You may be describing what happens when a screw used to anchor down the torn cartilage comes loose. Screws can break, come loose, and/or move in the shoulder joint. Sometimes the screw isn't placed in the best position. The tip of the screw may not be deep enough. It must go beneath the cartilage into the first layer of bone.

The result can be severe damage to the joint itself. It's best to let your doctor know about your symptoms as soon as possible. Early treatment to correct the problem can prevent severe destruction to the surface of the joint.