Patient-related factors influence stiffness of the soft tissue complex during intraoperative gap balancing in cruciate-retaining total knee arthroplasty.

PURPOSE: How much force is needed to pre-tension the ligaments during total knee arthroplasty? The goal of this study was to determine this force for extension and flexion, and for both compartments, and to identify predicting patient-related factors. METHODS: Eighty patients [55 females, mean age 71 (SD 9.7)] were recruited and had a navigated cruciate-retaining total knee arthroplasty. Distraction of the medial and lateral compartments of the extension and flexion gap (90°) with an instrumented bi-compartmental double-spring tensioner took place after finishing the bone cuts. Applied forces and resulting gap distances were recorded by the navigation system, resulting in a force-elongation curve. Lines were fitted with the intersection defined as the stiffness transition point. The slopes (N/mm) represented the stiffness of the ligamentous complex. Linear multiple regression analysis was performed to identify predicting factors. RESULTS: The amount of force at the stiffness transition point was on average 52.3 (CI95 50.7-53.9), 54.5 (CI95 52.7-56.3), 48.3 (CI95 46.2-50.2), and 59.3 (CI95 57.0-61.6) N for the medial and lateral extension and flexion gap, respectively, and varied considerably between patients. The force at the stiffness transition point was significantly different between extension and flexion and both compartments (P < 0.05). Stiffness of the ligaments statistically significantly helped to predict the amount of force at the stiffness transition point, as well as body mass index, gender, and varus-valgus alignment. CONCLUSION: The amount of force at the stiffness transition point varies between 48 and 59 N, depending on flexion/extension and compartment. Patient-related factors influence the stiffness transition point and can help predict the stiffness transition point. When forces higher than 60 N are used for gap distraction, the ligamentous sleeve of the knee might be over-tensioned. LEVEL OF EVIDENCE: Prognostic study, Level I-high-quality prospective cohort study with >80 % follow-up, and all patients enrolled at same time point in disease.

Program to improve nurses' knowledge of pediatric emergency medications.

The effects of an educational program designed to improve nurses' knowledge of the use of emergency medications in the pediatric intensive-care unit (PICU) are reported. The clinical pharmacist for a six-bed PICU and a clinical nurse educator developed a program to assess and extend PICU nurses' knowledge of emergency medications with respect to calculations of bolus and continuous infusions, pharmacology, and proper dosage and administration route. The program consisted of a pretest, a pharmacology lecture, calculation problems, a hands-on practicum, and a posttest. Drugs covered were atropine sulfate, sodium bicarbonate, calcium gluconate, calcium chloride, dopamine hydrochloride, dobutamine hydrochloride, epinephrine hydrochloride, isoproterenol hydrochloride, lidocaine hydrochloride, sodium nitroprusside, and norepinephrine bitartrate. A retest was given 13 months after the pretest. The program was completed by 21 nurses over seven months. There was a significant difference between the mean pretest score, 69.5%, and the mean posttest score, 87.3%, due to improvements in scores for the calculation questions. There was no significant difference in the mean time required to complete the pretest and the posttest. A significant correlation was observed between pretest score and months spent practicing in the PICU. Time to take the retest was significantly shorter than the posttest time, and scores continued to improve. An educational program developed cooperatively by pharmacy and nursing improved specific measures of PICU nurses' knowledge of emergency drugs.