The effect of losartan on range of motion and rates of manipulation in total knee arthroplasty: a retrospective matched cohort study

Introduction Arthrofibrosis remains a common cause of patient dissatisfaction and reoperation after total knee arthroplasty (TKA). Losartan is an angiotensin receptor blocker (ARB) with inhibitory effects on transforming growth factor beta, previously implicated in tissue repair induced fibrosis, and has been studied to prevent stiffness following hip arthroscopy. This study aimed to evaluate pre- and postoperative range of motion (ROM) and the incidence of manipulation under anesthesia (MUA) following primary TKA in patients taking Losartan preoperatively for hypertension. Materials and methods A retrospective review of 170 patients from 2012 to 2020 who underwent a primary, elective TKA and were prescribed Losartan at least three months prior to surgery. All patients who were prescribed Losartan and had a preoperative and postoperative ROM in their chart were included and were matched to a control group of patients who underwent TKA and had no Losartan prescription. ROM, MUA, readmissions, reoperations, and revisions were assessed using chi-square and independent sample t tests. Results Seventy-nine patients met the inclusion criteria. Preoperative ROM was similar between patients on Losartan and the control group (103.59 degrees +/- 16.14 degrees vs. 104.59 degrees +/- 21.59 degrees, respectively; p = 0.745). Postoperative ROM and Delta ROM were greater for patients prescribed Losartan (114.29 degrees +/- 12.32 degrees vs. 112.76 degrees +/- 11.65 degrees; p = 0.429 and 10.57 degrees +/- 14.95 degrees vs. 8.17 degrees +/- 21.68 degrees; p = 0.422), though this difference did not reach statistical significance. There was no difference in readmission, rate of manipulation for stiffness, or all-cause revision rates. Conclusion In this study, we found that the use of Losartan did not significantly improve postoperative ROM, reduce MUA or decrease revision rates. Further prospective studies using Losartan are required to elucidate the potential effects on ROM and incidence of arthrofibrosis requiring MUA. Level III evidence Retrospective cohort study.