Metabolic Bone Disease (MBD): This is a condition that is the direct result of poor husbandry. It results from the effects of poor diet, poor or no uvb, lack of Vitamin D, and poor calcium to phosphorus ratio. Pyramiding is a form of MBD which research shows is the result of all of the above and lack of humidity and exercise. If the onset of MBD begins when a turtle is young, it will develop obvious deformities. Tortoises will show raised or stacked scutes on the carapace, overgrown, duck or parrot like beak and the nails will grow oddly curved out and upward. They will have splayed legs and have difficulty walking upright. Many are forced to drag their hind legs because of this difficulty.

Turtles often show early signs of MBD by their shells growing curved upward, some looking like a saddled shape. They will appear to be thickened. Box turtles will not have a working hinge, but rather have it frozen in place. Some will show signs of resorption where you will no longer see a tail because the body is trying to get the calcium from the bones. Often the turtle’s legs will be thin and deformed. As with tortoises the beak will also become duck or parrot shaped. Water turtles will usually show raised scutes, some actually also pyramiding as with tortoises. Their shells will also become serrated even if they are a species that normally has a rounded shell.

To avoid MBD it’s important to provide a nutritional diet with proper calcium and vitamin d, give proper uvb lighting (natural sun is best), plenty of exercise and humidity in the case of land turtles. Providing a cuttlebone in addition to good diet is a good way to let your turtle supplement itself with added calcium.

Source: http://turtlerescues.com/common_health_problems.htm

Those words highlighted in bold are the symptoms i found on my friend's tortoise.

*Sorry for posting the long article.