Does lateral versus medial exposure influence total knee tibial component final external rotation? A CT based study.

INTRODUCTION: A previous study demonstrated that performing a total knee arthroplasty through a lateral approach including anterior tibial tuberosity (ATT) osteotomy (refixed in its original position) presented numerous advantages: correcting the preoperative patella lateral tilt and improving postoperative patella tracking. We hypothesized that these improvements in patella centering were, at least in part, due to an increased external rotation of the tibial component. Postoperative scannographic studies were, therefore, undertaken to measure tibial component rotation and analyze the results according the medial and lateral exposure used. HYPOTHESIS: Rotational positioning of the tibial component is influenced by the lateral or medial approach selected at surgery. MATERIALS AND METHODS: Forty-five CAT scans, performed according to the protocol criteria of the French Hip and Knee Society (SFHG), were studied 3 months postoperatively: 15 knees operated through the lateral approach and 30 knees operated through a standard medial approach. The total knee utilized in all these cases was a posteriorly stabilized, fixed-bearing, design. We measured first the angle formed between the perpendicular to the transverse axis of the tibial component and the axis joining the ATT to the center of the knee; second we also measured the coronal distance between the center of the component and the anterior tibial tuberosity (ATT). RESULTS: In the group using the medial approach, the lateral position of the ATT was 7 + or - 3mm with a rotation angle of 18 degrees . In the group using the lateral approach these measurements were respectively 1 + or - 4mm and 2 degrees (p<0.0001). DISCUSSION: External rotation of the tibial component is substantially increased by the lateral approach compared to the medial approach. Better exposure of the lateral tibial plateau is probably responsible of this difference. This increased external rotation improves postoperative patella tracking. TYPE OF STUDY: Prospective; comparative; non-randomized study; level 3.

[Diltiazem poisoning: hemodynamic aspects]. / Intoxication médicamenteuse par diltiazem: aspects hémodynamiques.

A case is reported of a 50-year-old man who took a massive overdose of diltiazem (5,400 mg), together with 1,350 mg potassium clorazepate and 390 mg nordazepate, five months after having experienced a myocardial infarction (MI). On admission, systolic blood pressure was 80 mmHg, with an irregular heart rate of 60 b.min-1. There was superficial polypnea (40 c.min-1) with hypoxia (PaO2: 63.5 mmHg). The ECG revealed, besides the MI scar, complete sinus arrest. Endotracheal intubation and mechanical ventilation were rapidly required. The patient then had gastric lavage, and was given activated charcoal. Treatment with 1.5 mg atropine and 2 g intravenous calcium chloride were unable to amend the cardiac dysrhythmia. A continuous isoproterenol infusion restored a sinus rhythm, but this was not maintained because of the risk of side-effects. Cardiovascular collapse was treated with dobutamine (10 micrograms.kg-1.min-1). As the peripheral and pulmonary vascular resistances were greatly diminished (464 dyn.s.cm-5 and 86 dyn.s.cm-5 respectively), alpha and beta mimetics were used: 1 microgram.kg-1.min-1 noradrenaline and 15 micrograms.kg-1.min-1 dobutamine. After 7 h of this treatment, spontaneous sinus rhythm returned abruptly. Noradrenaline and dobutamine were replaced thereafter with adrenaline (0.25 microgram.kg-1.min-1), which was stopped 24 h later. There was a marked respiratory and haemodynamic improvement, the patient leaving the intensive care unit on the fourth day and returning home one week after the overdose. The relationships between cellular calcium movements and the adrenergic system are discussed, as well as the possible mechanism of cardiac failure.

[Acute nicardipine poisoning]. / Intoxication aiguë par la nicardipine.

A 41 year old man with overdose of nicardipine is reported. Quickly after the poisoning, he developed a cardiovascular collapse picture with renal failure and myocardium ischemia. The clinical picture improved with injection of dobutamine and dopamine. The hemodynamic study showed a fall of the systemic resistances. The recovery was complete 40 hours after the ingestion.

[Pharmacokinetics and changes in the physical properties of blood and urine after administration of dextran 60000]. / Pharmacocinétique et modifications des propriétés physiques du sang et des urines apès administration d'un dextran 60,000.

A study was carried out to assess the changes induced by an infusion of dextran, molecular weight 60,000 daltons, in blood and urine. Plasma and urine dextran and serum protein concentrations, haematocrit, blood and urine viscosities, and blood oncotic pressure were measured in 10 consecutive male patients. Fifteen min after administration of 20 ml dextran 1000 (Promit), they were each given 500 ml (30 g) dextran 60 (Hemodex) over 30 min for plasma volume expansion. The measurements were carried out at the end of the infusion, and then at regular intervals over a 48 h period. The highest dextran blood concentrations were found at the end of the infusion, decreasing thereafter with a distribution half-life of 1.83 +/- 0.64 h, and an elimination half-life of 25.5 +/- 7.6 h. Haematocrit values decreased by 12%, and serum protein concentrations by 9.5%, after the end of the infusion. These changes remained significant for 9 h; they were probably due to the dilution effect of 500 ml of dextran. Colloid osmotic pressure was not significantly altered (20.7 +/- 4.7 mmHg vs. 23.1 +/- 5.1 mmHg 48 h after the end of the infusion). The colloid osmotic pressure due to dextran 60 compensated for the fall in protein concentration. A decrease in blood viscosity was found at different shear rates, despite dextran 60 being highly viscous. This could also be explained by a dilution effect. The highest degree of urinary excretion occurred 30 min after the end of the infusion, and lasted for 3 h. Forty-five percent of the total dextran dose had been excreted by the 48th hour.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypnotic efficacy of midazolam in pre-surgical patients: a dose-finding study.

The hypnotic effect of midazolam on the sleep of pre-surgical patients was studied in 99 patients (53 males, 46 females) due to undergo surgery the following day. One tablet of 15 mg midazolam was administered at 21.00 h and a second was given 45 min later if the subject had not fallen asleep, sleep-onset latency being measured from the time the second tablet was taken. Eighty patients required 1 tablet and 19 required 2 tablets. According to the subjective assessment, patients receiving 1 tablet fell asleep in 22.9 +/- 14.9 min and those taking 2 tablets fell asleep in 38.4 +/- 25.3 min (difference significant P less than 0.05). There was no statistically significant difference between the 1- and 2-tablet groups with regard to sleep duration, number of awakenings, overall assessment of the night's sleep, sleep quality and state on awakening. Factors which had a statistically significant influence on the dosage requirement were (a) sex, 30.4% females requiring a second tablet v. 9.4% males; (b) age, the mean age of the 2-tablet group being 36.5 v. 47 years in the lower dose group; (c) weight, patients with lower body weight requiring the higher dosage, mean 57.5 v. 66 kg; (d) current insomnia or a history of sleeping problems; (e) previous use of hypnotics; (f) degree of insomnia, moderate/severe insomnia needing a higher dosage (42% v. 21%).(ABSTRACT TRUNCATED AT 250 WORDS)

[A comparison of midazolam and diazepam for intramuscular premedication]. / La prémédication par voie intra-musculaire. Comparaison midazolam-diazépam.

Two groups of 27 individuals--12 males and 15 females each--were constituted thanks to the envelopes technique. The first group received 10 mg of midazolam and the second 15 mg of diazepam as an intramuscular premedication, 30 minutes before a surgical operation. Sedation of preoperatoire anxiety was relevant in 26 subjects after midazolam and in 11 after diazepam (p less than 0,001). Amnesia related to the different times of the operative procedure was more frequent in the midazolam group than in the diazepam group: 70 p. 100 versus 4 p. 100 for the arrival into the operating room (p less than 0,001) and 96 p. 100 versus 78 p. 100 for the recovery on operating table (p less than 0,05). The effects on blood pressure, pulse rate and respiratory rate are not significantly different in both groups: neither is the local and general tolerance. Considering its greater efficiency with a similar tolerance, midazolam as compared with diazepam can be regarded as a superior intramuscular premedicant.