Knee osteoarthritis: bisphosphonates linked to reduced rate of knee replacement surgery

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Takeaway
  • Bisphosphonate initiation was associated with a 24% lower risk for knee replacement (KR) surgery in older women with knee osteoarthritis (OA) compared with those who did not initiate bisphosphonates.

Why this matters

  • No approved agents have been proven to alter the disease course in knee OA. 
  • Joint replacement surgery remains the only definitive treatment for end-stage disease. 
  • Bone remodelling as a therapeutic target has gained interest. 
  • The effects of antiresorptive agents have been conflicting. 
  • This the first study to date to examine the effects of bisphosphonates on the clinically relevant endpoint of KR surgery. 
  • The present findings, taken together with other studies, support the ongoing evaluation of bone modulation as a potentially promising therapeutic target for knee OA.

Key results

  • 208 KR surgeries were performed overall (138 in initiators and 170 in non-initiators). 
  • Mortality rate was similar in both groups (39.7 and 38.2 per 1000 person-years, respectively). 
  • Crude incidence rate of KR was 22.0/1000 person-years among initiators and 29.1/1000 person-years among controls. 
  • Crude incidence rate ratio of KR was 0.75 (95% CI, 0.60-0.94). 
  • Adjusted HR for KR related to bisphosphonate initiation was 0.76 (95% CI, 0.60-0.95).

Study design

  • Sequential propensity score-matched cohort study of data from the UK Health Improvement Network (THIN) relating to 2006 older women (mean age, 76 y) who had initiated bisphosphonate use after incident knee OA diagnosis, matched to 2006 non-initiators, with mean follow-up of 3 y. 
  • Funding: National Institutes of Health and the Arthritis Foundation.

Limitations

  • THIN does not contain bone density results or standardised vitamin D levels. 
  • Diagnostic code for osteoporosis and osteopenia were not frequently recorded. 
  • Cohort limited to older women.