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.

After obtaining informed consent, a pre-surgical screening is conducted. Participants complete a history survey, a sarcopenia questionnaire, and the International Physical Activity Questionnaire (IPAQ).

The screening includes a comprehensive evaluation of baseline symptoms, followed by functional assessments that incorporate bioelectrical impedance analysis, muscle strength testing, and performance-based tests:

* A modified Charlson Comorbidity Index (CCI) is used to assess comorbidity burden, and a Numeric Pain Rating Scale (NPRS) records participants' initial pain levels.
* Radiographic assessments are performed to evaluate the frontal alignment of the lower extremities and the radiographic severity of knee osteoarthritis (OA) using the Kellgren-Lawrence (K-L) grading system.
* Multifrequency bioelectrical impedance analysis (BIA) is used to measure phase angle and body composition.
* Handgrip strength is measured through three trials on each side, with the average recorded.
* Knee strength is measured using an isokinetic dynamometer.
* Performance-based tests include the 10-meter walk test, the Timed Up and Go (TUG) test, and the Berg Balance Scale (BBS).

Follow-up assessments are conducted three months after total knee arthroplasty, with participants undergoing the same protocol for performance-based tests, isokinetic knee strength evaluation, and bioelectrical impedance analysis.

Eligibility Criteria:
Inclusion Criteria:

* Individuals aged 55 and over (based on the age on their national ID at the time of consent)
* Individuals diagnosed with knee OA based on medical history, physical examination, and radiographic assessments.
* Individuals who plan to perform total knee arthroplasty

Exclusion Criteria:

* Individuals with gait disturbance due to neurologic disorders such as Parkinson disease, stroke and dementia
* Individuals with severe cardiac, pulmonary, or musculoskeletal disorders that limited quadriceps strength and physical function
* Individuals with knee osteoarthritis due to secondary causes such as rheumatic or traumatic arthritis
* Individuals with a history of any knee surgery within one year.
* Individuals considered clinically unsuitable for the study by the researchers or person in charge based on significant medical findings.