How is it performed? of Knee replacement

Health encyclopaedia - Alphabetical Topic List

| A |

| B |

| C |

| D |

| E |

| F |

| G |

| H |

| I |

| J |

| K |

| L |

| M |

| N |

| O |

| P |

| Q |

| R |

| S |

| T |

| U |

| V |

| W |

| X |

| Y |

Surgery is usually performed under general anaesthetic. An epidural (spinal anaesthetic) can be used if a general anaesthetic is not suitable for a medical reason. Surgery usually takes between one and three hours. Many surgeons use a tourniquet (a tight band) around the thigh, which reduces blood flow around the knee.

The kneecap is exposed after the knee is opened through a long incision. The kneecap is then moved across to the outer side of the knee to expose the knee joint behind it, between the tibia (shin bone) and the femur (thigh bone). Any excess bone that has formed is removed, and tight soft tissue is loosened so the knee returns to its original shape.

The damaged ends of the bone are cut away. This is done with great precision, so the closely fitting components of the artificial knee (prosthesis) can cover the worn cartilage. The end of the femur is replaced by a single curved piece of steel alloy. A flat plate of steel alloy or titanium replaces the top end of the tibia. Plastic spacers are fixed to this flat plate to help the bones move easily. The plastic spacers are made from polyethylene, which is especially hard and smooth.

The knee prosthesis comes in different size ranges to reflect the variety of different sized individuals. The plastic spacers also come in a range of sizes to fit between the components. When there is a very great bone loss, extra pieces may need to be added. The combination of metal and plastic gives the joint very low friction.

When the bone has been measured and prepared precisely, a sample prosthesis is put in position and the joint tested to be sure that it is stable and moves properly. Final adjustments are then made, the bone ends are cleaned and the final prosthesis is fixed into position with special cement or a press-fit technique.

The wound is then closed with stitches or clips and dressed. A splint may be applied. Antibiotics may be prescribed for a short time after the operation to prevent infection.