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% 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.
Infection remains a significant and common complication after joint replacement and there is debate about which contributing factors are important. Few studies have investigated the effect of the operating time on infection. We collected data prospectively from 5277 hip and knee replacements which included the type of procedure, the operating time, the use of drains, the operating theatre, surgeon, age and gender. In a subgroup of 3449 knee replacements further analysis was carried out using the tourniquet time in place of the operating time. These variables were assessed by the use of generalised linear modelling against superficial, deep or joint-space post-operative infection as defined by the Australian Surgical-Site Infection criteria. The overall infection rate was 0.98%. In the replacement data set both male gender (z = 3.097, p = 0.00195) and prolonged operating time (z = 4.325, p <
0.001) were predictive of infection. In the knee subgroup male gender (z = 2.250, p = 0.02447), a longer tourniquet time (z = 2.867, p = 0.00414) and total knee replacement ( These findings support the view that a prolonged operating time and male gender are associated with an increased incidence of infection. Steps to minimise intra-operative delay should be instigated, and care should be exercised when introducing measures which prolong the duration of joint replacement.
