The John Charnley Award. Wear is a function of use, not time.

Polyethylene wear (linear penetration) in 37 hip replacements was assessed from digital images using a validated two-dimensional, edge detection-based computer algorithm. Patient activity was assessed with a pedometer, a step activity monitor and a simple visual analog scale. Joint use was related to wear at the 90% confidence level. Without three recognized outliers, wear was highly correlated to use. The visual analog scale activity rating was significantly related to wear for the 24 hip replacements with standard polyethylene. Univariate regression analysis indicated that male gender, height, weight (which were both highly correlated to male gender) and hip center of rotation were significantly correlated to wear. Multivariate regression analysis indicated that male gender, femoral off-set, and Hylamer were significantly correlated to wear. Based on the wear and activity data from the 24 hip replacements with standard polyethylene, the average volumetric wear rate per million cycles with a 70 kg patient weight was 30 mm3. This unique in vivo result can be considered a target wear rate for standard polyethylene in hip simulator studies.

Interpersonal perception: a theory and method for studying pharmacists' and patients' views of pharmaceutical care.

OBJECTIVES: To identify the congruency between pharmacists' and their patients' perceptions of the benefits of services a pharmacist would provide if practicing according to the pharmaceutical care model, and to characterize the relationship between the congruency of their perceptions and the extent to which each reports that such services are provided. DESIGN: This study employed the interpersonal perception method, a communication theory and tool through which two people's perceptions are compared to assess their agreement with and understanding of one another regarding a particular issue. SETTING AND PARTICIPANTS: Six independent community pharmacies participated in a written survey of perceptions of pharmaceutical care. Questionnaires were distributed to 100 adult patients from each store. Pharmacists completed a self-report of the pharmaceutical care services provided to their patients; patients were asked whether they received such services. MAIN OUTCOME MEASURES: Pharmacists' and patients' perceptions of pharmaceutical care; pharmacists' and patients' reports of pharmaceutical care activities. RESULTS: Pharmacists and patients were found to disagree on the potential benefits of pharmaceutical care services. Pharmacists tended not to understand their patients' perceptions. The differences were not found to be related to the level of pharmaceutical care reportedly provided. CONCLUSION: The extent to which pharmacists' and patients' perceptions serve as barriers to the provision of pharmaceutical care is yet unknown. This study shows that differences in these perceptions exist and may perpetuate both patients' traditional perceptions of dispensing activities in the community pharmacy and pharmacists' perceptions of lack of patient interest in pharmaceutical care.

Step activity monitor: increased accuracy in quantifying ambulatory activity.

This study compares the accuracy of a two-dimensional accelerometer worn on the ankle (a step activity monitor) with that of an electronic, digital pedometer worn on the belt line. Twenty-nine human subjects were evaluated while they briskly walked 400 M, slowly walked 10 M, and ascended and descended a flight of stairs. The step activity monitor had less error in all activities; its mean absolute error was 0.54%, whereas that of the pedometer was 2.82%. The difference was more pronounced in obese subjects (body mass index greater than 30), with an overall mean absolute error of 0.48% for the step activity monitor and 6.12% for the pedometer (nearly 13 times that of the step activity monitor). For subjects with a body mass index less than 30, the step activity monitor had an overall error of 0.56% and the pedometer had an overall error of 1.56% (less than 3 times that of the step activity monitor). The absolute error of the pedometer was positively correlated with body mass index (r = 0.792, p < 0.0001) and weight (r = 0.753, p < 0.0001), whereas the error of the step activity monitor was not significantly correlated with either. Neither device was significantly biased by age, gender, or the presence of a lower-extremity joint prosthesis. The accuracy and additional capabilities, including a real-time memory record of activity, of the step activity monitor make it well suited for objectively quantifying ambulatory activity, especially for obese subjects.