100 pre-operative and post-operative knee and function scores were analysed to assess whether a low pre-operative score was related to a poorer outcome, ie, are we operating too late? A two tailed student “t” test was performed showing that a pre-operative “function “ score of less than 30, resulted in a lower post-operative “function” score and the difference was statistically significant. These patients also showed the greatest improvement in scores and were the most satisfied with surgery. However, a low pre-operative “knee” score could not be related to a low post-operative “knee” score. Patients who had either a “knee” or “function” score of greater than 60 made no statistically significant improvement in either score. In conclusion, the pre-operative “knee” score is not a reliable indicator for when to perform surgery. However, the “pre-operative “ function score should be given more credence, along with clinical judgement, as it would appear that operating too late adversely affects the functional outcome of total knee arthroplasty.