A pathologic fracture can happen when the normal integrity of bone is impeded upon by some type of invasive disease or destructive force. The main causes of pathologic fractures include some kind of primary or metastatic cancer, bony necrosis (bone death), disuse of the bone, metabolic disease, surgical defect, or osteoporosis. Interestingly, fractures are more common in benign tumors than they are in malignant tumors and many patients have symptoms before their break. Common places for pathologic fractures are the humerus and the femur.
Primary Malignant Tumors
These are relatively rare and include the following:
- Ewing sarcoma
- Fibrous histiosarcoma
Patients who have had radiation treatment for cancer of the bone are also at risk for pathologic fractures. These are often seen in young people who have bones on x-ray that are poorly defined with a periosteal reaction and matrix production in the area of tumor. Pain at nighttime in these kinds of tumors is common.
If a pathologic fracture is found, a biopsy is warranted to see if the fracture was due to a malignancy or a benign condition of the bone. If it is due to a malignancy, local recurrence rates are high, even with treatment with radiation and chemotherapy. The biopsy should be done relatively soon, before fixation of the bone is undertaken.
If a fracture occurred with minimal trauma or during normal activities, a pathological fracture should be suspected. People with a history of multiple fractures or known metabolic or cancerous disease are more likely to suffer from pathological fractures. Some risk fractures include a past history of other fractures, a smoking history, and environmental exposure to carcinogens (cancer-causing agents).
When examining a patient with a pathological fracture, the doctor will often check for swollen lymph nodes near the site of the fracture or for other evidence of primary cancer, such as thyroid enlargement, breast or prostate masses, rectal masses or other painful areas.
Laboratory studies include doing a CBC (complete blood count), erythrocyte sedimentation rate (ESR), chemistry panel, stool test for blood, serum protein electrophoresis (to test for myeloma), tests for Paget’s disease, and things like thyroid tests, carcinoembryonic antigen, parathyroid hormone and prostate specific antigen (PSA).
X-ray evaluation should include plain film x-rays of the fracture, a chest x-ray to look for metastatic disease, bone scan for other bony lesions, CT scan of the bone, MRI scan of the affected area, PET scan for metastatic lesions, and endoscopy, upper and lower abdominal series, mammography, and CT scan of the chest, abdomen or pelvis. Primary disease won’t be found in 15 percent of cases of suspected metastatic disease.
Classifying Pathologic Fractures
This includes systemic and localized causes of bone fracture.
Systemic causes include:
- Osteoporosis. The most common cause of pathological fractures in older people.
- Metabolic bone disease. This includes things like osteomalacia, hyperparathyroidism, and renal osteodystrophy.
- Paget’s disease of bone. About 5-15 percent of older people have this. Some people have a pathologic fracture be the first sign that they have the disease.
Localized causes include:
- Primary bone malignancy. This is just cancer of the bone that weakens the bone to cause a fracture.
- Hematopoietic disorders. This includes things like multiple myeloma, leukemia, and lymphoma.
- Metastatic disease. This can occur from cancers of the breast, prostate, thyroid, and kidney. Bones affected include the ribs, spine, pelvis, humerus, and femur.
Correctable causes of Pathologic Fractures
Correctable causes are things like osteoporosis, osteomalacia, elevated parathyroid gland hormone, renal osteodystrophy, and steroid use. Noncorrectable causes include osteogenesis imperfecta, polyostotic fibrous dysplasia, Paget’s disease of bone, osteopetrosis, postmenopausal bone loss, rheumatoid arthritis, and Gaucher disease.
Local diseases such as non-ossifying fibroma, aneurysmal bone cyst, unicameral bone cyst, giant cell tumor, chondromyxoid fibroma, osteoblastoma, eosinophilic granuloma, and chondroblastoma. Malignant bone tumors like Ewing’s sarcoma, multiple myeloma, osteosarcoma, fibrosarcoma, non-Hodgkin’s lymphoma, and malignant fibrous histiosarcoma. Cancer can metastasize to bone, causing pathologic fractures.
Treatment of Pathologic Bone Fractures
Like all fractures, these need reduction and immobilization but a biopsy needs to be done first to define the cause of the fracture. Medical conditions need to be optimized. If the fracture is through a benign bony lesion, it will likely heal without surgery. Healing time is slower but can be expected to occur.
Surgery is necessary in some cases to prevent osteopenia from disuse of the bone. Internal fixation with or without the use of cement to keep the bony fragments together can be done but this will fail if the bone never unites itself. If the fracture is near the joint, resection and prosthetic reconstruction may be necessary or if internal fixation fails.
Loss of fixation is the most common complication of pathologic fractures because the bone quality is poor. The patient cannot have surgery if they are already debilitated and cannot tolerate anesthesia, have mental obtundation, or have a life expectancy of less than a month.
Many doctors are often involved. They include doctors for radiation, chemotherapy, and bone care. Cancer specialists care for cancer patients and bone specialists are needed for primary bone lesions. Surgeons are responsible for relief of pain, restoring function and helping nursing care.
About 75 percent of all patients with a pathologic fracture will still be living a year following their fracture. The average lifespan of a pathological fracture victim is about 21 months.
Plates and nails are used to hold bony fragments together surgically so that the bone has a chance to heal. Cement augmentation is often necessary to help bone knit together. Hip arthroplasty may be necessary for fractures around the hip.
Some patients need palliative care for symptoms and to decrease tumor size. Three –four percent of all fractures due to carcinomas have no known primary site. Many will have other bony metastases.
Femur fractures involve greater than 50 percent of long bone pathologic fractures. If the fracture is of the femoral neck, many do not heal unless they have replacement of the femoral head. Intramedullary nailing is possible in these fractures. Some patients have preventative fixation to prevent bony fracture from occurring.
If preventative fixation is done, there is often:
- Shorter hospitalization
- Decreased morbidity
- Easier time of rehabilitation
- Faster surgical recovery
- Decreased pain
- Less surgical blood loss.
In humeral fractures, prophylactic fixation is not recommended until the bone fractures. These are usually stabilized surgically to promote healing and to decrease pain.
Spine fractures can be treated with radiation in order to decrease pain. Cement can be used to heal spinal fractures caused by multiple myeloma, metastatic carcinoma, and osteoporosis. Spinal fusion can be done to prevent neurological problems with a spinal fracture.