Metal-on-metal hip replacements have a high failure rate and have led to patients suffering tissue damage

The initial process

1

2

3

Hip bone

4

Femur

1 Socket

Metal cup screwed to the hip bone

2 Insert

Generally made from plastic, metal or ceramic

3 Rotating ball

Made from the same material as the insert

4 Femoral stem

Attached to the femur bone and then connected to the ball

Possible reason for the failure

Rotation of the ball with the insert leads to wear and this produces high levels of cobalt and chromium particles in the bloodstream

Metal insert

Metal ball

The initial process

Possible reason for the failure

1

Metal insert

2

3

Hip bone

4

Femur

Metal ball

1 Socket

Metal cup screwed to the hip bone

2 Insert

Generally made from plastic, metal or ceramic

3 Rotating ball

Made from the same material as the insert

4 Femoral stem

Attached to the femur bone and then connected to the ball

Rotation of the ball with the insert leads to wear and this produces high levels of cobalt and chromium particles in the bloodstream