Outcome measures
All patients were evaluated the day before surgery and were then re-evaluated 6 weeks postoperatively using the German version of the 2011 New Knee Society Score (nKSS). For the preoperative and 6 weeks postoperative nKSS, the patients were asked to grade their symptoms (maximum of 25 points), satisfaction (maximum of 40 points), expectations (maximum of 15 points), and functional activities (maximum of 100 points). The ROM was measured with a double-armed goniometer twice by two observers.The study procedure followed accepted ethical, scientific, and medical standards and was conducted in compliance with recognized international standards, including the principles of the Declaration of Helsinki. Informed consent was obtained from all the study participants and the study protocol was approved by the local ethics committee (31-219 ex 18/19).