Introduction: Surgery and the use of pneumatic tourniquets lead to an increase in the activity of the fibrinolytic system, which in turn may accentuate the blood loss during knee arthroplasty. Drugs that inhibit the fibrinolytic system may thus be used to reduce blood loss. Tranexamic acid (TA) acts by binding to one of the enzymes at the start of the coagulation cascade, so inhibiting the fibrinolytic system. A concern is that this inhibition may have the side effect of increasing thromboembolic disease, a common complication of joint replacement surgery. We aim to confirm the reductions in blood loss and to assess the impact of TA usage on clinical and sub-clinical DVT.

Method: We performed a prospective, randomised, double blind, controlled trial, using patients due to undergo primary unilateral total knee arthroplasty. Patients were randomised to receive either 15mg/kg of tranexamic acid or a similar volume of normal saline at the time of cementing of the prosthesis. Perioperative blood loss was recorded and patients were screened for DVT with duplex ultrasound assessment of both legs on the fifth post-operative day.

Results: A statistically significant (p=0.006) decrease in blood loss in the early post operative period was noted in the group receiving tranexamic acid. This was not associated with a significant difference in total blood loss (p=0.55) or in transfusion requirements. There was no evidence of DVT in either group on duplex ultrasound screening of the lower limbs.

Interpretation: One injection of 15mg/kg of tranexamic given at the time of cementing the prosthesis in total knee arthroplasty, before deflation of the tourniquet, significantly decreases the amount of blood loss in the early post operative period. The treatment was not associated with an increase in thromboembolic complications.

Study Design: Prospective observational study.

Objective: To establish the sensitivity, specificity and cost-effectiveness of motor evoked potential (MEP) monitoring of lower lumbar nerve roots during instrumented spinal fusion.

Subjects: 161 patients undergoing elective lumbar spinal fusion monitored with the Neurosign 800 machine.

Outcome Measures: MEP evidence of pedicle breaches and nerve root over-distraction. Symptoms and signs of new neurological deficits postoperatively. EMG confirmation of neurological deficits in symptomatic post-operative patients.

Results: True positive results consisted of pedicle breaches detected in 15 patients (9.3%). Nerve root irritation on distraction was found in 9 patients (5.6%). These results allowed modification of the surgical technique to prevent subsequent neural injury. True negative results on active pedicle probing occurred in 134 patients (83.2%) and in 146 patients (90.7%) on passive monitoring. False positive results were detected in 7 patients (4.3%). Four patients had electrical connection problems and in three patients pedicle probing was positive but direct screw testing was negative. True negative results consisted of a failure of monitoring to detect clinically significant neurological events in five patients (3.1%). In four the symptoms and signs were transient, resolving within six weeks of surgery. In one, revision decompression of the L5 nerve roots was required.

Conclusions: MEP monitoring in our hands has a specificity of 95.4% and a sensitivity of 75%. The cost per case is around £75.