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Researchers from the Department of Orthopaedics at Kaiser Permanente recently discovered an association between atypical femur fractures, a thigh bone break typically associated with trauma, and the use of bisphosphonates, or drugs taken to enhance bone density and reduce fracture incidence caused by osteoporosis. Just one in 1,000 patients risk suffering an atypical femur fracture while taking osteoporosis drugs after six years of treatment, but researchers found discontinuing the treatment of these drugs can significantly lower that risk.

The Researchers said they believe bisphosphonates in certain patients may suppress the body's remodeling process, where old bones get replaced with healthy tissue. The result of this effect can be cause brittle bones to become more vulnerable to atypical fractures, particularly in the femur.

To test the theory, researchers studied patient data for individuals with an atypical femur fracture while on the osteoporosis medication. The study found the atypical femur fracture incidence rate was 53.9 percent in patients who took the osteoporosis medication for three or more years after their first fracture. Patients who discontinued the bisphospohonate use after the first fracture reported a 19.3 percent incidence rate. Overall, atypical femur fractures decreased by 65.6 percent when the osteoporosis medication was halted within one year of the first fracture.

"The risk of a contralateral atypical femur fracture (on the opposite side) increases over time if the bisphosphonates are continued," said lead investigator Richard Dell, MD, a researcher in the Department of Orthopaedics at Kaiser Permanente. "Based on these observations, we recommend discontinuing bisphosphonate use as soon as possible after the initial atypical femur fracture has occurred."

A study by researchers at Hospital for Special Surgery found metal-on-metal total hip replacements are also affecting skeletal health in seniors and failing patients. The findings mirror a massive failing of joint replacements all over the country that are prompting doctors and researchers to develop a better hip replacement option.

According to the study, the metal-on-metal contact may not be the defect in the replacements. Rather, the physical structure of the implants could be causing the failures.

Hip replacements with metal-polyethylne implants are the most common hip implants procedures performed. Recently, however, advances in the materials have allowed implants with bigger heads to be used to increase stability for patients. The study suggests this new design could be causing problems, said Timothy Wright, Kirby chair of orthopedic biomechanics at Hospital for Special Surgery.