Sunday, February 24, 2019

Eight-fold increase in shoulder arthroplasty complications in patients taking bisphosphonates

Preoperative bisphosphonate treatment may adversely affect the outcome after shoulder arthroplasty

Nitrogenous bisphosphonates act on bone metabolism by binding and blocking the enzyme farnesyl diphosphate synthase (FPPS) in the HMG-CoA reductase pathway (also known as the mevalonate pathway). They include

Pamidronate (APD, Aredia)
Neridronate (Nerixia)
Olpadronate
Alendronate (Fosamax)
Ibandronate (Boniva)
Risedronate (Actonel) and
Zoledronate (Zometa, Aclasta)


These authors investigated the effects of preoperative bisphosphonate treatment on the intra- and postoperative outcomes of arthroplasty of the shoulder in a retrospective cohort study of patients undergoing arthroplasty of the shoulder, at a single institution. Two patients with no previous bisphosphonate treatment were matched to each patient who had received this treatment preoperatively by gender, age, race, ethnicity, body mass index (BMI), and type of arthroplasty. Previous bisphosphonate treatment was defined as treatment occurring during the three-year period before the arthroplasty. The primary outcome measure was the incidence of intraoperative complications and those occurring at one and two years postoperatively. A total of 87 patients were included: 29 in the bisphosphonates-exposed (BP+) group and 58 in the non-exposed (BP-) group. In the BP+ group, there were 26 female and three male patients, with a mean age of 71.4 years (51 to 87). In the BP- group, there were 52 female and six male patients, with a mean age of 72.1 years (53 to 88). 

Previous treatment with bisphosphonates was positively associated with intraoperative complications (fracture; odds ratio (OR) 39.40, 95% confidence interval (CI) 2.42 to 6305.70) and one-year postoperative complications (OR 7.83, 95% CI 1.11 to 128.82). This represents essentially an eight-fold increase in the risk of postoperative complications..
As shown in the table below, this study also identified other risk factors for intraoperative fracture, complications, and revisions.




The authors concluded that patients who are treated with bisphosphonates during the three-year period before shoulder arthroplasty have a greater risk of intraoperative and one-year postoperative complications compared with those without this previous treatment. They suggest that the complications noted in this study are related to the over-suppression of bone turnover associated with the long-term use of bisphosphonates

Comment: These findings point out the importance of assessing the patient's history for evidence of previous bisphosphonate treatment and counseling the patient regarding the associated risks. There does not appear to be evidence that discontinuance of the bisphosphonates before surgery reduces the associated risks.
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