We conducted a randomized controlled trial (RCT) to investigate if iodine impregnated incision drapes (IIID) increases bacterial recolonization rates compared to no drape use under conditions of simulated total knee arthroplasty (TKA) surgery.

Background: To prevent surgical site infection (SSI), one of the important issues is managing the patient´s own skin flora. Many prophylactic initiatives have been suggested, including the use of IIID. IIID has been debated for many years and was deemed ineffective in preventing SSI in a recent systematic review [1], while some evidence suggests a potential increase in postoperative infection risk, as a result of IIID use [2].

IIID is sparsely investigated in orthopaedic surgery. An increase in the number of viable bacteria in the surgical field of an arthroplasty operation has a potential to increase the risk of SSI in an otherwise elective and clean procedure [3].

20 patients scheduled for TKA were recruited. Each patient had one knee randomized for draping with IIID [4] while the contralateral knee was left bare, thus the patients acted as their own controls. Operating theater settings with laminar airflow and standard perioperative procedures were simulated. Sampling was performed with the cup-scrup technique [5] using appropriate neutralizers. Samples were collected from the skin of each knee prior to disinfection and on 2 occasions after skin-preparation, 75 minutes apart. Bacterial quantities were estimated by spread plating with 48-hour aerobic incubation. Outcome was measured as colony forming units per square centimeter of skin. We used Wilcoxon signed-rank test for comparative analysis within and between knees.

Following skin-disinfection we found no significant difference in bacterial quantities between the intervention and the control knee (p = 0.388). Neither did we see any difference in bacterial quantities between the two groups after 75 minutes of simulated surgery (p = 0.367). When analyzed within the intervention and control group, bacterial quantities had not significantly increased at the end of surgery when compared to baseline, thus no recolonization was detected (p = 0.665 and 0.609, respectively).

Iodine impregnated incision drapes did not increase bacterial recolonization rates in simulated TKA surgery. Thus, the results of this RCT study does not support the hypothesis that iodine impregnated incision drapes promotes bacterial recolonization and postoperative infection risk.

Introduction: Recently there has been increasing interest in postoperative pain treatment by use of wound infil-tration with local anaesthetics. The technique has been reported effective following hip and knee arthroplasty. We hypothesized that repeated installations of intraar-ticular local anaesthetic in patients with femoral neck fracture would give pain relief without side effects and reduced opioid usage.

Material and Methods: 33 patients undergoing osteo-synthesis with two Hook Pins were randomized into 2 groups in a double-blinded study (Clinical Trials.gov id: NCT00529425). In group A (Active) 19 patients received 1 peroperative (30 ml=200 mg) and 6 postoperative (10 ml=100 mg) bolus instillations of ropivacaine through an intraarticular catheter which was removed after 48 hours. In group B (placebo) 14 patients were injected with the same volume of saline water. The need for opioid rescue analgesia standardized to mg equivalent of oxyco-done and pain measured on a 5 point scale were recorded during the intervention period of two days after surgery.

Results: No significant difference in consumption of rescue analgesia was found between the groups on day one and two: Group A (16.7 mg and 15 mg, both median values) opposed to group B (10 mg and 7.5 mg, both median values), (P=0.51 and P=0.36 Mann-Whitney). Testing for insufficient use of rescue analgesia by comparing the number of pain scores exceeding a defined limit of tolerable pain showed no difference between the groups on day 1 and 2 (P=0.31 and P=0.45). Comparing the maximum pain score we found no significant difference between the groups on day 1 (P=0.41). Although not significant, the maximum pain score was higher in group A on day 2 (P=0.051). There was no difference between the median pain score on day 1 (P=0,78) but on day 2 the median pain score was significantly higher in group A (P=0,03).

Conclusion: Repeated intraarticular application of ropi-vacaine provides no reduction in opioid requirements or pain after osteosynthesis of femoral neck fracture. This suggests that the technique has no clinically relevant analgesic effect in this category of patients.

Introduction: Microdialysis can detect ischemia in soft tissue. In a previous study we have shown the development of ischemia in the femoral head removed from patients undergoing total hip replacement.

This study also raised some methodological questions that this study tries to answer.

What is happening in the dead space around the catheter in the drill canal? And is there an equilibrium period after the insertion of the catheter.

Methods and materials:

Ex vivo study: in 5 syringes with 5 ml human blood a microdialysis catheter was inserted and microdialysis performed over 3 hours.

Results:

Ex vivo: the microdialysis results showed that lactate kept a steady level and glucose and glycerol all fell, pyruvate fell but leveled out. The lactate/pyruvate ratio increased from 13(4) to 32(6) (p< 0.001).

Conclusion: The ex vivo study showed a clear washout pattern, and is different from what we see in bone.

The in vivo study indicates that an equilibrium period is necessary or that a reference measurement in healthy bone must be used when performing short measurements in bone.

Introduction: We state that preserving the hip might be optimum in treatment of patients with dislocated femoral fractures presuming that the fractures unite. In order to be able to choose the right treatment for the patient with a dislocated femoral neck fracture, we have hypothesized that lack of blood flow and development of ischemia might have influence on outcome of the osteosynthesis. In this study we have established microdialysis and laser Doppler measurements in patients with a dislocated femoral neck fractures.

Methods and materials: 14 patients with dislocated fractures of the femoral neck were osteosynthezised by using 2 cannulated screws. During the operation blood flow was measured with laser Doppler in order to detect pulsatile flow, and microdialysis was performed to detect ischemia. Both measurements were made in the femoral head and with the greater trochanter as control. The parameters measured were lactate, pyruvate, glycerol and glucose concentrations. Lactate/pyruvate ratio was calculated in order to estimate ischemia defined as a value over 25. Measurements were done after the fracture was reduced, and during osteosynthesis. Data are presented as mean with standard deviation (SD) in brackets.

Results: In all but one patient laser Doppler showed pulsatile flow in the greater trochanter, whereas 8 patients had flow in the femoral head. In the greater trochanter the mean lactate/pyruvate ratio was 11 (7.55), in the femoral heads the mean ratio was 27.99 (21.24) although 4 heads did not show ischemia (p=0.0004). The values for glucose in the trochanter and the femoral head are 2.47 mM(1.92) and 1.53 mM(1.37) respectively, and for glycerol 0.16 mM(0.09) and 0.25 mM(0.22). During the observation period two patients were reoperated, one with hemiarthroplasty 3 months after the osteosynthesis due to failure of the osteosynthesis; the patient had flow measured by laser Doppler and ischemia with microdialysis. One had a resection arthroplasty due to infection.

Conclusion: To our knowledge it is the first time that laser Doppler and microdialysis has been established in patients with dislocated femoral neck fractures. Further studies will have to evaluate whether laser Doppler and microdialysis in combination with fracture related parameters can predict failure of the osteosynthesis. This might enable us to establish a treatment algorithm to be used in the daily clinic.