Arthrofibrosis following total knee replacement; does therapeutic warfarin make a difference?

Area of Science:

• Orthopedic Surgery
• Pharmacology

Background:

• Arthrofibrosis is a common complication after total knee replacement (TKR), leading to reduced knee range of motion and patient dissatisfaction.
• Effective anticoagulation strategies are crucial for preventing thromboembolic events post-TKR, but their impact on arthrofibrosis is not fully understood.

Purpose of the Study:

• To investigate the relationship between therapeutic warfarin anticoagulation and the incidence of arthrofibrosis following TKR.
• To compare arthrofibrosis rates in patients receiving therapeutic warfarin versus prophylactic low molecular weight heparin (LMWH).

Main Methods:

• Retrospective study of 874 primary TKRs performed between 1993 and 2002.
• Patients were divided into two groups: therapeutic warfarin (for thrombophilic tendencies or medical necessity) and prophylactic LMWH.
• Arthrofibrosis was defined as knee flexion <80 degrees at 6-8 weeks post-TKR, requiring manipulation under anesthesia (MUA).

Main Results:

• Overall, 9% of TKRs developed arthrofibrosis requiring MUA.
• The warfarinized group had a significantly higher rate of arthrofibrosis (26%) compared to the non-warfarinized group (8%) (P<0.0001).
• Knee flexion improved to at least 95 degrees in 95% of cases after MUA, with 8 cases experiencing residual fixed flexion deformity.

Conclusions:

• Therapeutic warfarin anticoagulation post-TKR is associated with a statistically significant increase in the risk of developing arthrofibrosis.
• Prophylactic LMWH appears to be associated with lower rates of arthrofibrosis compared to therapeutic warfarin.
• Patients undergoing TKR should be counseled regarding the potential increased risk of arthrofibrosis when therapeutic warfarin is indicated.