Improving acetabular shell deformation testing.

BACKGROUND: To be FDA approved, acetabular shells must undergo rigorous testing. To prevent implant failure, acetabular shells must be able to tolerate peak loads during impaction with minimal deformation. The implants must therefore be validated in order to ensure that their structural integrity can tolerate peak loads. The current ISO 7206-12 recommends manufacturing an expensive single-purpose testing device to measure the deformation of acetabular shells. In the article, we provide an open access methodology, that can be conducted with minimal expense, for testing acetabular shell deformation. METHODS: We designed our experimental setup to utilize a servohydraulic materials testing device (Instron) commonly found in biomechanics laboratories and then validated the measurements optically with optical data. Furthermore, we designed an inexpensive acetabular screw fastener which acts as an adaptor that can be used to mount a variety of acetabular shell types just as effectively as current methods and is in compliance with the standards outlined in ISO 7206-12:2016. RESULTS: A Bland-Altman plot comparing the Instron and optical displacement measurements found the standard deviation of bias to be 0.046 mm and an insignificant systemic bias. CONCLUSION: We have developed and validated a low-cost open-source system that can effectively test acetabular shell deformation that meets ISO standards.

Covalent Functionalization of Flexible Polyvinyl Chloride Tubing.

Polyvinyl chloride (PVC) tubing is a vital part of many industries, including the medical and food sectors. The ability to chemically modify PVC has previously been reported mainly on powdered or rigid forms of the plastic. Here, we describe the chemical modification of flexible PVC tubing with azide (and the attempted modification with cyanide) facilitated by phase transfer catalysts and characterization of the resulting materials. These modifications provide convenient handles for click chemistry linkages via azide-akyne cycloaddition, which allows for diverse surface functionalization of PVC for a variety of applications.