Amid the benefits of osteoporosis therapy, an unexpected risk

Hans S. Moller, M.D.
Medical director, Providence Orthopedic Institute Fracture Care Program

Bisphosphonates are widely accepted for treating postmenopausal osteoporosis and as maintenance following fragility fractures. It’s well understood that these drugs lower the rate of recurrent fractures and halt bone mineral loss.

Unfortunately, as use of bisphosphonates has grown, orthopedic surgeons have seen an unexpected complication: proximal femoral stress reactions and spontaneous fractures. The biological and histopathological reasons for this reaction are unknown. Patients typically present with a nontraumatic, vague thigh or groin pain aggravated by weight-bearing activities and increasing in intensity and severity over several weeks or months.

Nontraumatic history and the patient’s age prompt many practitioners to evaluate arthritis, metastatic cancer, metabolic bone disease, endocrine abnormalities, spinal conditions and infection as possible differential diagnoses.

The left femur shows signs of "beaking." Notice the repair on the right femur from the previous year. This sign went undetected until the patient sustained a fracture when walking up the stairs.

An intramedullary rod strengthens the fracture site.

X-rays are typically negative at first, but eventually they reveal proximal femoral lateral cortex thickening, or “beaking.” Radiologists do not always pick this up, and while MRI and indium scans are not necessary, bone scans will be positive for a stress reaction. Without treatment, many of these stress reactions spontaneously fracture as a typical transverse or oblique fracture at the beaking site.


When conservative treatment is exhausted

Orthopedists caring for patients with this history individualize treatment, starting with activity modification, restricted weight bearing and discontinuation of bisphosphonates. If conservative therapy doesn’t reduce symptoms and pain persists, proactive surgical placement of an intramedullary, or IM, rod will strengthen the bone and prevent an uncontrolled spontaneous fracture.

Certainly, surgery is the last resort, but it is easier and safer for the patient to have a planned surgery than to sustain an unexpected trauma at home. Activity modification in highly symptomatic stress fractures requires prolonged weight-bearing restrictions and is not well tolerated by elderly patients. Most eventually choose surgical intervention.

To prevent stress reactions, current orthopedic recommendations emphasize a one-year bisphosphonate holiday for asymptomatic patients for every five to seven years of previous bisphosphonate treatment.

It’s important to note that bisphosphonate therapy has improved the lives of many people and is still an important and excellent treatment. In addition to knowing the signs and symptoms of impending fractures, it is also crucial that these patients’ vitamin D and calcium levels are evaluated and, if necessary, corrected.

To learn  more or to refer a patient, visit Providence Orthopedic Institute.

Clinical articles by Hans S. Moller, M.D.