Factors associated with prolonged length of stay following a total knee replacement in patients aged over 75

The aim of this study was to examine factors associated with a prolonged length of stay (LOS) in patients over 75 undergoing a total knee replacement (TKR). Patients over 75 undergoing a TKR at our institution from January 2008 to February 2009 were identified (n = 112). Patient and operative factors previously shown to affect length of stay were identified. Patient notes were reviewed for details on each of these and data analysed for their effect on length of stay. Discrete data were analysed for their effect on post-operative length of stay using either the Mann-Whitney U test or the Kruskall-Wallis test and continuous data analysed with the Spearman's rank correlation coefficient. The following factors were associated with length of stay at the 95 % confidence level: patient age, pre-operative mobility and the use of walking aids, BMI, whether the patient was able to mobilise within 24 or 48 hours of the surgery, the day on which the patient first walked ten metres and achieved 90A degrees active knee flexion, pre and post-operative haemoglobin and the need for a blood transfusion. Pre-operative use of walking aids, peri-operative haemoglobin concentration, failure to mobilise early following the operation and post-operative complications (including the need for a blood transfusion) seem to be the significant factors associated with a prolonged stay in hospital in the over 75 year olds.