ROME — Osteoarthritis of the knee or hip might hurt like the dickens, but affected patients can take a measure of solace from new evidence that their ailment is associated with less hip fracture.
Preliminary results from a large Swedish population-based study show that an inverse relationship exists between knee or hip osteoarthritis (OA) and incident hip fracture. The OA patients had roughly a 15% lower-than-expected rate of the traumatic injury, Dr. Martin Englund reported at the meeting.
The study captured all 11,901 adult residents of the southernmost county of Sweden who had hip OA, as well as the 23,866 with knee OA.
During the study years of 2004-2007, there were 398 hip fractures among the knee OA group.
This was significantly fewer than the 470 hip fractures that would have been expected based on age- and sex-standardized data from the general population of the county, which contains 1.1 million residents, he reported.
Similarly, there were 233 hip fractures in patients with OA of the hip, compared with an expected 271, noted Dr. Englund, who is affiliated with the department of orthopedics at Lund (Sweden) University and the clinical epidemiology research and training unit at Boston University.
This translates to an observed hip fracture rate in the knee OA group of 763/100,000 per year, compared with an expected rate of 900/100,000 per year.
The observed rate of hip fracture in patients with hip OA was 884/100,000 per year, compared with the expected rate of 1,028 hip fractures per 100,000 per year.
The mechanism responsible for this protective effect remains unclear, according to Dr. Englund, who noted that there are some reports of increased bone mineral density in patients who have hip OA. More frequent obesity among OA patients may possibly also protect against fracture when patients fall—through the extra “padding” in the hip.
Disclosures: Dr. Englund reported having no conflicts of interest. The study was funded by the Swedish Research Council, the Swedish Social Insurance Agency, the Lund University Faculty of Medicine, and Region Skåne, Sweden.