ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION – WHAT IS SUCCESS? A CRITICAL ANALYSIS OF THE KNEE INJURY AND OSTEOARTHRITIS OUTCOME SCORE (KOOS)

Abstract

Aim: Patient Relevant Outcome Measures are increasingly used to assess the quality of care and clinical effectiveness of surgical intervention but lack clear definitions of success or failure. We sought to evaluate and compare the ability of two outcome scores, the Lysholm and the KOOS, to determine a successful outcome following ACL reconstruction by defining discrete criteria.

Methods & Results: 204 patients underwent single bundle ACL reconstruction (four strand hamstring graft) from 2003 – 2007 and had minimum 12 months follow up. 118 (58%) patients had complete KOOS and Lysholm scores recorded pre-operatively and at 12 months post operation.

Lysholm scores at 12 months gave an average score of 90 with 82% of scores categorised “good” or “excellent” according to previously published ratings.

The 12 month KOOS were then analysed against previously published, calculated KOOS cut-off criteria for a symptomatic knee and in addition, the magnitude of change in pre- & post-op scores, as reported by the Scandinavian Ligament Registries. Applying these two patient derived definitions produced results with noticeably varied rates of success. For the most valid and sensitive KOOS subscales - Sport & Recreation and Quality of Life – the results ranged from 95% to 37%, depending on criteria selected.

Conclusions: The Lysholm Score and KOOS have to date been used primarily for comparison studies in ACL reconstruction. There has been no consensus regarding specific scores that define ‘successful outcome’ following a surgical intervention. We have shown that a patient derived KOOS could be used with a combination of absolute values and change in score to identify a successful surgical outcome.

Use of “Change in Score” represents the “Value – Added” effect of surgical intervention and demonstrates clinical effectiveness, as well as permitting comparison of individual surgeon’s performance with the standards being established by the Scandinavian Ligament Registries.