Outcome measurement in the ACL deficient knee--what's the score?

There is increasing pressure within the United Kingdom for transparent assessment of the performance of every doctor along with the procedures they perform. Unfortunately, the validation of the outcome measures used to assess such procedures has been questioned. This has been well illustrated in the anterior cruciate ligament (ACL) deficient knee. Over 54 different outcome measures used to assess the ACL deficient knee have been identified, few of which were formally assessed at their initial publication. For those most frequently used the Lysholm (I and II) knee scoring scale and Tegner activity score are the only ones to have been adequately validated prior to use. The Cincinnati rating system and International Knee Documentation Committee (IKDC) form were not assessed and the reliability of both measures has since been questioned. Appropriately tested newer measures include the IKDC subjective knee evaluation form, Mohtadi's ACL quality of life outcome measure and the Knee injury and osteoarthritis outcome score (KOOS). We recommend use of the Lysholm II knee scoring scale and Tegner activity score for clinical follow-up of patients and for use as a gold standard to which future measures can be compared. These have their deficiencies and will ultimately require replacement. In view of the international standing of its authors, the IKDC subjective knee evaluation form is likely to be used in preference to the KOOS despite its attractions. For long-term clinical trials the SF-36 should also be used. Further research is required to produce suitable measures for assessing the ACL deficient knee and this work should be appropriately funded.