Comparison of the long-term cause of failure and survivorship of four hundred and twenty seven metal-on-metal hip arthroplasties: resurfacing versus large head total hip arthroplasty.

Comparison of mid- to long-term cause of failure and survivorship of metal-on-metal (MoM) resurfacing hip arthroplasty (RHA) and large head total hip arthroplasty (THA) remains sparse. This study aimed to identify and compare the cause of failure and survivorship of MoM RHA and THA at a minimum ten year follow-up. Four hundred twenty-seven MoM hip arthroplasties (286 THA and 141 RHA) were retrospectively analyzed at a mean follow-up of 13 ± three years. Causes of failure were reported as MoM specific (i.e., adverse reaction to metal debris (ARMD) and painful hip with ion elevation) or MoM non-specific (i.e., fracture, infection, and dislocation). Chromium (Cr) and cobalt (Co) ion levels and Co/Cr ratio were compared. Survivorship was compared according to the cause of failure with revision as the endpoint. The rate of ARMD was significantly higher in THA (OR = 2.9 [95%-CI: 1-7]; p = 0.02). No significant difference was detected in failure rate due to other causes between the two groups (p = 0.2-0.9). Ion levels and Co/Cr ratio were both significantly higher in THA (p < 0.01). Survivorship was significantly lower in THA compared to RHA at ten years [89% (95%-CI: 85%-91%) vs 96% (95%-CI: 91%-98%); p = 0.01] and 15 years [73% (95%-CI: 67%-78%) vs 83% (95%-CI: 73%-90%); p = 0.01]. RHA survivorship was significantly higher at any time point. Failure rate due to ARMD was significantly higher in THA while no significant difference in other causes of failure was observed between the two groups. This result emphasizes the role of fretting corrosion at the head-neck junction (i.e., trunnionosis) with significantly higher ion levels and Co/Cr ratio dissociation in THA

Emotions and motivation in mathematics education: theoretical considerations and empirical contributions

Emotions and motivation are important prereq-uisites, mediators, and outcomes of learning and achieve-ment. In this article, we first review major theoretical approaches and empirical findings in research on students\u27 emotions and motivation in mathematics, including a dis-cussion of how classroom instruction can support emo-tions and motivation. Based on this review, we encourage researchers from mathematics education and other dis-ciplines of educational research to combine their efforts. Second, we provide an overview of the contributions in this special issue, most of which reflect such a combination of efforts by considering perspectives from both mathematics education and other fields of educational research. Finally, we consider the neglect of intervention studies and outline directions for future research. We identify intervention studies that target emotions and motivation as one promis-ing but so far underrepresented line of research in mathe-matics education and review results from existing interven-tion studies. For future research, we suggest that researchers should implement fine-grained concepts, assessment instru-ments, theoretical hypotheses, and methods of analysis tai-lored to the specific features of the mathematical domain to adequately investigate students\u27 emotions and motivation in this domain