Function, Pain, and Alignment Following Knee Replacement for the Treatment of Osteoarthritis

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

-- Midline incision, no tourniquet, medial parapatellar arthrotomy, resect anterior osteophytes

• Place femoral pins in proximal incision, tibial pins 4 finger breadths under joint line
• Map and evaluate the knee, ROM, varus valgus testing at 0 & 90 degrees flexion
• Distal femoral cut based on cartilage loss on medial and lateral femoral condyle (9mm total cut/condyle).
• Perform distal femoral cut, maintain the joint line (femoral axis +/- 5 degrees)
• Perform proximal tibial cut within +/- 3 degrees, balance the gaps, differential between medial and lateral gaps = 1- 3mm.
• Assess extension space, resect posterior osteophytes
• Remap posterior condylar axis, place 4 in 1 at 0 degrees to the post condylar axis (aim = 9mm posterior condylar cuts)
• Resect posterior osteophytes, place trial components. Adjust cuts to achieve a balanced knee, maintain HKA axis +/- 3 degrees
• Patellar replacement per surgeon discretion
• Cement the components with tourniquet inflation