Background: Although the Japanese Orthopaedic Association (JOA) originally developed in Japan, the modified English version (mJOA) has become widely used and is arguably now the accepted standard.
Objective: In order to apply the mJOA successfully at an international level, we have translated it with a validated approach into Dutch to pave the way for other translated versions.
Methods: After a thorough forward and backward translation procedure, a final Dutch version of the mJOA was developed. This translated version was used to assess the interobserver reliability among 2 independent examiners by using a cohort of patients with neurological impairment due to spinal pathology.
Results: The mJOA grading scale was used by 2 independent examiners in 25 patients with a variety of spinal diseases. Initially, the interobserver reliability expressed as kappa was 0.56 +/- 0.11. Then, instructions were given to the instructors to refrain from providing patients with an interpretation of the symptoms. Patients were asked to restrict themselves to the questionnaire and select the most appropriate score without bias from the examiner. Kappa increased to 0.78 +/- 0.05. This difference reached statistical significance (P < .001).
Conclusion: We present a streamlined approach to translate the mJOA into a language other than English. The approach resulted in a Dutch version of the mJOA that had a high degree of interobserver reliability.