Comparison of Functional Recovery After Total Knee Arthroplasty Between Low Phase Angle and High Phase Angle Group

The goal of this observational study is to compare the functional outcome of patients with end-stage knee osteoarthritis (OA) before and after total knee arthroplasty based on the phase angle level. The main questions it aims to answer are: * Do patients with low phase angle show worse functional recovery after total knee arthroplasty compared to those with high phase angle? * Is postoperative physical function associated with preoperative phase angle level? Researchers will compare postoperative physical function and muscle strength between the low and high phase angle groups to determine whether a low phase angle is associated with poorer functional recovery. Participants will: Perform physical function tests, isokinetic strength assessments, and bioelectrical impedance analysis before and three months after surgery.