Functionalization of screw implants with superelastic structured Nitinol anchoring elements

Background Demographic change is leading to an increase in the number of osteoporotic patients, so a rethink is required in implantology in order to be able to guarantee adequate anchoring stability in the bone. The functional modification of conventional standard screw implants using superelastic, structured Ti6Al4V anchoring elements promises great potential for increasing anchoring stability. Methods For this purpose, conventional screw implants were mechanically machined and extended so that structured-superelastic-positionable-Ti6Al4V anchoring elements could be used. The novel implants were investigated with three tests. The setup of the anchoring elements was investigated in CT studies in an artificial bone. In a subsequent simplified handling test, the handling of the functional samples was evaluated under surgical conditions. The anchorage stability compared to standard screw implants was investigated in a final pullout test according to ASTM F543—the international for the standard specification and test methods for metallic medical bone screws. Results The functionalization of conventional screw implants with structured superelastic Ti6Al4V anchoring elements is technically realizable. It was demonstrated that the anchoring elements can be set up in the artificial bone without any problems. The anchorage mechanism is easy to handle under operating conditions. The first simplified handling test showed that at the current point of the investigations, the anchoring elements have no negative influence on the surgical procedure (especially under the focus of screw implantation). Compared to conventional standard screws, more mechanical work is required to remove the functional patterns completely from the bone. Conclusion In summary, it was shown that conventional standard screw implants can be functionalized with Ti6Al4V-structured NiTi anchoring elements and the new type of screws are suitable for orthopedic and neurosurgical use. A first biomechanical test showed that the anchoring stability could be increased by the anchoring elements.

Efficacy of Platelet-rich Plasma Impregnation for Unidirectional Porous Β-tricalcium Phosphate in Lateral Lumbar Interbody Fusion: Study Protocol for a Randomized Controlled Trial

BackgroundPlatelet-rich plasma has been increasingly used in spinal fusion surgery. However, the efficacy of platelet-rich plasma in lateral lumbar interbody fusion is unclear. In Japan, Affinos® (Kuraray Co., Tokyo, Japan), which is a β-tricalcium phosphate artificial bone, has been increasingly used for spinal fusion as a bone graft. The purpose of this trial is to demonstrate whether Affinos® impregnated with platelet-rich plasma can achieve a higher fusion rate, more rapid fusion, and better clinical outcomes than Affinos® alone.Methods/DesignThe current study is a prospective randomized controlled trial. The current trial will include consecutive patients scheduled for lateral lumbar interbody fusion. Since an intervertebral cage for lateral lumbar interbody fusion has two spaces for a bone graft, two bone grafts are inserted for each intervertebral level. In the current study, an artificial bone with plate-rich plasma will be inserted into one space and an artificial bone without platelet-rich plasma will be inserted into the other space. We will compare the fusion rates between the bone graft with and without platelet-rich plasma. Our primary endpoint will be the interbody fusion rate at 1 year after surgery. DiscussionThe current trial will verify the efficacy of platelet-rich plasma with Affinos® for bony fusion in lateral lumbar interbody fusion. This trial will provide substantial evidence for the effectiveness and safety of platelet-rich plasma in spinal fusion surgery.Trial registrationJapan Registry of Clinical Trials (jRCT), ID: jRCTb032200199. First registered on 13 November 2020, https://jrct.niph.go.jp/latest-detail/jRCTb032200199. jRCT is approved as a member of the Primary Registry Network of WHO ICTRP.

Selective Detection of an Infection Biomarker by an Osteo-Friend Scaffold: Development of a Multifunctional Artificial Bone Substitute

Developments in three-dimensional (3D) printing technologies have led to many potential applications in various biomedical fields, especially artificial bone substitutes (ABSs). However, due to the characteristics of artificial materials, biocompatibility and infection remain issues. Here, multifunctional ABSs have been designed to overcome these issues by the inclusion of a biochemical modality that allows simultaneous detection of an infection biomarker by osteo-friend 3D scaffolds. The developed multifunctional scaffolds consist of calcium-deficient hydroxyapatite (CDHA), which has a similar geometric structure and chemical composition to human bone, and gold nanoparticles (Au NPs), which assists osteogenesis and modulates the fluorescence of labels in their microenvironment. The Au NPs were subsequently conjugated with fluorescent dye-labeled probe DNA, which allowed selective interaction with a specific target biomarker, and the fluorescent signal of the dye was temporally quenched by the Au NP-derived Förster resonance energy transfer (FRET). When the probe DNA unfolded to bind to the target biomarker, the fluorescence signal was recovered due to the increased distance between the dye and Au NPs. To demonstrate this sensing mechanism, a microbial oligonucleotide was selected as a target biomarker. Consequently, the multifunctional scaffold simultaneously facilitated osteogenic proliferation and the detection of the infection biomarker.

Surface Modification of Carbon Fiber-Polyetheretherketone Composite to Impart Bioactivity by Using Apatite Nuclei

The authors aimed to impart the apatite-forming ability to 50 wt% carbon fiber-polyetheretherketone composite (50C-PEEK), which has more suitable mechanical properties as artificial bone materials than pure PEEK. First, the 50C-PEEK was treated with sulfuric acid in a short time to form pores on the surface. Second, the surface of the 50C-PEEK was treated with oxygen plasma to improve the hydrophilicity. Finally, fine particles of calcium phosphate, which the authors refer to as “apatite nuclei”, were precipitated on the surface of the 50C-PEEK by soaking in an aqueous solution containing multiple inorganic ions such as phosphate and calcium (modified-SBF) at pH 8.20, 25 °C. The 50C-PEEK without the modified-SBF treatment did not show the formation of apatitic phase even after immersion in simulated body fluid (SBF) for 7 days. The 50C-PEEK treated with the modified-SBF showed the formation of apatitic phase on the entire surface within 1 day in the SBF. The apatite nuclei-precipitated 50C-PEEK will be expected as a new artificial bone material with high bioactivity that is obtained without complicated fabrication processes.

Screw tightness and stripping rates vary between biomechanical researchers and practicing orthopaedic surgeons

Background Screws are the most frequently inserted orthopaedic implants. Biomechanical, laboratory-based studies are used to provide a controlled environment to investigate revolutionary and evolutionary improvements in orthopaedic techniques. Predominantly, biomechanical trained, non-surgically practicing researchers perform these studies, whilst it will be orthopaedic surgeons who will put these procedures into practice on patients. Limited data exist on the comparative performance of surgically and non-surgically trained biomechanical researchers when inserting screws. Furthermore, any variation in performance by surgeons and/or biomechanical researchers may create an underappreciated confounder to biomechanical research findings. This study aimed to identify the differences between surgically and non-surgically trained biomechanical researchers’ achieved screw tightness and stripping rates with different fixation methods. Methods Ten orthopaedic surgeons and 10 researchers inserted 60 cortical screws each into artificial bone, for three different screw diameters (2.7, 3.5 and 4.5 mm), with 50% of screws inserted through plates and 50% through washers. Screw tightness, screw hole stripping rates and confidence in screw purchase were recorded. Three members of each group also inserted 30 screws using an augmented screwdriver, which indicated when optimum tightness was achieved. Results Unstripped screw tightness for orthopaedic surgeons and researchers was 82% (n = 928, 95% CI 81–83) and 76% (n = 1470, 95% CI 75–76) respectively (p < 0.001); surgeons stripped 48% (872/1800) of inserted screws and researchers 18% (330/1800). Using washers was associated with increased tightness [80% (95% CI 80–81), n = 1196] compared to screws inserted through plates [76% (95% CI 75–77), n = 1204] (p < 0.001). Researchers were more accurate in their overall assessment of good screw insertion (86% vs. 62%). No learning effect occurred when comparing screw tightness for the first 10 insertions against the last 10 insertions for any condition (p = 0.058–0.821). Augmented screwdrivers, indicating optimum tightness, reduced stripping rates from 34 to 21% (p < 0.001). Experience was not associated with improved performance in screw tightness or stripping rates for either group (p = 0.385–0.965). Conclusions Surgeons and researchers showed different screw tightness under the same in vitro conditions, with greater rates of screw hole stripping by surgeons. This may have important implications for the reproducibility and transferability of research findings from different settings depending on who undertakes the experiments.