Summary
Two potential pharmaceutical tools were studied for their association with postoperative knee stiffness following total knee arthroplasty in a consecutive retrospective cohort.
Abstract
Introduction
Postoperative stiffness is a common complication following total knee arthroplasty (TKA), resulting in limited range of motion (ROM), persistent pain, and reduced knee function. Previous studies have identified heightened risks of postoperative stiffness with direct oral anticoagulants (DOACs), prescribed as perioperative prophylaxis, to prevent deep vein thrombosis. Additionally, angiotensin receptor blockers (ARBs), a set of hypertensive drugs, have been associated with a decreased risk of postoperative complications associated with knee stiffness. We aim to elucidate the impact of the choice of post-operative prophylaxis (DOACs vs. Aspirin) and administration of ARBs on TKA patient range of motion.
Methods
One thousand fifty-four (1,054) consecutive patients who underwent primary TKA by the senior author between November 2021 and May 2023 were retrospectively identified from an institutional research database. Records were examined from the pre-operative and at 2 weeks, 6 weeks, and >1 year post-operatively. Successful ROM was defined as 90˚ flexion and 0˚ extension at the 2-week visit and 125˚ flexion and 0˚ extension at the 6-week visit. A secondary endpoint of manipulation under anesthesia (MUA), a common treatment for persistent stiffness following TKA, was examined. 6-week post-operative metrics were analyzed using Univariable logistic regression was used to assess the unadjusted associations between each independent variable and ROM success at 2- and 6-weeks postoperatively. Multivariable logistic regression was performed to predict ROM success at 2- and 6-weeks using DVT prophylaxis group and concomitant ARB while adjusting for age, sex, surgery center, patellar resurfacing, removal of hardware, preoperative knee flexion, and preoperative knee extension.
Results
Among the 1,054 patients, 565 (54%) were female, median age was 65 (range 36-87), 143 (14%) patients were prescribed a DOAC, and 142 (13%) were taking an ARB concomitantly. Use of Eliquis or Xarelto (DOACs) was not significantly associated with lessened ROM success at two weeks (OR=0.969, 95% CI [0.880,1.066], p=0.517) or six weeks (OR=1.025, 95% CI [0.929,1.132], p=0.773) relative to patients treated with Aspirin. Likewise, taking an ARB was not significantly associated with ROM success at two weeks (OR=0.959, 95% CI [0.869,1.057], p=0.396) or six weeks (OR=1.069, 95% CI [0.968,1.179], p=0.344). Adjusting for other patient details via multivariable logistic regression did not yield substantively different results from the bivariate analysis. Relatively few cases required subsequent MUA (n=30), yielding low statistical power for risk factor analysis. Regardless, neither the choice of DOAC nor concomitantly taking an ARB were significantly associated with the risk of requiring an MUA procedure. One patient (aspirin) was identified to have a DVT 8 weeks following surgery and 1 other patient (aspirin) was identified to have a PE 3 days following surgery.
Discussion
This study did not demonstrate an association between postoperative ROM and thromboprophylaxis medication or concomitant ARB. Previous studies have used lower ROM boundaries, assessed solely follow-up MUAs, and assessed patients earlier in the recovery timeline. Study limitations included the low number of MUA patients, which patients must elect to undergo, and lessened available data beyond the 6-week postoperative timepoint.