PRIMA Stem Surgical technique
Insertion of the Trial Stem
For this step, the impactor must be assembled onto the PRIMA Trial Stem by using the proper size adaptor. Connect the proper size adaptor to the impactor, then assemble the trial stem to the impactor. The retroversion may be verified by screwing the alignment rod in the marked screw holes of the impactor (0°, 20° or 30°) (Figure 24). For a left shoulder, the mark “L” shall be visible on the front of the impactor and vice versa the mark “R” for a right shoulder. Impact the trial stem of the selected size into the humerus (Figure 25). The impactor has been designed to provide two impaction directions, along the axis of the stem and perpendicular to the resected surface. During insertion it is possible to verify the proper insertion by utilizing the ML marking on the trial stem that should be aligned with the medial marking, if performed during the sizing step (Figure 26). Additionally, the impactor features a mark to visualize the trial stem axis (Figure 27). Stop impacting when the adaptor comes fully in contact with the resected surface. Remove the impactor and adaptor from the trial stem. Optional during this phase, the impactor knob features a central hole for the 3.5mm hexagonal screwdriver to support the removal of the impactor from the implanted trial stem. Once the impactor and the adaptor are removed, the trial stem will be 0.5mm protruded from the resection plane to compensate the subsidence during subsequent phases (Figure 28).
Figure 24
Figure 25
Figure 26
marking
0.5mm
Figure 28
Figure 27
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