In this study of older women with osteoarthritis in their knees, fewer bisphosphonate users went on to need
knee replacement surgery
Osteoarthritis is a common condition that makes a person’s joints stiff and painful, particularly in the morning. It is caused by changes in the whole joint tissues, including thinning of the cartilage within the joints, bony enlargement, and eventually bones rubbing against each other. Joint swelling and pain are frequent symptoms. It is the most common of all the different types of arthritis, and typically becomes more common as people get older. Osteoarthritis in the knees is a leading cause of disability, and many people have to have knee replacement surgery.
Bisphosphonates are medicines that are used in people with osteoporosis (weak or brittle bones). They work by slowing down bone loss, and can help to strengthen bones. While bisphosphonates have been studied in osteoporosis, where they are effective, studies of bisphosphonates in osteoarthritis have had conflicting results,
and are usually not done for long enough to see whether there are long-term side effects.
WHAT DID THE AUTHORS HOPE TO FIND?
The authors wanted to find out whether bisphosphonates could be used as a treatment for osteoarthritis. They predicted that if bisphosphonates were beneficial in osteoarthritis, then people taking bisphosphonates should have lower rates of getting their knees replaced than those not taking bisphosphonates, suggesting that bisphosphonates prevent osteoarthritic knees from getting bad enough to need surgery.
WHO WAS STUDIED?
The study looked at 2006 women who had started taking bisphosphates, and compared them to 2006 women who had not taken these drugs. Everyone was over 50 years of age, because younger people do do not have much osteoarthritis and are unlikely to use bisphosphonates, and the average age was 76 years. The authors looked at data over a 3-year period.
HOW WAS THE STUDY CONDUCTED?
The study used a large database of medical records in the UK that has anonymous information for over 12 million patients collected as part of their routine care by their general practitioners (GPs). Among women with a new diagnosis of knee osteoarthritis, the authors compared those who were newly prescribed bisphosphonates after their diagnosis with those who were never prescribed bisphosphonates. They then compared how many in
each group went on to have their knees replaced.
WHAT WERE THE MAIN FINDINGS OF THE STUDY?
The main finding was that women who were taking bisphosphonates had about a 25% lower risk of going on to have a knee replacement surgery than those who were not on bisphosphonates over an average of 3 years of follow-up. This suggests that bisphosphonates help slow the progression of knee osteoarthritis. The authors did not find any negative side effects of using bisphosphonate in this group of people.
ARE THESE FINDINGS NEW?
Yes, these findings are new. However, at the same time that these findings were published, another group of researchers in Taiwan published very similar findings using their own national healthcare database.
WHAT ARE THE LIMITATIONS OF THE STUDY?
The study does have some limitations. For example, other factors that may differ between the women could account for this finding, though the authors did carefully match the women on numerous factors and performed additional analyses to try to address this issue. Based on those analyses, it would be highly unlikely that other
factors could explain the findings. Another limitation is that because this study looked only at older women, it is not possible to say whether there would be any benefit in men, or in people younger than 50.
WHAT DO THE AUTHORS PLAN ON DOING WITH THIS INFORMATION?
The authors believe that these findings support the need for more trials in people with osteoarthritis to test bisphosphonates and other drugs that strengthen bones. They are studying the effects of bisphosphonates on other aspects of knee osteoarthritis as well.
WHAT DOES THIS MEAN FOR ME?
If you have osteoarthritis, there could be new treatments available in the future to help strengthen your knee
joints and prevent your disease getting bad enough to need knee replacement surgery.
If you have osteoporosis and osteoarthritis and have been prescribed a bisphosphonate, you should take your
medication regularly as this may be beneficial for both these diseases.
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Date prepared: January 2018
Summary based on research article published on: 11th December 2017
From: Neogi, T. et al. Effect of Bisphosphonates on Knee Replacement Surgery. Ann Rheum Dis 2018;77:92–97.
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