Infection is a leading indication for revision
arthroplasty. Established criteria used to diagnose prosthetic joint infection
(PJI) include a range of laboratory tests. Leucocyte esterase (LE)
is widely used on a colorimetric reagent strip for the diagnosis
of urinary tract infections. This inexpensive test may be used for
the diagnosis or exclusion of PJI. Aspirates from 30 total hip arthroplasties
(THAs) and 79 knee arthroplasties (KA) were analysed for LE activity. Semi-quantitative
reagent strip readings of 15, 70, 125 and 500 white blood cells
(WBC) were validated against a manual synovial white cell count
(WCC). A receiver operating characteristic (ROC) curve was constructed
to determine the optimal cut-off point for the semi-quantitative
results. Based on established criteria, six THAs and 15 KAs were
classified as infected. The optimal cut-off point for the diagnosis
of PJI was 97 WBC. The closest semi-quantitative reading for a positive
result was 125 WBC, achieving a sensitivity of 81% and a specificity
of 93%. The positive and negative predictive values of the LE test
strip were 74% and 95% respectively. The LE reagent strip had a high specificity and negative predictive
value. A negative result may exclude PJI and negate the need for
further diagnostic tests. Cite this article:
Following the outcomes of the RECORD trials the protocol of extended thromboprophylaxis in patients undergoing elective primary total hip or knee arthroplasty has been changed in our institution. Between June 2008 and May 2009 patients were offered extended thromboprophylaxis with 150mg of aspirin daily, commencing preoperatively on admission and continuing for a total of six weeks. From June 2009 onwards patients were treated with 10mg of rivaroxaban once daily for two weeks following total knee and five weeks following total hip arthroplasty commencing 4 to 6 hours postoperatively. Our cohorts were 700 patients before and after the introduction of the new regimen. The two groups were matched for age, sex and type of operation. All patients with no contraindication to treatment with aspirin or rivaroxaban respectively undergoing elective primary total hip or knee arthroplasty were included in the study. Patients receiving warfarin on admission were treated with warfarin postoperatively and were excluded. We have compared the two treatment protocols in terms of safety and efficacy. Results focus on 4 safety outcome measures including mortality, haemorrhagic complications, transfusion requirements and infection rates and 2 efficacy outcome measures including thromboembolic complications and length of inpatient stay. Rates of DVT were equal in the two cohorts (P< 0.005) as were the mortality rates. Transfusion requirements post-operatively were not affected by the introduction of the new regimen however there was a significant increase in both return to theatre rates and prolonged wound ooze (P< 0.005). Infection rates were slightly higher in the cohort treated with rivaroxaban but this was not statistically significant. We conclude that further trials need to be done to confirm the suitability of routine use of rivaroxiban.
