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Basic Science
intermediate
X-Type

Cobalt-Chrome Alloys in Arthroplasty

Biomaterials

A 62-year-old male presents with painful bilateral metal-on-metal (MoM) hip resurfacing arthroplasties performed 8 years ago. Blood tests reveal elevated serum cobalt (120 ppb, normal less than 1 ppb) and chromium (95 ppb, normal less than 1 ppb) levels. MRI shows pseudotumor formation around the left hip. During case discussion, a medical student asks why cobalt-chrome alloys are used in arthroplasty and what complications can occur. You explain that cobalt-chrome-molybdenum (Co-Cr-Mo) alloys have excellent wear resistance and corrosion resistance, making them ideal for bearing surfaces, but metal ion release can cause local tissue reactions (ALVAL - aseptic lymphocyte-dominated vasculitis-associated lesion) and systemic toxicity (cobaltism). Regarding cobalt-chrome alloys in arthroplasty:

Mark each as TRUE or FALSE

A

Cobalt-chrome-molybdenum (Co-Cr-Mo) alloys used in arthroplasty typically contain 60-65% cobalt, 25-...

B

Cobalt-chrome alloys have superior wear resistance compared to stainless steel and titanium alloys, ...

C

Metal-on-metal (MoM) hip arthroplasties using cobalt-chrome bearings have been largely abandoned due...

D

The elastic modulus (Young's modulus) of cobalt-chrome alloys is approximately 220-240 GPa, signific...

E

Cobalt-chrome alloys have poor biocompatibility and are highly cytotoxic to osteoblasts, making them...

Answer the questions to see explanations

Click T (True) or F (False) for each option