Mechanical assessment of new continuous compression implants
Continuous compression implants (CCIs) are part of a broader category of metallic staples used for fracture fixation, arthrodesis, and corrective osteotomies. Recently, new CCIs from the CrossRoads Extremity Systems (CRE) family were introduced for either stand-alone applications or use in combination with plates, featuring the ability for flush insertion and full engagement of the legs in the boreholes (Fig 1).
The aim of this project was to evaluate the effects of spreading the new CCIs at room temperature after deployment on implant compression to determine if plastic deformation occurs because of the spreading and if the implants fulfill established acceptance criteria for application after spreading.
Materials and Methods
Six different CCIs from the CRE family—240003-EP (MotoClip Max line), 240004-EP (HiMax line), 240012-EP (HiMax line), 240401-EP (HiMax Plus line), 240417-EP (HiMax Plus line), and 240000-EP (MotoClip Max line)—were tested with a sample size of 6 per implant type. The legs of each CCI were stepwise spread to 0°, 10°, and 20° at room temperature. Following each step of spreading, the compressive force exerted between the two legs was measured at 37 °C and the implant was cooled down to room temperature to measure the angle between the two legs and to determine the degree of angular deformation after spreading (Fig 2).
The compressive force and angle between the two legs, measured after the three stages of spreading the CCIs from the CRE family, are summarized in Table 1. Each CCI type demonstrated non-inferior compressive force considering the corresponding acceptance criteria of 48.6 N for the HiMax and HiMax Plus lines, and of 14.47 N for the MotoClip Max line.
All tested CCI types from the CRE family fulfilled the acceptance criteria of minimum compressive force after 0°, 10°, and 20° spreading; and thus, can be considered as valid alternatives to other existing conventional CCI implants.