Reliability and validity of the Tegner and Marx activity rating scales in Iranian patients with anterior cruciate ligament injury.

Purpose: The aims of this study were to culturally translate and validate the Persian version of Tegner and Marx activity rating scales and to investigate their psychometric properties in a sample of patients (n = 100) with anterior cruciate ligament (ACL) injury.
Method: Four questionnaires were completed by the respondents: Tegner and Marx activity scales, Knee injury and Osteoarthritis Outcome Score (KOOS) and Short-Form 12 Health Survey (SF-12). The Tegner and Marx were re-administered to 45 patients in the retest session, with time interval of 2-6 days between the two sessions. Test-retest reliability and internal consistency were assessed using intra-class correlation coefficient (ICC) and Cronbach's alpha, respectively. To evaluate construct validity of Tegner and Marx compared to similar and dissimilar concepts of KOOS and SF-12, the Spearman's rank correlation was used.
Results: Both Tegner and Marx activity scales have a high ICC level. The minimum Cronbach's alpha level of 0.70 was exceeded by Marx scale. In terms of construct validity, most of a priori hypotheses were confirmed.
Conclusions: The Persian version of Tegner and Marx seems to be suitable for Iranian patients with ACL injury. Future studies are needed to investigate the psychometric properties of these questionnaires for Iranian patients with different knee problems.