Deep vein thrombosis remains a significant and common complication following joint replacement and debate exists over which contributing factors are important. This study investigates the effect of a number of variables on the incidence of symptomatic deep vein thrombosis in knee arthroplasty surgery. Data was collected prospectively on 3449 knee replacements including procedure type, tourniquet time, surgeon, patient age, and gender. These variables were assessed by the use of generalised linear modelling against the presence or absence of symptomatic deep vein thrombosis demonstrated on duplex ultrasonography. The overall deep vein thrombosis rate was 1.6%. The only variable which had an association with confirmed symptomatic DVT was operation type with total knee replacements having a higher incidence than unicompartmental knee replacements (2.2% vs 0.3% p=0.0003). Tourniquet time did not exhibit a statistically significant effect (p=0.63) These data show that the DVT rate in unicompartmental knee replacement is statistically significantly lower than that of total knee replacement. They do not support the notion that increased tourniquet time is associated with an increased risk of DVT.

Symptomatic and asymptomatic deep-vein thrombosis (DVT) is a common complication of knee replacement, with an incidence of up to 85% in the absence of prophylaxis. National guidelines for thromboprophylaxis in knee replacement are derived from total knee replacement (TKR) data. No guidelines exist specific to unicompartmental knee replacement (UKR). We investigated whether the type of knee arthroplasty (TKR or UKR) was related to the incidence of DVT and discuss the applicability of existing national guidelines for prophylaxis following UKR.

Data were collected prospectively on 3449 knee replacements, including procedure type, tourniquet time, surgeon, patient age, use of drains and gender. These variables were related to the incidence of symptomatic DVT.

The overall DVT rate was 1.6%. The only variable that had an association with DVT was operation type, with TKR having a higher incidence than UKR (2.2% versus 0.3%, p < 0.001). These data show that the incidence of DVT after UKR is both clinically and statistically significantly lower than that after TKR.

TKR and UKR patients have different risk profiles for symptomatic DVT. The risk-benefit ratio for TKR that has been used to produce national guidelines may not be applicable to UKR. Further research is required to establish the most appropriate form of prophylaxis for UKR.