Validation and application of a subjective knee questionnaire

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Abstract
Patients' complaints on limitations in activities of daily living (ADL) and sports are possible signs for various injuries of the knee joint. These complaints can be easily assessed by the patient using a questionnaire with visual analogue scale (VAS) responses. A German translation of the English questionnaire concerning knee complaints [4] has been validated and tested for clinical use. It consists of 28 questions. For the statistical analysis, an overall score (VAS score) of the questionnaire was determined. The validation included an expert evaluation on the content of the questionnaire, a test for the reliability, a comparison with subjective knee scoring systems (Cincinnati score, Lysholm score) and a test on VAS score results in patient groups with various knee injuries (discrimination of patients). For the evaluation of operative treatment results, the responsiveness of the questionnaire was tested in patients undergoing arthroscopic meniscus surgery and anterior cruciate ligament reconstruction. The investigation was conducted prior to the operation, 2, 6, 12 and 24 weeks after surgery for both groups and also 36 weeks after surgery for the cruciate ligament patients. Interviews conducted with knee surgeons (so-called knee experts) revealed that 85% judged the questionnaire as being acceptable for clinical use. The reliability of the VAS score for healthy individuals wasr=0.86. The reliability for patients in a postoperative rehabilitation programme wasr=0.92. The correlation coefficient for the Lysholm score wasr=0.88 and for the Cincinnati scorer=0.91. By means of the VAS score we were able to assess the extent of limitations in knee function in various patient groups with meniscus lesions, insufficiency of the anterior and posterior cruciate ligaments and chondromalacia. However, the VAS score was not specific for a single knee disorder. In patients who had undergone partial meniscal resection and anterior cruciate ligament (ACL) reconstruction, alterations in knee function could be adequately evaluated by means of the VAS score. When comparing the VAS score prior to and after the operation, an evaluation of the treatment result was possible. With such a questionnaire using the patient's VAS responses, subjective data can be assessed time-saving for the physician, without observer bias and submitted to statistical analysis. The questionnaire can be used as a simple and valid instrument for measuring the subjective outcome in knee surgery.