A pathological fracture is a break in a bone that occurs because of an underlying disease or medical condition, rather than a significant external injury. Unlike a traumatic fracture, which requires substantial force, a pathological fracture happens when the bone is already structurally compromised. This means the bone breaks under stresses that a healthy bone would normally withstand, such as standing up or stepping off a curb. The diagnosis of a pathological fracture is often the first indication that a person has a serious, undiagnosed illness weakening their skeletal system.
What Makes a Fracture Pathological
The fundamental difference between a pathological and a traumatic fracture lies in the quality of the bone tissue itself. A pathological fracture results from “normal stress on abnormal bone,” meaning the mechanical load is routine, but the bone’s internal integrity is defective.
This compromised structure allows a low-energy event, which might be as minor as a quick twist or minor bump, to exceed the bone’s reduced load-bearing capacity. The bone’s structural failure occurs because the disease process has either destroyed bone material, replaced healthy tissue with weaker material, or prevented proper mineralization.
Primary Conditions Leading to Bone Weakness
The conditions that predispose an individual to a pathological fracture fall into several major categories, each weakening the bone through a distinct biological mechanism. Malignancy is one of the most serious causes, with metastatic cancer being far more common than primary bone tumors.
Cancer cells that spread to the bone (such as those from breast, lung, kidney, or prostate cancers) release chemicals that dramatically increase the activity of osteoclasts, the cells that break down bone tissue. This process creates lytic lesions, which are areas of bone destruction that appear as dark spots on imaging, leaving the bone hollowed and prone to collapse.
Metabolic and endocrine disorders also represent a large group of causes, with osteoporosis being the most frequent overall culprit. Osteoporosis causes a loss of overall bone density, making the bone porous and brittle due to decreased mineralization. This can lead to common fragility fractures in the hip, spine, and wrist. Osteomalacia is another metabolic condition where bone softening occurs due to a lack of Vitamin D, impairing the body’s ability to absorb and utilize calcium.
Infections can also severely weaken bone. Osteomyelitis is a bacterial or fungal infection that invades the bone tissue, triggering an inflammatory response and leading to localized bone destruction. This process often results in the formation of pus-filled pockets, compromising the bone’s strength.
Less common causes include genetic or developmental conditions. These include Paget’s disease, where disorganized bone remodeling leads to fragile bone, and fibrous dysplasia, where normal bone is replaced by fibrous, scar-like tissue.
Identifying Pathological Fractures
The diagnostic process begins with a high suspicion of a pathological cause, especially when a fracture occurs with minimal or no trauma, or when a patient reports persistent pain preceding the actual break. This pre-fracture pain, often called an impending pathological fracture, is caused by the underlying lesion expanding within the bone. Standard X-ray imaging is the initial step, confirming the fracture and often revealing the appearance of the underlying bone lesion.
The X-ray can show whether the lesion is lytic (bone-destroying) or blastic (bone-forming, though often structurally weak), providing clues about the likely underlying condition. Computed Tomography (CT) scans and Magnetic Resonance Imaging (MRI) are then used to better characterize the lesion, evaluating its size, precise location, and the extent of soft tissue involvement. If malignancy or infection is suspected, a tissue biopsy is often performed to obtain a definitive diagnosis of the root cause before proceeding with specialized treatment.
Treating the Fracture and the Root Cause
The management of a pathological fracture is always dual-focused, requiring immediate stabilization of the broken bone while simultaneously addressing the disease that caused the weakness. Surgical intervention is frequently required to stabilize the fracture because the underlying condition often compromises the bone’s natural ability to heal. Surgeons may use specialized techniques, such as placing metal rods, plates, or screws, often reinforced with bone cement, to create a robust internal scaffold.
Treating the root cause is necessary to prevent future breaks and manage the patient’s overall health; this involves medical specialists collaborating with the orthopedic team. For fractures caused by metastatic cancer, parallel treatments often include targeted radiation therapy or chemotherapy to shrink the tumor and reduce osteoclast activity. Metabolic diseases like osteoporosis are managed with specific drug therapies, such as bisphosphonates or biological agents, to increase bone density and reduce long-term fracture risk.