Final answer:
Paget's disease often has a comorbidity of osteoarthritis due to the bone deformities and increased bone mass in the nearby joints.
Step-by-step explanation:
Paget's disease of bone is a chronic disorder that can lead to enlarged and misshapen bones. The most common comorbidity associated with Paget's disease is osteoarthritis, which can occur due to the deformity and increased bone mass in the joints that are near the affected bone. While Paget's disease can lead to several other complications, including bone fractures and cardiovascular disorders due to the increased cardiac output required to supply the affected bones, the direct comorbidity often seen is osteoarthritis. This is not to be confused with other conditions like hyperparathyroidism, which can lead to increased bone resorption and possible fractures, or autoimmune diseases of the heart such as rheumatic fever.