Biomechanical Comparison of Prototype of a Novel Intramedullary Injectable Bioresorbable Polymer-Bioresorbable Balloon Osteosynthesis and a Volar Locking Plate for Treatment of Distal Radius Fractures

Abstract

Background: There is a large assortment of modalities for the surgical treatment/management of distal radius fractures (DRFs), where the most widely used is the fixed-angle volar plating (VLP) system, which, sometimes, is referred to as the "surgical modality of choice". While outcomes with each modality are usually good to excellent, each has its share of shortcomings and complications. Thus, there is scope for improvements to existing modalities and/or introduction of new ones. Study Purpose: We introduce a novel modality, namely, the prototype of an intramedullary injectable bioresorbable polymer-bioresorbable balloon osteosynthesis (IPBO) system, and investigated its plausibility. Experimental Procedures: The biomechanical performance of a construct comprising a synthetic distal radius (fourth-generation Sawbones ® ) on which a simulated fracture was created (4-mm wide osteotomy positioned 25 mm from the most distal end of the radius) and fixated with a placement of the IPBO system (SIPBO Construct) was compared to that when the fixation was with an approved Ti-6Al-4V alloy VLP system (SVLP Construct), under a clinically-relevant compressive loading protocol. Performance involved determination of quantitative parameters of the construct (initial longitudinal stiffness (ICLS), final longitudinal stiffness (FCLS), and load-to-failure (P f )) and observation and recording of features of the construct at the fracture point. We also determined the quantitative parameters for the intact synthetic distal radius (control). Results: For each of the quantitative parameters, the range of values for SIPBO Construct was within that for SVLP Construct, suggesting that the IPBO System is a plausible modality. Also, for SIPBO Construct, failure occurred within the polymer zone, whereas, for SVLP Con- 310struct, some failure features were fracture of the cortical wall and of the dorsal proximal fragments. Conclusion: The findings suggest that the IPBO system is plausible. As such, it merits further study; for example, determination of the influence of fracture gap fill ratio (defined as the proportion of the fracture gap that is filled by the expanding balloon as the polymer is injected into the balloon) on a large collection of quantitative biomechanical parameters.

Finite Element Analysis Study of Prototype of a Novel Intramedullary Injectable Bioresorbable Polymer Fixator versus a Volar Plate for Surgical Treatment of Distal Radius Fractures

“…Furthermore, the stiffnesses of the FIXATOR CONSTRUCT Model cases are within the range of values reported in the aforementioned literature studies (see Table A1 in Appendix). It is also worth pointing out that the present FEA results buttress those obtained in our experimental biomechanical study of these two constructs [11].…”

“…In brief, it is envisaged that using the fixator would involve creating an entry portal into the fractured bone, using a flexible cannulated drill to prepare the intramedullary canal, inserting a compliant balloon catheter into the bone, reducing the fracture, injecting a bioresorbable polymer into the balloon, expanding the balloon to fully conform to the shape of the canal, and allowing the polymer to cure. In that study, we found that each of the determined biomechanical parameters of a construct that included the fixator was comparable to that when fixation was with a commercially-available volar locking plate [11].…”

“…In our recent contribution, we presented the conceptual features of one such modality, namely, the prototype of a novel intramedullary injectable bioresorbable polymer-bioresorbable balloon osteosynthesis system (for short, "injectable bioresorbable polymer fixator") and results of an in vitro experimental biomechanical evaluation of a construct that comprised a simulated fracture created in a synthetic distal radius and fixated using the fixator [11]. In brief, it is envisaged that using the fixator would involve creating an entry portal into the fractured bone, using a flexible cannulated drill to prepare the intramedullary canal, inserting a compliant balloon catheter into the bone, reducing the fracture, injecting a bioresorbable polymer into the balloon, expanding the balloon to fully conform to the shape of the canal, and allowing the polymer to cure.…”

Practical Method to Evaluate the Stiffness of Fractured Radius

“…To avoid high variabilities in geometry and material properties, as well as to accommodate the special handling requirements of cadaver radii, the synthetic radius was designed to simulate structural and material properties of cadaveric radius, while providing the low variabilities in geometry and material properties, as well as fulfilling the simple handling requirements. Synthetic radii have frequently been used for the biomechanical tests of treated DRFs [ 8 , 9 , 10 ]. Although the variabilities in geometry and material properties of synthetic radii can be controlled, the high deviations of stiffness are surprisingly observed in these studies.…”

“…During biomechanical tests, pure compression without any bending and/or shear is expected. It is speculated that the high deviations of stiffness [ 8 , 9 , 10 ] may relate to the inconsistency of applied mechanical actions (i.e., the tested synthetic radii may be under the various combinations between compression, bending, and shear). In the present study, a biomechanical apparatus and an experimental procedure were proposed for the biomechanical tests of radii under pure compression.…”