Usual care:

• Midline incision, no tourniquet, medial Parapatellar arthrotomy, resect anterior osteophytes
• Distal femoral cut with 3-5 degrees of valgus from the anatomical axis (Based on the angle measurement on the 4 foot standing Xray). Correct for flexion contracture.
• Measure the femoral size with the anterior referencing guides. Use 3 degrees external rotation to the Posterior condylar axis
• Perform anterior, posterior and chamfer cuts with the 4 in 1 in appropriate external rotation
• Extramedullary tibial alignment guide with 3-5 degrees posterior slope, and orthogonal cut to the tibial axis.
• Resect posterior osteophytes
• Place trial components and perform appropriate release/balance the gaps
• Patellar replacement based on surgeon's discretion
• Cementing the components with tourniquet inflation

• Midline incision, no tourniquet, medial Parapatellar arthrotomy, resect anterior osteophytes
• Place the femoral pins in the proximal incision and the tibial pins 4 finger breadths under the joint line
• Map the knee and perform evaluation
• Assess gaps, adjust the femoral axis to decrease soft tissue release (+/- 2 degrees), correct for flexion contracture
• Verify and perform distal femoral cut, proximal tibial cut orthogonal (90 Degrees) to the tibial axis
• Assess and balance extension gap with appropriate releases
• Remap the posterior condylar axis, assess the flexion space, 3 degrees external rotation to the posterior condylar axis
• Perform anterior, posterior and chamber cuts with the 4 in 1 (appropriate external rotation), followed by posterior osteophyte resection
• Place trial components and balance the knee, soft tissue releases (1-2 mm)
• Patellar replacement based on surgeon's discretion
• Cementing the components with tourniquet inflation

Surgical technique for Total knee replacement will be standardized with a MicroPort prosthetic knee joint, patella replacement is optional based on the surgeon's assessment. The participants will receive local anesthetic infiltration by the surgeon, and a similar anesthetic technique with spinal anesthesia using epidural morphine and single shot peripheral nerve blocks. They will receive weight based antibiotics and tranexamic acid. Participants will be randomized to one of three groups. 1)Manual adjusted mechanical knee alignment (usual care) involves the surgeon manually. 2) Robot assisted surgery will include using the ROSA© device from Zimmer©. Robot assisted mechanical alignment aims for neutral alignment of the knee joint. 3) Robot assisted restricted kinematic alignment aims to place the knee joint closer to the participant's anatomical positioning.

Oxford knee score

EuroQol 5D index

EuroQol 5D index

unanticipated visits to emergency department, primary care provide, surgeon due to knee surgery