2 met the inclusion criteria (203 patients). Of these, four provided a comparison of BMP2 and bone graft whereas the other two solely investigated the use of BMP2. The primary outcome was seen in 92.3% (108/117) of patients following surgery with BMP2. Although none of the studies showed superiority of BMP2 to bone graft for fusion, its use was associated with a statistically quicker time to achieving fusion. BMP2 did not appear to increase the risk of complication.

Conclusion

The use of BMP2 is both safe and effective within the revision setting, ideally in cases where bone graft is unavailable or undesirable. Further research is required to define its optimum role.

Cite this article: Mr P. Bodalia. Effectiveness and safety of recombinant human bone morphogenetic protein-2 for adults with lumbar spine pseudarthrosis following spinal fusion surgery: A systematic review. Bone Joint Res 2016;5:145–152. DOI: 10.1302/2046-3758.54.2000418.