The present study aims to be a multicenter prospective analysis aimed at validating the Italian version of the new KSS introduced in 2011 15. To do this it is first necessary to create the translation of the questionnaire. Several steps will be performed to obtain an adequate Italian version of the new KSS:

1. The English version of the KSS will be translated into Italian by 3 bilingual translators
2. The 2 versions will be submitted to the study collaborators (one per centre), the final version (accepted by all the study collaborators) will be translated back into English by 2 bilingual translators (native English) not aware of the initial version. The back translation will then be sent to the original author (Prof. Scott) to ensure that the consistency of the questionnaire has been maintained throughout all processes despite the necessary cultural adaptations.
3. Once the definitive version has been obtained, it will be tested by 300 Italian patients (with an estimated dropout of 20%) suffering from gonarthrosis. The patients will be distributed as follows: approximately 50 patients in each of the 6 centers (total 300). The number of patients was chosen considering approximately 17-18 patients for each of the 17 items, this choice is consistent with previously published studies on translation into other languages

Inclusion Criteria:

• Diagnosis of gonarthrosis and indication for primary TKA surgery
• Age between 18 and 85 years
• Ability to respond to the proposed questionnaires and provide informed consent
• Availability for follow-up for one year after surgery

Exclusion Criteria:

• Concomitant hip or spinal problems, understood as a cause of patient discomfort even if not yet undergoing medical or rehabilitation therapy
• History of ipsilateral or contralateral knee surgery
• Congenital knee deformities
• Previous septic arthritis
• Neuromuscular pathology (e.g. polio)
• Simultaneous bilateral prosthesis or within 12 months of both knee, hip and ankle

The analysis will be performed on all patients undergoing primary Total Knee Replacement (TKA) surgery at one of the centers included in the study