Background: The Kerlan-Jobe Orthopedic Clinic Shoulder and Elbow Score (KJOC) originally developed in English, assesses the functional status of the shoulder and elbow in overhead athletes. To date, no German version of the questionnaire exists.
Objective: The aim of the study was to translate and to culturally adapt the KJOC into German (KJOC-G) and to test its psychometric properties.
Methods: The first part of the study consisted of a translation and cross-cultural adaptation process which was performed in six stages according to international recommendations: Initial translations, synthesis, back translations, expert committee review, pretesting of the prefinal version, and final adaptations. Secondly, reliability, validity, and feasibility of the KJOC-G were assessed in German overhead athletes.
Results: The translation and adaptation process led to minor alterations due to cultural differences while maintaining the general structure and content of the original score. A total of 152 overhead athletes (age 25.0 ± 6.6 years; 87 men/65 women) were included in the main analyses. The internal consistency (Cronbach's alpha = 0.93) and test-retest reliability (ICC2.1 = 0.94) of the overall questionnaire were excellent. Moderate correlations with the German version of the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire (r = -0.51, p < .05) as well as the DASH-sports module (r = -0.54, p < .05) suggest moderate construct validity. Known-group method analysis showed the ability of the KJOC-G to discriminate between actively playing symptomatic (score: 71.2 ± 16.0) and asymptomatic (score: 93.1 ± 8.7) athletes.
Conclusion: The KJOC-G score is valid, reliable, and suitable for assessing the functional shoulder and elbow status in German-speaking overhead athletes.
Keywords: Overhead athlete; outcome measurement; patient-reported outcome; questionnaire; shoulder.