Changes in bone shape

Paget’s disease disrupts the delicate balance of bone renewal, which may lead to structural changes that can affect quality of life. When Paget’s disease was first described by Sir James Paget in 1877, one of the presenting features of his original patient was that he had bowed limbs and an expanding skull, leading to him requiring progressively larger hats. It is encouraging news that Paget’s disease has become less common and less severe.

What causes bones to become misshapen?

Understanding how Paget’s disease affects the bone starts with knowing how healthy bone naturally renews itself. Bone is a living tissue that is constantly renewed and repaired through a process called bone remodelling. In healthy bone this process is well‑regulated, producing new bone in an organised, structured way. When examining normal bone under a microscope, a uniform pattern can be seen. 

In Paget’s disease, the rate of bone remodelling becomes markedly accelerated. The new bone, known as Pagetic bone, forms in a disorganised way and an irregular pattern is apparent when viewed under a microscope. This abnormal bone is structurally weaker than healthy bone and often becomes enlarged and misshapen. These changes develop gradually over several years and may be noticeable or they may only be detected when an x‑ray is taken. These gradual changes can alter the shape of the affected bone and sometimes lead to visible differences in appearance, such as enlargement, bending or changes in symmetry.

Symptoms caused by changes in bone shape

Symptoms will depend on which bones are affected by Paget’s disease. If, for example, the bones of the leg are affected, they may bend under the stress of carrying body weight. As the bone bends, it changes how it carries weight. With the thigh bone (femur), the inner side tends to become thicker, and in contrast, the outer side becomes thinner and weaker. This weaker area is more likely to develop small cracks, known as stress fractures, which can cause pain and may develop into a complete fracture.

A bowed leg can also make the leg shorter than the other. This may affect walking and cause pain. An enlarged bone can put extra strain on nearby joints, leading to joint pain or osteoarthritis. This is common in the hip joint when the pelvis is affected. When the skull is affected, there may be a visible increase in the size of the skull and a high forehead may be noticed. In some cases, an enlarged bone may press on a nerve, causing symptoms such as pain, tingling, numbness or weakness.

Can changes in bone shape be prevented or treated?

While existing changes in bone shape cannot be reversed with medication, treatment with bisphosphonates can help slow or sometimes prevent further changes. Bisphosphonates are commonly used to calm the overactive bone‑remodelling process, helping to reduce pain, prevent or slow further changes and lower the risk of fractures. Depending on which bones are affected, supportive aids, including walking aids or shoe inserts, may be beneficial. In more severe cases, surgery may be required to repair fractures, realign significantly bowed bones or replace damaged joints, such as the hip joint.

Straightening a bent bone

In Paget’s disease bending of the long bones that take the weight of the body, such as the femur or shin (tibia) bone can make the bone more likely to fracture. The bend in the bone may put abnormal stresses on the surrounding tissues and cause pain. An orthopaedic surgeon may recommend straightening the bone by an osteotomy operation. Osteotomy means ‘cutting of the bone’. It may also be carried out to shorten or lengthen a bone.

You can read more about treatment and surgery here.

Feb 2026