Development of a bioresorbable self‐hardening bone adhesive based on a composite consisting of polylactide methacrylates and β‐tricalcium phosphate

Abstract

In this work, a novel bioresorbable bone adhesive based on radically polymerizable polylactide with methacrylate endgroups known from polymethylmethacrylate (PMMA) cements and varying amounts of bioresorbable/biodegradable lactide moieties was developed. The swelling and degradation properties as well as the hardening time, viscosity, and adhesion properties (tension and shear resistance) were subsequently measured in vitro and optimized. For a broad use in surgery the handling properties, the shelf life and the storage temperature are important issues. The finally developed material consists of three substances that have to be mixed to start the reaction: a highly viscous mixture of oligomers and two beta-tricalcium phosphate (beta-TCP, Cerasorb) powders with the radical starter and the promoter. The material has a processing time of 2 min and is completely cured after another minute. The tension and shear resistance of the material is 3.1-13.9 MPa that will decrease by storing the substance in a humid atmosphere. Degradation experiments showed a mass loss of 20-35% during the first 5 weeks. Tests with MC3T3-E1 cells showed an increase of the alkaline phosphatase activity over a period of 14 days. The mechanical and handling properties and the in vitro data are showing a promising biomaterial for bone regeneration.

A Bone Glue with Sustained Adhesion under Wet Conditions

“…The addition of mineral fillers such as gypsum, struvite, or newberyite in such bone glues is thought to enhance the degradation ability and to create porosity for an improved bone healing. This is a different concept to the works of Heiss et al, in which adhesive degradation occurs by hydrolysis of the organic matrix while the filler β‐tricalcium phosphate is mainly thought to neutralize acidic degradation products. All fillers from the current study have a higher solubility than β‐tricalcium phosphate (0.39 mg L −1 ) with struvite showing the lowest solubility (14.61 mg L −1 ) followed by newberyite (232.83 mg L −1 ) and gypsum that can be dissolved in water up to 2–2.5 g L −1 under equilibrium conditions .…”

Magnesium Phosphate Cement as Mineral Bone Adhesive

“…Grover et al [31] substituted orthophosphoric by pyrophosphoric acid in a brushite forming cement system to improve its bonding on cortical bone and on different biomaterial surfaces [31]. More attempts to enlarge the application field of CaP towards bone adhesives focused on the incorporation of ceramic particles e.g., monocalcium phosphate [19] or β-tricalcium phosphate [18,19,20] into biodegradable methacrylated polylactide-based adhesives [18,19,20]. However, because of their similarity to the mineral phase of bone [15,32], CPC are still promising for applications, where bone-bonding is required [15].…”

“…In contrast, mineral bone cement formulations based on calcium and magnesium phosphate chemistry (CPC and MPC) are biodegradable in vivo [16,17], but were actually not developed for the application as bone adhesives. In particular CPC are considered to have relatively low bone adhesiveness [15], why most research focused on the implementation of calcium phosphate fillers into methacrylated polymer-based composite systems [18,19,20]. Compared to CPC, some of the material characteristics of MPC are outstanding, which includes their high initial strength [21], a more reliable degradation potential [16,17] and they are considered to have a higher bone affinity [15,22].…”

Enhanced tendon-to-bone repair through adhesive films

“…Ideal adhesives could either be biologically inert or guide the healing response as with a tissue engineering approach [53]: the same biomechanical design principles apply to minimizing stress concentrations for tissue engineered biomaterials at interfaces between soft and hard tissues. Current adhesive approaches to orthopedic repair primarily use bone cements (e.g., [54]), cyanoacrylate- [55, 56, 57, 58, 59] or methacrylate-based chemistries [60, 61, 62, 63], which may be appropriate for fracture repair but are significantly more stiff than desirable for tendon-to-bone repair. Furthermore, biocompatibility is limited unless all free acrylate moieties are consumed.…”