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Evaluation of Tower et al for Cobalturia Following Joint Replacement

Description

Cobalt is a mitochondrial toxin and can results in cardiomyopathy and encephalopathy. Wear and tear of a joint prosthesis made of cobalt-chrome alloys can result in periprosthetic cobalt-chrome metallosis. Systemic absorption can result in systemic symptoms and cobalturia.


Patient selection: joint replacement component containing cobalt-chrome alloy

 

Analysis: cobalt concentration in a spot urine, reported in parts per billion (ppb)

 

estimated cobalt concentration in blood =

= 0.25 * (concentration in the urine)

 

estimated cobalt concentration in joint fluid =

= 20 * (concentration in the urine)

 

Risk factors for cobalturia:

(1) amount of cobalt-chrome alloy present

(2) metal-on-metal prosthesis

(3) tendency to corrode

(4) greater wear-and-tear

(5) periprosthetic inflammation

 

Cobalt Level in Urine

Risk Level

> 20 ppb

extreme

1 to 20 ppb

high

< 1 ppb

low

 

 

Risk Level

Mean Urine Cobalt

Types of Prosthesis

extreme

54.1 ppb

metal-on-metal hip

high

6.1 ppb

cobalt-chrome acetabular part; modular cobalt-chrome neck; metal-on-plastic hip prone to head-neck taper corrosion; non-hip cobalt-chrome prostheses; knee prostheses; shoulder prostheses

low

0.4 ppb

ceramic-on-plastic hip with no cobalt-chrome part; metal-on-plastic hip with cobalt-chrome femoral head; head-neck taper not prone to corrosion; unilateral primary knee replacements with metal-on-plastic and no taper junctions

 


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