Fixation of a trabecular metal knee arthroplasty component. A prospective randomized study.

BACKGROUND: Uncemented tibial components of total knee replacements have lower survival rates than cemented components. Radiostereometric analysis is a highly accurate, effective tool for investigating new implant designs. The purpose of this study was to compare an uncemented Trabecular Metal tibial component with a conventional cemented stemmed tibial component of the same design. METHODS: Seventy subjects undergoing total knee replacement were randomized to receive either the Trabecular Metal or the cemented tibial component. Radiostereometric analysis of micromotion of the tibial components was performed postoperatively at six, twelve, and twenty-four months, and the maximum total point motion of the implant and three-dimensional translations and rotations were recorded. RESULTS: Follow-up was complete for twenty-eight subjects in the Trabecular Metal group and twenty-one subjects in the cemented group. A subset of the Trabecular Metal components migrated extensively in the postoperative period, but all stabilized by one year and the proportion considered to be at risk for early aseptic loosening was 0.0 (95% confidence interval, 0.0 to 0.12) in the group as a whole. Four cemented components were considered to be at risk for early aseptic loosening (proportion at risk, 0.19; 95% confidence interval, 0.08 to 0.4). CONCLUSIONS: This study suggests that the Trabecular Metal component may be an effective alternative to the standard cemented tibial component.

Decision making in migraine patients taking sumatriptan: an exploratory study.

Until recently, much of the medical and psychological literature has examined and conceptualized the taking of medication from the viewpoint of adherence to or compliance with recommendations from health professionals. However, some authors have argued that medication taking is mostly determined by patient decision making. In order to investigate the factors and processes influencing the patient's decision to take or not take abortive therapy for migraines, 20 migraineurs (according to International Headache Society criteria) were asked, using a semistandardized interview, what factors influenced their decision to take or not take sumatriptan when they had a migraine. Qualitative analysis revealed a 2-stage decision-making process. First, the patient collects information from interoceptive and environmental cues (symptom monitoring) to predict whether the headache that is beginning will become a migraine. Then, if the patient decides it is a migraine, he or she weighs various factors to decide whether to take sumatriptan. These results are consistent with the current cognitive psychology literature on decision-making processes and could lead to significant improvements in understanding the process by which patients make decisions about taking sumatriptan and, ultimately, could lead to better patient education and more effective headache control. They also open a whole new field in the empirical investigation of medication-taking behavior.