3.2.2. Dynamic Variant

3.2.2. Dynamic Variant The dynamic implant variant with the conical spikes for fixation, which allow the implant to sink, was also fixed in a test block. This test block has a convex surface and The dynamic implant variant with the conical spikes for fixation, which allow the implant to sink, was also fixed in a test block. This test block has a convex surface and parallel holes to accommodate the fixing pins; see Figure 11.

parallel holes to accommodate the fixing pins; see Figure 11.

(**a**)

**Figure 11.** Test abutment for the dynamic implant variant: (**a**) view of the actual test setup; (**b**) schematic view of the test block. **Figure 11.** Test abutment for the dynamic implant variant: (**a**) view of the actual test setup; (**b**) schematic view of the test block.

The test implant was loaded in the same way as in the static loading test of the rigid implant variant. The load did not cause any mechanical damage to the test implant. The test implant was loaded in the same way as in the static loading test of the rigid implant variant. The load did not cause any mechanical damage to the test implant.

The dynamic test implant was also tested with dynamic loads, where it was attached to the test block and the pendulum frame was made to vibrate. This resulted in a fracture of the conical pins in the area of the thread transition. However, the fracture did not occur until a forced extreme load was applied, with the force being applied eccentrically and transversely (pivot point of the joint ball outside the central axis). Such loads are not to be expected under real conditions, so this test also confirmed the stability of the dynamic implant variant. The dynamic test implant was also tested with dynamic loads, where it was attached to the test block and the pendulum frame was made to vibrate. This resulted in a fracture of the conical pins in the area of the thread transition. However, the fracture did not occur until a forced extreme load was applied, with the force being applied eccentrically and transversely (pivot point of the joint ball outside the central axis). Such loads are not to be expected under real conditions, so this test also confirmed the stability of the dynamic implant variant. (**a**) (**b**) **Figure 11.** Test abutment for the dynamic implant variant: (**a**) view of the actual test setup; (**b**) schematic view of the test block.

### *3.3. Abrasion Measurement 3.3. Abrasion Measurement* The test implant was loaded in the same way as in the static loading test of the rigid

The summary of all abrasion measurement results is shown in Figure 12a–d. The different diagrams show the measurement curves of test objects 1–4 (compare Table 2). Figure 12a contains additional descriptive elements. The summary of all abrasion measurement results is shown in Figure 12a–d. The different diagrams show the measurement curves of test objects 1–4 (compare Table 2). Figure 12a contains additional descriptive elements. implant variant. The load did not cause any mechanical damage to the test implant. The dynamic test implant was also tested with dynamic loads, where it was attached to the test block and the pendulum frame was made to vibrate. This resulted in a fracture of the conical pins in the area of the thread transition. However, the fracture did not occur

The position along the implant surface (geometric longitudinal axis) is plotted on the x-axis and the deflection (normal distance) of the galvo scanner measuring tip is plotted on the y-axis. The y-axis thus represents the measured abrasion. A standardized abrasion value in µm/100 cycles is exhibited for each object. Sudden, strongly deviating signals correspond to depressions in the surface and are a direct measure of the abrasion occurring at this point. until a forced extreme load was applied, with the force being applied eccentrically and transversely (pivot point of the joint ball outside the central axis). Such loads are not to be expected under real conditions, so this test also confirmed the stability of the dynamic implant variant. *3.3. Abrasion Measurement* 

The results clearly show that the abrasion to be expected with the glenoid protective prosthesis is much lower than with a standard glenoid component of an anatomical shoulder prosthesis made of PE. The summary of all abrasion measurement results is shown in Figure 12a–d. The different diagrams show the measurement curves of test objects 1–4 (compare Table 2). Figure 12a contains additional descriptive elements.

**Figure 12.** Abrasion measurement curves: (**a**) test object 1, including additional description of the sections of the curve; (**b**) test object 2; (**c**) test object 3; (**d**) test object 4. **Figure 12.** Abrasion measurement curves: (**a**) test object 1, including additional description of the sections of the curve; (**b**) test object 2; (**c**) test object 3; (**d**) test object 4.

The position along the implant surface (geometric longitudinal axis) is plotted on the x-axis and the deflection (normal distance) of the galvo scanner measuring tip is plotted on the y-axis. The y-axis thus represents the measured abrasion. A standardized abrasion value in µm/100 cycles is exhibited for each object. Sudden, strongly deviating signals correspond to depressions in the surface and are a direct measure of the abrasion occur-This result corresponds to the order of magnitude of a study already carried out, in which a wear factor was determined that is 10 times higher for a friction pairing of UHMWPE with CoCrMo steel than for PEEK with CoCrMo steel [50], as compared in Table 4.

The results clearly show that the abrasion to be expected with the glenoid protective prosthesis is much lower than with a standard glenoid component of an anatomical shoul-

ring at this point.

der prosthesis made of PE.


**Table 4.** Total Wear Factors (values times 10−<sup>6</sup> mm3/Nm) for Carbon Fiber-Reinforced PEEK-OPTIMA against different Counterparts and UHMWPE against CoCrMo steel [47].

The difference between the result with the technical PEEK (test object 1) and the medical grade PEEK (test objects 2 and 3) can be explained by different mechanical properties due to the use of different starting materials for the synthesis. The technical PEEK used for the test has a notched impact strength of 3.5 kJ/m<sup>2</sup> , whereas the medical grade PEEK has a notched impact strength of 5.5 kJ/m<sup>2</sup> .
