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

Abstract 

Arthrofibrosis following total knee replacement (TKR) is a relatively common complication which results in a reduction in knee range of movement and patient dissatisfaction.

A retrospective study examined the relationship between anticoagulation with therapeutic warfarin and rates of arthrofibrosis following TKR.

Arthrofibrosis was defined as less than 80° of knee flexion 6–8 weeks post-TKR.

Patients were warfarinised if they had a history of thrombophilic tendencies or medical conditions necessitating anti-coagulation, rather than as routine thromboprophylaxis.

All other patients received thromboprophylaxis using low molecular weight heparin.

A total of 728 patients underwent 874 primary TKR between 1993 and 2002 in one centre, performed by four surgeons. Mean age was 68 years (range 48–89 years) and there were 483 female and 391 male knees.

Eighty cases were warfarinised post-operatively (53 female, 27 male).

Overall, 83 of 874 TKRs (9%) had arthrofibrosis (57 female, 26 male) requiring manipulation under anaesthetic (MUA).

In the warfarinised group, 21 knees (26%) had an MUA (15 female, 6 male).

This compared to 62 cases (8%) requiring MUA in the non-warfarinised group (42 female, 20 male). There was a statistically significant difference on Fisher's exact testing (P<0.0001) between groups.

Following MUA, knee flexion improved in 95% cases to a minimum 95° but 8 cases had a fixed flexion deformity of 5–10°.

In conclusion, therapeutic warfarinisation post-TKR leads to a statistically greater chance of the patient developing arthrofibrosis compared to prophylactic low molecular weight heparin and that patients should be counseled appropriately.

Keywords: Total knee replacement, Arthrofibrosis, Warfarin, Therapeutic