The Knee injury and Osteoarthritis Outcome Score (KOOS) for lateral tibial plateau fractures– relevance, reliability and responsiveness

This study aimed to evaluate the patient-reported relevance, test-retest reliability, and responsiveness for each of the five KOOS subscales in patients with lateral tibial plateau fractures.

Adult patients with surgically treated lateral tibial plateau fractures (AO 41B) were included. The primary outcome measure was the KOOS subscales: Pain, Symptoms, Activity of Daily Living (ADL), Sport and Recreational Activities (Sport/rec), and kne-related Quality of Life (QOL). The KOOS was repeated at 14 and 15 days, six weeks, and 6 and 12 months. Content validity was partly evaluated by patients ranking the relevance of all the items in the KOOS, test-retest reliability by an interclass correlation coefficient, and responsiveness by effect size and based on 3 pre-defined hypotheses related the the global rating of change.

Forty-one patients with a mean age of 54.8 years (ranging from 21 to 81 years) were included. The results showed an acceptable relevance of all the KOOS subscales. The test-retest reliability was moderate to high for all five subscales, with an interclass-correlation coefficient ranging from 0.6 to 0.9. At the 6- and 12-month follow-ups, the responsiveness showed large effect sizes for all the KOOS subscales, ranging from 0.9 to 2.1. Moderate to high correlations (r ≥ 0.4)was observed for the predefine hypotheses.

The KOOS questionnaire showed acceptable relevance, high test-retest reliability and acceptable responsivness within one year following a lateral tibial plateau fracture. More research is needed for further validation of psychometric properties of KOOS for patients with lateral tibial plateau fractures.