Total knee arthroplasty (TKA) has a high success rate for addressing pain and improving function. However, in instances where incorrect positioning and malignment of the TKA components are observed, patients can experience a range of negative postoperative outcomes such as loss of thickness of polyethylene tibial bearings, eccentric loading, implant loosening, and eventual early revision. To avoid these complications, achieving a postoperative alignment within the range of 0°±3° of the mechanical axis is recommended. Manual intramedullary/extramedullary guides are not thought to be capable of consistently achieving axes in this range, and though computer-assisted navigation has shown superior results in comparison with conventional instrumentation, it is also limited by increased surgical times and no clear superiority in improving short-term clinical outcomes. Thus, there has been in a push in the orthopaedic community to create more precise technologies to aid in the reconstruction of the knee's mechanical axis. Patient-specific instrumentation (PSI), which uses anatomical data obtained primarily from pre-operative axial computed tomography (CT) or magnetic resonance imaging (MRI) to create disposable cutting jigs individualized to the patient's unique anatomy, was created with this goal.

This study aims to compare the clinical results of conventional and patient-specific instruments in total knee arthroplasty.

The objective of this work was to compare pain, stiffness, function and accuracy between groups at minimum 2 year postoperatively. The investigators hypothesized that PSI would lead to a neutral mechanical axis on average more frequently than conventional instrumentation.

The study design is a double-blind randomized controlled trial. Randomly, fifty patients planed to undergo total knee arthroplasty using conventional instruments and other fifty patients undergo total knee arthroplasty using patient-specific instruments. The clinical outcome is comparative preoperative, postoperative 6weeks, 3months, 6months and 1years. And clinical score consists of Range of Motion (ROM), WOMAC (Western Ontario and McMaster University Arthritis Index) pain scale (preoperative and postoperative 6, 12, 24 months), Knee Society Score (preoperative and postoperative 6, 12, 24 months), Anterior and posterior stress view on X-ray (preoperative and postoperative 6, 12, 24 months).

Inclusion Criteria:

• over 19 year old
• Patients for total knee arthroplasty of both knee
• over 5 degree in lateral bowing of femur
• having medicare insurance

Exclusion Criteria:

• Rheumatoid arthritis
• Other inflammatory arthritis
• Neuropsychiatric patients
• Hepatic insufficiency
• Renal insufficiency
• over 40 of body mass index
• Chronic opioid use (taking opioids for longer than 3 months)