Increasing age and female gender are associated with early knee replacement following arthroscopy

Early knee replacement following arthroscopy may be perceived as a failure of the original treatment and thus a poor use of resources. Factors that may be associated with increased risk of early replacement were explored in this study. All adult patients who underwent planned knee arthroscopy in a national cohort over a 6-month period in 2005 were extracted from the administrative hospital admissions database and linked to determine whether and when a knee replacement occurred on the same knee within the subsequent 5 years. A combination of survival analysis and mixed effect modelling was used to investigate risk factors for replacement. There were a total of 20,556 arthroscopies, of which 2,161 (10.6 %) subsequently underwent knee replacement. For patients under 60 years, female gender (62.1 % higher risk, p < 0.001) and increasing age (12.7 % increased risk per increasing year of age, p < 0.001) were significant associations for requiring knee replacement, after risk adjusting. Of those aged a parts per thousand yen60, 12.7 % (576) had undergone a replacement at 1 year following arthroscopy. Females (33 % higher risk), increasing age (7.3 % increased risk per increasing year of age, p < 0.001) and hypertension (1,600 % higher risk, p < 0.001) were significant predictors. The risk associated with increased age was not proportional for the older age group, with risk declining as time passed from arthroscopy, indicating other factors were influencing progression to knee replacement. The predictors of early knee replacement following arthroscopy were female sex, age over 60 years and hypertension, irrespective of type of operation. This work may contribute to national recommendations regarding the provision of arthroscopy for patients over 60 years. III.