**3. Components of Ti6Al7Nb and Ti6Al4V explanted modular prostheses (proximal module)**

Two components of modular orthopedic prostheses—proximal module (**Figure 13**)—were explanted after 7 years. The proximal parts are made of Ti6Al7Nb (Lot 02-PL-06, Plus 662, PI 793—Gr. BS, art. 11,940, 1 series, lot 02.1424) and Ti6Al4V (Lot 03-PL-06, Plus 662, Gr. BL, art. 11,973—2 series, lot 03.463).

The aim was to observe and analyze the two components of the explanted modular prostheses (proximal module) and to compare them with the results of the cyclic fatigue dynamic tests with crevice corrosion stimulation (**Figure 14a** and **b**).

**Figure 14a** and **b** show the penetration of biological fluids at the interface of the proximal/distal modules and reveal significant similarities, in particular with regard to the phenomena of electrolyte penetration, product deposition, and corrosion.

**Figure 15a** reveals the presence of mechanical wear (SEM). The presence of a deposit originating from the biological fluids which have penetrated the interface is noted by the presence of C and Na (**Figure 15b**). Pumping effects of the electrolyte may be observed after 3 million cycles in laboratory tests. This type of effect is also observed on the explanted Ti6Al7Nb prosthesis.

The comparison between **Figure 16a** (explanted Ti6Al4V proximal module) and **Figure 16b** (Ti6Al4V proximal module, sample #8, after the cyclic fatigue

**213**

**Figure 16.**

*Multicomponent Alloys for Biomedical Applications DOI: http://dx.doi.org/10.5772/intechopen.88250*

*Ti6Al7Nb proximal modules. (a) Lot 02, Ti6Al7Nb proximal module explanted and (b) Ti6Al7Nb proximal module, sample #4, previously subjected to cyclic fatigue dynamic test with crevice corrosion stimulation.*

*Lot 02-Ti6Al7Nb proximal module explanted. (a) Lot 02-Ti6Al7Nb proximal module explanted (SEM) and* 

*Ti6Al4V proximal module. (a) Lot 03-Ti6Al4V proximal module explanted, (b) Ti6Al4V proximal module, sample #8, prior subjected to cyclic fatigue dynamic test with crevice corrosion stimulation, (c) lot 03-Ti6Al4V* 

*(b) lot 02-Ti6Al7Nb proximal module explanted. Spectrum EDX analysis.*

*proximal module explanted (SEM) and (d) spectrum EDX analysis.*

**Figure 14.**

**Figure 15.**

**Figure 13.** *Proximal module explanted.*

*Multicomponent Alloys for Biomedical Applications DOI: http://dx.doi.org/10.5772/intechopen.88250*

#### **Figure 14.**

*Engineering Steels and High Entropy-Alloys*

static tests (#6 and #9).

any sign of corrosion.

**(proximal module)**

In cyclic dynamic tests with crevice stimulation, the electrolyte enters the interface between the distal and proximal modules, which is not the case during

tion. This phenomenon is particularly visible on sample #8.

observed on the explanted Ti6Al7Nb prosthesis.

Samples #3 and #4 of series 1 reveal cracks in the distal module. Samples #3 and #5, also series 1, reveal holes in the crevice proximity. Metallic interferential staining of the distal/proximal module interfaces of the series 1 samples (#3, #4 and #5) is indicative of electrolyte reactions with the substrate and helps highlighting the corrosion process. This coloration does not appear in case of series 2 samples. Series 2 samples (#7, #8, and #10) do not show cracks or holes as observed in case of series 1 samples. On the other hand, at crevice level, the surface of the proximal module and to a lesser extent the surface of the distal module present an increase of roughness after the cyclic dynamic corrosion test with crevice stimula-

The observation of the samples only subjected to the static test does not reveal

**3. Components of Ti6Al7Nb and Ti6Al4V explanted modular prostheses** 

Ti6Al7Nb (Lot 02-PL-06, Plus 662, PI 793—Gr. BS, art. 11,940, 1 series, lot 02.1424) and Ti6Al4V (Lot 03-PL-06, Plus 662, Gr. BL, art. 11,973—2 series, lot 03.463). The aim was to observe and analyze the two components of the explanted modular prostheses (proximal module) and to compare them with the results of the cyclic fatigue dynamic tests with crevice corrosion stimulation (**Figure 14a** and **b**). **Figure 14a** and **b** show the penetration of biological fluids at the interface of the proximal/distal modules and reveal significant similarities, in particular with regard to the phenomena of electrolyte penetration, product deposition, and corrosion. **Figure 15a** reveals the presence of mechanical wear (SEM). The presence of a deposit originating from the biological fluids which have penetrated the interface is noted by the presence of C and Na (**Figure 15b**). Pumping effects of the electrolyte may be observed after 3 million cycles in laboratory tests. This type of effect is also

The comparison between **Figure 16a** (explanted Ti6Al4V proximal module) and **Figure 16b** (Ti6Al4V proximal module, sample #8, after the cyclic fatigue

Two components of modular orthopedic prostheses—proximal module (**Figure 13**)—were explanted after 7 years. The proximal parts are made of

**212**

**Figure 13.**

*Proximal module explanted.*

*Ti6Al7Nb proximal modules. (a) Lot 02, Ti6Al7Nb proximal module explanted and (b) Ti6Al7Nb proximal module, sample #4, previously subjected to cyclic fatigue dynamic test with crevice corrosion stimulation.*

#### **Figure 15.**

*Lot 02-Ti6Al7Nb proximal module explanted. (a) Lot 02-Ti6Al7Nb proximal module explanted (SEM) and (b) lot 02-Ti6Al7Nb proximal module explanted. Spectrum EDX analysis.*

#### **Figure 16.**

*Ti6Al4V proximal module. (a) Lot 03-Ti6Al4V proximal module explanted, (b) Ti6Al4V proximal module, sample #8, prior subjected to cyclic fatigue dynamic test with crevice corrosion stimulation, (c) lot 03-Ti6Al4V proximal module explanted (SEM) and (d) spectrum EDX analysis.*

dynamic test with crevice corrosion stimulation) shows that the location of the visible spots on the proximal explanted module approximately corresponds to the electrolyte deposits observed during cyclic fatigue dynamic tests with crevice corrosion stimulation. SEM observation does not reveal obvious localized corrosion in the spots area (**Figure 16c**). In exchange, the EDX analysis (**Figure 16d**) reveals the presence of C and Na, which suggests that biological fluids have penetrated and diffused at the proximal/distal module interface. The evaluation of cyclic dynamic corrosion with crevice stimulation on Ti6Al4V modular prostheses shows a similar analogue phenomenon of electrolyte pumping at the interface of the proximal/ distal modules.

The comparison of the explanted proximal parts with modular prostheses of the same type evaluated by cyclic fatigue dynamic tests with crevice corrosion stimulation reveals that there are significant similarities, in particular with regard to the electrolyte diffusion, deposition of products, and corrosion. Thus, these observations justify the use of cyclic fatigue dynamic tests with crevice corrosion stimulation in order to compare and evaluate different types of materials for the development of modular prostheses.
