This study aims to design a patient-specific instrumentation to be used in total knee arthroplasty and evaluate its accuracy of femoral component rotation and intramedullary guide so as to explore its clinical effects.

Total knee arthroplasty (TKA) is the most universal and effective means for treating terminal stage osteoarthritis (OA) of knee. With the development of three-dimensional printing (3DP) technology in the medical domain, the application of patient-specific instrumentation (PSI) in arthroplasty has become more common. The aim of this study was to design a PSI to achieve appropriate femoral resection and accurate component rotation for a successful TKA, and to explore its clinical effects.

Inclusion Criteria:

• Patients with advanced OA of the knee, varus deformity of no more than 15 degrees, flexion-contracture deformity of no more than 10 degrees, without extra-articular deformity of the knee;
• Weight-bearing radiograph of the X-ray image showed the OA Kellgren-Lawrence classification grade Ⅳ;
• The treatment for the patient was TKA, whether or not to use PSI depends on the actual grouping.

Exclusion Criteria:

• Patients with varus deformity of more than 15 degrees, flexion-contracture deformity of more than 10 degrees of the knee;
• Patients with traumatic arthritis and inflammatory arthritis;
• Patients with huge bone defects around the knee
• Patients who had active infection around the knee;
• Patients with knee valgus deformity;
• Patients with severe extra-articular deformity;
• Patients who had previous knee surgery;
• Patients who had periarticular soft tissue dysfunction and neuropathy;
• Patients who had poor physical condition and could not withstand the operation;
• Patients who refused to be followed.