This retrospective real-world study aims to compare the medium- and long-term clinical outcomes, safety, and economic benefits of different knee prosthesis brands used in primary unilateral total knee arthroplasty (TKA) at our hospital. The study will include adult patients who underwent first-time unilateral TKA between January 1, 2022 and December 31, 2025. Outcomes such as postoperative knee function, complications, length of hospital stay, quality of life, and medical costs will be evaluated. The results are expected to provide evidence to support prosthesis selection and optimize healthcare resource allocation.

This is a single-center, retrospective, open-label, non-randomized cohort study based on real-world clinical data from the Second Affiliated Hospital of Wenzhou Medical University.

The study population will include all adult patients who underwent first-time unilateral primary total knee arthroplasty (TKA) between January 1, 2022 and December 31, 2025. Patients who underwent revision arthroplasty, simultaneous bilateral arthroplasty, concomitant arthroplasty of other joints, arthroplasty for tumor or acute trauma, or who had severely incomplete data will be excluded.

Participants will be grouped according to the prosthesis brand and model documented in the operative record. Baseline variables will include age, sex, body mass index, preoperative diagnosis, ASA classification, comorbidities, and preoperative knee function score. Surgery-related variables will include prosthesis brand and model, fixation method, operative duration, intraoperative blood loss, surgeon seniority, use of a tourniquet, and drainage duration.

The primary outcome will be knee function score at 1 year after surgery, assessed using the HSS score or KSS score. Secondary outcomes will include postoperative complications, length of hospital stay, functional recovery, quality of life, and patient-reported outcomes at different postoperative time points. Economic outcomes will include direct medical costs, direct non-medical costs, indirect costs, and cost-effectiveness analysis. Safety outcomes will include all postoperative adverse events.

The objective of this study is to comprehensively compare the medium- and long-term clinical effectiveness, safety, and economic benefits of different prosthesis brands used in TKA, and to provide evidence to support clinical prosthesis selection and healthcare resource optimization.

Inclusion Criteria:

• Age >= 18 years.
• Diagnosis of end-stage knee osteoarthritis, rheumatoid arthritis, or other conditions meeting the indication for TKA.
• First-time unilateral knee arthroplasty.
• Complete medical records, including perioperative records, prosthesis model records, detailed cost information, and regular postoperative follow-up records.

Exclusion Criteria:

• Revision knee arthroplasty, simultaneous bilateral arthroplasty, or concomitant arthroplasty of other joints.
• Arthroplasty performed for non-degenerative conditions such as tumour or acute trauma.
• Perioperative death or loss to follow-up.
• Severely incomplete clinical data that preclude valid analysis.

The study population will include adult patients who underwent first-time unilateral primary total knee arthroplasty at the Second Affiliated Hospital of Wenzhou Medical University between January 1, 2022 and December 31, 2025. Eligible patients must have complete perioperative records, prosthesis model information, cost data, and postoperative follow-up records. Patients undergoing revision arthroplasty, simultaneous bilateral arthroplasty, concomitant arthroplasty of other joints, or arthroplasty for tumor or acute trauma will be excluded.

Individual participant data will not be shared publicly. The study uses retrospective hospital medical record data, and data sharing is limited by institutional regulations, ethics requirements, and the need to protect participant confidentiality.