Battlements. The top of the castle walls were the battlements, a protective, tooth shaped parapet often with a wall walk behind it for the soldiers to stand on.The defenders could fire missiles through gaps (crenels). The raised sections between, called merlons, helped to shelter the defenders during an enemy attack.long the curtain wall, at intervals, are thirteen square or rectangular towers. Battlements. The top of the castle walls were the battlements, a protective, tooth shaped parapet often with a wall walk behind it for the soldiers to stand on. The defenders could fire missiles through gaps (crenels).
A common reply to this question is that total joint replacement lasts 15-20 years. A more accurate way to think about longevity is via the annual failure rates. Most current data suggests that both hip and knee replacements have an annual failure rate between 0.5-1.0%. This means that if you have your total joint replaced today, you have a 90-95% chance that your joint will last 10 years, and a 80-85% that it will last 20 years. With improvements in technology, these numbers may improve.
The question remains of how long the knee replacement will last, and it is a question with a different answer for every patient. Depending on health, size, weight, strength, pain tolerance and a multitude of other factors, patients will vary from person to person on how long the prosthetic knee will last.