Objective: To determine the construct validity and responsiveness of the Lysholm knee scoring scale and the WOMAC osteoarthritis index in adolescents and young adults with knee complaints in general practice.
Study design and setting: In the framework of a prospective cohort study with 1-year follow-up, we included 314 patients aged 12-35 years consulting the general practitioner for incident knee complaints. Subgroup analyses of traumatic and nontraumatic knee complaints and of adolescents and adults were performed.
Results: Construct validity was adequate for both questionnaires both in traumatic and nontraumatic patients (aged 12-35) and in adolescents (12-17) and young adults (18-35). Effect size (ES) and standardized response mean (SRM) for both Lysholm and WOMAC global scores were moderate in nontraumatic patients and high in traumatic patients. Guyatt's responsiveness statistic was high in both subpopulations. Adolescents showed high responsiveness with all measures on the Lysholm scale, and moderate (Guyatt's statistic) to high responsiveness (ES and SRM) on the WOMAC index. Young adults showed high responsiveness with all measures on both instruments.
Conclusion: Although neither of the scales was developed for use in adolescents and young adults in general practice, both scales show adequate responsiveness, content, and construct validity in this population.