Comparison of two techniques for positioning the prosthesis during total knee replacement surgery

INTERVENTION: This is a randomized controlled clinical trial including 60 participants undergoing total knee arthroplasty, allocated into two groups of 30 participants through computer‐generated block randomization in blocks of 10, with allocation concealed using opaque sealed envelopes opened intraoperatively; the operating surgeon will be aware of the assigned technique, whereas postoperative outcome assessors will remain blinded to group allocation; in the Measured Resection group, 30 participants will undergo a single total knee arthroplasty in which femoral component rotation will be determined intraoperatively using the surgical transepicondylar axis, Whiteside line and posterior condylar axis, with the Measured Sizer of the Attune knee system used to determine femoral rotation before the posterior femoral cuts; in the Gap Balancing group, 30 participants will undergo a single total knee arthroplasty in which femoral component rotation will be determined intraoperatively according to ligament tension using the Balanced Sizer before the posterior femoral cuts to dynamically adjust rotation and obtain balanced flexion and extension gaps; after femoral rotation has been established, both groups will follow the same standardized surgical protocol using the Attune knee system instrumentation, including component implantation, wound closure and the anesthetic protocol; intraoperative data will include the thickness of medial and lateral posterior condylar bone resections, the need for ligament release and ligament balance in flexion and extension; all participants will undergo radiographs and one bilateral computed tomography examination of the knees without intravenous contrast in the immediate postoperative period, lasting approximately 15 minutes, to assess femoral component rotation; participants will undergo a postoperative review at 15 days and clinical and functional assessments at 6 months and 2 years after surgery, including range of motion, joint stability, pain, satisfaction and the Knee Injury and Osteoarthritis Outcome Score CONDITION: C05.550.114.606 Osteoarthritis, Knee; Other primary gonarthrosis ; Osteoarthritis PRIMARY OUTCOME: To evaluate the difference in femoral component rotational alignment between the Measured Resection and Gap Balancing techniques using computed tomography performed in the early postoperative period; femoral component rotation will be measured in degrees relative to the Surgical Transepicondylar Axis, Posterior Condylar Axis, Whiteside Line and Anterior Cortical Axis, and the mean angular measurements obtained in the two groups will be compared; a minimum difference of 2 degrees between the techniques will be considered the parameter of interest, corresponding to the difference used for the sample size calculation INCLUSION CRITERIA: Male and female patients aged between 50 and 80 years; diagnosis of primary knee osteoarthritis grade III or IV according to the Kellgren‐Lawrence classification; indication for total knee arthroplasty after failure of conservative treatment; agreement to participate in the study by providing written informed consent SECONDARY OUTCOME: To evaluate the clinical and functional outcomes of participants undergoing the Measured Resection and Gap Balancing techniques at 6 months and 2 years after surgery; knee range of motion in degrees, varus and valgus joint stability, patient satisfaction and the Knee Injury and Osteoarthritis Outcome Score, including pain, symptoms, activities of daily living, sport and recreation function and quality of life domains, will be assessed; values obtained in the two groups and their changes across the two follow‐up periods will be compared To evaluate the difference in intraoperative ligament balance between the Measured Resection and Gap Balancing techniques; the need for ligament release, classified as minimal or considerable, and ligament tension in flexion and extension will be recorded during surgery; the frequency and extent of ligament releases and the presence or absence of symmetrical flexion and extension joint spaces will be compared between the groups To evaluate the difference in the amount of bone resected between the Measured Resection and Gap Balancing techniques during surgery; the thickness of the medial and lateral posterior femoral condylar resections will be measured in millimeters intraoperatively; medial and lateral resection measurements and the difference between these measurements will be compared between the groups