Improved quadriceps' mechanical advantage in single radius TKRs is not due to an increased patellar tendon moment arm

Single femoral radius TKRs have been reported to improve quadriceps' mechanical advantage, leading to enhanced patient function. An increased patellar tendon moment arm (PTMA) has been cited as the main feature leading to improved quadriceps' mechanical advantage. However, these designs often incorporate a recessed trochlea which alters the patellar mechanism and may contribute to improved quadriceps' mechanical advantage. This study simultaneously measured the PTMA using two and three dimensional methods, as well as quadriceps forces (QF), patellofemoral kinematics and tibiofemoral kinematics in a motion analysis laboratory during an open chain leg extension activity. Six cadaveric knees were tested in the normal state and after implantation of three different single femoral radius TKR designs: cruciate retaining, posterior stabilised and rotating platform posterior stabilised (Stryker, Newbury, UK). QFs in the TKRs were between 15% and 20% lower than normal between 60° and 70° flexion. The increase in PTMA was insufficient to explain the reduced QF in the TKRs. The patellar flexion angle (PFA) of the TKRs was lower than normal at knee flexion angles greater than 50°, probably as a result of the recessed trochlea. A simple patellar model demonstrated that the reduced PFA may explain a large proportion of the reduction in QF after single radius TKR

The changing global patterns of female breast cancer incidence and mortality.

One in ten of all new cancers diagnosed worldwide each year is a cancer of the female breast, and it is the most common cancer in women in both developing and developed areas. It is also the principal cause of death from cancer among women globally. We review the descriptive epidemiology of the disease, focusing on some of the key elements of the geographical and temporal variations in incidence and mortality in each world region. The observations are discussed in the context of the numerous aetiological factors, as well as the impact of screening and advances in treatment and disease management in high-resource settings

A systematic review of occupational exposure to synthetic vitreous fibers and mesothelioma

Objective We investigated whether available epidemiological and toxicological data suggest an increased risk of mesothelioma among workers exposed to synthetic vitreous fibers (SVF). Methods We conducted a systematic review of epidemiological studies on the risk of mesothelioma among workers exposed to SVF, and toxicological studies on SVF and mesothelioma. Results Seven cohort studies were conducted among workers employed in production of rock/slag wool, glass wool, or continuous glass filament in the United States, Canada, and Europe. Of the six deaths from mesothelioma identified in these studies, three had exposure to asbestos. A review of death certificates in a study of rock wool production workers identified one additional probable death. A formal comparison with expected deaths is not feasible. Four community-based case-control studies were identified, of which three reported an increased risk among SVF-exposed workers. The number of cases not exposed to asbestos was less, and residual confounding from asbestos exposure misclassification may explain the association in these studies. The toxicology review of SVF suggested that they present a low hazard mostly due to their low biopersistence, typically with a half-life in rat studies of tens of days compared to amphibole asbestos which has a half-life of 400-500 days. Conclusions The combined evidence from epidemiology and toxicology provide little evidence that exposure to SVF increases the risk of mesothelioma. © 2014 Informa Healthcare USA, Inc